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cache_builder/NewSharedCacheBuilder.cpp dyld-1340 dyld-1245.1
--- dyld/dyld-1340/cache_builder/NewSharedCacheBuilder.cpp
+++ dyld/dyld-1245.1/cache_builder/NewSharedCacheBuilder.cpp
@@ -28,7 +28,6 @@
 #include "NewAdjustDylibSegments.h"
 #include "CacheDylib.h"
 #include "ClosureFileSystem.h"
-#include "JSONReader.h"
 #include "JSONWriter.h"
 #include "StringUtils.h"
 #include "Array.h"
@@ -40,7 +39,6 @@
 #include "JustInTimeLoader.h"
 #include "OptimizerObjC.h"
 #include "OptimizerSwift.h"
-#include "Platform.h"
 #include "PrebuiltLoader.h"
 #include "DyldProcessConfig.h"
 #include "DyldRuntimeState.h"
@@ -49,17 +47,7 @@
 #include "CString.h"
 #include "Version32.h"
 #include "ExternalGenericMetadataBuilderImport.h"
-#include "SnapshotShared.h"
-#include "AAREncoder.h"
 #include <SharedCacheLinker/SharedCacheLinker.h>
-#include "ThreadLocalVariables.h"
-#include "Algorithm.h"
-
-// mach_o
-#include "ExportsTrie.h"
-#include "Header.h"
-#include "Image.h"
-#include "Misc.h"
 
 // FIXME: Remove this once we don't write to the old objc header struct.  See emitObjCOptsHeader()
 #include "objc-shared-cache.h"
@@ -72,27 +60,18 @@
 #include <sys/stat.h>
 #include <unordered_set>
 
+using dyld3::GradedArchs;
 using dyld3::MachOFile;
 
 using dyld4::JustInTimeLoader;
 using dyld4::KernelArgs;
 using dyld4::Loader;
 using dyld4::ProcessConfig;
-using dyld4::RuntimeLocks;
 using dyld4::RuntimeState;
 using dyld4::SyscallDelegate;
 using dyld4::RuntimeLocks;
 
 using lsl::Allocator;
-
-using mach_o::Header;
-using mach_o::Platform;
-using mach_o::Image;
-using mach_o::ExportsTrie;
-using mach_o::Symbol;
-using mach_o::LinkedDylibAttributes;
-using mach_o::Version32;
-using error::Error;
 
 using metadata_visitor::SwiftConformance;
 using metadata_visitor::SwiftVisitor;
@@ -118,13 +97,9 @@
             // Note, don't change the form of this message without checking in with MRM, as they
             // parse it.  We really need to add structured errors/warnings some time
             std::string reason = "Dylib located at '" + inputFile.path + "' not placed in shared cache because: ";
-            for ( const error::Error& err : inputFile.getErrors() )
-                callback(reason + err.message());
-        }
-    }
-
-    for ( const std::string& warning : this->warnings )
-        callback(warning);
+            callback(reason + inputFile.getError().message());
+        }
+    }
 }
 
 void SharedCacheBuilder::forEachError(void (^callback)(const std::string_view& str)) const
@@ -155,157 +130,32 @@
     }
 }
 
-struct DylibSizes
-{
-    uint64_t textSegment        = 0;
-    uint64_t dataSegment        = 0;
-    uint64_t dataConstSegment   = 0;
-    uint64_t dataDirtySegment   = 0;
-    uint64_t authSegment        = 0;
-    uint64_t authConstSegment   = 0;
-    uint64_t linkeditSegment    = 0;
-
-    // any other segment not in the above
-    uint64_t otherSegment       = 0;
-
-    // Just the __TEXT __text section
-    uint64_t textSection        = 0;
-
-    // parts of the linkedit
-    uint64_t exportTrie         = 0;
-    uint64_t symbolTable        = 0;
-    uint64_t symbolStrings      = 0;
-};
-
-static DylibSizes getDylibSizes(std::span<const SubCache> subCaches,
-                                std::span<const CacheDylib> cacheDylibs)
-{
-    __block DylibSizes dylibSizes;
-    __block std::unordered_set<uint64_t> linkeditSizes;
-
-    // segment sizes
-    for ( const CacheDylib& cacheDylib : cacheDylibs ) {
-        cacheDylib.cacheHdr->forEachSegment(^(const Header::SegmentInfo& info, bool& stop) {
-            if ( info.segmentName == "__TEXT" )
-                dylibSizes.textSegment += info.vmsize;
-            else if ( info.segmentName == "__DATA" )
-                dylibSizes.dataSegment += info.vmsize;
-            else if ( info.segmentName == "__DATA_CONST" )
-                dylibSizes.dataConstSegment += info.vmsize;
-            else if ( info.segmentName == "__DATA_DIRTY" )
-                dylibSizes.dataDirtySegment += info.vmsize;
-            else if ( info.segmentName == "__AUTH" )
-                dylibSizes.authSegment += info.vmsize;
-            else if ( info.segmentName == "__AUTH_CONST" )
-                dylibSizes.authConstSegment += info.vmsize;
-            else if ( info.segmentName == "__LINKEDIT" )
-                linkeditSizes.insert(info.vmsize);
-            else
-                dylibSizes.otherSegment += info.vmsize;
-        });
-    }
-    for ( uint64_t size : linkeditSizes )
-        dylibSizes.linkeditSegment += size;
-
-    // section sizes
-    for ( const CacheDylib& cacheDylib : cacheDylibs ) {
-        cacheDylib.cacheHdr->forEachSection(^(const Header::SectionInfo& info, bool& stop) {
-            if ( (info.segmentName == "__TEXT") && (info.sectionName == "__text") )
-                dylibSizes.textSection += info.size;
-        });
-    }
-
-    // linkedit sizes
-    for ( const CacheDylib& cacheDylib : cacheDylibs ) {
-        for ( const LinkeditDataChunk& chunk : cacheDylib.linkeditChunks ) {
-            if ( chunk.kind == Chunk::Kind::linkeditExportTrie )
-                dylibSizes.exportTrie += chunk.cacheVMSize.rawValue();
-        }
-
-        if ( !cacheDylib.optimizedSymbols.nlist64.empty() ) {
-            dylibSizes.symbolTable += (sizeof(struct nlist_64) * cacheDylib.optimizedSymbols.nlist64.size());
-        } else {
-            dylibSizes.symbolTable += (sizeof(struct nlist) * cacheDylib.optimizedSymbols.nlist64.size());
-        }
-    }
-
-    for ( const SubCache& subCache : subCaches ) {
-        if ( subCache.optimizedSymbolStrings )
-            dylibSizes.symbolStrings += subCache.optimizedSymbolStrings->cacheVMSize.rawValue();
-    }
-
-    return dylibSizes;
-}
-
-std::string SharedCacheBuilder::stats(uint64_t startTimeNanos) const
-{
-    uint64_t endTimeNanos = clock_gettime_nsec_np(CLOCK_UPTIME_RAW);
-    uint64_t totalTime = (endTimeNanos - startTimeNanos) / 1000000000;
-
-    DylibSizes dylibSizes = getDylibSizes(this->subCaches, this->cacheDylibs);
-
-    std::string result;
-    result += "{\n";
-
-    // add all the top level fields
-    result += std::string("  \"version\": 1,\n");
-    result += std::string("  \"minor-version\": 0,\n");
-    result += std::string("  \"update\": \"") + this->options.updateName + "\",\n";
-    result += std::string("  \"device\": \"") + this->options.deviceName + "\",\n";
-    result += std::string("  \"platform\": \"") + this->options.platform.name().c_str() + "\",\n";
-    result += std::string("  \"arch\": \"") + this->options.arch.name() + "\",\n";
-
-    // main stats
-    result += std::string("  \"dylibs-count\": ") + std::to_string(this->cacheDylibs.size()) + ",\n";
-    result += std::string("  \"total-vm-size\": ") + std::to_string(this->totalVMSize.rawValue()) + ",\n";
-    result += std::string("  \"total-text-segment-size\": ") + std::to_string(dylibSizes.textSegment) + ",\n";
-    result += std::string("  \"total-data-segment-size\": ") + std::to_string(dylibSizes.dataSegment) + ",\n";
-    result += std::string("  \"total-data-dirty-segment-size\": ") + std::to_string(dylibSizes.dataDirtySegment) + ",\n";
-    result += std::string("  \"total-data-const-segment-size\": ") + std::to_string(dylibSizes.dataConstSegment) + ",\n";
-    result += std::string("  \"total-auth-segment-size\": ") + std::to_string(dylibSizes.authSegment) + ",\n";
-    result += std::string("  \"total-auth-const-segment-size\": ") + std::to_string(dylibSizes.authConstSegment) + ",\n";
-    result += std::string("  \"total-other-segment-size\": ") + std::to_string(dylibSizes.otherSegment) + ",\n";
-    result += std::string("  \"total-linkedit-segment-size\": ") + std::to_string(dylibSizes.linkeditSegment) + ",\n";
-    result += std::string("  \"total-text-section-size\": ") + std::to_string(dylibSizes.textSection) + ",\n";
-
-    // optimization stats
-    result += std::string("  \"objc-selector-hash-table-size\": ") + std::to_string(this->objcSelectorOptimizer.selectorHashTableTotalByteSize) + ",\n";
-    result += std::string("  \"objc-class-hash-table-size\": ") + std::to_string(this->objcClassOptimizer.classHashTableTotalByteSize) + ",\n";
-    result += std::string("  \"objc-protocol-hash-table-size\": ") + std::to_string(this->objcProtocolOptimizer.protocolHashTableTotalByteSize) + ",\n";
-    result += std::string("  \"objc-selectors-count\": ") + std::to_string(this->objcSelectorOptimizer.selectorsMap.size()) + ",\n";
-    result += std::string("  \"objc-classes-count\": ") + std::to_string(this->objcClassOptimizer.namesMap.size()) + ",\n";
-    result += std::string("  \"objc-protocols-count\": ") + std::to_string(this->objcProtocolOptimizer.namesMap.size()) + ",\n";
-
-    // linkedit breakdown
-    result += std::string("  \"linkedit-export-trie-size\": ") + std::to_string(dylibSizes.exportTrie) + ",\n";
-    result += std::string("  \"linkedit-symbol-table-size\": ") + std::to_string(dylibSizes.symbolTable) + ",\n";
-    result += std::string("  \"linkedit-symbol-strings-size\": ") + std::to_string(dylibSizes.symbolStrings) + ",\n";
-
-    // cache metadata
-    result += std::string("  \"patch-table-size\": ") + std::to_string(this->patchTableOptimizer.patchTableChunk->cacheVMSize.rawValue()) + ",\n";
-    result += std::string("  \"dylib-loaders-size\": ") + std::to_string(this->prebuiltLoaderBuilder.cacheDylibsLoaderSize) + ",\n";
-    result += std::string("  \"executable-loaders-size\": ") + std::to_string(this->prebuiltLoaderBuilder.executablesLoaderSize) + ",\n";
-
-    // Times
-    result += std::string("  \"total-build-time\": ") + std::to_string(totalTime) + "\n";
-
-    result += "}\n";
-    return result;
-}
-
 void SharedCacheBuilder::addFile(const void* buffer, size_t bufferSize, std::string_view path,
                                  uint64_t inode, uint64_t modTime, bool forceNotCacheEligible)
 {
+    Diagnostics diag;
     const bool  isOSBinary = false;
-    uint64_t    sliceOffset = 0;
     uint64_t    sliceLen = 0;
+    if ( const MachOFile* mf = MachOFile::compatibleSlice(diag, sliceLen, buffer, bufferSize, path.data(),
+                                                          this->options.platform, isOSBinary,
+                                                          this->options.archs) ) {
+        InputFile inputFile;
+        inputFile.mf                    = mf;
+        inputFile.inode                 = inode;
+        inputFile.mtime                 = modTime;
+        inputFile.size                  = sliceLen;
+        inputFile.path                  = path;
+        inputFile.forceNotCacheEligible = forceNotCacheEligible;
+        allInputFiles.push_back(std::move(inputFile));
+        return;
+    }
 
     // On macOS, also allow iOSMac dylibs
-    if ( this->options.platform == Platform::macOS ) {
-        Diagnostics diag;
-        if ( const MachOFile* mf = MachOFile::compatibleSlice(diag, sliceOffset, sliceLen, buffer, bufferSize, path.data(),
-                                                              Platform::macCatalyst, isOSBinary,
-                                                              this->options.gradedArchs) ) {
+    if ( this->options.platform == dyld3::Platform::macOS ) {
+        diag.clearError();
+        if ( const MachOFile* mf = MachOFile::compatibleSlice(diag, sliceLen, buffer, bufferSize, path.data(),
+                                                              dyld3::Platform::iOSMac, isOSBinary,
+                                                              this->options.archs) ) {
             InputFile inputFile;
             inputFile.mf                    = mf;
             inputFile.inode                 = inode;
@@ -317,49 +167,6 @@
             return;
         }
     }
-
-    Diagnostics diag;
-    if ( const MachOFile* mf = MachOFile::compatibleSlice(diag, sliceOffset, sliceLen, buffer, bufferSize, path.data(),
-                                                          this->options.platform, isOSBinary,
-                                                          this->options.gradedArchs) ) {
-        InputFile inputFile;
-        inputFile.mf                    = mf;
-        inputFile.inode                 = inode;
-        inputFile.mtime                 = modTime;
-        inputFile.size                  = sliceLen;
-        inputFile.path                  = path;
-        inputFile.forceNotCacheEligible = forceNotCacheEligible;
-        allInputFiles.push_back(std::move(inputFile));
-        return;
-    }
-
-    // If we have an error, then add an input file just in case its useful for later
-    if ( diag.hasError() ) {
-        // Only add dylibs to track for later error emission
-        __block bool isDylib = false;
-        const std::span<uint8_t> bufferSpan = { (uint8_t*)buffer, bufferSize };
-        mach_o::Error parseErr = mach_o::forEachHeader(bufferSpan, path,
-                                                       ^(const mach_o::Header* mh, size_t sliceHeader, bool& stop) {
-            if ( mh->isDylib() ) {
-                isDylib = true;
-                stop = true;
-            }
-        });
-
-        if ( !isDylib )
-            return;
-
-        InputFile inputFile;
-        inputFile.mf                    = nullptr;
-        inputFile.inode                 = 0;
-        inputFile.mtime                 = 0;
-        inputFile.size                  = 0;
-        inputFile.path                  = path;
-        inputFile.forceNotCacheEligible = true;
-        inputFile.addError(Error("%s", (const char*)diag.errorMessageCStr()));
-        allInputFiles.push_back(std::move(inputFile));
-        return;
-    }
 }
 
 void SharedCacheBuilder::setAliases(const std::vector<FileAlias>& aliases,
@@ -368,7 +175,6 @@
     this->inputAliases = aliases;
     this->inputIntermediateAliases = intermediateAliases;
 }
-
 
 //
 // MARK: --- SharedCacheBuilder build methods ---
@@ -393,7 +199,6 @@
         return Error("Cannot build cache with no dylibs");
 
     this->sortDylibs();
-    this->sortExecutables();
 
     // Note this needs to be after sorting, so the order of objc dylibs is consistent with all dylibs list
     this->findObjCDylibs();
@@ -441,9 +246,8 @@
     this->estimateSwiftHashTableSizes();
 
     this->calculateCacheDylibsTrie();
-    this->estimateFunctionVariantsSize();
+    this->estimatePatchTableSize();
     this->estimateCacheLoadersSize();
-    this->estimatePrewarmingSize();
 
     this->setupStubOptimizer();
 
@@ -456,10 +260,6 @@
 // Outputs: subCaches
 Error SharedCacheBuilder::createSubCaches()
 {
-    Timer::Scope timedScope(this->config, "createSubCaches time");
-    Timer::AggregateTimer aggregateTimerOwner(this->config);
-    auto& aggregateTimer = aggregateTimerOwner;
-
     this->computeSubCaches();
 
     // Per-subCache optimizations
@@ -468,54 +268,8 @@
     if ( Error error = this->calculateUniqueGOTs(); error.hasError() )
         return error;
 
-    // Finalize the subcaches, by removing any unused regions
-    for ( SubCache& subCache : this->subCaches ) {
-        // Add slide info for each DATA/AUTH segment.  Do this after we've added any other DATA*
-        // segments
-        if ( this->config.slideInfo.slideInfoFormat.has_value() )
-            subCache.addSlideInfoChunks();
-
-        subCache.removeEmptyRegions();
-    }
-
-    // Analyze the dylibs to work out binds and patch table info
-    {
-        this->initializePatchTableOptimizer();
-
-        // Because blocks...
-        std::vector<const CacheDylib*> builderCacheDylibsOwner;
-        auto& builderCacheDylibs = builderCacheDylibsOwner;
-        for ( const CacheDylib& cacheDylib : this->cacheDylibs )
-            builderCacheDylibs.push_back(&cacheDylib);
-
-        Error err = parallel::forEach(this->cacheDylibs, ^(size_t index, CacheDylib& cacheDylib) {
-            Diagnostics diag;
-            PatchInfo& dylibPatchInfo = this->patchTableOptimizer.patchInfos[cacheDylib.cacheIndex];
-
-            std::vector<Error> symbolErrors = cacheDylib.calculateBindTargets(diag, this->config, aggregateTimer, builderCacheDylibs,
-                                                                              dylibPatchInfo);
-            if ( !symbolErrors.empty() ) {
-                for ( const Error& symbolErr : symbolErrors )
-                    this->errors.push_back(symbolErr.message());
-            }
-            if ( diag.hasError() )
-                return Error("%s", diag.errorMessageCStr());
-
-            cacheDylib.calcuatePatchInfo(diag, this->config, aggregateTimer, dylibPatchInfo);
-            if ( diag.hasError() )
-                return Error("%s", diag.errorMessageCStr());
-
-            return Error();
-        });
-
-        if ( err )
-            return err;
-    }
-
     this->sortSubCacheSegments();
     this->calculateSlideInfoSize();
-    if ( Error error = this->calculatePatchTableSize(); error.hasError() )
-        return error;
     this->calculateCodeSignatureSize();
     this->printSubCaches();
     if ( Error error = this->computeSubCacheLayout(); error.hasError() )
@@ -526,6 +280,216 @@
     return Error();
 }
 
+// This name is used only to create a placeholder input file and determine the library order.
+const std::string_view swiftPrespecializedDylibInstallName = "/usr/lib/libswiftPrespecialized.dylib";
+
+bool SharedCacheBuilder::shouldBuildSwiftPrespecializedDylib()
+{
+    if ( options.platform == dyld3::Platform::driverKit )
+        return false;
+
+    // build the dylib, only if the order file is defined
+    if ( options.swiftGenericMetadataFile.empty() )
+        return false;
+
+    // check if the metadata builder is available
+#if !BUILDING_CACHE_BUILDER_UNIT_TESTS && !BUILDING_SIM_CACHE_BUILDER
+    if ( swift_externalMetadataBuilder_create == nullptr )
+        return false;
+#endif // !BUILDING_CACHE_BUILDER_UNIT_TESTS
+
+    return true;
+}
+
+Error SharedCacheBuilder::buildSwiftPrespecializedDylibJSON()
+{
+#if !BUILDING_CACHE_BUILDER_UNIT_TESTS && !BUILDING_SIM_CACHE_BUILDER
+    Timer::Scope timedScope(this->config, "buildSwiftPrespecializedDylibJSON time");
+
+    SwiftExternalMetadataBuilder* builder = swift_externalMetadataBuilder_create((int)options.platform, options.archs.name());
+    if ( !builder )
+        return Error("swift_externalMetadataBuilder_create failed");
+
+    for ( const CacheDylib& dylib : this->cacheDylibs ) {
+        if ( dylib.inputMF == nullptr ) continue;
+
+        // TODO: rdar://132262275 (dyld shared cache builder should tell Swift Metadata builder also about dyld)
+        if ( dylib.inputMF->isDyld() ) continue;
+
+        if ( const char* err = swift_externalMetadataBuilder_addDylib(builder, dylib.inputMF->installName(),
+                (const struct mach_header*)dylib.inputMF, dylib.inputFile->size) )
+            return Error("swift_externalMetadataBuilder_addDylib failed: %s", err);
+    }
+
+    if ( const char* err = swift_externalMetadataBuilder_readNamesJSON(builder, options.swiftGenericMetadataFile.c_str()) )
+        return Error("swift_externalMetadataBuilder_readNamesJSON failed: %s", err);
+
+    if ( const char* err = swift_externalMetadataBuilder_buildMetadata(builder) )
+        return Error("swift_externalMetadataBuilder_buildMetadata failed: %s", err);
+
+    if ( const char* json = swift_externalMetadataBuilder_getMetadataJSON(builder) )
+        swiftPrespecializedDylibJSON = json;
+    else
+        return Error("swift_externalMetadataBuilder_getMetadataJSON returned an empty JSON");
+
+    const std::string_view placeholderVersion = R"("platformVersion": "1.0")";
+    // Patch platformVersion if it's 1.0 until rdar://122585868 is fixed
+    if ( auto pos = swiftPrespecializedDylibJSON.find(placeholderVersion);
+            pos != swiftPrespecializedDylibJSON.npos ) {
+
+        __block mach_o::Version32 newMinOS;
+        // determine new deployment target based on dyld's version
+        for ( const InputFile& inputFile : allInputFiles ) {
+            if ( !inputFile.mf )
+                continue;
+
+            if ( !endsWith(inputFile.path, "dyld") )
+                continue;
+
+            inputFile.mf->forEachSupportedPlatform(^(dyld3::Platform platform, uint32_t currentMinOS, uint32_t sdk) {
+                if ( platform == options.platform )
+                    newMinOS = mach_o::Version32(currentMinOS);
+            });
+            break;
+        }
+
+        if ( newMinOS > mach_o::Version32(1, 0) ) {
+            char verStr[32];
+            newMinOS.toString(verStr);
+            std::string newVersion = "\"platformVersion\": \"";
+            newVersion += verStr;
+            newVersion += "\"";
+
+            swiftPrespecializedDylibJSON.replace(pos, placeholderVersion.size(), newVersion);
+        }
+    }
+
+    swift_externalMetadataBuilder_destroy(builder);
+
+    if ( options.debug ) {
+        std::string path;
+        if ( const char* dir = getenv("TMPDIR") )
+            path = dir;
+        if ( path.empty() )
+            path = "/tmp";
+        path += "/swift-prespecialized.json-XXXXXX";
+
+        int outFileFd = mkstemp(path.data());
+        if ( outFileFd != -1 ) {
+            write(outFileFd, swiftPrespecializedDylibJSON.data(), swiftPrespecializedDylibJSON.size());
+        }
+    }
+#endif // !BUILDING_CACHE_BUILDER_UNIT_TESTS
+
+    return Error::none();
+}
+
+bool SharedCacheBuilder::reserveSwiftPrespecializedInputFile()
+{
+    if ( !shouldBuildSwiftPrespecializedDylib() )
+        return false;
+
+    InputFile inputFile;
+    inputFile.mf = nullptr;
+    inputFile.inode = 0;
+    inputFile.mtime = 0;
+    inputFile.path = swiftPrespecializedDylibInstallName;
+    allInputFiles.push_back(std::move(inputFile));
+    cacheDylibs.push_back(CacheDylib(swiftPrespecializedDylibInstallName));
+    return true;
+}
+
+Error SharedCacheBuilder::createSwiftPrespecializedDylib()
+{
+    if ( !shouldBuildSwiftPrespecializedDylib() )
+        return Error::none();
+
+    if ( Error err = buildSwiftPrespecializedDylibJSON() )
+        return err;
+
+    InputFile* inputFile = nullptr;
+    if ( allInputFiles.empty() || allInputFiles.back().path != swiftPrespecializedDylibInstallName )
+        return Error("missing input file placeholder for Swift prespecialized dylib");
+    inputFile = &allInputFiles.back();
+
+    std::vector<const char*> dylibsList;
+    // the dylib list needs to be in order of objc dylibs
+    for ( const CacheDylib* dylib : this->objcOptimizer.objcDylibs )
+        dylibsList.push_back(CString::dup(dylib->installName).c_str());
+
+    // TODO: support in-memory file buffer
+    std::string path;
+    if ( const char* dir = getenv("TMPDIR") )
+        path = dir;
+    if ( path.empty() )
+        path = "/tmp";
+    path += "/libswiftPrespecialized.dylib-XXXXXX";
+
+    int outFileFd = mkstemp(path.data());
+    if ( outFileFd == -1 )
+        return Error("couldn't create a temporary file for Swift prespecialized dylib: %s", (const char*)strerror(errno));
+
+    close(outFileFd);
+    if ( const char* err = ldMakeDylibFromJSON(swiftPrespecializedDylibJSON, dylibsList, path.c_str()) )
+        return Error("%s", err);
+
+    // cleanup dylibs list
+    for ( const char* str : dylibsList )
+        free((void*)str);
+
+    // re-open output file
+    outFileFd = open(path.c_str(), O_RDONLY);
+    if ( outFileFd < 0 )
+        return Error("could not open swift dylib file because: %s", (const char*)strerror(errno));
+
+    struct stat stat_buf;
+    if (  fstat(outFileFd, &stat_buf) == -1 )
+        return Error("could not stat swift dylib file because: %s", (const char*)strerror(errno));
+
+    vm_size_t bufferSize = stat_buf.st_size;
+    void* buffer = mmap(nullptr, bufferSize, PROT_READ, MAP_FILE | MAP_SHARED, outFileFd, 0);
+    if ( buffer == MAP_FAILED ) {
+        // Failed to mmap the file
+        return Error("could not mmap swift dylib file because: %s", (const char*)strerror(errno));
+    }
+
+    Diagnostics diag;
+    inputFile->mf = MachOFile::compatibleSlice(diag, inputFile->size, buffer, bufferSize, path.data(),
+                                    this->options.platform, /* isOSBinary */ false,
+                                    this->options.archs);
+    if ( diag.hasError() )
+        return Error("%s", diag.errorMessageCStr());
+
+    // recreate cache dylib at the reserved slot
+    auto cacheDylibIt = std::find_if(cacheDylibs.begin(), cacheDylibs.end(), [](CacheDylib& dylib) {
+            return dylib.inputMF == nullptr && dylib.installName == swiftPrespecializedDylibInstallName;
+    });
+    if ( cacheDylibIt == cacheDylibs.end() )
+        return Error("missing cache dylib slot for Swift prespecialized dylib");
+
+    // save previously computed cache index
+    uint32_t index = cacheDylibIt->cacheIndex;
+    // recreate cache dylib with the updated input file
+    *cacheDylibIt = CacheDylib(*inputFile);
+    cacheDylibIt->cacheIndex = index;
+    // rdar://122906481 (Shared cache builder - explicitly model dylibs without a need for a patch table)
+    cacheDylibIt->needsPatchTable = false;
+    this->swiftPrespecializedDylib = &*cacheDylibIt;
+
+    // sanity check Swift dylib compatibility
+    __block Error err = Error::none();
+    inputFile->mf->withFileLayout(diag, ^(const mach_o::Layout& layout) {
+        mach_o::SplitSeg splitSeg(layout);
+
+        if ( !splitSeg.isV2() )
+            err = Error("Swift prespecialized dylib must use split seg V2");
+    });
+    if ( !inputFile->mf->hasChainedFixups() )
+        err = Error("Swift prespecialized dylib must use chained fixups");
+
+    return std::move(err);
+}
+
 // This is phase 4 of the build() process. It takes the inputs and Optimizers
 // from the previous phases, and emits them to the cache buffers
 // Inputs:  subCaches, various Optimizers
@@ -560,6 +524,12 @@
     Timer::AggregateTimer aggregateTimerOwner(this->config);
     auto& aggregateTimer = aggregateTimerOwner;
 
+    // Because blocks...
+    std::vector<const CacheDylib*> builderCacheDylibsOwner;
+    auto& builderCacheDylibs = builderCacheDylibsOwner;
+    for ( const CacheDylib& cacheDylib : this->cacheDylibs )
+        builderCacheDylibs.push_back(&cacheDylib);
+
     Error err = parallel::forEach(this->cacheDylibs, ^(size_t index, CacheDylib& cacheDylib) {
         Diagnostics diag;
 
@@ -580,34 +550,39 @@
         if ( diag.hasError() )
             return Error("%s", diag.errorMessageCStr());
 
-        cacheDylib.bind(diag, this->config, aggregateTimer, dylibPatchInfo, this->functionVariantsOptimizer);
+        std::vector<Error> symbolErrors = cacheDylib.calculateBindTargets(diag, this->config, aggregateTimer, builderCacheDylibs,
+                                                                          dylibPatchInfo);
+        if ( !symbolErrors.empty() ) {
+            for ( const Error& symbolErr : symbolErrors )
+                this->errors.push_back(symbolErr.message());
+        }
         if ( diag.hasError() )
             return Error("%s", diag.errorMessageCStr());
 
-        // Disable objc optimizations from EK shared cache
-        bool emitObjcOpts = !this->options.platform.isExclaveKit();
-        if ( emitObjcOpts ) {
-            cacheDylib.updateObjCSelectorReferences(diag, this->config, aggregateTimer, this->objcSelectorOptimizer);
-            if ( diag.hasError() )
-                return Error("%s", diag.errorMessageCStr());
-
-            cacheDylib.convertObjCMethodListsToOffsets(diag, this->config, aggregateTimer, this->objcSelectorOptimizer.selectorStringsChunk);
-            if ( diag.hasError() )
-                return Error("%s", diag.errorMessageCStr());
-
-            // Note, must be after updating selector references and converting relative methods to selector offsets
-            cacheDylib.sortObjCMethodLists(diag, this->config, aggregateTimer, this->objcSelectorOptimizer.selectorStringsChunk);
-            if ( diag.hasError() )
-                return Error("%s", diag.errorMessageCStr());
-
-            cacheDylib.optimizeLoadsFromConstants(this->config, aggregateTimer,
-                                                  this->objcSelectorOptimizer.selectorStringsChunk);
-
-            Error error = cacheDylib.emitObjCIMPCaches(this->config, aggregateTimer, this->objcIMPCachesOptimizer,
-                                                       this->objcSelectorOptimizer.selectorStringsChunk);
-            if ( error.hasError() )
-                return error;
-        }
+        cacheDylib.bind(diag, this->config, aggregateTimer, dylibPatchInfo);
+        if ( diag.hasError() )
+            return Error("%s", diag.errorMessageCStr());
+
+        cacheDylib.updateObjCSelectorReferences(diag, this->config, aggregateTimer, this->objcSelectorOptimizer);
+        if ( diag.hasError() )
+            return Error("%s", diag.errorMessageCStr());
+
+        cacheDylib.convertObjCMethodListsToOffsets(diag, this->config, aggregateTimer, this->objcSelectorOptimizer.selectorStringsChunk);
+        if ( diag.hasError() )
+            return Error("%s", diag.errorMessageCStr());
+
+        // Note, must be after updating selector references and converting relative methods to selector offsets
+        cacheDylib.sortObjCMethodLists(diag, this->config, aggregateTimer, this->objcSelectorOptimizer.selectorStringsChunk);
+        if ( diag.hasError() )
+            return Error("%s", diag.errorMessageCStr());
+
+        cacheDylib.optimizeLoadsFromConstants(this->config, aggregateTimer,
+                                              this->objcSelectorOptimizer.selectorStringsChunk);
+
+        Error error = cacheDylib.emitObjCIMPCaches(this->config, aggregateTimer, this->objcIMPCachesOptimizer,
+                                                   this->objcSelectorOptimizer.selectorStringsChunk);
+        if ( error.hasError() )
+            return error;
 
         cacheDylib.optimizeStubs(this->options, this->config, aggregateTimer, this->stubOptimizer,
                                  dylibPatchInfo);
@@ -627,55 +602,47 @@
 // Outputs: emitted optimizations in the subCache buffers
 Error SharedCacheBuilder::postDylibEmitChunks()
 {
-    // Disable objc optimizations from EK shared cache
-    bool emitObjcOpts = !this->options.platform.isExclaveKit();
-
-    if ( Error error = this->emitPrewarmingData(); error.hasError() )
-        return error;
 
     this->optimizeTLVs();
 
     if ( Error error = this->emitUniquedGOTs(); error.hasError() )
         return error;
 
-    if ( emitObjcOpts ) {
-        // Note this has to be before we emit the protocol hash table
-        if ( Error error = this->emitCanonicalObjCProtocols(); error.hasError() )
-            return error;
-    }
+    // Note this has to be before we emit the protocol hash table
+    if ( Error error = this->emitCanonicalObjCProtocols(); error.hasError() )
+        return error;
 
     this->emitCacheDylibsTrie();
-    if ( Error error = this->emitPatchTable() )
+    if ( Error error = this->emitPatchTable(); error.hasError() )
         return error;
-
-    this->emitFunctionVariants();
 
     // Note, this must be after we emit the patch table
     if ( Error error = this->emitCacheDylibsPrebuiltLoaders(); error.hasError() )
         return error;
 
-    if ( emitObjcOpts ) {
-        this->emitObjCHashTables();
-        
+    this->emitObjCHashTables();
+
+    bool preAttachedCategories = true;
+    if ( preAttachedCategories ) {
         // Note this has to be after anyone walking the objc metadata format
         if ( Error error = this->emitPreAttachedObjCCategories(); error.hasError() )
             return error;
-
-        // Note, this must be after emitCacheDylibsPrebuiltLoaders() as it needs the offset to the SectionLocations*
-        // in the PrebuiltLoader*
-        this->emitObjCHeaderInfo();
-        if ( Error error = this->computeObjCClassLayout(); error.hasError() )
+    }
+
+    // Note, this must be after emitCacheDylibsPrebuiltLoaders() as it needs the offset to the SectionLocations*
+    // in the PrebuiltLoader*
+    this->emitObjCHeaderInfo();
+    if ( Error error = this->computeObjCClassLayout(); error.hasError() )
         return error;
 
-        // Note this must be after computeObjCClassLayout() as we need it to set the flags for whether
-        // we have missing weak superclasses or not
-        this->emitObjCOptsHeader();
-
-        // Note, this has to be after we've emitted the objc class hash table, and after emitting
-        // the objc header info
-        if ( Error error = this->emitSwiftHashTables(); error.hasError() )
-            return error;
-    }
+    // Note this must be after computeObjCClassLayout() as we need it to set the flags for whether
+    // we have missing weak superclasses or not
+    this->emitObjCOptsHeader();
+
+    // Note, this has to be after we've emitted the objc class hash table, and after emitting
+    // the objc header info
+    if ( Error error = this->emitSwiftHashTables(); error.hasError() )
+        return error;
 
     // Note, this has to be after we've emitted the objc hash tables and the objc header infos
     if ( Error error = this->emitExecutablePrebuiltLoaders(); error.hasError() )
@@ -697,12 +664,12 @@
 // Outputs: final emitted data in the sub caches
 Error SharedCacheBuilder::finalize()
 {
+
     // Do objc very late, as it adds segments to the mach-o, which aren't in sync with
     // the segments on the CacheDylib
     this->addObjcSegments();
     this->computeCacheHeaders();
     this->codeSign();
-    this->buildAtlas();
 
     return Error();
 }
@@ -779,101 +746,63 @@
     Stats        stats(this->config);
     Timer::Scope timedScope(this->config, "categorizeInputs time");
 
-    struct Chunk
-    {
-        std::vector<CacheDylib>                         cacheDylibs;
-        std::vector<InputFile*>                         exeInputFiles;
-        std::vector<InputFile*>                         nonCacheDylibInputFiles;
-    };
-
-    mapReduce(std::span(allInputFiles), 32, ^(size_t i, Chunk& chunk, std::span<InputFile> files){
-        for ( InputFile& inputFile : files ) {
-            if ( inputFile.mf == nullptr ) continue;
-
-            // only process valid images
-            if ( ((Header*)inputFile.mf)->isDyldManaged() ) {
-                // don't try to validate kernel or firmware mach-o binaries
-                Image image(inputFile.mf, inputFile.size, Image::MappingKind::wholeSliceMapped);
-                if ( mach_o::Error err = image.validate() ) {
-                    inputFile.addError(Error("%s", err.message()));
-                    continue;
-                }
-            }
-
-            if ( inputFile.mf->isDylib() || inputFile.mf->isDyld() ) {
-                auto failureHandler = ^(const char* format, ...) __attribute__((format(printf, 1, 2))) {
-                    char*   output_string;
-                    va_list list;
-                    va_start(list, format);
-                    vasprintf(&output_string, format, list);
-                    va_end(list);
-                    inputFile.addError(Error("%s", (const char*)output_string));
-                    free(output_string);
-                };
-
-                std::string_view installName = ((const Header*)inputFile.mf)->installName();
-                std::string_view dylibPath = inputFile.path;
-                if ( (installName != dylibPath) && ((this->options.platform == Platform::macOS) || startsWith(dylibPath, "/System/Cryptexes/OS/")) ) {
-                    // We now typically require that install names and paths match.  However symlinks may allow us to bring in a path which
-                    // doesn't match its install name.
-                    // For example:
-                    //   /usr/lib/libstdc++.6.0.9.dylib is a real file with install name /usr/lib/libstdc++.6.dylib
-                    //   /usr/lib/libstdc++.6.dylib is a symlink to /usr/lib/libstdc++.6.0.9.dylib
-                    // So long as we add both paths (with one as an alias) then this will work, even if dylibs are removed from disk
-                    // but the symlink remains.
-                    // Apply the same symlink crawling for dylibs that will install their contents to Cryptex paths but will have
-                    // install names with the cryptex paths removed.
-                    char resolvedSymlinkPath[PATH_MAX];
-                    if ( fileSystem.getRealPath(installName.data(), resolvedSymlinkPath) ) {
-                        if ( resolvedSymlinkPath == dylibPath ) {
-                            // Symlink is the install name and points to the on-disk dylib
-                            //fprintf(stderr, "Symlink works: %s == %s\n", inputFile.path, installName.c_str());
-                            dylibPath = installName;
-                        }
+    for ( InputFile& inputFile : this->allInputFiles ) {
+        if ( inputFile.mf == nullptr ) continue;
+
+        if ( inputFile.mf->isDylib() || inputFile.mf->isDyld() ) {
+            auto failureHandler = ^(const char* format, ...) __attribute__((format(printf, 1, 2))) {
+                char*   output_string;
+                va_list list;
+                va_start(list, format);
+                vasprintf(&output_string, format, list);
+                va_end(list);
+                inputFile.setError(Error("%s", (const char*)output_string));
+                free(output_string);
+            };
+
+            std::string_view installName = inputFile.mf->installName();
+            std::string_view dylibPath = inputFile.path;
+            if ( (installName != dylibPath) && ((this->options.platform == dyld3::Platform::macOS) || startsWith(dylibPath, "/System/Cryptexes/OS/")) ) {
+                // We now typically require that install names and paths match.  However symlinks may allow us to bring in a path which
+                // doesn't match its install name.
+                // For example:
+                //   /usr/lib/libstdc++.6.0.9.dylib is a real file with install name /usr/lib/libstdc++.6.dylib
+                //   /usr/lib/libstdc++.6.dylib is a symlink to /usr/lib/libstdc++.6.0.9.dylib
+                // So long as we add both paths (with one as an alias) then this will work, even if dylibs are removed from disk
+                // but the symlink remains.
+                // Apply the same symlink crawling for dylibs that will install their contents to Cryptex paths but will have
+                // install names with the cryptex paths removed.
+                char resolvedSymlinkPath[PATH_MAX];
+                if ( fileSystem.getRealPath(installName.data(), resolvedSymlinkPath) ) {
+                    if ( resolvedSymlinkPath == dylibPath ) {
+                        // Symlink is the install name and points to the on-disk dylib
+                        //fprintf(stderr, "Symlink works: %s == %s\n", inputFile.path, installName.c_str());
+                        dylibPath = installName;
                     }
                 }
-
-                if ( !inputFile.forceNotCacheEligible && inputFile.mf->canBePlacedInDyldCache(dylibPath.data(), true /* check objc */, failureHandler) ) {
-                    CacheDylib cacheDylib(inputFile);
-                    chunk.cacheDylibs.push_back(std::move(cacheDylib));
-                }
-                else {
-                    chunk.nonCacheDylibInputFiles.push_back(&inputFile);
-                }
-                continue;
-            }
-
-            if ( inputFile.mf->isDynamicExecutable() ) {
-                auto failureHandler = ^(const char* reason) {
-                    inputFile.addError(Error("%s", reason));
-                };
-                if ( inputFile.mf->canHavePrebuiltExecutableLoader(options.platform, inputFile.path, failureHandler) ) {
-                    chunk.exeInputFiles.push_back(&inputFile);
-                }
-
-                continue;
-            }
-        }
-    }, ^(std::span<Chunk> chunks) {
-        size_t cacheDylibsSize = 0;
-        size_t nonCacheSize = 0;
-        size_t exeSize = 0;
-        for ( Chunk& chunk : chunks ) {
-            cacheDylibsSize += chunk.cacheDylibs.size();
-            nonCacheSize += chunk.nonCacheDylibInputFiles.size();
-            exeSize += chunk.exeInputFiles.size();
-        }
-
-        cacheDylibs.reserve(cacheDylibsSize);
-        nonCacheDylibInputFiles.reserve(cacheDylibsSize);
-        exeInputFiles.reserve(exeSize);
-
-        for ( Chunk& chunk : chunks ) {
-            std::move(chunk.cacheDylibs.begin(), chunk.cacheDylibs.end(), std::back_inserter(cacheDylibs));
-            std::move(chunk.nonCacheDylibInputFiles.begin(), chunk.nonCacheDylibInputFiles.end(), std::back_inserter(nonCacheDylibInputFiles));
-            std::move(chunk.exeInputFiles.begin(), chunk.exeInputFiles.end(), std::back_inserter(exeInputFiles));
-        }
-    });
+            }
+
+            if ( !inputFile.forceNotCacheEligible && inputFile.mf->canBePlacedInDyldCache(dylibPath.data(), failureHandler) ) {
+                CacheDylib cacheDylib(inputFile);
+                this->cacheDylibs.push_back(std::move(cacheDylib));
+            }
+            else {
+                this->nonCacheDylibInputFiles.push_back(&inputFile);
+            }
+            continue;
+        }
+
+        if ( inputFile.mf->isDynamicExecutable() ) {
+            auto failureHandler = ^(const char* reason) {
+                inputFile.setError(Error("%s", reason));
+            };
+            if ( inputFile.mf->canHavePrebuiltExecutableLoader(options.platform, inputFile.path, failureHandler) ) {
+                this->exeInputFiles.push_back(&inputFile);
+            }
+
+            continue;
+        }
+    }
 
     if ( this->config.log.printStats ) {
         stats.add("  inputs: found %lld cache eligible dylibs\n", (uint64_t)this->cacheDylibs.size());
@@ -886,23 +815,13 @@
 {
     Timer::Scope timedScope(this->config, "verifySelfContained time");
 
-    __block std::unordered_set<std::string_view> badDylibs;
-
-    __block std::unordered_map<std::string_view, const InputFile*> allDylibs;
+    __block std::unordered_set<std::string_view> allDylibs;
     allDylibs.reserve(this->allInputFiles.size());
     for ( const InputFile& inputFile : this->allInputFiles ) {
-        if ( inputFile.mf == nullptr ) {
-            // Add the file if its path looks like it might be cache eligible. This is
-            // better than getting no errors at all later
-            if ( inputFile.hasError() && Header::isSharedCacheEligiblePath(inputFile.path.data()) ) {
-                allDylibs.insert({ inputFile.path, &inputFile });
-                badDylibs.insert(inputFile.path);
-            }
-            continue;
-        }
+        if ( inputFile.mf == nullptr ) continue;
 
         if ( inputFile.mf->isDylib() )
-            allDylibs.insert({ ((const Header*)inputFile.mf)->installName(), &inputFile });
+            allDylibs.insert(inputFile.mf->installName());
     }
 
     __block std::unordered_set<std::string_view> potentialCacheDylibs;
@@ -910,10 +829,8 @@
     for ( const CacheDylib& cacheDylib : this->cacheDylibs )
         potentialCacheDylibs.insert(cacheDylib.installName);
 
-
-    // Keep track of all errors in case we need them to diagnose libsystem being missing
-    __block std::unordered_map<std::string_view, std::list<std::string>> missingDependencies;
-    __block std::unordered_map<std::string_view, std::list<std::string>> ineligibleDependencies;
+    __block std::unordered_set<std::string_view> badDylibs;
+
 
     // check all dependencies to assure every dylib in cache only depends on other dylibs in cache
     __block bool doAgain = true;
@@ -940,97 +857,33 @@
                         }
                     }
                 }
-
-                // Break weak edges, but only if we haven't seen the dylib.
-                if ( isWeak && (allDylibs.count(loadPath) == 0) )
-                    return;
-                if ( isWeak && allowedMissingWeakDylibs.count(loadPath) )
-                    return;
-
-                if ( badDylibs.count(loadPath) ) {
-                    std::string reason          = std::string("Depends on ineligible/bad dylib '") + loadPath + "'";
-                    cacheDylib.inputFile->addError(Error("%s", reason.c_str()));
+                if ( potentialCacheDylibs.count(loadPath) == 0 ) {
+                    // Break weak edges, but only if we haven't seen the dylib.
+                    if ( isWeak && (allDylibs.count(loadPath) == 0) )
+                        return;
+                    if ( isWeak && allowedMissingWeakDylibs.count(loadPath) )
+                        return;
+                    std::string reason          = std::string("Could not find dependency '") + loadPath + "'";
+                    cacheDylib.inputFile->setError(Error("%s", reason.c_str()));
                     badDylibs.insert(cacheDylib.installName);
-                    ineligibleDependencies[cacheDylib.installName].push_back(loadPath);
                     doAgain = true;
+                    stop    = true;
                     return;
                 }
 
-                if ( potentialCacheDylibs.count(loadPath) == 0 ) {
-                    std::string reason          = std::string("Could not find dependency '") + loadPath + "'";
-                    cacheDylib.inputFile->addError(Error("%s", reason.c_str()));
+                if ( badDylibs.count(loadPath) ) {
+                    // Break weak edges, but only if we haven't seen the dylib.
+                    if ( isWeak && (allDylibs.count(loadPath) == 0) )
+                        return;
+                    std::string reason          = std::string("Depends on ineligible/bad dylib '") + loadPath + "'";
+                    cacheDylib.inputFile->setError(Error("%s", reason.c_str()));
                     badDylibs.insert(cacheDylib.installName);
-                    missingDependencies[cacheDylib.installName].push_back(loadPath);
                     doAgain = true;
+                    stop    = true;
                     return;
                 }
             });
         }
-    }
-
-    // If libsystem is bad, give up, but try make a better error
-    for ( const CacheDylib& cacheDylib : this->cacheDylibs ) {
-        if ( cacheDylib.inputFile == nullptr )
-            continue;
-
-        if ( !cacheDylib.inputFile->hasError() )
-            continue;
-
-        bool isLibSystem = cacheDylib.installName.ends_with("/usr/lib/libSystem.dylib") || cacheDylib.installName.ends_with("/usr/lib/libSystem.B.dylib");
-        if ( !isLibSystem )
-            continue;
-
-        // Walk the dependency tree to try find the real error which caused us to fail
-        std::unordered_set<std::string> seenFiles;
-        std::list<std::string> worklist;
-        worklist.push_back(std::string(cacheDylib.installName));
-        while ( !worklist.empty() ) {
-            std::string dylibInstallName = worklist.back();
-            worklist.pop_back();
-
-            // Check if the dylib depends on something missing
-            // If so, we've found an issue
-            if ( auto it = missingDependencies.find(dylibInstallName); it != missingDependencies.end() ) {
-                for ( auto depInstallName : it->second ) {
-                    std::string reason = "Dylib located at '";
-                    reason += dylibInstallName;
-                    reason += "' not placed in shared cache because: ";
-                    reason += "Could not find dependency '";
-                    reason += depInstallName;
-                    reason += "'";
-                    this->errors.push_back(reason);
-                }
-            }
-
-            // Add bad dependencies to the worklist, hoping to eventually walk to the root cause
-            if ( auto dylibIt = ineligibleDependencies.find(dylibInstallName); dylibIt != ineligibleDependencies.end() ) {
-                for ( auto depInstallName : dylibIt->second ) {
-                    if ( seenFiles.count(depInstallName) )
-                        continue;
-
-                    seenFiles.insert(depInstallName);
-                    worklist.push_back(depInstallName);
-
-                    if ( auto depIt = allDylibs.find(depInstallName); depIt != allDylibs.end() ) {
-                        const InputFile* inputFile = depIt->second;
-                        // Walk the errors on this depenency, skip deps which are just more bad dylibs, and see if we can
-                        // find the root cause
-                        for ( const error::Error& err : inputFile->getErrors() ) {
-                            if ( err.messageContains("Depends on ineligible/bad dylib") )
-                                continue;
-
-                            std::string reason = "Dylib located at '";
-                            reason += depInstallName;
-                            reason += "' not placed in shared cache because: ";
-                            reason += err.message();
-                            this->errors.push_back(reason);
-                        }
-                    }
-                }
-            }
-        }
-
-        cacheDylibs.clear();
     }
 
     // Add bad dylibs to the "other" dylibs for use in prebuilt loaders
@@ -1078,38 +931,39 @@
 {
     Timer::Scope timedScope(this->config, "sortDylibs time");
 
-    auto sortOrder = [this](const CacheDylib& dylib) -> uint64_t {
+    std::sort(this->cacheDylibs.begin(), this->cacheDylibs.end(), [&](const CacheDylib& a, const CacheDylib& b) {
         // HACK: See addObjCOptimizationsToSubCache() and addObjCTextChunk()
         // We put the libobjc __TEXT first in the sub cache so that offsets from it to OBJC_RO are
         // positive.  But dyld4 and objc HeaderInfo data structures rely on the cache dylibs being
         // sorted by mach_header, and moving objc first breaks the order we determine here.  So hack
         // this too and put libobjc first for now.
-        if ( endsWith(dylib.installName, "/usr/lib/libobjc.A.dylib") )
-            return (1ULL << 32);
-        // rdar://147457741 (dyld shared cache builder should guarnatee that dyld and libdyld end up in the same split cache)
-        if ( endsWith(dylib.installName, "/usr/lib/system/libdyld.dylib") )
-            return (2ULL << 32);
-        if ( endsWith(dylib.installName, "/usr/lib/dyld") )
-            return (3ULL << 32);
-
-        // fixed order first
-        if ( const auto& fixedOrder = options.dylibOrdering.find(std::string(dylib.installName)); fixedOrder != options.dylibOrdering.end() )
-            return (4ULL << 32) + fixedOrder->second;
+        bool isObjCA = (a.installName == "/usr/lib/libobjc.A.dylib");
+        bool isObjCB = (b.installName == "/usr/lib/libobjc.A.dylib");
+        if ( isObjCA != isObjCB )
+            return isObjCA;
+
+        const auto& orderA = options.dylibOrdering.find(std::string(a.installName));
+        const auto& orderB = options.dylibOrdering.find(std::string(b.installName));
+        bool        foundA = (orderA != options.dylibOrdering.end());
+        bool        foundB = (orderB != options.dylibOrdering.end());
+
+        // Order all __DATA_DIRTY segments specified in the order file first, in
+        // the order specified in the file, followed by any other __DATA_DIRTY
+        // segments in lexicographic order.
+        if ( foundA && foundB )
+            return orderA->second < orderB->second;
+        else if ( foundA )
+            return true;
+        else if ( foundB )
+            return false;
 
         // Sort mac before iOSMac
-        if ( startsWith(dylib.installName, "/System/iOSSupport/") )
-            return (6ULL << 32);
-        return (5ULL << 32);
-    };
-
-    std::sort(this->cacheDylibs.begin(), this->cacheDylibs.end(), [&](const CacheDylib& a, const CacheDylib& b) {
-        uint64_t aOrder = sortOrder(a);
-        uint64_t bOrder = sortOrder(b);
-
-        if ( aOrder != bOrder )
-            return aOrder < bOrder;
-
-        // Finally sort by install name if there's no explicit ordering
+        bool isIOSMacA = startsWith(a.installName, "/System/iOSSupport/");
+        bool isIOSMacB = startsWith(b.installName, "/System/iOSSupport/");
+        if ( isIOSMacA != isIOSMacB )
+            return !isIOSMacA;
+
+        // Finally sort by install name
         return a.installName < b.installName;
     });
 
@@ -1117,46 +971,6 @@
     uint32_t cacheIndex = 0;
     for ( CacheDylib& cacheDylib : cacheDylibs )
         cacheDylib.cacheIndex = cacheIndex++;
-}
-
-void SharedCacheBuilder::sortExecutables()
-{
-    Timer::Scope timedScope(this->config, "sortExecutables time");
-
-    // make a list of the position on all binaries for anything we don't explicitly sort
-    std::unordered_map<const InputFile*, uint32_t> originalPositions;
-    for ( const InputFile* file : this->exeInputFiles )
-        originalPositions[file] = (uint32_t)originalPositions.size();
-
-    // TODO: Use a file from the perf teams if we have one
-    auto sortOrder = [&originalPositions](const InputFile* file) -> uint64_t {
-        uint32_t originalPos = originalPositions.at(file);
-
-        // Sort some paths first
-        if ( file->path.starts_with("/usr/libexec/") )
-            return (1ULL << 32) + originalPos;
-        if ( file->path.starts_with("/Applications/") )
-            return (2ULL << 32) + originalPos;
-        if ( file->path.starts_with("/private/var/staged_system_apps/") )
-            return (3ULL << 32) + originalPos;
-        if ( file->path.starts_with("/usr/bin/") )
-            return (4ULL << 32) + originalPos;
-
-        // Sort some other paths last
-        if ( file->path.starts_with("/AppleInternal/") )
-            return (62ULL << 32) + originalPos;
-        if ( file->path.starts_with("/usr/local/bin/") )
-            return (63ULL << 32) + originalPos;
-
-        // Any path not in the lists above gets sorted by original position
-        return (32ULL << 32) + originalPos;
-    };
-
-    // Just in case we overflow the buffer in emitExecutablePrebuiltLoaders(), sort the exe files to prioritize
-    // daemons and other common apps
-    std::sort(this->exeInputFiles.begin(), this->exeInputFiles.end(), [&](const InputFile* a, const InputFile* b) {
-        return sortOrder(a) < sortOrder(b);
-    });
 }
 
 Error SharedCacheBuilder::calculateDylibDependents()
@@ -1229,7 +1043,7 @@
         // otherwise loading the library would pull in lots of other dependencies
         if ( swiftPrespecializedDylib && &cacheDylib == swiftPrespecializedDylib ) {
             if ( cacheDylib.dependents.empty() || cacheDylib.dependents.front().dylib->installName.find("libSystem") == std::string_view::npos ) {
-                diag.error("expected libSystem as the first linked dylib of %s", cacheDylib.inputHdr->installName());
+                diag.error("expected libSystem as the first linked dylib of %s", cacheDylib.inputMF->installName());
             } else {
                 cacheDylib.dependents.erase(cacheDylib.dependents.begin()+1, cacheDylib.dependents.end());
             }
@@ -1366,39 +1180,36 @@
 }
 
 static void forEachObjCMethodName(const CacheDylib& cacheDylib,
-                                  void (^callback)(const char* str))
-{
-    __block objc_visitor::Visitor objcVisitor = makeInputDylibObjCVisitor(cacheDylib);
-
-    auto visitPointerBasedMethod = ^(const objc_visitor::Method& method) {
-        const char* selectorString = method.getName(objcVisitor);
-        callback(selectorString);
-    };
-
-    auto visitMethodList = ^(const objc_visitor::MethodList& methodList) {
-        if ( methodList.numMethods() == 0 )
+                                  void (^callback)(std::string_view str))
+{
+    const MachOFile* mf = cacheDylib.inputMF;
+    mf->forEachSection(^(const MachOFile::SectionInfo& sectInfo, bool malformedSectionRange, bool& stop) {
+        if ( strcmp(sectInfo.segInfo.segName, "__TEXT") != 0 )
             return;
-        if ( methodList.usesRelativeOffsets() )
+        if ( strcmp(sectInfo.sectName, "__objc_methname") != 0 )
             return;
-
-        // Check pointer based method lists
-        uint32_t numMethods = methodList.numMethods();
-        for ( uint32_t i = 0; i != numMethods; ++i ) {
-            const objc_visitor::Method& method = methodList.getMethod(objcVisitor, i);
-            visitPointerBasedMethod(method);
-        }
-    };
-
-    // selector references
-    objcVisitor.forEachSelectorReference(^(VMAddress selRefVMAddr, VMAddress selRefTargetVMAddr,
-                                           const char* selectorString) {
-        callback(selectorString);
-    });
-
-    // classes/categories/protocols/swift generics
-    objcVisitor.forEachMethodList(^(objc_visitor::MethodList& objcMethodList,
-                                    std::optional<metadata_visitor::ResolvedValue> extendedMethodTypes) {
-        visitMethodList(objcMethodList);
+        if ( sectInfo.segInfo.isProtected || ((sectInfo.sectFlags & SECTION_TYPE) != S_CSTRING_LITERALS) ) {
+            stop = true;
+            return;
+        }
+        if ( malformedSectionRange ) {
+            stop = true;
+            return;
+        }
+
+        // Use the file offset in the section to get the correct content
+        const char* content     = (const char*)mf + sectInfo.sectFileOffset;
+        uint64_t    sectionSize = sectInfo.sectSize;
+
+        const char* s   = (const char*)content;
+        const char* end = s + sectionSize;
+        while ( s < end ) {
+            std::string_view str = s;
+            callback(str);
+            s += str.size() + 1;
+        }
+
+        stop = true;
     });
 }
 
@@ -1408,7 +1219,7 @@
     VMOffset          offsetInDylib;
 };
 
-static FoundSymbol findTargetClass(Diagnostics& diag,
+static FoundSymbol findTargetClass(Diagnostics diag,
                                    const std::vector<CacheDylib>& cacheDylibs,
                                    std::string_view symbolName, std::optional<uint32_t> cacheIndex)
 {
@@ -1452,7 +1263,8 @@
         return;
 
     // Only arm64* are is supported by the runtime
-    if ( !this->options.arch.sameCpu(mach_o::Architecture::arm64) )
+    std::string_view archName = this->options.archs.name();
+    if ( archName != "arm64e" && archName != "arm64")
         return;
 
     // Skip everything if the JSON file is empty
@@ -1610,7 +1422,6 @@
             bool                    isWeakImport     = false;
         };
 
-        auto& dylibMethodMap = objcIMPCachesOptimizer.methodMap[cacheDylib.installName];
         __block std::vector<BindTarget> bindTargets;
         __block Diagnostics diag;
         cacheDylib.inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
@@ -1701,6 +1512,7 @@
                     objc_visitor::Method objcMethod = objcMethodList.getMethod(objcVisitor, i);
 
                     imp_caches::BucketMethod methodKey = {
+                        .installName = cacheDylib.installName,
                         .className = impCacheClass.name,
                         .methodName = objcMethod.getName(objcVisitor),
                         .isInstanceMethod = !impCacheClass.isMetaClass
@@ -1711,7 +1523,7 @@
                         &cacheDylib,
                         InputDylibVMAddress(impVMAddr.rawValue())
                     };
-                    dylibMethodMap[methodKey] = inputDylibLocation;
+                    objcIMPCachesOptimizer.methodMap[methodKey] = inputDylibLocation;
                 }
             }
 
@@ -1776,6 +1588,7 @@
                         objc_visitor::Method objcMethod = objcMethodList.getMethod(objcVisitor, i);
 
                         imp_caches::BucketMethod methodKey = {
+                            .installName = cacheDylib.installName,
                             .className = impCacheCategory.cls->name,
                             .methodName = objcMethod.getName(objcVisitor),
                             .isInstanceMethod = true
@@ -1785,7 +1598,7 @@
                             &cacheDylib,
                             InputDylibVMAddress(impVMAddr.rawValue())
                         };
-                        dylibMethodMap[methodKey] = inputDylibLocation;
+                        objcIMPCachesOptimizer.methodMap[methodKey] = inputDylibLocation;
                     }
                 }
 
@@ -1797,6 +1610,7 @@
                         objc_visitor::Method objcMethod = objcMethodList.getMethod(objcVisitor, i);
 
                         imp_caches::BucketMethod methodKey = {
+                            .installName = cacheDylib.installName,
                             .className = impCacheCategory.cls->name,
                             .methodName = objcMethod.getName(objcVisitor),
                             .isInstanceMethod = false
@@ -1806,7 +1620,7 @@
                             &cacheDylib,
                             InputDylibVMAddress(impVMAddr.rawValue())
                         };
-                        dylibMethodMap[methodKey] = inputDylibLocation;
+                        objcIMPCachesOptimizer.methodMap[methodKey] = inputDylibLocation;
                     }
                 }
             }
@@ -1821,10 +1635,6 @@
     // We should probably keep the piece here to walk the classes as that can perhaps give us a good estimate of the size of the IMP caches
     // themselves, minus the strings which need their own buffer
     this->objcIMPCachesOptimizer.builder->buildImpCaches();
-
-    for ( const std::string& warning : this->objcIMPCachesOptimizer.builder->diags.warnings() ) {
-        this->warning("IMP caches: %s", warning.data());
-    }
 
     // Push all the IMP cache selectors in to the main selectors buffer.
     // We could try have an IMP cache selectors buffer and a regular selectors buffer, but that complicates
@@ -1855,7 +1665,6 @@
 
     // Add space for the IMP caches themselves
     this->objcIMPCachesOptimizer.dylibIMPCaches.resize(dylibs.size());
-    size_t discardedCaches = 0;
     for ( uint32_t dylibIndex = 0; dylibIndex != dylibs.size(); ++dylibIndex ) {
         imp_caches::Dylib& dylib = dylibs[dylibIndex];
         ObjCIMPCachesOptimizer::IMPCacheMap& dylibIMPCaches = objcIMPCachesOptimizer.dylibIMPCaches[dylibIndex];
@@ -1864,24 +1673,6 @@
             if ( !impCache.has_value() )
                 continue;
 
-            // rdar://147219191 (Selector bucket overflows in IMP caches result in malformed tables)
-            // validate selector offsets point to matching buckets
-            bool discard = false;
-            for ( uint32_t slot = 0; slot < impCache->buckets.size(); ++slot ) {
-                const imp_caches::Bucket& bucket = impCache->buckets[slot];
-                if ( !bucket.isEmptyBucket ) {
-                    uint32_t expectedSlot = (bucket.selOffset >> impCache->cache_shift) & impCache->cache_mask;
-                    if ( expectedSlot != slot ) {
-                        discard = true;
-                        break;
-                    }
-                }
-            }
-            if ( discard ) {
-                ++discardedCaches;
-                continue;
-            }
-
             VMOffset currentOffset((uint64_t)this->objcIMPCachesOptimizer.impCachesTotalByteSize);
             assert((this->objcIMPCachesOptimizer.impCachesTotalByteSize % 8) == 0);
             this->objcIMPCachesOptimizer.impCachesTotalByteSize += sizeof(ImpCacheHeader_v2);
@@ -1893,10 +1684,6 @@
         }
     }
 
-    if ( discardedCaches != 0 ) {
-        this->warning("[ERROR] discarded IMP caches: %lu", discardedCaches);
-    }
-
     if ( this->config.log.printStats ) {
         stats.add("  objc: found %lld imp cache selectors\n", (uint64_t)this->objcSelectorOptimizer.selectorsMap.size());
         stats.add("  objc: using %lld bytes\n", this->objcSelectorOptimizer.selectorStringsTotalByteSize);
@@ -1907,7 +1694,7 @@
 void SharedCacheBuilder::findObjCDylibs()
 {
     // driverKit has no objc
-    if ( this->options.platform == Platform::driverKit )
+    if ( this->options.platform == dyld3::Platform::driverKit )
         return;
 
     Stats        stats(this->config);
@@ -1915,9 +1702,9 @@
 
     assert(this->objcOptimizer.objcDylibs.empty());
     for ( CacheDylib& cacheDylib : this->cacheDylibs ) {
-        if ( cacheDylib.inputHdr == nullptr ) continue;
-
-        if ( cacheDylib.inputHdr->hasObjC() )
+        if ( cacheDylib.inputMF == nullptr ) continue;
+
+        if ( cacheDylib.inputMF->hasObjC() )
             this->objcOptimizer.objcDylibs.push_back(&cacheDylib);
     }
 
@@ -1958,19 +1745,11 @@
     Error err = parallel::forEach(this->cacheDylibs, ^(size_t index, CacheDylib& cacheDylib) {
         std::vector<std::string_view>& strings = dylibSelectors[index];
 
-        __block std::unordered_set<const void*> seenStrings;
-        forEachObjCMethodName(cacheDylib, ^(const char* str) {
-            auto itAndInserted = seenStrings.insert(str);
-            if ( itAndInserted.second )
-                strings.push_back(str);
+        forEachObjCMethodName(cacheDylib, ^(std::string_view str) {
+            strings.push_back(std::move(str));
         });
 
-        // sort strings as we used to walk the __objc_methname section in order, so by sorting we
-        // should get close to possible to the old order
-        std::sort(strings.begin(), strings.end(), [](const std::string_view& a, const std::string_view& b) {
-            // note pointer comparison as we want the string location in the binary not its contents
-            return a.data() < b.data();
-        });
+        // FIXME: Walk selector references, classes, categories, protocols, etc
 
         return Error();
     });
@@ -2342,7 +2121,7 @@
     size_t objcIndex = 0;
     for (size_t cacheIndex = 0; cacheIndex < this->cacheDylibs.size(); cacheIndex++) {
         CacheDylib& cacheDylib = this->cacheDylibs[cacheIndex];
-        if ( !cacheDylib.inputHdr->hasObjC() )
+        if ( !cacheDylib.inputMF->hasObjC() )
             continue;
 
         // Skip dylibs with opcode fixups, as the Category visitor operates on chained fixups to find classes
@@ -2492,10 +2271,7 @@
     uint32_t elementsWithPadding = maxElements * 11 / 10; // if close to power of 2, perfect hash may fail, so don't get within 10% of that
     uint32_t powTwoCapacity      = 1 << (32 - __builtin_clz(elementsWithPadding - 1));
     uint32_t headerSize          = 4 * (8 + 256);
-    uint32_t totalSize = headerSize + powTwoCapacity / 2 + powTwoCapacity + powTwoCapacity * perElementData;
-
-    // Add in a little extra room for very small tables when we are building unit tests
-    return std::max(totalSize, 4096U);
+    return headerSize + powTwoCapacity / 2 + powTwoCapacity + powTwoCapacity * perElementData;
 }
 
 void SharedCacheBuilder::estimateObjCHashTableSizes()
@@ -2645,7 +2421,7 @@
     Stats        stats(this->config);
     Timer::Scope timedScope(this->config, "estimateSwiftHashTableSizes time");
 
-    this->swiftOptimizer.optsHeaderByteSize = sizeof(SwiftOptimizationHeader);
+    this->swiftProtocolConformanceOptimizer.optsHeaderByteSize = sizeof(SwiftOptimizationHeader);
 
     __block uint32_t numTypeConformances = 0;
     __block uint32_t numMetadataConformances = 0;
@@ -2691,7 +2467,7 @@
         });
     }
 
-    auto& optimizer = this->swiftOptimizer;
+    auto& optimizer = this->swiftProtocolConformanceOptimizer;
 
     if ( swiftPrespecializedDylib ) {
         Diagnostics diagVal;
@@ -2764,7 +2540,7 @@
 
     // For each alias, also see if we have intermediate aliases
     // This is the "Current -> A" symlink in say "/S/L/F/CF.fw/Current/CF"
-    if ( this->options.platform == Platform::macOS ) {
+    if ( this->options.platform == dyld3::Platform::macOS ) {
         for ( const cache_builder::FileAlias& alias : this->inputIntermediateAliases ) {
             const auto& pos = dylibPathToDylibIndex.find(alias.realPath);
             if ( pos != dylibPathToDylibIndex.end() ) {
@@ -2784,78 +2560,91 @@
     }
 }
 
-void SharedCacheBuilder::initializePatchTableOptimizer()
-{
+void SharedCacheBuilder::estimatePatchTableSize()
+{
+    Stats        stats(this->config);
+    Timer::Scope timedScope(this->config, "estimatePatchTableSize time");
+
+    // The patch table consists of a series of arrays.
+    // For each dylib, we have a list of all clients of that dylib
+    // For each dylib we also have a list of used exports
+    // For each client we then have a list of symbols used
+    // And for each list of symbols, we have a list of locations to patch
+    // We need to estimate a patch table based on the above lists
+
+    __block uint32_t bindStringsLength = 0;
+    __block uint32_t numBindTargets = 0;
+    __block uint32_t numBinds = 0;
+    uint32_t numClients = 0;
+    for ( const CacheDylib& cacheDylib : this->cacheDylibs ) {
+        if ( !cacheDylib.needsPatchTable )
+            continue;
+        __block Diagnostics diag;
+        cacheDylib.inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
+            mach_o::Fixups fixups(layout);
+            fixups.forEachBindTarget(diag, true, 0,
+                                     ^(const mach_o::Fixups::BindTargetInfo& info, bool &stop) {
+                ++numBindTargets;
+                bindStringsLength += strlen(info.symbolName) + 1;
+            }, ^(const mach_o::Fixups::BindTargetInfo &info, bool &stop) {
+                ++numBindTargets;
+                bindStringsLength += strlen(info.symbolName) + 1;
+            });
+
+            if ( cacheDylib.inputMF->hasChainedFixups() ) {
+                fixups.withChainStarts(diag, ^(const dyld_chained_starts_in_image* starts) {
+                    fixups.forEachFixupInAllChains(diag, starts, false,
+                                                   ^(mach_o::ChainedFixupPointerOnDisk* fixupLoc,
+                                                     uint64_t fixupSegmentOffset,
+                                                     const dyld_chained_starts_in_segment* segInfo,
+                                                     bool& stop) {
+                        uint32_t bindOrdinal = ~0U;
+                        int64_t  addend = -1;
+                        if ( fixupLoc->isBind(segInfo->pointer_format, bindOrdinal, addend) )
+                            ++numBinds;
+                    });
+                });
+            } else {
+                fixups.forEachBindLocation_Opcodes(diag,
+                                                   ^(uint64_t runtimeOffset, uint32_t segmentIndex,
+                                                     unsigned int targetIndex, bool &stop) {
+                    ++numBinds;
+                }, ^(uint64_t runtimeOffset, uint32_t segmentIndex, unsigned int overrideBindTargetIndex,
+                     bool &stop) {
+                    ++numBinds;
+                });
+            }
+        });
+
+        numClients += (uint32_t)cacheDylib.dependents.size();
+    }
+
+    // Start with the patch header
+    uint64_t size = sizeof(dyld_cache_patch_info_v3);
+
+    // One of these for each dylib
+    size += sizeof(dyld_cache_image_patches_v2) * this->cacheDylibs.size();
+
+    // Estimate that 2/3 of exports are used
+    size += (sizeof(dyld_cache_image_export_v2) * numBindTargets * 2) / 3;
+    size += (bindStringsLength * 2) / 3;
+
+    // 1 entry per client
+    size += sizeof(dyld_cache_image_clients_v2) * numClients;
+
+    // 1 entry per bind target
+    size += sizeof(dyld_cache_patchable_export_v2) * numBindTargets;
+
+    // 1 entry per location we bind to
+    size += sizeof(dyld_cache_patchable_location_v4) * numBinds;
+
+    this->patchTableOptimizer.patchTableTotalByteSize = size;
+    
     // Reserve space for the patch infos, one per dylib
-    // TODO: Just move these to the dylib.  We don't really need them to be owned by the PatchTableOptimizer
     this->patchTableOptimizer.patchInfos.resize(this->cacheDylibs.size());
-}
-
-void SharedCacheBuilder::estimateFunctionVariantsSize()
-{
-    this->functionVariantsOptimizer.fvInfoTotalByteSize = sizeof(dyld_cache_function_variant_entry) * 256;  // FIXME
-}
-
-void SharedCacheBuilder::estimatePrewarmingSize()
-{
-    // Skip everything if the JSON file is empty
-    if ( this->options.prewarmingOptimizations.empty() )
-        return;
-
-    using json::Node;
-    using json::NodeValueType;
-
-    Stats        stats(this->config);
-    Timer::Scope timedScope(this->config, "estimatePrewarmingSize time");
-
-    Diagnostics diag;
-    Node rootNode = json::readJSON(diag, this->options.prewarmingOptimizations.data(),
-                                   this->options.prewarmingOptimizations.size(),
-                                   false /* useJSON5 */);
-    if ( diag.hasError() )
-        return;
-
-    // Format is something like:
-    // [
-    //     {
-    //         "install_name": "..."
-    //         "locations": [
-    //             {
-    //                 "name": "symbol name",
-    //                 "offset": 0
-    //             }
-    //         ]
-    //     },
-    // ...
-    // ]
-    if ( rootNode.type != NodeValueType::Array )
-        return;
-
-    uint64_t numElements = 0;
-    for ( const Node& fileNode : rootNode.array ) {
-        auto locationsIt = fileNode.map.find("locations");
-        if ( locationsIt == fileNode.map.end() ) {
-            // FIXME: Should we error out if the JSON isn't what we expect
-            // For now just skip bad data
-            continue;
-        }
-
-        if ( locationsIt->second.type != NodeValueType::Array ) {
-            // FIXME: Should we error out if the JSON isn't what we expect
-            // For now just skip bad data
-            continue;
-        }
-
-        numElements += locationsIt->second.array.size();
-    }
-
-    this->prewarmingOptimizer.prewarmingByteSize = 0;
-    this->prewarmingOptimizer.prewarmingByteSize += sizeof(dyld_prewarming_header);
-    this->prewarmingOptimizer.prewarmingByteSize += numElements * sizeof(dyld_prewarming_entry);
-    this->prewarmingOptimizer.prewarmingByteSize = (uint32_t)alignTo((uint64_t)this->prewarmingOptimizer.prewarmingByteSize, 8);
 
     if ( this->config.log.printStats ) {
-        stats.add("  dyld4 prewarming estimated size: %lld\n", (uint64_t)this->prewarmingOptimizer.prewarmingByteSize);
+        stats.add("  patch table estimated size: %lld\n", (uint64_t)this->patchTableOptimizer.patchTableTotalByteSize);
     }
 }
 
@@ -2879,7 +2668,7 @@
             size += sizeof(Loader::Region) * cacheDylib.segments.size();
 
             // iOSMac dylibs likely contain a patch table
-            if ( (this->options.platform == Platform::macOS)
+            if ( (this->options.platform == dyld3::Platform::macOS)
                 && startsWith(cacheDylib.installName, "/System/iOSSupport") ) {
                 __block Diagnostics diag;
                 cacheDylib.inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
@@ -2901,7 +2690,7 @@
     // patch tables, etc.  For now, 20KB/executable seems about right
     // FIXME: Small programs like daemons need just 500 bytes or so, but large /Applications need up to 1MB
     // Come up with a better estimate
-    this->prebuiltLoaderBuilder.executablesLoaderSize = 30_KB * this->exeInputFiles.size();
+    this->prebuiltLoaderBuilder.executablesLoaderSize = 20_KB * this->exeInputFiles.size();
 
     // Estimate the trie size
     // Assume they are all at a high offset
@@ -2914,7 +2703,7 @@
         // Assumes that cdHash strings at runtime use lowercase a-f digits
         uint32_t codeSignFileOffset = 0;
         uint32_t codeSignFileSize   = 0;
-        if ( ((const Header*)inputFile->mf)->hasCodeSignature(codeSignFileOffset, codeSignFileSize) ) {
+        if ( inputFile->mf->hasCodeSignature(codeSignFileOffset, codeSignFileSize) ) {
             auto handler = ^(const uint8_t cdHash[20]) {
                 std::string cdHashStr = "/cdhash/";
                 cdHashStr.reserve(24);
@@ -2996,10 +2785,6 @@
 // This adds all of them to the given subCache
 void SharedCacheBuilder::addObjCOptimizationsToSubCache(SubCache& subCache)
 {
-    // Disable objc optimizations for EK
-    if ( this->options.platform.isExclaveKit() )
-        return;
-
     // Add objc header info RW
     subCache.addObjCHeaderInfoReadWriteChunk(this->config, this->objcOptimizer);
 
@@ -3010,7 +2795,7 @@
     subCache.addObjCCategoriesChunk(this->config, this->objcCategoryOptimizer);
 
     // Add objc opts header
-    subCache.addObjCOptsHeaderChunk(this->config, this->objcOptimizer);
+    subCache.addObjCOptsHeaderChunk(this->objcOptimizer);
 
     // Add objc header info RO
     subCache.addObjCHeaderInfoReadOnlyChunk(this->config, this->objcOptimizer);
@@ -3035,16 +2820,16 @@
     subCache.addObjCProtocolSwiftDemangledNamesChunk(this->config, this->objcProtocolOptimizer);
 
     // Add ObjC IMP Caches
-    subCache.addObjCIMPCachesChunk(this->config, this->objcIMPCachesOptimizer);
+    subCache.addObjCIMPCachesChunk(this->objcIMPCachesOptimizer);
 
     // Add Swift opts header
-    subCache.addSwiftOptsHeaderChunk(this->config, this->swiftOptimizer);
+    subCache.addSwiftOptsHeaderChunk(this->swiftProtocolConformanceOptimizer);
 
     // Add Swift hash tables
-    subCache.addSwiftTypeHashTableChunk(this->config, this->swiftOptimizer);
-    subCache.addSwiftMetadataHashTableChunk(this->config, this->swiftOptimizer);
-    subCache.addSwiftForeignHashTableChunk(this->config, this->swiftOptimizer);
-    subCache.addSwiftPrespecializedMetadataPointerTableChunks(this->config, this->swiftOptimizer);
+    subCache.addSwiftTypeHashTableChunk(this->swiftProtocolConformanceOptimizer);
+    subCache.addSwiftMetadataHashTableChunk(this->swiftProtocolConformanceOptimizer);
+    subCache.addSwiftForeignHashTableChunk(this->swiftProtocolConformanceOptimizer);
+    subCache.addSwiftPrespecializedMetadataPointerTableChunks(this->swiftProtocolConformanceOptimizer);
 }
 
 // The shared cache contains many global optimizations such as dyld4 loaders, trie's, etc.
@@ -3058,9 +2843,6 @@
     // Add patch table
     subCache.addPatchTableChunk(this->patchTableOptimizer);
 
-    // Add function-variants table
-    subCache.addFunctionVariantsChunk(this->functionVariantsOptimizer);
-
     // Add cache dylib Loader's
     subCache.addCacheDylibsLoaderChunk(this->prebuiltLoaderBuilder);
 
@@ -3069,57 +2851,24 @@
 
     // Add executable trie
     subCache.addExecutablesTrieChunk(this->prebuiltLoaderBuilder);
-
-    // Add prewarming data
-    subCache.addPrewarmingDataChunk(this->config, this->prewarmingOptimizer);
 }
 
 // Every subCache needs a code signature, and subCache's with DATA* need slide info.  This adds
 // anything we need, based on whatever else is already in the SubCache.
 void SharedCacheBuilder::addFinalChunksToSubCache(SubCache& subCache)
 {
-    subCache.addCacheHeaderChunk(this->options, this->config, this->cacheDylibs);
+    subCache.addCacheHeaderChunk(this->config, this->cacheDylibs);
+
+    // Add slide info for each DATA/AUTH segment.  Do this after we've added any other DATA*
+    // segments
+    if ( this->config.slideInfo.slideInfoFormat.has_value() )
+        subCache.addSlideInfoChunks();
 
     // Add a code signature region
     subCache.addCodeSignatureChunk();
-}
-
-static std::optional<Header::SectionInfo> getStubsSection(const DylibSegmentChunk* dylibChunk)
-{
-    if ( dylibChunk == nullptr )
-        return std::nullopt;
-    if ( dylibChunk->kind != Chunk::Kind::dylibText )
-        return std::nullopt;
-
-    const MachOFile* mf = dylibChunk->inputFile->mf;
-    __block std::optional<Header::SectionInfo> stubsSection;
-    ((const Header*)mf)->forEachSection(^(const Header::SectionInfo &sectInfo, bool &stop) {
-        if ( dylibChunk->segmentName != sectInfo.segmentName )
-            return;
-
-        unsigned sectionType = (sectInfo.flags & SECTION_TYPE);
-        if ( sectionType != S_SYMBOL_STUBS )
-            return;
-
-        if ( sectInfo.segmentName != "__TEXT" ) {
-            // stubs aren't in __TEXT.  Give up on this one for now
-            return;
-        }
-
-        if ( mf->isArch("arm64e") ) {
-            // For arm64e, we can only optimize __auth_stubs
-            if ( sectInfo.sectionName != "__auth_stubs" )
-                return;
-        } else {
-            // For non-arm64e, we can only optimize __stubs
-            if ( sectInfo.sectionName != "__stubs" )
-                return;
-        }
-
-        stubsSection = sectInfo;
-    });
-
-    return stubsSection;
+
+    // Finalize the SubCache, by removing any unused regions
+    subCache.removeEmptyRegions();
 }
 
 // Add stubs Chunk's for every stubs section in the given text subCache
@@ -3133,29 +2882,60 @@
         const DylibSegmentChunk* textChunk = textRegionChunk->isDylibSegmentChunk();
         if ( textChunk == nullptr )
             continue;
-
-        std::optional<Header::SectionInfo> sectInfo = getStubsSection(textChunk);
-        if ( !sectInfo )
+        if ( textChunk->kind != Chunk::Kind::dylibText )
             continue;
 
-        // Make a stubs chunk for this stubs section
-        CacheDylib* cacheDylib = fileToDylibMap.at(textChunk->inputFile);
-        StubsChunk* devStubsChunk = &cacheDylib->developmentStubs;
-        StubsChunk* customerStubsChunk = &cacheDylib->customerStubs;
-
-        assert(devStubsChunk->segmentName.empty());
-        devStubsChunk->segmentName = sectInfo->segmentName;
-        devStubsChunk->sectionName = sectInfo->sectionName;
-        devStubsChunk->subCacheFileSize = CacheFileSize(sectInfo->size);
-        devStubsChunk->cacheVMSize = CacheVMSize(sectInfo->size);
-        devStubsSubCache.addStubsChunk(devStubsChunk);
-
-        assert(customerStubsChunk->segmentName.empty());
-        customerStubsChunk->segmentName = sectInfo->segmentName;
-        customerStubsChunk->sectionName = sectInfo->sectionName;
-        customerStubsChunk->subCacheFileSize = CacheFileSize(sectInfo->size);
-        customerStubsChunk->cacheVMSize = CacheVMSize(sectInfo->size);
-        customerStubsSubCache.addStubsChunk(customerStubsChunk);
+        const MachOFile* mf = textChunk->inputFile->mf;
+        mf->forEachSection(^(const dyld3::MachOFile::SectionInfo &sectInfo,
+                             bool malformedSectionRange, bool &stop) {
+            if ( textChunk->segmentName != sectInfo.segInfo.segName )
+                return;
+
+            unsigned sectionType = (sectInfo.sectFlags & SECTION_TYPE);
+            if ( sectionType != S_SYMBOL_STUBS )
+                return;
+
+            if ( strcmp(sectInfo.segInfo.segName, "__TEXT") != 0 ) {
+                // stubs aren't in __TEXT.  Give up on this one for now
+                return;
+            }
+
+            // Make a stubs chunk for this stubs section
+            CacheDylib* cacheDylib = fileToDylibMap.at(textChunk->inputFile);
+            StubsChunk* devStubsChunk = nullptr;
+            StubsChunk* customerStubsChunk = nullptr;
+
+            if ( mf->isArch("arm64e") ) {
+                // For arm64e, we can only optimize __auth_stubs
+                if ( !strcmp(sectInfo.sectName, "__auth_stubs") ) {
+                    devStubsChunk       = &cacheDylib->developmentStubs;
+                    customerStubsChunk  = &cacheDylib->customerStubs;
+                }
+            } else {
+                // For non-arm64e, we can only optimize __stubs
+                if ( !strcmp(sectInfo.sectName, "__stubs") ) {
+                    devStubsChunk       = &cacheDylib->developmentStubs;
+                    customerStubsChunk  = &cacheDylib->customerStubs;
+                }
+            }
+
+            if ( devStubsChunk == nullptr )
+                return;
+
+            assert(devStubsChunk->segmentName.empty());
+            devStubsChunk->segmentName = sectInfo.segInfo.segName;
+            devStubsChunk->sectionName = sectInfo.sectName;
+            devStubsChunk->subCacheFileSize = CacheFileSize(sectInfo.sectSize);
+            devStubsChunk->cacheVMSize = CacheVMSize(sectInfo.sectSize);
+            devStubsSubCache.addStubsChunk(devStubsChunk);
+
+            assert(customerStubsChunk->segmentName.empty());
+            customerStubsChunk->segmentName = sectInfo.segInfo.segName;
+            customerStubsChunk->sectionName = sectInfo.sectName;
+            customerStubsChunk->subCacheFileSize = CacheFileSize(sectInfo.sectSize);
+            customerStubsChunk->cacheVMSize = CacheVMSize(sectInfo.sectSize);
+            customerStubsSubCache.addStubsChunk(customerStubsChunk);
+        });
     }
 }
 
@@ -3331,101 +3111,39 @@
 {
     SubCache* currentSubCache = firstSubCache;
 
-    std::string_view libObjcInstallName = "/usr/lib/libobjc.A.dylib";
-    if ( this->options.platform.isExclaveKit() )
-        libObjcInstallName = "/System/ExclaveKit/usr/lib/libobjc.A.dylib";
-
-    // If we have an objc dylib, then gets its optimizations now to work out their size first
-    // The subCache with libobjc gets the header info sections, which for now we assume is the first subcache
-    // Add all the objc tables.  This must be done before we add libobjc's __TEXT
+    // Walk all the dylibs, and create a new subCache every time we are about to cross
+    // the subCacheTextLimit
+    CacheVMSize subCacheTextSize(0ULL);
     for ( CacheDylib& cacheDylib : this->cacheDylibs ) {
-        if ( cacheDylib.installName == libObjcInstallName ) {
+        // Peek ahead to find the __TEXT size
+        CacheVMSize textSize(0ULL);
+        for ( DylibSegmentChunk& segmentInfo : cacheDylib.segments ) {
+            if ( segmentInfo.kind == DylibSegmentChunk::Kind::dylibText )
+                textSize += segmentInfo.cacheVMSize;
+        }
+
+        // If we exceed the current limit, then the current subCache is complete and we need
+        // to start a new one
+        if ( (subCacheTextSize + textSize) > this->config.layout.subCacheTextLimit ) {
+            // Create a new subCache
+            otherCaches.push_back(SubCache::makeSubCache(this->options));
+            currentSubCache = &otherCaches.back();
+
+            // Reset the limit for the next subCache
+            subCacheTextSize = CacheVMSize(0ULL);
+        }
+
+        subCacheTextSize += textSize;
+
+        // The subCache with libobjc gets the header info sections
+        // Add all the objc tables.  This must be done before we add libobjc's __TEXT
+        std::string_view libObjcInstallName = "/usr/lib/libobjc.A.dylib";
+        if ( dyld3::MachOFile::isExclaveKitPlatform(this->options.platform) )
+            libObjcInstallName = "/System/ExclaveKit/usr/lib/libobjc.A.dylib";
+        if ( cacheDylib.installName == libObjcInstallName )
             this->addObjCOptimizationsToSubCache(*currentSubCache);
-            break;
-        }
-    }
-
-    // Walk all the dylibs, and create a new subCache every time we are about to cross
-    // the subCache size limit
-    if ( this->config.layout.discontiguous.has_value() ) {
-        const CacheVMSize subCacheTextLimit = this->config.layout.discontiguous.value().subCacheTextLimit;
-        CacheVMSize subCacheTextSize(0ULL);
-        for ( CacheDylib& cacheDylib : this->cacheDylibs ) {
-            // Peek ahead to find the __TEXT size
-            CacheVMSize textSize(0ULL);
-            for ( DylibSegmentChunk& segmentInfo : cacheDylib.segments ) {
-                if ( segmentInfo.kind == DylibSegmentChunk::Kind::dylibText )
-                    textSize += segmentInfo.cacheVMSize;
-            }
-
-            // If we exceed the current limit, then the current subCache is complete and we need
-            // to start a new one
-            if ( (subCacheTextSize + textSize) > subCacheTextLimit ) {
-                // Create a new subCache
-                otherCaches.push_back(SubCache::makeSubCache(this->options));
-                currentSubCache = &otherCaches.back();
-
-                // Reset the limit for the next subCache
-                subCacheTextSize = CacheVMSize(0ULL);
-            }
-
-            subCacheTextSize += textSize;
-
-            currentSubCache->addDylib(this->config, cacheDylib);
-            currentSubCache->addLinkeditFromDylib(cacheDylib);
-        }
-    } else {
-        const CacheVMSize subCacheTextDataLimit = this->config.layout.contiguous.value().subCacheTextDataLimit;
-        const CacheVMSize regionPadding = this->config.layout.contiguous.value().subCachePadding;
-        CacheVMSize subCacheTextDataSize(regionPadding);
-
-        // If we added any objc optimizations, then take their size in to account now
-        for ( const Region& region : currentSubCache->regions ) {
-            if ( region.kind == Region::Kind::linkedit )
-                continue;
-            if ( region.chunks.empty() )
-                continue;
-            for ( const Chunk* chunk : region.chunks ) {
-                // Assume the worst in terms of padding, ie, that every segment is preceded by the max
-                // possible number of padding bytes
-                subCacheTextDataSize += CacheVMSize(chunk->alignment()) + chunk->cacheVMSize;
-            }
-        }
-
-        for ( CacheDylib& cacheDylib : this->cacheDylibs ) {
-            // Peek ahead to find the __TEXT size
-            CacheVMSize textDataSize(0ULL);
-            for ( DylibSegmentChunk& segmentInfo : cacheDylib.segments ) {
-                if ( segmentInfo.kind == DylibSegmentChunk::Kind::dylibLinkedit )
-                    continue;
-
-                // Assume the worst in terms of padding, ie, that every segment is preceded by the max
-                // possible number of padding bytes
-                textDataSize += CacheVMSize(segmentInfo.alignment()) + segmentInfo.cacheVMSize;
-
-                // The One Cache stubs will also be included in this limit so account for them too
-                // See addStubsChunks()
-                if ( std::optional<Header::SectionInfo> sectInfo = getStubsSection(&segmentInfo) )
-                    textDataSize += CacheVMSize(sectInfo->size);
-            }
-
-            // If we exceed the current limit, then the current subCache is complete and we need
-            // to start a new one
-            if ( (subCacheTextDataSize + textDataSize) > subCacheTextDataLimit ) {
-                // Create a new subCache
-                otherCaches.push_back(SubCache::makeSubCache(this->options));
-                currentSubCache = &otherCaches.back();
-
-                // Reset the limit for the next subCache
-                subCacheTextDataSize = CacheVMSize(regionPadding);
-            }
-
-            subCacheTextDataSize += textDataSize;
-
-            // We'll add LINKEDIT at the end, not here
-            currentSubCache->addDylib(this->config, cacheDylib);
-            currentSubCache->addLinkeditFromDylib(cacheDylib);
-        }
+
+        currentSubCache->addDylib(this->config, cacheDylib);
     }
 
     // Add all the remaining content in to the final (current) subCache
@@ -4076,54 +3794,17 @@
     return Error();
 }
 
-// returns empty string if symbol is in specified boundDylibName,
-// otherwise it return where symbol actually is defined
-static CString getActualSymbolImplDylib(CString symbolName, CString boundDylibName,
-                                        const std::unordered_map<std::string_view, CacheDylib*>& installNameToDylibMap,
-                                        bool& symbolImplIsFunctionVariant, uint16_t& functionVariantIndex)
-{
-    // find if bind target is really in another dylib or is a function variant
-    __block CString betterDylib;
-    const auto& posi = installNameToDylibMap.find(boundDylibName);
-    if ( posi != installNameToDylibMap.end() ) {
-        CacheDylib* targetDylib = posi->second;
-        Symbol      symbol;
-        if ( targetDylib->inputImage->hasExportsTrie() && targetDylib->inputImage->exportsTrie().hasExportedSymbol(symbolName.c_str(), symbol) ) {
-            betterDylib = (const char*)(targetDylib->installName.data()); // FIXME
-            uint32_t fvi;
-            if (symbol.isFunctionVariant(fvi) ) {
-                symbolImplIsFunctionVariant = true;
-                functionVariantIndex        = fvi;
-            }
-        }
-        else {
-            // check if symbol is from re-exported dylib
-            const Header* targetHdr = (Header*)targetDylib->inputMF;
-            targetHdr->forEachLinkedDylib(^(const char* loadPath, LinkedDylibAttributes kind, Version32 compatVersion, Version32 curVersion, bool synthesizedLink, bool &stop) {
-                if ( kind.reExport ) {
-                    betterDylib = getActualSymbolImplDylib(symbolName, loadPath, installNameToDylibMap, symbolImplIsFunctionVariant, functionVariantIndex);
-                    if ( !betterDylib.empty() ) {
-                        stop = true;
-                    }
-                }
-            });
-        }
-    }
-    return betterDylib;
-}
-
-
 static void parseGOTs(const CacheDylib* dylib, const DylibSegmentChunk* chunk,
                       std::string_view segmentName, std::string_view sectionName,
-                      const std::unordered_map<std::string_view, CacheDylib*>& installNameToDylibMap,
-                      OptimizedGOTSection& dylibOptimizedSection)
-{
+                      DylibSectionCoalescer::OptimizedSection& dylibOptimizedSection)
+{
+    const MachOFile* mf = dylib->inputMF;
     __block Diagnostics diag;
 
     const bool log = false;
 
     // Skip ineligible dylibs
-    if ( !dylib->inputMF->hasChainedFixups() )
+    if ( !mf->hasChainedFixups() )
         return;
 
     // Some dylibs have auth gots in segments other than __AUTH_CONST. Skip them for now
@@ -4131,7 +3812,7 @@
         return;
 
     __block bool supportsGOTUniquing = false;
-    dylib->inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
+    mf->withFileLayout(diag, ^(const mach_o::Layout& layout) {
         mach_o::SplitSeg splitSeg(layout);
 
         if ( splitSeg.isV2() )
@@ -4141,11 +3822,13 @@
     if ( !supportsGOTUniquing )
         return;
 
-    if ( dylib->inputHdr->isArch("x86_64") || dylib->inputHdr->isArch("x86_64h") ) {
+    if ( mf->isArch("x86_64") || mf->isArch("x86_64h") ) {
         __block bool oldLinker = false;
-        dylib->inputHdr->forEachBuildTool(^(Platform platform, uint32_t tool, uint32_t version) {
+        mf->forEachSupportedBuildTool(^(dyld3::Platform platform, uint32_t tool, uint32_t version) {
             uint32_t majorVersion = version >> 16;
-            
+            // uint32_t minorVersion = (version >> 8) && 0xFF;
+            // uint32_t veryMinorVersion = version && 0xFF;
+
             if ( tool == TOOL_LD ) {
                 if ( majorVersion < 803 )
                     oldLinker = true;
@@ -4157,37 +3840,37 @@
     }
 
     // rdar://89319146
-    if ( dylib->inputHdr->isArch("x86_64") || dylib->inputHdr->isArch("x86_64h") ) {
-        if ( !strcmp(dylib->inputHdr->installName(), "/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation") )
+    if ( mf->isArch("x86_64") || mf->isArch("x86_64h") ) {
+        if ( !strcmp(mf->installName(), "/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation") )
             return;
-        if ( !strcmp(dylib->inputHdr->installName(), "/usr/lib/system/libdispatch.dylib") )
+        if ( !strcmp(mf->installName(), "/usr/lib/system/libdispatch.dylib") )
             return;
     }
 
     // rdar://86911139
-    if ( dylib->inputHdr->builtForPlatform(Platform::iOS)
-        && !strcmp(dylib->inputHdr->installName(), "/System/Library/PrivateFrameworks/CoreUI.framework/CoreUI") )
+    if ( mf->builtForPlatform(dyld3::Platform::iOS)
+        && !strcmp(mf->installName(), "/System/Library/PrivateFrameworks/CoreUI.framework/CoreUI") )
         return;
 
     // Dylib segment is eligible.  Walk the GOTs
-    __block std::optional<std::pair<Header::SegmentInfo, Header::SectionInfo>> gotSectionInfo;
+    __block std::optional<dyld3::MachOAnalyzer::SectionInfo> gotSectionInfo;
     __block uint16_t chainedFixupFormat = 0;
-    dylib->inputHdr->forEachSection(^(const Header::SegmentInfo& segInfo, const Header::SectionInfo& sectInfo, bool& stop) {
-        if ( sectInfo.segmentName != segmentName )
+    mf->forEachSection(^(const dyld3::MachOAnalyzer::SectionInfo& sectInfo, bool malformedSectionRange, bool& stop) {
+        if ( sectInfo.segInfo.segName != segmentName )
             return;
-        if ( sectInfo.sectionName != sectionName)
+        if ( sectInfo.sectName != sectionName)
             return;
-        gotSectionInfo = { segInfo, sectInfo };
+        gotSectionInfo = sectInfo;
 
         // As we found the section we want, also get its chained fixup format
-        dylib->inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
+        mf->withFileLayout(diag, ^(const mach_o::Layout& layout) {
             mach_o::Fixups fixups(layout);
 
             fixups.withChainStarts(diag, ^(const dyld_chained_starts_in_image* starts) {
                 MachOFile::forEachFixupChainSegment(diag, starts,
                                                     ^(const dyld_chained_starts_in_segment* segmentInfo,
                                                       uint32_t segIndex, bool& stopSegment) {
-                    if ( segIndex == sectInfo.segIndex ) {
+                    if ( segIndex == sectInfo.segInfo.segIndex ) {
                         chainedFixupFormat = segmentInfo->pointer_format;
                         stopSegment = true;
                     }
@@ -4206,7 +3889,7 @@
         return;
 
     __block std::vector<mach_o::Fixups::BindTargetInfo> bindTargets;
-    dylib->inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
+    mf->withFileLayout(diag, ^(const mach_o::Layout& layout) {
         mach_o::Fixups fixups(layout);
 
         fixups.forEachBindTarget(diag, false, 0, ^(const mach_o::Fixups::BindTargetInfo& info, bool& stop) {
@@ -4223,19 +3906,20 @@
         return;
 
     __block std::vector<const char*> dependents;
-    dylib->inputMF->forEachDependentDylib(^(const char *loadPath, bool isWeak, bool isReExport, bool isUpward, uint32_t compatVersion, uint32_t curVersion, bool &stop) {
+    mf->forEachDependentDylib(^(const char *loadPath, bool isWeak, bool isReExport, bool isUpward, uint32_t compatVersion, uint32_t curVersion, bool &stop) {
         dependents.push_back(loadPath);
     });
 
-    bool hasFunctionVariantFixups = dylib->inputHdr->hasFunctionVariantFixups();
+    auto* cacheGotSection = (CoalescedGOTSection*)dylibOptimizedSection.subCacheSection;
+    DylibSectionCoalescer::DylibSectionOffsetToCacheSectionOffset& offsetMap = dylibOptimizedSection.offsetMap;
 
     // Walk the entries in this section
     // File layout so just add the file offset
-    const uint8_t* content      = (const uint8_t*)dylib->inputHdr + gotSectionInfo->second.fileOffset;
+    const uint8_t* content      = (const uint8_t*)mf + gotSectionInfo->sectFileOffset;
     const uint8_t* pos          = content;
-    const uint8_t* end          = content + gotSectionInfo->second.size;
-    uint32_t       pointerSize  = dylib->inputHdr->pointerSize();
-    assert((gotSectionInfo->second.size % pointerSize == 0));
+    const uint8_t* end          = content + gotSectionInfo->sectSize;
+    uint32_t       pointerSize  = mf->pointerSize();
+    assert((gotSectionInfo->sectSize % pointerSize == 0));
     while ( pos != end ) {
         const dyld3::MachOLoaded::ChainedFixupPointerOnDisk* fixup = (const dyld3::MachOLoaded::ChainedFixupPointerOnDisk*)pos;
         pos += pointerSize;
@@ -4246,83 +3930,56 @@
         uint32_t sourceSectionOffset = (uint32_t)((uint64_t)fixup - (uint64_t)content);
 
         // Note down rebases, but otherwise skip them
-        __block bool     targetIsFunctionVariant  = false;
-        __block uint16_t functionVariantIndex     = 0;
         if ( !isBind ) {
-            if ( hasFunctionVariantFixups ) {
-                // see if this rebase is the local of an internal function variant
-                uint32_t segIndex = gotSectionInfo->first.segmentIndex;
-                dylib->inputImage->functionVariantFixups().forEachFixup(^(mach_o::FunctionVariantFixups::InternalFixup fixupInfo) {
-                    if ( fixupInfo.segIndex != segIndex )
-                        return;
-                    uint64_t segOffset = sourceSectionOffset + gotSectionInfo->second.address - gotSectionInfo->first.vmaddr;
-                    if ( fixupInfo.segOffset == segOffset ) {
-                        targetIsFunctionVariant = true;
-                        functionVariantIndex = fixupInfo.variantIndex;
-                    }
-                });
-            }
-            if ( !targetIsFunctionVariant ) {
-                dylibOptimizedSection.addUnoptimizedOffset(sourceSectionOffset);
-                continue;
-            }
-        }
-
-        const CacheDylib*           targetDylib          = nullptr;
-        CoalescedGOTSection::GOTKey key;
-        if ( targetIsFunctionVariant ) {
-            MachOFile::PointerMetaData pmd(fixup, chainedFixupFormat);
-            char* synthName;
-            asprintf(&synthName, "internal-function-variant#%d", functionVariantIndex);
-            key         = { synthName, dylib->installName, pmd, false, true };
-            targetDylib = dylib;
-        }
-        else {
-            // We don't support addends right now.  But hopefully GOTs don't need them anyway
-            if ( addend != 0 )
-                continue;
-
-            const mach_o::Fixups::BindTargetInfo& bindTarget = bindTargets[bindOrdinal];
-
-            // TODO: Weak GOTs.  See rdar://86510941
-            const char* targetInstallName = nullptr;
-            if ( (bindTarget.libOrdinal > 0) && ((unsigned)bindTarget.libOrdinal <= dependents.size()) ) {
-                targetInstallName = dependents[bindTarget.libOrdinal - 1];
-            } else {
-                dylibOptimizedSection.addUnoptimizedOffset(sourceSectionOffset);
-                continue;
-            }
-
-            // find if bind target is really in another dylib or is a function variant
-            CString betterDylib = getActualSymbolImplDylib(bindTarget.symbolName, targetInstallName, installNameToDylibMap, targetIsFunctionVariant, functionVariantIndex);
-            if ( !betterDylib.empty() && (betterDylib != targetInstallName) ) {
-                targetInstallName = betterDylib.c_str();
-                //    fprintf(stderr, "%s found in %s instead of %s\n", bindTarget.symbolName, betterDylib.c_str(), targetInstallName);
-            }
-
-            if ( targetIsFunctionVariant )
-                targetDylib = installNameToDylibMap.at(targetInstallName);
-
-            MachOFile::PointerMetaData pmd(fixup, chainedFixupFormat);
-            key = { bindTarget.symbolName, targetInstallName, pmd, bindTarget.weakImport, targetIsFunctionVariant };
-        }
-
-        if ( dylibOptimizedSection.addOptimizedOffset(sourceSectionOffset, pointerSize, key) ) {
+            dylibOptimizedSection.unoptimizedOffsets.insert(sourceSectionOffset);
+            continue;
+        }
+
+        // We don't support addends right now.  But hopefully GOTs don't need them anyway
+        if ( addend != 0 )
+            continue;
+
+        const mach_o::Fixups::BindTargetInfo& bindTarget = bindTargets[bindOrdinal];
+
+        // TODO: Weak GOTs.  See rdar://86510941
+        const char* targetInstallName = nullptr;
+        if ( (bindTarget.libOrdinal > 0) && ((unsigned)bindTarget.libOrdinal <= dependents.size()) ) {
+            targetInstallName = dependents[bindTarget.libOrdinal - 1];
+        } else {
+            dylibOptimizedSection.unoptimizedOffsets.insert(sourceSectionOffset);
+            continue;
+        }
+
+        MachOFile::PointerMetaData pmd(fixup, chainedFixupFormat);
+
+        typedef CoalescedGOTSection::GOTKey Key;
+        Key key = { bindTarget.symbolName, targetInstallName, pmd, bindTarget.weakImport };
+
+        int cacheSectionOffset = (int)(cacheGotSection->gotTargetsToOffsets.size() * pointerSize);
+        auto itAndInserted = cacheGotSection->gotTargetsToOffsets.insert({ key, cacheSectionOffset });
+        if ( itAndInserted.second ) {
+            // We inserted the element, so its offset is already valid.  Nothing else to do
+
             if (log) {
                 uint64_t gotOffset = ((uint64_t)pos - (uint64_t)content) - pointerSize;
                 printf("%s[%lld]: %s -> (%s, %s)\n",
-                       sectionName.data(), gotOffset, dylib->inputHdr->installName(),
+                       sectionName.data(), gotOffset, mf->installName(),
                        key.targetDylibName.data(), key.targetSymbolName.data());
             }
-        }
-
-        // store function-variant index in other map
-        if ( targetIsFunctionVariant )
-            dylibOptimizedSection.addFunctionVariantInfo(key, { targetDylib->cacheIndex, functionVariantIndex });
-    }
-
-    // Record which section we just visited
-    dylibOptimizedSection.setSourceSectionInfo(gotSectionInfo->second);
+        } else {
+            // Debugging only.  If we didn't include the GOT then we saved that many bytes
+            cacheGotSection->savedSpace += pointerSize;
+            cacheSectionOffset = itAndInserted.first->second;
+        }
+
+        // Now keep track of this offset in our source dylib as pointing to this offset
+        offsetMap[sourceSectionOffset] = cacheSectionOffset;
+    }
+
+    // Record which segment/section we just visited
+    uint32_t segmentIndex = gotSectionInfo->segInfo.segIndex;
+    dylibOptimizedSection.segmentIndex = segmentIndex;
+    dylibOptimizedSection.sectionVMOffsetInSegment = VMOffset(gotSectionInfo->sectAddr - gotSectionInfo->segInfo.vmAddr);
 }
 
 // This runs after we've assigned Chunk's to SubCache's, but before we've actually
@@ -4341,12 +3998,9 @@
 
     // DylibSegmentChunk's don't have a pointer to their cache dylib.  Make a map for them
     std::unordered_map<const InputFile*, CacheDylib*> fileToDylibMap;
-    std::unordered_map<std::string_view, CacheDylib*> installNameToDylibMap;
     fileToDylibMap.reserve(this->cacheDylibs.size());
-    for ( CacheDylib& dylib : this->cacheDylibs ) {
+    for ( CacheDylib& dylib : this->cacheDylibs )
         fileToDylibMap[dylib.inputFile] = &dylib;
-        installNameToDylibMap[dylib.installName] = &dylib;
-    }
 
     for ( SubCache& subCache : this->subCaches ) {
         // Find the DATA_CONST/AUTH_CONST in each SubCache, if it has any
@@ -4377,6 +4031,9 @@
             // Skip sections if their segment doesn't exist
             switch ( sectionKind ) {
                 case UniquedGOTKind::regular:
+                    if ( dataConstRegion == nullptr )
+                        continue;
+
                     region = dataConstRegion;
                     segmentName = "__DATA_CONST";
                     sectionName = "__got";
@@ -4384,6 +4041,9 @@
                     subCacheUniquedGOTs = &subCache.uniquedGOTsOptimizer.regularGOTs;
                     break;
                 case UniquedGOTKind::authGot:
+                    if ( authConstRegion == nullptr )
+                        continue;
+
                     region = authConstRegion;
                     segmentName = "__AUTH_CONST";
                     sectionName = "__auth_got";
@@ -4391,6 +4051,9 @@
                     subCacheUniquedGOTs = &subCache.uniquedGOTsOptimizer.authGOTs;
                     break;
                 case UniquedGOTKind::authPtr:
+                    if ( authConstRegion == nullptr )
+                        continue;
+
                     region = authConstRegion;
                     segmentName = "__AUTH_CONST";
                     sectionName = "__auth_ptr";
@@ -4398,10 +4061,8 @@
                     subCacheUniquedGOTs = &subCache.uniquedGOTsOptimizer.authPtrs;
                     break;
             }
-            if ( region == nullptr )
-                continue;
-
-            std::vector<OptimizedSection*> dylibOptimizedSections;
+
+            std::vector<DylibSectionCoalescer::OptimizedSection*> dylibOptimizedSections;
             dylibOptimizedSections.reserve(region->chunks.size());
             for ( const Chunk* chunk : region->chunks ) {
                 const DylibSegmentChunk* segmentChunk = chunk->isDylibSegmentChunk();
@@ -4412,7 +4073,7 @@
                     continue;
 
                 CacheDylib* dylib = fileToDylibMap.at(segmentChunk->inputFile);
-                OptimizedGOTSection* dylibUniquedGOTs = nullptr;
+                DylibSectionCoalescer::OptimizedSection* dylibUniquedGOTs = nullptr;
                 switch ( sectionKind ) {
                     case UniquedGOTKind::regular:
                         dylibUniquedGOTs = &dylib->optimizedSections.gots;
@@ -4426,19 +4087,112 @@
                 }
 
                 // Set the dylib GOTs to point to the subCache they'll be uniqued to
-                dylibUniquedGOTs->setSubCacheSection(subCacheUniquedGOTs);
-
-                parseGOTs(dylib, segmentChunk, segmentName, sectionName, installNameToDylibMap, *dylibUniquedGOTs);
-            }
-
-            if ( subCacheUniquedGOTs->empty() )
+                dylibUniquedGOTs->subCacheSection = subCacheUniquedGOTs;
+                dylibOptimizedSections.push_back(dylibUniquedGOTs);
+
+                parseGOTs(dylib, segmentChunk, segmentName, sectionName, *dylibUniquedGOTs);
+            }
+
+            if ( subCacheUniquedGOTs->gotTargetsToOffsets.empty() )
                 continue;
 
-            subCacheUniquedGOTs->finalize(pointerSize, sectionName, config, subCache, *region);
+            // Sort the coalesced GOTs based on the target install name.  We find GOTs in the order we parse
+            // the fixups in the dylibs, but we want the final cache to keep all GOTs for the same target near
+            // each other
+            typedef CoalescedGOTSection::GOTKey Key;
+            std::vector<Key> sortedKeys;
+            sortedKeys.reserve(subCacheUniquedGOTs->gotTargetsToOffsets.size());
+            for ( const auto& keyAndValue : subCacheUniquedGOTs->gotTargetsToOffsets )
+                sortedKeys.push_back(keyAndValue.first);
+
+            std::sort(sortedKeys.begin(), sortedKeys.end(),
+                      [](const Key& a, const Key& b) {
+                // Put libSystem first, then all the /usr/lib/system dylibs
+                // That way any GOTs for re-exports from libsystem will be close to similar GOTs
+                bool isLibsystemA = a.targetDylibName.find("libSystem.B.dylib") != std::string_view::npos;
+                bool isLibsystemB = b.targetDylibName.find("libSystem.B.dylib") != std::string_view::npos;
+                if ( isLibsystemA != isLibsystemB )
+                    return isLibsystemA;
+
+                bool isLibsystemReexportA = a.targetDylibName.find("/usr/lib/system") != std::string_view::npos;
+                bool isLibsystemReexportB = b.targetDylibName.find("/usr/lib/system") != std::string_view::npos;
+                if ( isLibsystemReexportA != isLibsystemReexportB )
+                    return isLibsystemReexportA;
+
+                if ( a.targetDylibName != b.targetDylibName )
+                    return (a.targetDylibName < b.targetDylibName);
+
+                // Install names are the same.  Sort by symbol name
+                return a.targetSymbolName < b.targetSymbolName;
+            });
+
+            // Rewrite entries from their original offset to the new offset
+            std::unordered_map<uint32_t, uint32_t> oldToNewOffsetMap;
+            for ( uint32_t i = 0; i != sortedKeys.size(); ++i ) {
+                const Key& key = sortedKeys[i];
+                auto it = subCacheUniquedGOTs->gotTargetsToOffsets.find(key);
+                assert(it != subCacheUniquedGOTs->gotTargetsToOffsets.end());
+
+                uint32_t newCacheSectionOffset = i * pointerSize;
+
+                // Record the offset mapping for updating the dylibs
+                oldToNewOffsetMap[it->second] = newCacheSectionOffset;
+
+                const bool log = false;
+                if ( log ) {
+                    printf("%s[%d]: %s\n", sectionName.data(), newCacheSectionOffset, key.targetSymbolName.data());
+                }
+
+                it->second = newCacheSectionOffset;
+            }
+
+            // Also rewrite entries in each dylib
+            for ( DylibSectionCoalescer::OptimizedSection* dylibOptimizedSection : dylibOptimizedSections ) {
+                for ( auto& keyAndCacheOffset : dylibOptimizedSection->offsetMap ) {
+                    auto it = oldToNewOffsetMap.find(keyAndCacheOffset.second);
+                    assert(it != oldToNewOffsetMap.end());
+                    keyAndCacheOffset.second = it->second;
+                }
+            }
+
+            // Add the new chunks to the subCache
+            switch ( sectionKind ) {
+                case UniquedGOTKind::regular:
+                    subCache.uniquedGOTs                    = std::make_unique<UniquedGOTsChunk>();
+                    subCache.uniquedGOTs->cacheVMSize       = CacheVMSize((uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size() * pointerSize);
+                    subCache.uniquedGOTs->subCacheFileSize  = CacheFileSize((uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size() * pointerSize);
+
+                    region->chunks.push_back(subCache.uniquedGOTs.get());
+
+                    subCache.uniquedGOTsOptimizer.regularGOTs.cacheChunk = subCache.uniquedGOTs.get();
+                    break;
+                case UniquedGOTKind::authGot:
+                    subCache.uniquedAuthGOTs                    = std::make_unique<UniquedGOTsChunk>();
+                    subCache.uniquedAuthGOTs->cacheVMSize       = CacheVMSize((uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size() * pointerSize);
+                    subCache.uniquedAuthGOTs->subCacheFileSize  = CacheFileSize((uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size() * pointerSize);
+
+                    region->chunks.push_back(subCache.uniquedAuthGOTs.get());
+
+                    subCache.uniquedGOTsOptimizer.authGOTs.cacheChunk = subCache.uniquedAuthGOTs.get();
+                    break;
+                case UniquedGOTKind::authPtr:
+                    subCache.uniquedAuthPtrs                    = std::make_unique<UniquedGOTsChunk>();
+                    subCache.uniquedAuthPtrs->cacheVMSize       = CacheVMSize((uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size() * pointerSize);
+                    subCache.uniquedAuthPtrs->subCacheFileSize  = CacheFileSize((uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size() * pointerSize);
+
+                    region->chunks.push_back(subCache.uniquedAuthPtrs.get());
+
+                    subCache.uniquedGOTsOptimizer.authPtrs.cacheChunk = subCache.uniquedAuthPtrs.get();
+                    break;
+            }
 
             if ( this->config.log.printStats ) {
+                uint64_t totalSourceGOTs = 0;
+                for ( DylibSectionCoalescer::OptimizedSection* dylibOptimizedSection : dylibOptimizedSections ) {
+                    totalSourceGOTs += dylibOptimizedSection->offsetMap.size();
+                }
                 stats.add("  got uniquing: uniqued %lld %s GOTs to %lld GOTs\n",
-                          subCacheUniquedGOTs->numSourceGOTs(), kindName, subCacheUniquedGOTs->numCacheGOTs());
+                          totalSourceGOTs, kindName, (uint64_t)subCacheUniquedGOTs->gotTargetsToOffsets.size());
             }
         }
     }
@@ -4516,11 +4270,6 @@
     };
 
     auto tproConstSortOrder = [](const Chunk* a, const Chunk* b) -> bool {
-        // Sort uniqued GOTs before dylib TPRO_CONST.  This puts the uniqued
-        // GOTs before the libdyld TPRO_CONST, but should still be on the same page
-        if ( a->sortOrder() != b->sortOrder() )
-            return a->sortOrder() < b->sortOrder();
-
         const DylibSegmentChunk* dylibA = a->isTPROChunk();
         const DylibSegmentChunk* dylibB = b->isTPROChunk();
         // Note this shouldn't be possible, but best to be safe and avoid asserting
@@ -4538,7 +4287,7 @@
         return false;
     };
 
-    auto readOnlySortOrder = [](const Chunk* a, const Chunk* b) -> bool {
+    auto linkeditSortOrder = [](const Chunk* a, const Chunk* b) -> bool {
         // Sort read-only segments before LINKEDIT
         if ( a->sortOrder() != b->sortOrder() )
             return a->sortOrder() < b->sortOrder();
@@ -4550,31 +4299,20 @@
 
     for ( SubCache& subCache : this->subCaches ) {
         for ( Region& region : subCache.regions ) {
-            switch ( region.kind ) {
-                case Region::Kind::text:
-                    std::stable_sort(region.chunks.begin(), region.chunks.end(), textSortOrder);
-                    break;
-                case Region::Kind::dataConst:
-                case Region::Kind::authConst:
-                    std::stable_sort(region.chunks.begin(), region.chunks.end(), dataConstSortOrder);
-                    break;
-                case Region::Kind::tproConst:
-                case Region::Kind::tproAuthConst:
-                    std::stable_sort(region.chunks.begin(), region.chunks.end(), tproConstSortOrder);
-                    break;
-                case Region::Kind::data:
-                case Region::Kind::auth:
-                    std::stable_sort(region.chunks.begin(), region.chunks.end(), dataSortOrder);
-                    break;
-                case Region::Kind::readOnly:
-                case Region::Kind::linkedit:
-                    std::stable_sort(region.chunks.begin(), region.chunks.end(), readOnlySortOrder);
-                    break;
-                case Region::Kind::unmapped:
-                case Region::Kind::dynamicConfig:
-                case Region::Kind::codeSignature:
-                case Region::Kind::numKinds:
-                    break;
+            if ( region.kind == Region::Kind::text ) {
+                std::stable_sort(region.chunks.begin(), region.chunks.end(), textSortOrder);
+            }
+            else if ( (region.kind == Region::Kind::data) || (region.kind == Region::Kind::auth) ) {
+                std::stable_sort(region.chunks.begin(), region.chunks.end(), dataSortOrder);
+            }
+            else if ( region.kind == Region::Kind::dataConst ) {
+                std::stable_sort(region.chunks.begin(), region.chunks.end(), dataConstSortOrder);
+            }
+            else if ( (region.kind == Region::Kind::tproConst) || (region.kind == Region::Kind::tproAuthConst) ) {
+                std::stable_sort(region.chunks.begin(), region.chunks.end(), tproConstSortOrder);
+            }
+            else if ( region.kind == Region::Kind::linkedit ) {
+                std::stable_sort(region.chunks.begin(), region.chunks.end(), linkeditSortOrder);
             }
         }
     }
@@ -4696,7 +4434,7 @@
 
 void SharedCacheBuilder::printSubCaches() const
 {
-    const bool printSegments = this->config.log.printDebugCacheLayout;
+    const bool printSegments = this->config.log.printDebug;
 
     if ( !this->config.log.printStats )
         return;
@@ -5193,6 +4931,7 @@
         const Region& lastRegion = subCache.regions.back();
         uint64_t      bufferSize = (lastRegion.subCacheFileOffset + lastRegion.subCacheFileSize).rawValue();
 
+#if SUPPORT_CACHE_BUILDER_MEMORY_BUFFERS
         // The MRM builder has no file system, so use an in-memory buffer
         vm_address_t fullAllocatedBuffer;
         if ( kern_return_t kr = vm_allocate(mach_task_self(), &fullAllocatedBuffer, bufferSize, VM_FLAGS_ANYWHERE); kr != 0 ) {
@@ -5202,6 +4941,47 @@
         uint8_t *buffer = (uint8_t*)fullAllocatedBuffer;
         subCache.buffer     = buffer;
         subCache.bufferSize = bufferSize;
+#else
+        char pathTemplate[] = "/tmp/temp.XXXXXX";
+        int  fd             = mkstemp(pathTemplate);
+        if ( fd == -1 ) {
+            // Failed to create the file
+            return Error("could not create shared cache file because: %s", strerror(errno));
+        }
+
+        // Resize the file
+        if ( int result = ftruncate(fd, bufferSize); result == -1 ) {
+            // Failed to resize to the space we need
+            return Error("could not truncate shared cache file because: %s", strerror(errno));
+        }
+
+        void* buffer = mmap(nullptr, (vm_size_t)bufferSize, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, fd, 0);
+        if ( buffer == MAP_FAILED ) {
+            // Failed to mmap the file
+            return Error("could not mmap shared cache file because: %s", strerror(errno));
+        }
+
+        // TODO: It would be great to unlink the file, so that it won't be there on disk if the builder crashes
+#if 0
+        // Unlink the file.  This way, it'll be removed if we crash
+        if ( int result = unlinkat(fd, pathTemplate, 0) ) {
+            // Failed to unlink the file
+            return Error("could not unlink shared cache file because: %s", strerror(errno));
+        }
+
+        // Close the file as we don't need it now that we have the mmapped buffer
+        if ( int result = close(fd) ) {
+            // Failed to close the file
+            return Error("could not close shared cache file because: %s", strerror(errno));
+        }
+#endif
+
+        subCache.buffer     = (uint8_t*)buffer;
+        subCache.bufferSize = bufferSize;
+        subCache.fd         = fd;
+        subCache.tempPath   = pathTemplate;
+
+#endif // SUPPORT_CACHE_BUILDER_MEMORY_BUFFERS
 
         if ( log ) {
             this->config.log.log("SubCache[%d] allocated (%p..%p)\n",
@@ -5227,7 +5007,6 @@
         assert(!cacheDylib.segments.empty());
         assert(cacheDylib.segments[0].kind == cache_builder::DylibSegmentChunk::Kind::dylibText);
         cacheDylib.cacheMF          = (MachOFile*)cacheDylib.segments[0].subCacheBuffer;
-        cacheDylib.cacheHdr         = (const Header*)cacheDylib.segments[0].subCacheBuffer;
         cacheDylib.cacheLoadAddress = cacheDylib.segments[0].cacheVMAddress;
     }
 
@@ -5243,7 +5022,7 @@
     }
 
     // Add a watchpoint for anything we need to debug
-#if 0
+#if DEBUG
     {
         CacheVMAddress vmAddrToWatch(0x00007FFB40FB4D58ULL);
         for ( const SubCache& subCache : this->subCaches ) {
@@ -5265,31 +5044,6 @@
     }
 #endif
 
-
-    // Add a watchpoint for anything we need to debug
-#if 0
-    {
-        CacheFileOffset fileOffsetToWatch(0x0012bc0ULL);
-        std::string_view suffixToWatch = ".01";
-        for ( const SubCache& subCache : this->subCaches ) {
-            if ( subCache.fileSuffix != suffixToWatch )
-                continue;
-            for ( const Region& region : subCache.regions ) {
-                for ( const Chunk* chunk : region.chunks ) {
-                    if ( fileOffsetToWatch < chunk->subCacheFileOffset )
-                        continue;
-                    if ( fileOffsetToWatch >= (chunk->subCacheFileOffset + chunk->subCacheFileSize) )
-                        continue;
-                    uint64_t offsetInChunk = fileOffsetToWatch.rawValue() - chunk->subCacheFileOffset.rawValue();
-                    uint8_t* addrToWatch = chunk->subCacheBuffer + offsetInChunk;
-                    printf("watchpoint set expression -w w -s 8 -- %p\n", addrToWatch);
-                    printf("");
-                }
-            }
-        }
-    }
-#endif
-
     return Error();
 }
 
@@ -5340,6 +5094,7 @@
 
                 assert(segment.subCacheFileSize.rawValue() == 0);
                 segment.subCacheFileSize = region->subCacheFileSize;
+
             }
         }
 
@@ -5396,10 +5151,7 @@
                 case Chunk::Kind::linkeditExportTrie:
                     movedLinkedit.kind = MovedLinkedit::Kind::exportTrie;
                     break;
-                case Chunk::Kind::linkeditFunctionVariants:
-                    movedLinkedit.kind = MovedLinkedit::Kind::functionVariants;
-                    break;
-               default:
+                default:
                     assert(0);
                     break;
             }
@@ -5446,40 +5198,6 @@
     });
 
     assert(!err.hasError());
-
-    // Now that we have an adjustor, use it to adjust the bindTargets
-    err = parallel::forEach(this->cacheDylibs, ^(size_t index, CacheDylib& cacheDylib) {
-        for ( CacheDylib::BindTarget& bindTarget : cacheDylib.bindTargets ) {
-            // Adjust the bind target.  We have a runtime offset for the target input dylib, but we need to know where that runtime Offset will
-            // map to in the target cache dylib
-            switch ( bindTarget.kind ) {
-                case CacheDylib::BindTarget::Kind::absolute:
-                    // Skip these.  They won't change due to shifting the input dylib in to the cache
-                    break;
-                case CacheDylib::BindTarget::Kind::inputImage: {
-                    // Convert from an input dylib offset to the cache dylib offset
-                    CacheDylib::BindTarget::InputImage inputImage = bindTarget.inputImage;
-                    InputDylibVMAddress    targetInputVMAddr = inputImage.targetDylib->inputLoadAddress + inputImage.targetRuntimeOffset;
-                    CacheVMAddress         targetCacheVMAddr = inputImage.targetDylib->adjustor->adjustVMAddr(targetInputVMAddr);
-
-                    // Actually change the bindTarget to reflect the new type
-                    bindTarget.kind = CacheDylib::BindTarget::Kind::cacheImage;
-                    bindTarget.inputImage.~InputImage();
-                    bindTarget.cacheImage = (CacheDylib::BindTarget::CacheImage) {
-                        VMOffset(targetCacheVMAddr - inputImage.targetDylib->cacheLoadAddress),
-                        inputImage.targetDylib, inputImage.isWeakDef,
-                        inputImage.isFunctionVariant, inputImage.functionVariantTableIndex
-                    };
-                    break;
-                }
-                case CacheDylib::BindTarget::Kind::cacheImage:
-                    return Error("Shouldn't see cacheImage fixups at this point");
-            }
-        }
-        return Error();
-    });
-
-    assert(!err.hasError());
 }
 
 void SharedCacheBuilder::adjustObjCClasses()
@@ -5588,34 +5306,11 @@
     }
 }
 
-Error SharedCacheBuilder::calculatePatchTableSize()
-{
-    Stats        stats(this->config);
-    Timer::Scope timedScope(this->config, "calculatePatchTableSize time");
-    
-    PatchTableBuilder& builder = this->patchTableOptimizer.builder;
-    Error err = builder.prepare(this->cacheDylibs, this->patchTableOptimizer.patchInfos);
-    if ( err.hasError() )
-        return err;
-
-    uint64_t patchTableSize = builder.getPatchTableSize();
-
-    auto* patchTableChunk = this->patchTableOptimizer.patchTableChunk;
-    patchTableChunk->cacheVMSize = CacheVMSize(patchTableSize);
-    patchTableChunk->subCacheFileSize = CacheFileSize(patchTableSize);
-
-    if ( this->config.log.printStats ) {
-        stats.add("  patch table: used %lld bytes\n", patchTableSize);
-    }
-    
-    return Error();
-}
-
 Error SharedCacheBuilder::emitPatchTable()
 {
     Stats        stats(this->config);
     Timer::Scope timedScope(this->config, "emitPatchTable time");
-
+    
     // Skip this optimization on simulator until we've qualified it there
     __block PatchTableBuilder::PatchableClassesSet      patchableObjCClasses;
     __block PatchTableBuilder::PatchableSingletonsSet   patchableCFObj2;
@@ -5627,204 +5322,38 @@
                 patchableObjCClasses.insert(cacheDylib.adjustor->adjustVMAddr(inputVMAddr));
             });
 
-            cacheDylib.cacheHdr->forEachSingletonPatch(^(uint64_t runtimeOffset) {
+            // Note we have a diagnostic object here, but we don't care if it fails.  Then we'll
+            // just skip singleton patching on this dylib
+            Diagnostics diag;
+            cacheDylib.cacheMF->forEachSingletonPatch(diag, ^(MachOFile::SingletonPatchKind kind, uint64_t runtimeOffset) {
                 patchableCFObj2.insert(cacheDylib.cacheLoadAddress + VMOffset(runtimeOffset));
             });
         }
     }
-
-    const auto* patchTableChunk = this->patchTableOptimizer.patchTableChunk;
+    
+    PatchTableBuilder builder;
+    Error err = builder.build(this->cacheDylibs, this->patchTableOptimizer.patchInfos,
+                              patchableObjCClasses,
+                              patchableCFObj2,
+                              this->config.layout.cacheBaseAddress);
+    if ( err.hasError() )
+        return err;
+    
+    auto* patchTableChunk = this->patchTableOptimizer.patchTableChunk;
     uint8_t* buffer = patchTableChunk->subCacheBuffer;
     uint64_t bufferSize = patchTableChunk->subCacheFileSize.rawValue();
     uint64_t patchInfoAddr = patchTableChunk->cacheVMAddress.rawValue();
-
-    PatchTableBuilder& builder = this->patchTableOptimizer.builder;
-    if ( Error error = builder.build(this->cacheDylibs, this->patchTableOptimizer.patchInfos, patchableObjCClasses, patchableCFObj2, this->config.layout.cacheBaseAddress) )
-        return error;
     if ( Error error = builder.write(buffer, bufferSize, patchInfoAddr); error.hasError() )
         return error;
-
+    
     // We don't need the patchInfos, so clear it to save memory
     this->patchTableOptimizer.patchInfos.clear();
 
-    return Error();
-}
-
-Error SharedCacheBuilder::emitPrewarmingData()
-{
-    // Skip everything if the JSON file is empty
-    if ( this->options.prewarmingOptimizations.empty() )
-        return Error::none();
-
-    using json::Node;
-    using json::NodeValueType;
-
-    Stats        stats(this->config);
-    Timer::Scope timedScope(this->config, "emitPrewarmingData time");
-
-    __block Diagnostics diag;
-    Node rootNode = json::readJSON(diag, this->options.prewarmingOptimizations.data(),
-                                   this->options.prewarmingOptimizations.size(),
-                                   false /* useJSON5 */);
-    if ( diag.hasError() )
-        return Error("%s", diag.errorMessageCStr());
-
-    std::unordered_map<std::string_view, const CacheDylib*> dylibMap;
-    for ( const CacheDylib& cacheDylib : cacheDylibs )
-        dylibMap[cacheDylib.installName] = &cacheDylib;
-
-    // Add install names too, just in case dylibs are moving
-    dylibMap.insert(this->dylibAliases.begin(), this->dylibAliases.end());
-
-    // Format is something like:
-    // [
-    //     {
-    //         "install_name": "..."
-    //         "locations": [
-    //             {
-    //                 "name": "symbol name",
-    //                 "offset": 0
-    //             }
-    //         ]
-    //     },
-    // ...
-    // ]
-    if ( rootNode.type != NodeValueType::Array )
-        return Error::none();
-
-    std::vector<dyld_prewarming_entry> prewarmingEntries;
-
-    const uint64_t PrewarmingPageSize = DYLD_CACHE_PREWARMING_DATA_PAGE_SIZE;
-    const uint64_t PrewarmingPageMask = ~(PrewarmingPageSize - 1);
-
-    // FIXME: Do this in parallel if needed, or even in CacheDylib when it goes parallel
-    for ( const Node& fileNode : rootNode.array ) {
-        // Find the install name and locations array
-        auto installNameIt = fileNode.map.find("install_name");
-        auto locationsIt = fileNode.map.find("locations");
-        if ( (installNameIt == fileNode.map.end()) || (locationsIt == fileNode.map.end()) )
-            continue;
-
-        const Node& installNameNode = installNameIt->second;
-        const Node& locationsNode = locationsIt->second;
-
-        // Find the cache dylib for this install name
-        const CacheDylib* cacheDylib = nullptr;
-        if ( auto it = dylibMap.find(installNameNode.value); it != dylibMap.end() )
-            cacheDylib = it->second;
-        else
-            continue;
-
-        // Get the exports trie
-        __block const uint8_t* trieStart = nullptr;
-        __block size_t trieSize = 0;
-        cacheDylib->inputMF->withFileLayout(diag, ^(const mach_o::Layout &layout) {
-            if ( layout.linkedit.exportsTrie.hasValue() ) {
-                trieStart = layout.linkedit.exportsTrie.buffer;
-                trieSize  = layout.linkedit.exportsTrie.bufferSize;
-            }
-        });
-        if ( diag.hasError() )
-            return Error("%s", diag.errorMessageCStr());
-
-        if ( trieStart == nullptr )
-            continue;
-
-        ExportsTrie exportsTrie(trieStart, trieSize);
-
-        // Lazily make a map of local symbols if we need it
-        __block std::unordered_map<std::string_view, uint64_t> localsMap;
-        auto populateLocals = ^() {
-            cacheDylib->inputMF->withFileLayout(diag, ^(const mach_o::Layout& layout) {
-                mach_o::SymbolTable symbolTable(layout);
-
-                symbolTable.forEachLocalSymbol(diag, ^(const char *symbolName, uint64_t n_value, uint8_t n_type,
-                                                       uint8_t n_sect, uint16_t n_desc, bool& stop) {
-                    if ( ((n_type & N_TYPE) == N_SECT) && ((n_type & N_STAB) == 0) ) {
-                        localsMap[symbolName] = (n_value - cacheDylib->inputLoadAddress.rawValue());
-                    }
-                });
-            });
-        };
-
-        // Walk all locations, looking them up in exports/locals
-        for ( const Node& locationNode : locationsNode.array ) {
-            auto nameIt = locationNode.map.find("name");
-            auto offsetIt = locationNode.map.find("offset");
-            if ( (nameIt == locationNode.map.end()) || (offsetIt == locationNode.map.end()) )
-                continue;
-
-            uint64_t offset = parseRequiredInt(diag, offsetIt->second);
-            if ( diag.hasError() )
-                return Error("%s", diag.errorMessageCStr());
-
-            // Check for an export first, then a local
-            uint64_t implOffset = 0;
-            mach_o::Symbol symbol;
-            if ( exportsTrie.hasExportedSymbol(nameIt->second.value.c_str(), symbol) ) {
-                if ( !symbol.isRegular(implOffset) )
-                    continue;
-            } else {
-                if ( localsMap.empty() ) {
-                    populateLocals();
-                    if ( diag.hasError() )
-                        return Error("%s", diag.errorMessageCStr());
-                }
-
-                if ( auto localsIt = localsMap.find(nameIt->second.value); localsIt != localsMap.end() )
-                    implOffset = localsIt->second;
-            }
-
-            InputDylibVMAddress inputVMAddr(cacheDylib->inputLoadAddress + VMOffset(implOffset));
-            CacheVMAddress cacheVMAddr = cacheDylib->adjustor->adjustVMAddr(inputVMAddr);
-            cacheVMAddr += VMOffset(offset);
-
-            VMOffset cacheVMOffset = cacheVMAddr - this->config.layout.cacheBaseAddress;
-
-            prewarmingEntries.push_back({ cacheVMOffset.rawValue() & PrewarmingPageMask, 1 });
-        }
-    }
-
-    PrewarmingOptimizer& opt = this->prewarmingOptimizer;
-    dyld_prewarming_header* header = (dyld_prewarming_header*)opt.prewarmingChunk->subCacheBuffer;
-    const void* bufferEnd = opt.prewarmingChunk->subCacheBuffer + opt.prewarmingChunk->subCacheFileSize.rawValue();
-
-    if ( prewarmingEntries.empty() ) {
-        header->version = 1;
-        header->count = 0;
-        return Error::none();
-    }
-
-    // Sort by ascending VM addresses
-    std::sort(prewarmingEntries.begin(), prewarmingEntries.end(),
-              [](const dyld_prewarming_entry& a, const dyld_prewarming_entry& b) {
-        return a.cacheVMOffset < b.cacheVMOffset;
-    });
-
-    // Combine adjacent entries
-    std::vector<dyld_prewarming_entry> combinedEntries;
-    combinedEntries.push_back(prewarmingEntries.front());
-    for ( const dyld_prewarming_entry& entry : std::span(prewarmingEntries).subspan(1) ) {
-        dyld_prewarming_entry& last = combinedEntries.back();
-        if ( entry.cacheVMOffset == last.cacheVMOffset )
-            continue;
-        if ( entry.cacheVMOffset == (last.cacheVMOffset + PrewarmingPageSize) ) {
-            ++last.numPages;
-        } else {
-            combinedEntries.push_back(entry);
-        }
-    }
-
-    // write the results
-    dyld_prewarming_entry* firstOutputEntry = &header->entries[0];
-    dyld_prewarming_entry* lastOutputEntry = &header->entries[combinedEntries.size()];
-    if ( lastOutputEntry > bufferEnd )
-        return Error("overflow in prewarming optimizer (%p vs %p)", lastOutputEntry, bufferEnd);
-
-    header->version = 1;
-    header->count = (uint32_t)combinedEntries.size();
-    memcpy(firstOutputEntry, combinedEntries.data(), sizeof(dyld_prewarming_entry) * header->count);
-
+    if ( this->config.log.printStats ) {
+        uint64_t patchInfoSize = builder.getPatchTableSize();
+        stats.add("  patch table: used %lld out of %lld bytes of buffer\n", patchInfoSize, bufferSize);
+    }
+    
     return Error();
 }
 
@@ -5854,7 +5383,7 @@
         }
     } else {
         const char* binPath = "/usr/bin/";
-        if ( options.platform == Platform::driverKit )
+        if ( options.platform == dyld3::Platform::driverKit )
             binPath = "/System/Library/DriverExtensions/";
         for ( const InputFile* exeFile : executableFiles ) {
             if ( startsWith(exeFile->path, binPath) )
@@ -5912,8 +5441,8 @@
             }
 
             // The cache segments don't have the permissions.  Get that from the load commands
-            cacheDylib.cacheHdr->forEachSegment(^(const Header::SegmentInfo& info, bool& stop) {
-                segments[info.segmentIndex].protections = info.initProt;
+            cacheDylib.cacheMF->forEachSegment(^(const MachOFile::SegmentInfo& info, bool& stop) {
+                segments[info.segIndex].protections = info.protections;
             });
             this->dylibSegmentLayout.push_back(std::move(segments));
         }
@@ -5940,11 +5469,6 @@
                         linkeditLayout.exportsTrie.entryCount  = 0; // Not needed here
                         linkeditLayout.exportsTrie.hasLinkedit = true;
                         break;
-                    case MovedLinkedit::Kind::functionVariants:
-                        linkeditLayout.functionVariants.buffer      = kindAndLinkdit.second.cacheLocation;
-                        linkeditLayout.functionVariants.bufferSize  = (uint32_t)kindAndLinkdit.second.dataSize.rawValue();
-                        linkeditLayout.functionVariants.hasLinkedit = true;
-                        break;
                     case MovedLinkedit::Kind::numKinds:
                         // This should never happen
                         assert(false);
@@ -5970,21 +5494,21 @@
         this->executableSegmentLayout.reserve(executableFiles.size());
         for ( const InputFile* executableFile : executableFiles ) {
             __block std::vector<mach_o::SegmentLayout> segments;
-            ((const Header*)executableFile->mf)->forEachSegment(^(const Header::SegmentInfo& info, bool& stop) {
+            executableFile->mf->forEachSegment(^(const MachOFile::SegmentInfo& info, bool& stop) {
                 // Note file layout here, not VM layout
                 uint8_t*              segmentBuffer = (uint8_t*)executableFile->mf + info.fileOffset;
                 mach_o::SegmentLayout segment;
-                segment.vmAddr      = info.vmaddr;
-                segment.vmSize      = info.vmsize;
+                segment.vmAddr      = info.vmAddr;
+                segment.vmSize      = info.vmSize;
                 segment.fileOffset  = info.fileOffset;
                 segment.fileSize    = info.fileSize;
                 segment.buffer      = segmentBuffer;
-                segment.protections = info.initProt;
+                segment.protections = info.protections;
 
                 segment.kind        = mach_o::SegmentLayout::Kind::unknown;
-                if ( info.segmentName == "__TEXT" ) {
+                if ( !strcmp(info.segName, "__TEXT") ) {
                     segment.kind    = mach_o::SegmentLayout::Kind::text;
-                } else if ( info.segmentName == "__LINKEDIT" ) {
+                } else if ( !strcmp(info.segName, "__LINKEDIT") ) {
                     segment.kind    = mach_o::SegmentLayout::Kind::linkedit;
                 }
 
@@ -6076,7 +5600,7 @@
         }
     }
 
-    Loader::LoadOptions::Finder loaderFinder = ^(Diagnostics& loadDiag, Platform, const char* loadPath, const dyld4::Loader::LoadOptions& options) {
+    Loader::LoadOptions::Finder loaderFinder = ^(Diagnostics& loadDiag, dyld3::Platform, const char* loadPath, const dyld4::Loader::LoadOptions& options) {
         auto pos = loadersMap.find(loadPath);
         if ( pos != loadersMap.end() ) {
             return (const Loader*)pos->second;
@@ -6225,14 +5749,14 @@
             __block InputDylibVMAddress inputOptPtrsVMAddress;
             __block uint64_t            sectionSize = 0;
             __block bool                found       = false;
-            cacheDylib->inputHdr->forEachSection(^(const Header::SectionInfo& sectInfo, bool& stop) {
-                if ( !sectInfo.segmentName.starts_with("__DATA") && !sectInfo.segmentName.starts_with("__AUTH") )
+            cacheDylib->inputMF->forEachSection(^(const dyld3::MachOAnalyzer::SectionInfo& sectInfo, bool malformedSectionRange, bool& stop) {
+                if ( (strncmp(sectInfo.segInfo.segName, "__DATA", 6) != 0) && (strncmp(sectInfo.segInfo.segName, "__AUTH", 6) != 0) )
                     return;
-                if ( sectInfo.sectionName != "__objc_opt_ptrs" )
+                if ( strcmp(sectInfo.sectName, "__objc_opt_ptrs") != 0 )
                     return;
 
-                inputOptPtrsVMAddress = InputDylibVMAddress(sectInfo.address);
-                sectionSize           = sectInfo.size;
+                inputOptPtrsVMAddress = InputDylibVMAddress(sectInfo.sectAddr);
+                sectionSize           = sectInfo.sectSize;
 
                 found = true;
                 stop  = true;
@@ -6249,7 +5773,7 @@
             //     T protocolClass;
             // };
             // typedef struct objc_opt_pointerlist_tt<uintptr_t> objc_opt_pointerlist_t;
-            if ( sectionSize < cacheDylib->inputHdr->pointerSize() ) {
+            if ( sectionSize < cacheDylib->inputMF->pointerSize() ) {
                 return Error("libobjc's pointer list section is too small (metadata not optimized)");
             }
 
@@ -6343,8 +5867,8 @@
         }
 
         // Assume last segment file size is the overall file size
-        __block uint32_t fileSize = 0;
-        ((const Header*)inputFile->mf)->forEachSegment(^(const Header::SegmentInfo& info, bool& stop) {
+        __block uint64_t fileSize = 0;
+        inputFile->mf->forEachSegment(^(const MachOFile::SegmentInfo& info, bool& stop) {
             fileSize = std::max(fileSize, info.fileOffset + info.fileSize);
         });
         otherMapping[inputFile->path] = { inputFile->mf, fileSize };
@@ -6379,7 +5903,7 @@
         KernelArgs       kernArgs(mainMF, { "test.exe" }, {}, {});
         SyscallDelegate  osDelegate;
         osDelegate._mappedOtherDylibs = otherMapping;
-        osDelegate._gradedArchs       = &this->options.gradedArchs;
+        osDelegate._gradedArchs       = &this->options.archs;
         //osDelegate._dyldCache           = dyldCache;
         STACK_ALLOCATOR(alloc, 0);
         ProcessConfig      processConfig(&kernArgs, osDelegate, alloc);
@@ -6388,7 +5912,7 @@
         RuntimeState*      statePtr = &state;
         Diagnostics        launchDiag;
 
-        processConfig.reset(mainMF, exeFile->path.c_str(), exeFile->size, nullptr);
+        processConfig.reset(mainMF, exeFile->path.c_str(), nullptr);
         state.resetCachedDylibsArrays(cachedDylibsLoaderSet);
 
         // FIXME: This is terrible and needs to be a real reset method
@@ -6396,9 +5920,7 @@
         processConfig.dyldCache.dylibsExpectedOnDisk = !this->options.dylibsRemovedFromDisk;
         processConfig.dyldCache.development = isDevelopmentSharedCache(this->options);
 
-        // Disable objc optimizations from EK shared cache
-        bool emitObjcOpts = !this->options.platform.isExclaveKit();
-        if ( !this->objcOptimizer.objcDylibs.empty() && emitObjcOpts ) {
+        if ( !this->objcOptimizer.objcDylibs.empty() ) {
             processConfig.dyldCache.objcClassHashTable = (const objc::ClassHashTable*)this->objcClassOptimizer.classHashTableChunk->subCacheBuffer;
             processConfig.dyldCache.objcSelectorHashTable = (const objc::SelectorHashTable*)this->objcSelectorOptimizer.selectorHashTableChunk->subCacheBuffer;
             processConfig.dyldCache.objcProtocolHashTable = (const objc::ProtocolHashTable*)this->objcProtocolOptimizer.protocolHashTableChunk->subCacheBuffer;
@@ -6409,15 +5931,9 @@
             processConfig.dyldCache.unslidLoadAddress = config.layout.cacheBaseAddress.rawValue();
         }
 
-        // check if main executable is valid mach-o
-        if ( mach_o::Error lerr = state.config.process.mainExecutableHdr->valid(state.config.process.mainExecutableSliceSize) ) {
-            fprintf(stderr, "warning: can't build PrebuiltLoaderSet for '%s': %s\n", exeFile->path.c_str(), lerr.message());
-            return Error();
-        }
-
-        Loader::LoadOptions::Finder loaderFinder = ^(Diagnostics& diag, Platform plat, const char* loadPath, const dyld4::Loader::LoadOptions& loadOptions) {
+        Loader::LoadOptions::Finder loaderFinder = ^(Diagnostics& diag, dyld3::Platform plat, const char* loadPath, const dyld4::Loader::LoadOptions& loadOptions) {
             // when building macOS cache, there may be some incorrect catalyst paths
-            if ( (plat == Platform::macCatalyst) && (strncmp(loadPath, "/System/iOSSupport/", 19) != 0) ) {
+            if ( (plat == dyld3::Platform::iOSMac) && (strncmp(loadPath, "/System/iOSSupport/", 19) != 0) ) {
                 char altPath[PATH_MAX];
                 strlcpy(altPath, "/System/iOSSupport", PATH_MAX);
                 strlcat(altPath, loadPath, PATH_MAX);
@@ -6497,39 +6013,40 @@
         return Error();
     });
 
-    const PrebuiltLoaderChunk* loaderChunk = this->prebuiltLoaderBuilder.executablesLoaderChunk;
-    const uint64_t loaderBufferSize = loaderChunk->subCacheFileSize.rawValue();
-
     assert(!err.hasError());
+
     std::map<std::string_view, const dyld4::PrebuiltLoaderSet*> prebuiltsMap;
     uint64_t prebuiltsSpace = 0;
-    uint64_t requiredPrebuiltsSpace = 0;
     for ( uint64_t i = 0; i != this->exeInputFiles.size(); ++i ) {
         const InputFile*                exeFile   = this->exeInputFiles[i];
         const dyld4::PrebuiltLoaderSet* loaderSet = executableLoaders[i];
         if ( loaderSet == nullptr )
             continue;
 
-        uint64_t requiredSpace = alignTo(loaderSet->size(), alignof(dyld4::PrebuiltLoaderSet));
-        requiredPrebuiltsSpace += requiredSpace;
-        if ( (prebuiltsSpace + requiredSpace) > loaderBufferSize ) {
-            // skip this loader if it doesn't fit
-            this->warning("cache buffer too small to hold executable PrebuiltLoaderSet '%s' (size=%lldKB)",
-                          exeFile->path.c_str(), requiredSpace / 1024);
-            continue;
-        }
-
         prebuiltsMap[exeFile->path.c_str()] = loaderSet;
-        prebuiltsSpace += requiredSpace;
-    }
-
-    if ( requiredPrebuiltsSpace != prebuiltsSpace ) {
-        this->warning("cache buffer too small to hold executable PrebuiltLoaderSet (prebuiltLoaderSet size=%lluKB, buffer size=%lldKB)",
-                      requiredPrebuiltsSpace / 1024, loaderBufferSize / 1024);
-    }
+        prebuiltsSpace += alignTo(loaderSet->size(), 8);
+    }
+
+    const PrebuiltLoaderChunk* loaderChunk = this->prebuiltLoaderBuilder.executablesLoaderChunk;
+    uint64_t loaderBufferSize = loaderChunk->subCacheFileSize.rawValue();
 
     if ( this->config.log.printStats ) {
         stats.add("  dyld4 executable Loader's : used %lld out of %lld bytes of buffer\n", prebuiltsSpace, loaderBufferSize);
+    }
+
+    if ( prebuiltsSpace > loaderBufferSize ) {
+        if ( dylibHasMissingDependency ) {
+            // At least one dylib was evicted.  If it was soemthing common, like UIKit/AppKit, then its going to
+            // end up being included in every executable loader and the buffer will overflow
+            this->warning("cache buffer too small to hold executable PrebuiltLoaderSet (prebuiltLoaderSet size=%lluKB, buffer size=%lldKB)",
+                          prebuiltsSpace / 1024, loaderBufferSize / 1024);
+
+            // For now, just empty the map.  That'll let us emit an empty Trie and PBLS
+            prebuiltsMap.clear();
+        } else {
+            return Error("cache buffer too small to hold executable PrebuiltLoaderSet (prebuiltLoaderSet size=%lluKB, buffer size=%lldKB)",
+                         prebuiltsSpace / 1024, loaderBufferSize / 1024);
+        }
     }
 
     // copy all PrebuiltLoaderSets into cache
@@ -6567,7 +6084,7 @@
 
         size_t size = pbls->size();
         ::memcpy(poolBase + currentPoolOffset, pbls, size);
-        currentPoolOffset += alignTo(size, alignof(dyld4::PrebuiltLoaderSet));
+        currentPoolOffset += alignTo(size, 8);
     }
 
     const CacheTrieChunk* trieChunk = this->prebuiltLoaderBuilder.executableTrieChunk;
@@ -7011,25 +6528,26 @@
         if ( cacheDylib.installName != "/usr/lib/libobjc.A.dylib" )
             continue;
 
-        cacheDylib.cacheHdr->forEachSection(^(const Header::SegmentInfo &segInfo, const Header::SectionInfo &sectInfo, bool &stop) {
-            if ( sectInfo.segmentName != "__TEXT" )
+        cacheDylib.cacheMF->forEachSection(^(const dyld3::MachOFile::SectionInfo &sectInfo,
+                                             bool malformedSectionRange, bool &stop) {
+            if (strcmp(sectInfo.segInfo.segName, "__TEXT") != 0)
                 return;
-            if ( sectInfo.sectionName != "__objc_opt_ro" )
+            if (strcmp(sectInfo.sectName, "__objc_opt_ro") != 0)
                 return;
 
             // Find the buffer for the section
             stop = true;
 
-            const DylibSegmentChunk& segment = cacheDylib.segments[sectInfo.segIndex];
-
-            VMAddress sectionVMAddr(sectInfo.address);
-            VMAddress segmentVMAddr(segInfo.vmaddr);
+            const DylibSegmentChunk& segment = cacheDylib.segments[sectInfo.segInfo.segIndex];
+
+            VMAddress sectionVMAddr(sectInfo.sectAddr);
+            VMAddress segmentVMAddr(sectInfo.segInfo.vmAddr);
             VMOffset sectionOffsetInSegment = sectionVMAddr - segmentVMAddr;
             uint8_t* sectionBuffer = segment.subCacheBuffer + sectionOffsetInSegment.rawValue();
 
             // All fields in the old header are offsets from the header.  This is how much to
             // shift them by
-            uint64_t headerCacheOffset = sectInfo.address - this->config.layout.cacheBaseAddress.rawValue();
+            uint64_t headerCacheOffset = sectInfo.sectAddr - this->config.layout.cacheBaseAddress.rawValue();
 
             // Found the section, now write the content
             objc_opt::objc_opt_t* libROHeader = (objc_opt::objc_opt_t *)sectionBuffer;
@@ -7075,12 +6593,22 @@
     }
 }
 
+// Struct matching dyld4::LibdyldDyld4Section to be used with a variable pointer size.
+// This is so we can use it in the shared cache builder, which is always
+// 64-bit but can emit 32-bit structs
+template <typename P>
+struct FixedSizeLibdyldDyld4Section {
+    P apis;
+    P allImageInfos;
+    P defaultVars[5];
+    P dyldLookupFuncAddr;
+    P tlv_get_addrAddr;
+};
+
+static_assert(sizeof(FixedSizeLibdyldDyld4Section<intptr_t>) == sizeof(dyld4::LibdyldDyld4Section));
+
 void SharedCacheBuilder::optimizeTLVs()
 {
-    // driverkit does not support thread-locals, all other platforms do
-    if ( options.platform == Platform::driverKit )
-        return;
-
     Stats        stats(this->config);
     Timer::Scope timedScope(this->config, "optimizeTLVs time");
 
@@ -7107,20 +6635,61 @@
         return;
     }
 
-    // Find _tlv_get_addr function in libdyld.dylib
-    const Image& libdyldImg = *libdyldDylib->inputImage;
-
-    Symbol tlvBootstrapSymbol;
-    if ( !libdyldImg.hasExportsTrie() || !libdyldImg.exportsTrie().hasExportedSymbol("__tlv_bootstrap", tlvBootstrapSymbol) ) {
-        this->warning("Could not find '_tlv_get_addr' in libdyld");
+    // Find the tlv_get_addrAddr from inside the __dyld4 section
+    __block CacheVMAddress getAddrVMAddr;
+    __block bool foundTLVGetAddr = false;
+    libdyldDylib->cacheMF->forEachSection(^(const MachOFile::SectionInfo &sectInfo,
+                                            bool malformedSectionRange, bool &stop) {
+        if ( strcmp(sectInfo.sectName, "__dyld4") != 0 )
+            return;
+
+        if ( (strncmp(sectInfo.segInfo.segName, "__DATA", 6) != 0)
+            && (strncmp(sectInfo.segInfo.segName, "__AUTH", 6) != 0)
+            && (strncmp(sectInfo.segInfo.segName, "__TPRO_CONST", 12) != 0))
+            return;
+
+        // Found the section we need.  Now to check if its valid
+        stop = true;
+
+        const DylibSegmentChunk& segment = libdyldDylib->segments[sectInfo.segInfo.segIndex];
+
+        VMAddress sectionVMAddr(sectInfo.sectAddr);
+        VMAddress segmentVMAddr(sectInfo.segInfo.vmAddr);
+        VMOffset sectionOffsetInSegment = sectionVMAddr - segmentVMAddr;
+        uint8_t* sectionBuffer = segment.subCacheBuffer + sectionOffsetInSegment.rawValue();
+
+
+        if ( this->config.layout.is64 ) {
+            typedef FixedSizeLibdyldDyld4Section<uint64_t> dyld4_section_t;
+            if ( sectInfo.sectSize < sizeof(dyld4_section_t) ) {
+                // Old libdyld without the field we need
+                return;
+            }
+
+            const dyld4_section_t* dyldSection = (dyld4_section_t*)sectionBuffer;
+            CacheVMAddress cacheBaseAddress = this->config.layout.cacheBaseAddress;
+            getAddrVMAddr = Fixup::Cache64::getCacheVMAddressFromLocation(cacheBaseAddress,
+                                                                          &dyldSection->tlv_get_addrAddr);
+        } else {
+            typedef FixedSizeLibdyldDyld4Section<uint32_t> dyld4_section_t;
+            if ( sectInfo.sectSize < sizeof(dyld4_section_t) ) {
+                // Old libdyld without the field we need
+                return;
+            }
+
+            const dyld4_section_t* dyldSection = (dyld4_section_t*)sectionBuffer;
+            CacheVMAddress cacheBaseAddress = this->config.layout.cacheBaseAddress;
+            getAddrVMAddr = Fixup::Cache32::getCacheVMAddressFromLocation(cacheBaseAddress,
+                                                                          &dyldSection->tlv_get_addrAddr);
+        }
+
+        foundTLVGetAddr = true;
+    });
+
+    if ( !foundTLVGetAddr ) {
+        this->warning("Could not find tlv_get_addr (TLVs not optimized)");
         return;
     }
-    // NOTE:  magic here:
-    // To cleanly error of if TLVs are not set up, the on-disk thunks bind to _tlv_bootstrap, which aborts in invoked.
-    // The thunks when setup are changed to point to _tlv_get_addr, which is not an exported symbol.  Therefore
-    // the cache builder has no way to find it. The fix/hack is that _tlv_bootstrap and _tlv_get_addr are written
-    // in assembly and always 8 bytes apart.
-    CacheVMAddress getAddrVMAddr(libdyldDylib->cacheLoadAddress.rawValue() + tlvBootstrapSymbol.implOffset() + 8);
 
     // We read the value for this symbol to know the first key we can allocate for TLVs
     // We then have to stop optimizing if and when we reach "end", that's the
@@ -7172,7 +6741,7 @@
             return;
         }
 
-        if ( !cacheDylib.cacheHdr->hasThreadLocalVariables() )
+        if ( !cacheDylib.cacheMF->hasThreadLocalVariables() )
             continue;
 
         // Get the next available key (one key per dylib)
@@ -7189,117 +6758,69 @@
             return;
         }
 
-        // find initial content for all thread locals in this dylib
-        __block bool        initialContentNonZero = false;
-        __block uint64_t    initialContentAddr    = 0;
-        __block size_t      initialContentSize    = 0;
-        cacheDylib.cacheHdr->forEachSection(^(const Header::SectionInfo& sectInfo, bool& stop) {
-            switch ( sectInfo.flags & SECTION_TYPE ) {
-                case S_THREAD_LOCAL_REGULAR:
-                    initialContentNonZero = true;
-                    [[clang::fallthrough]];
-                case S_THREAD_LOCAL_ZEROFILL:
-                    if ( initialContentSize == 0 ) {
-                        // first of N contiguous TLV template sections, record as if this was only section
-                        initialContentAddr = sectInfo.address;
-                        initialContentSize = sectInfo.size;
-                    }
-                    else {
-                        // non-first of N contiguous TLV template sections, accumlate values
-                        initialContentSize = sectInfo.address + sectInfo.size - initialContentAddr;
-                    }
-                    break;
-            }
-        });
-
-        cacheDylib.cacheHdr->forEachSection(^(const Header::SegmentInfo &segInfo, const Header::SectionInfo& sectInfo, bool& stop) {
-            if ( (sectInfo.flags & SECTION_TYPE) != S_THREAD_LOCAL_VARIABLES )
+        cacheDylib.cacheMF->forEachSection(^(const MachOFile::SectionInfo& sectInfo,
+                                             bool malformedSectionRange, bool& stop) {
+            if ( (sectInfo.sectFlags & SECTION_TYPE) != S_THREAD_LOCAL_VARIABLES )
                 return;
 
-            DylibSegmentChunk& segment = cacheDylib.segments[sectInfo.segIndex];
-
-            VMAddress sectionVMAddr(sectInfo.address);
-            VMAddress segmentVMAddr(segInfo.vmaddr);
+            DylibSegmentChunk& segment = cacheDylib.segments[sectInfo.segInfo.segIndex];
+
+            VMAddress sectionVMAddr(sectInfo.sectAddr);
+            VMAddress segmentVMAddr(sectInfo.segInfo.vmAddr);
             VMOffset sectionOffsetInSegment = sectionVMAddr - segmentVMAddr;
             uint8_t* sectionBuffer = segment.subCacheBuffer + sectionOffsetInSegment.rawValue();
 
             if ( this->config.layout.is64 ) {
-                struct tlv_disk_thunk64_t
+                struct tlv_thunk_t
                 {
-                    uint64_t func;
+                    uint64_t thunk;
                     uint64_t key;
                     uint64_t offset;
                 };
 
-                uint32_t            count       = (uint32_t)(sectInfo.size / sizeof(tlv_disk_thunk64_t));
-                tlv_disk_thunk64_t* thunkBuffer = (tlv_disk_thunk64_t*)sectionBuffer;
-                for ( uint32_t i = 0; i < count; ++i ) {
-                    size_t                                      offset   = thunkBuffer[i].offset; // only value needed from disk format
-                    dyld::ThreadLocalVariables::TLV_Thunkv2&   newThunk = *((dyld::ThreadLocalVariables::TLV_Thunkv2*)&thunkBuffer[i]);
-
-                    // Reset the fields using TLV_Thunkv2 format
-                    newThunk.key                 = key;
-                    newThunk.offset              = (uint32_t)offset;
-                    newThunk.initialContentSize  = (uint32_t)initialContentSize;
-                    newThunk.initialContentDelta = 0;
-                    if ( initialContentNonZero ) {
-                        uint64_t newThunkDeltaFieldAddr = (sectInfo.address + i*sizeof(tlv_disk_thunk64_t) + offsetof(dyld::ThreadLocalVariables::TLV_Thunkv2,initialContentDelta));
-                        newThunk.initialContentDelta = (int32_t)(initialContentAddr - newThunkDeltaFieldAddr);
-                    }
+                uint32_t count = (uint32_t)(sectInfo.sectSize / sizeof(tlv_thunk_t));
+                tlv_thunk_t* thunkBuffer = (tlv_thunk_t*)sectionBuffer;
+                for ( uint32_t i = 0; i != count; ++i ) {
+                    tlv_thunk_t& tlvThunk = thunkBuffer[i];
+
+                    // Set the key to the next available key
+                    tlvThunk.key = key;
 
                     // Set the thunk to tlv_get_addr()
-                    uint8_t  high8          = 0;
-                    uint16_t authDiversity  = 0;
-                    bool     authHasAddrDiv = false;
-                    uint8_t  authKey        = ptrauth_key_asia;
-                    bool     isAuth         = this->config.layout.hasAuthRegion;
-                    Fixup::Cache64::setLocation(this->config.layout.cacheBaseAddress, &newThunk.func,
+                    uint8_t high8 = 0;
+                    uint16_t authDiversity = 0;
+                    bool authHasAddrDiv = false;
+                    uint8_t authKey = ptrauth_key_asia;
+                    bool isAuth = this->config.layout.hasAuthRegion;
+                    Fixup::Cache64::setLocation(this->config.layout.cacheBaseAddress, &tlvThunk.thunk,
                                                 getAddrVMAddr, high8,
                                                 authDiversity, authHasAddrDiv, authKey, isAuth);
 
                     // Add to ASLR tracker
-                    segment.tracker.add(&newThunk.func);
+                    segment.tracker.add(&tlvThunk.thunk);
                 }
-            } 
-            else {
-                struct tlv_disk_thunk32_t
+            } else {
+                struct tlv_thunk_t
                 {
-                    uint32_t func;
+                    uint32_t thunk;
                     uint32_t key;
                     uint32_t offset;
                 };
-                struct tlv_cache_thunk32_t
-                {
-                    uint32_t     func;
-                    uint16_t     key;
-                    uint16_t     offset;
-                    int32_t      machHeaderDelta; // if < 0, content is found by walking load commands. If > 0, then it is size and content is all zeros
-                };
-                static_assert(sizeof(tlv_disk_thunk32_t) == sizeof(tlv_cache_thunk32_t));
-                uint32_t            loadAddr    = (uint32_t)(cacheDylib.cacheHdr->preferredLoadAddress());
-                uint32_t            count       = (uint32_t)(sectInfo.size / sizeof(tlv_disk_thunk32_t));
-                tlv_disk_thunk32_t* thunkBuffer = (tlv_disk_thunk32_t*)sectionBuffer;
-                for ( uint32_t i = 0; i < count; ++i ) {
-                    uint32_t               offset   = thunkBuffer[i].offset; // only value needed from disk format
-                    tlv_cache_thunk32_t&   newThunk = *((tlv_cache_thunk32_t*)&thunkBuffer[i]);
-
-                    if ( offset > 0xFFFF )
-                        this->warning("thread-local too large (%u max 65535) in %s", offset, cacheDylib.inputFile->path.c_str());
-
-                    // Reset the fields using TLV_Thunkv2 format
-                    newThunk.key                 = (uint16_t)key;
-                    newThunk.offset              = (uint16_t)offset;    // FIXME: error if offset > 0xFFFF
-                    newThunk.machHeaderDelta     = (uint32_t)initialContentSize;
-                    if ( initialContentNonZero ) {
-                        uint64_t newThunkDeltaFieldAddr = (sectInfo.address + i*sizeof(tlv_disk_thunk32_t) + offsetof(tlv_cache_thunk32_t,machHeaderDelta));
-                        newThunk.machHeaderDelta = (int32_t)(loadAddr - newThunkDeltaFieldAddr);
-                    }
+
+                uint32_t count = (uint32_t)(sectInfo.sectSize / sizeof(tlv_thunk_t));
+                tlv_thunk_t* thunkBuffer = (tlv_thunk_t*)sectionBuffer;
+                for ( uint32_t i = 0; i != count; ++i ) {
+                    tlv_thunk_t& tlvThunk = thunkBuffer[i];
+
+                    // Set the key to the next available key
+                    tlvThunk.key = key;
 
                     // Set the thunk to tlv_get_addr()
-                    Fixup::Cache32::setLocation(this->config.layout.cacheBaseAddress, &newThunk.func, getAddrVMAddr);
+                    Fixup::Cache32::setLocation(this->config.layout.cacheBaseAddress, &tlvThunk.thunk,
+                                                getAddrVMAddr);
 
                     // Add to ASLR tracker
-                    segment.tracker.add(&newThunk.func);
+                    segment.tracker.add(&tlvThunk.thunk);
                 }
             }
         });
@@ -7347,24 +6868,32 @@
             // Skip sections if their segment doesn't exist
             switch ( sectionKind ) {
                 case UniquedGOTKind::regular:
+                    if ( dataConstRegion == nullptr )
+                        continue;
+
                     region = dataConstRegion;
                     subCacheUniquedGOTs = &subCache.uniquedGOTsOptimizer.regularGOTs;
                     break;
                 case UniquedGOTKind::authGot:
+                    if ( authConstRegion == nullptr )
+                        continue;
+
                     region = authConstRegion;
                     subCacheUniquedGOTs = &subCache.uniquedGOTsOptimizer.authGOTs;
                     break;
                 case UniquedGOTKind::authPtr:
+                    if ( authConstRegion == nullptr )
+                        continue;
+
                     region = authConstRegion;
                     subCacheUniquedGOTs = &subCache.uniquedGOTsOptimizer.authPtrs;
                     break;
             }
 
-            if ( region == nullptr )
+            if ( subCacheUniquedGOTs->cacheChunk == nullptr )
                 continue;
 
-            if ( subCacheUniquedGOTs->empty() )
-                continue;
+            UniquedGOTsChunk* subCacheGOTChunk = subCacheUniquedGOTs->cacheChunk->isUniquedGOTsChunk();
 
             std::set<const void*> seenFixups;
             std::vector<PatchInfo::GOTInfo> gots;
@@ -7396,38 +6925,36 @@
                             break;
                     }
 
-                    if ( bindUses.empty() )
-                        continue;
-
                     // For absolute binds, just set the pointers and move on
                     if ( bindTarget.kind == CacheDylib::BindTarget::Kind::absolute ) {
                         for ( const PatchInfo::GOTInfo& got : bindUses ) {
-                            CacheVMAddress gotVMAddr = got.useLocation.clientGOT->cacheVMAddress + got.useLocation.clientGOTOffset;
-                            const void* fixupLoc = subCacheUniquedGOTs->gotLocation(gotVMAddr);
-                            uint64_t targetValue = std::get<uint64_t>(got.targetValue);
+                            CacheVMAddress gotVMAddr = got.patchInfo.cacheVMAddr;
+                            assert(gotVMAddr >= subCacheGOTChunk->cacheVMAddress);
+                            assert(gotVMAddr < (subCacheGOTChunk->cacheVMAddress + subCacheGOTChunk->cacheVMSize));
+                            VMOffset cacheSectionVMOffset = gotVMAddr - subCacheGOTChunk->cacheVMAddress;
+
+                            const void* fixupLoc = subCacheGOTChunk->subCacheBuffer + cacheSectionVMOffset.rawValue();
                             if ( this->config.layout.is64 ) {
-                                *(uint64_t*)fixupLoc = targetValue;
+                                *(uint64_t*)fixupLoc = got.targetValue.rawValue();
                             } else {
-                                *(uint32_t*)fixupLoc = (uint32_t)targetValue;
+                                *(uint32_t*)fixupLoc = (uint32_t)got.targetValue.rawValue();
                             }
                         }
                         continue;
                     }
 
-                    assert(bindTarget.kind == CacheDylib::BindTarget::Kind::cacheImage);
                     gots.insert(gots.end(), bindUses.begin(), bindUses.end());
                 }
             }
 
             // Found all the GOTs/authGOTS for this subCache.  Now we need to emit them
             for ( const PatchInfo::GOTInfo& got : gots ) {
-                CacheVMAddress gotVMAddr = got.useLocation.clientGOT->cacheVMAddress + got.useLocation.clientGOTOffset;
-
-                // Function variants don't get emitted right now
-                if ( !subCacheUniquedGOTs->shouldEmitGOT(gotVMAddr) )
-                    continue;
-
-                void* rawFixupLoc = subCacheUniquedGOTs->gotLocation(gotVMAddr);
+                CacheVMAddress gotVMAddr = got.patchInfo.cacheVMAddr;
+                assert(gotVMAddr >= subCacheGOTChunk->cacheVMAddress);
+                assert(gotVMAddr < (subCacheGOTChunk->cacheVMAddress + subCacheGOTChunk->cacheVMSize));
+                VMOffset cacheSectionVMOffset = gotVMAddr - subCacheGOTChunk->cacheVMAddress;
+
+                void* rawFixupLoc = subCacheGOTChunk->subCacheBuffer + cacheSectionVMOffset.rawValue();
 
                 // Ignore dupes
                 if ( seenFixups.count(rawFixupLoc) )
@@ -7435,13 +6962,11 @@
 
                 seenFixups.insert(rawFixupLoc);
 
-                const DylibOffset& dylibOffset = std::get<DylibOffset>(got.targetValue);
-                InputDylibVMAddress inputVMAddr = dylibOffset.cacheDylib->inputLoadAddress + dylibOffset.vmOffset;
-                CacheVMAddress targetVMAddr = dylibOffset.cacheDylib->adjustor->adjustVMAddr(inputVMAddr);
+                CacheVMAddress targetVMAddr = config.layout.cacheBaseAddress + got.targetValue;
                 if ( this->config.layout.is64 ) {
                     uint64_t high8 = 0;
                     uint64_t finalVMAddr = targetVMAddr.rawValue();
-                    if ( !got.useLocation.authenticated ) {
+                    if ( !got.patchInfo.authenticated ) {
                         high8 = (finalVMAddr >> 56);
                         if ( high8 != 0 ) {
                             // Remove high8 from the vmAddr
@@ -7452,16 +6977,16 @@
                                                 rawFixupLoc,
                                                 CacheVMAddress(finalVMAddr),
                                                 high8,
-                                                got.useLocation.discriminator,
-                                                got.useLocation.usesAddressDiversity, got.useLocation.key,
-                                                got.useLocation.authenticated);
+                                                got.patchInfo.discriminator,
+                                                got.patchInfo.usesAddressDiversity, got.patchInfo.key,
+                                                got.patchInfo.authenticated);
                 } else {
                     Fixup::Cache32::setLocation(this->config.layout.cacheBaseAddress,
                                                 rawFixupLoc,
                                                 CacheVMAddress(targetVMAddr));
                 }
 
-                subCacheUniquedGOTs->trackFixup(rawFixupLoc);
+                subCacheGOTChunk->tracker.add(rawFixupLoc);
             }
         }
     }
@@ -7518,7 +7043,7 @@
         objc_visitor::Visitor& objcVisitor = objcVisitors[dylibObjCIndex];
 
         if ( log ) {
-            printf("  at 0x%llx in %s\n", protocolVMAddr, objcVisitor.hdr()->installName());
+            printf("  at 0x%llx in %s\n", protocolVMAddr, objcVisitor.mf()->installName());
         }
 
         __block bool foundProtocol = false;
@@ -7676,7 +7201,7 @@
                         error = Error("Superclass of class '%s' is weak-import"
                                       "and missing.  Referenced in %s",
                                       objcClass.getName(objcVisitor),
-                                      objcVisitor.hdr()->installName());
+                                      objcVisitor.mf()->installName());
                     stopClass = true;
                     this->objcOptimizer.foundMissingWeakSuperclass = true;
                 }
@@ -7709,7 +7234,7 @@
                 classMap[classVMAddr] = (uint32_t)classInfos.size();
 
             if ( log ) {
-                printf("%s: [0x%08llx] %s%s\n", objcVisitor.hdr()->installName(), classVMAddr.rawValue(),
+                printf("%s: [0x%08llx] %s%s\n", objcVisitor.mf()->installName(), classVMAddr.rawValue(),
                        objcClass.getName(objcVisitor), objcClass.isMetaClass ? " (meta)" : "");
             }
 
@@ -8195,7 +7720,7 @@
     size_t objcIndex = 0;
     for (size_t cacheIndex = 0; cacheIndex < this->cacheDylibs.size(); cacheIndex++) {
         CacheDylib& cacheDylib = this->cacheDylibs[cacheIndex];
-        if ( !cacheDylib.inputHdr->hasObjC() )
+        if ( !cacheDylib.inputMF->hasObjC() )
             continue;
 
         this->objcCategoryOptimizer.preAttachedDylibs.insert(objcIndex);
@@ -8253,64 +7778,12 @@
                          this->objcOptimizer.headerInfoReadWriteChunk->subCacheBuffer,
                          this->objcOptimizer.headerInfoReadOnlyChunk->cacheVMAddress,
                          swiftPrespecializedDylib,
-                         this->swiftOptimizer);
+                         this->swiftProtocolConformanceOptimizer);
     if ( diag.hasError() )
         return Error("Couldn't build Swift protocol opts because: %s", diag.errorMessageCStr());
 
     return Error();
 }
-
-static void getFunctionVariantTable(const CacheDylib& cacheDylib, uint64_t& vmAddr, uint64_t& vmSize)
-{
-    vmAddr = 0;
-    vmSize = 0;
-    for ( const LinkeditDataChunk& chunk : cacheDylib.linkeditChunks ) {
-        if ( chunk.isFunctionVariantsTable() ) {
-            vmAddr = chunk.cacheVMAddress.rawValue();
-            vmSize = chunk.cacheVMSize.rawValue();
-        }
-    }
-}
-
-void SharedCacheBuilder::emitFunctionVariants()
-{
-    // find uniqued GOT slots in each subcache that point to function variants
-    for ( SubCache& subCache : this->subCaches ) {
-        subCache.uniquedGOTsOptimizer.forEachFunctionVariant(^(const CoalescedGOTSection::FunctionVariantInfo& fv, uint64_t gotVMAddr,
-                                                               dyld3::MachOFile::PointerMetaData pmd) {
-            uint32_t targetDylibIndex = fv.dylibIndex;
-            uint64_t fvTableVmAddr;
-            uint64_t fvTableVmSize;
-            getFunctionVariantTable(this->cacheDylibs[targetDylibIndex], fvTableVmAddr, fvTableVmSize);
-            dyld_cache_function_variant_entry entry;
-            entry.fixupLocVmAddr               = gotVMAddr;
-            entry.functionVariantTableVmAddr   = fvTableVmAddr;
-            entry.functionVariantTableSizeDiv4 = fvTableVmSize/4;
-            entry.dylibHeaderVmAddr            = this->cacheDylibs[targetDylibIndex].cacheLoadAddress.rawValue();
-            entry.variantIndex                 = fv.variantIndex;
-            entry.pacAuth                      = pmd.authenticated;
-            entry.pacAddress                   = pmd.usesAddrDiversity;
-            entry.pacKey                       = pmd.key;
-            entry.pacDiversity                 = pmd.diversity;
-            entry.targetDylibIndex             = targetDylibIndex;
-            assert(entry.variantIndex == fv.variantIndex);
-            this->functionVariantsOptimizer.infos.push_back(entry);
-        });
-    }
-
-    // make sure it fits in estimated size
-    size_t actualSize = offsetof(dyld_cache_function_variant_info, entries[this->functionVariantsOptimizer.infos.size()]);
-    assert(actualSize < this->functionVariantsOptimizer.fvInfoTotalByteSize);
-    this->functionVariantsOptimizer.fvInfoTotalByteSize = actualSize;
-    
-    // write table to LINKEDIT
-    dyld_cache_function_variant_info* table = (dyld_cache_function_variant_info*)(this->functionVariantsOptimizer.chunk->subCacheBuffer);
-    table->version = 1;
-    table->count   = (uint32_t)this->functionVariantsOptimizer.infos.size();
-    if ( table->count > 0 )
-        memcpy(table->entries, &this->functionVariantsOptimizer.infos[0], sizeof(dyld_cache_function_variant_entry)*this->functionVariantsOptimizer.infos.size());
-}
-
 
 void SharedCacheBuilder::emitCacheDylibsTrie()
 {
@@ -8394,11 +7867,6 @@
     // We must be a largeContiguous cache. Others were dealt with above in the x86_64 and/or sim cases
     assert(this->config.layout.contiguous.has_value());
 
-    // Some caches have a fixed max slide
-    if ( this->config.layout.cacheFixedSlide.has_value() ) {
-        return this->config.layout.cacheFixedSlide.value();
-    }
-
     // Start off making sure we can't slide past the end of the cache
     CacheVMAddress maxVMAddress(0ULL);
     for ( const Region& region : this->subCaches.back().regions ) {
@@ -8459,6 +7927,9 @@
     if ( swiftPrespecializedDylib == nullptr )
         return Error::none();
 
+    Timer::Scope timedScope(this->config, "patchLinkedDylibs time");
+    Timer::AggregateTimer aggregateTimerOwner(this->config);
+
     Diagnostics diag;
     if ( &cacheDylib == swiftPrespecializedDylib ) {
         // remove all but libSystem
@@ -8474,203 +7945,30 @@
     return Error::none();
 }
 
-void SharedCacheBuilder::addSubCacheFileInfo(uint64_t cacheVMAddress, PropertyList::Array &files, const SubCache &subCache) {
-    using Array         = PropertyList::Array;
-    using Integer       = PropertyList::Integer;
-    using String        = PropertyList::String;
-    using Dictionary    = PropertyList::Dictionary;
-
-    uuid_t subcacheUUID;
-    uuid_parse(subCache.uuidString, subcacheUUID);
-    auto& subCacheFile = files.addObject<Dictionary>();
-
-    subCacheFile.addObjectForKey<String>("name", options.mainCacheFileName + subCache.fileSuffix);
-    subCacheFile.addObjectForKey<PropertyList::UUID>(kDyldAtlasSharedCacheUUIDKey,subcacheUUID);
-    subCacheFile.addObjectForKey<Integer>("voff",subCache.subCacheVMAddress.rawValue()-cacheVMAddress);
-    subCacheFile.addObjectForKey<Integer>("fsze", subCache.bufferSize);
-    subCacheFile.addObjectForKey<Integer>("padr", subCache.subCacheVMAddress.rawValue());
-    auto& mappingsArray = subCacheFile.addObjectForKey<Array>(kDyldAtlasSharedCacheMappingArrayKey);
-
-    dyld_cache_header* subCacheHeader   = (dyld_cache_header*)subCache.buffer;
-    auto* mappings                      = (dyld_cache_mapping_info*)((uint8_t*)subCacheHeader + subCacheHeader->mappingOffset);
-
-    uint64_t lastAddress = 0;
-    for ( auto i = 0; i < subCacheHeader->mappingCount; ++i) {
-        auto& mapping = mappingsArray.addObject<Dictionary>();
-        mapping.addObjectForKey<Integer>(kDyldAtlasSharedCacheMappingsSizeKey, mappings[i].size);
-        mapping.addObjectForKey<Integer>(kDyldAtlasSharedCacheMappingsPreferredLoadAddressKey, mappings[i].address);
-        mapping.addObjectForKey<Integer>(kDyldAtlasSharedCacheMappingsFileOffsetKey, mappings[i].fileOffset);
-        mapping.addObjectForKey<Integer>(kDyldAtlasSharedCacheMappingsMaxProtKey, mappings[i].maxProt);
-        if (mappings[i].address + mappings[i].size > lastAddress) {
-            lastAddress = mappings[i].address + mappings[i].size;
-        }
-    }
-    subCacheFile.addObjectForKey<Integer>("size", lastAddress-subCacheHeader->sharedRegionStart);
-}
-
-void SharedCacheBuilder::addCacheAtlasInfo(PropertyList::Dictionary *cacheAtlas, const SubCache &mainCache) {
-    using Array         = PropertyList::Array;
-    using Integer       = PropertyList::Integer;
-    using String        = PropertyList::String;
-
-    uint64_t cacheVMAddress = mainCache.subCacheVMAddress.rawValue();
-    uuid_t cacheUUID;
-    uuid_parse(mainCache.uuidString, cacheUUID);
-    cacheAtlas->addObjectForKey<PropertyList::UUID>(kDyldAtlasSharedCacheUUIDKey, cacheUUID);
-    cacheAtlas->addObjectForKey<Integer>(kDyldAtlasSharedCachePreferredLoadAddressKey, mainCache.subCacheVMAddress.rawValue());
-    cacheAtlas->addObjectForKey<Integer>(kDyldAtlasSharedCacheVMSizeKey, this->totalVMSize.rawValue());
-    dyld_cache_header*   cacheHeader        = (dyld_cache_header*)mainCache.buffer;
-
-    if (!uuid_is_null(cacheHeader->symbolFileUUID)) {
-        cacheAtlas->addObjectForKey<String>(kDyldAtlasSharedCacheSymbolFileName, options.mainCacheFileName + ".symbols");
-        cacheAtlas->addObjectForKey<PropertyList::UUID>(kDyldAtlasSharedCacheSymbolFileName, cacheHeader->symbolFileUUID);
-    }
-
-    auto& files = cacheAtlas->addObjectForKey<Array>("dscs");
-    addSubCacheFileInfo(cacheVMAddress, files, mainCache);
-    for (auto& subCache : mainCache.subCaches) {
-        addSubCacheFileInfo(cacheVMAddress, files, *subCache);
-    }
-
-    // FIXME: Remove once deprecate legacy APIs that need this
-    if (strncmp(cacheHeader->magic, "dyld_v1arm64_32", 15) != 0) {
-        cacheAtlas->addObjectForKey<Integer>("psze", 4);
-    } else {
-        cacheAtlas->addObjectForKey<Integer>("psze", 8);
-    }
-}
-
-// This generates the atlas binary plist included with the shared cache
-void SharedCacheBuilder::buildAtlas() {
-    STACK_ALLOCATOR(allocator, 0);
-    using Array         = PropertyList::Array;
-    using Dictionary    = PropertyList::Dictionary;
-    using Integer       = PropertyList::Integer;
-    using String        = PropertyList::String;
-    auto propertyListEncoder            = PropertyList(allocator);
-    auto& rootDictionary                = propertyListEncoder.rootDictionary();
-    // The same plist contains both the customer and shared cache data, since they share layouts
-    // We include dictionaries at the root so they can be lookup by leaf name or UUID
-    auto& byUuidDictionary              = rootDictionary.addObjectForKey<Dictionary>("uuids");
-    auto& byNameDictionary              = rootDictionary.addObjectForKey<Dictionary>("names");
-    Dictionary* customerCacheAtlas      = nullptr;
-    Dictionary* devCacheAtlas           = nullptr;
-    Array* images                       = nullptr;
-    uuid_string_t customerCacheUUID     = {0};
-    uuid_string_t devCacheUUID          = {0};
-    std::string   customerCacheName;
-    std::string   devCacheName;
-
-    for ( const SubCache& subCache : this->subCaches ) {
-        if ( subCache.isMainCustomerCache() ) {
-            customerCacheName = options.mainCacheFileName + subCache.fileSuffix;
-            customerCacheAtlas = &byUuidDictionary.addObjectForKey<Dictionary>(subCache.uuidString);
-            byNameDictionary.insertObjectForKey(customerCacheName, *customerCacheAtlas);
-            addCacheAtlasInfo(customerCacheAtlas, subCache);
-            strcpy(customerCacheUUID, subCache.uuidString);
-        } else if ( subCache.isMainDevelopmentCache() ) {
-            devCacheName = options.mainCacheFileName + subCache.fileSuffix;
-            devCacheAtlas = &byUuidDictionary.addObjectForKey<Dictionary>(subCache.uuidString);
-            byNameDictionary.insertObjectForKey(devCacheName, *devCacheAtlas);
-            addCacheAtlasInfo(devCacheAtlas, subCache);
-            strcpy(devCacheUUID, subCache.uuidString);
-        }
-    }
-    assert((customerCacheAtlas != nullptr) || (devCacheAtlas != nullptr));
-
-    // The bplist00 format supports uniquing objects, but uniquing collections is slow. Since we know a priori the images for both cache variants
-    // will be the same we create it int he first cache atlas, and if there is a second we insert a reference to the already existing one.
-    if (customerCacheAtlas) {
-        images = &customerCacheAtlas->addObjectForKey<Array>(kDyldAtlasSharedCacheImageArrayKey);
-        if (devCacheAtlas) {
-            devCacheAtlas->insertObjectForKey(kDyldAtlasSharedCacheImageArrayKey, *images);
-        }
-    } else {
-        images = &devCacheAtlas->addObjectForKey<Array>(kDyldAtlasSharedCacheImageArrayKey);
-    }
-
-    for ( const CacheDylib& cacheDylib : this->cacheDylibs ) {
-        auto& image = images->addObject<Dictionary>();
-        auto& segments = image.addObjectForKey<Array>(kDyldAtlasImageSegmentArrayKey);
-        image.addObjectForKey<String>(kDyldAtlasImageInstallnameKey, cacheDylib.installName);
-        image.addObjectForKey<Integer>(kDyldAtlasImagePreferredLoadAddressKey, cacheDylib.cacheLoadAddress.rawValue());
-        uuid_t uuid;
-        assert(cacheDylib.cacheHdr->getUuid(uuid));
-        image.addObjectForKey<PropertyList::UUID>(kDyldAtlasImageUUIDKey, uuid);
-
-        for ( const DylibSegmentChunk& segmentChunk : cacheDylib.segments ) {
-            auto& segment = segments.addObject<Dictionary>();
-            segment.addObjectForKey<String>(kDyldAtlasSegmentNameKey, segmentChunk.name());
-            segment.addObjectForKey<Integer>(kDyldAtlasSegmentPreferredLoadAddressKey, segmentChunk.cacheVMAddress.rawValue());
-            segment.addObjectForKey<Integer>(kDyldAtlasSegmentSizeKey, segmentChunk.cacheVMSize.rawValue());
-            segment.addObjectForKey<Integer>(kDyldAtlasSegmentFileOffsetKey, segmentChunk.subCacheFileOffset.rawValue());
-            segment.addObjectForKey<Integer>(kDyldAtlasSegmentFileSizeKey, segmentChunk.subCacheFileSize.rawValue());
-            if ( strcmp("__TEXT", segmentChunk.name()) == 0 ) {
-                segment.addObjectForKey<Integer>(kDyldAtlasSegmentPermissionsKey, VM_PROT_READ | VM_PROT_EXECUTE);
-            } else if ( strcmp("__LINKEDIT", segmentChunk.name()) == 0 ) {
-                segment.addObjectForKey<Integer>(kDyldAtlasSegmentPermissionsKey, VM_PROT_READ);
-            } else {
-                segment.addObjectForKey<Integer>(kDyldAtlasSegmentPermissionsKey, VM_PROT_READ | VM_PROT_WRITE);
-            }
-        }
-    }
-
-    ByteStream fileStream(allocator);
-    propertyListEncoder.encode(fileStream);
-    AAREncoder aarEncoder(allocator);
-
-    if (customerCacheUUID[0]) {
-        std::string plistPath = std::string("caches/uuids/") + customerCacheUUID + ".plist";
-        std::string symlinkTarget = std::string("../uuids/") + customerCacheUUID + ".plist";
-        std::string symlinkSource = std::string("caches/names/") + customerCacheName + ".plist";
-
-        aarEncoder.addFile(plistPath, fileStream.span());
-        aarEncoder.addSymLink(symlinkSource, symlinkTarget);
-        if (devCacheUUID[0]) {
-            std::string devPlistPath = std::string("caches/uuids/") + devCacheUUID + ".plist";
-            std::string devSymlinkSource = std::string("caches/names/") + devCacheName + ".plist";
-            aarEncoder.addSymLink(devPlistPath, symlinkTarget);
-            aarEncoder.addSymLink(devSymlinkSource, symlinkTarget);
-        }
-    } else {
-        assert(devCacheUUID[0] != 0);
-        std::string plistPath = std::string("caches/uuids/") + devCacheUUID + ".plist";
-        std::string symlinkTarget = std::string("../uuids/") + devCacheUUID + ".plist";
-        std::string symlinkSource = std::string("caches/names/") + devCacheName + ".plist";
-
-        aarEncoder.addFile(plistPath, fileStream.span());
-        aarEncoder.addSymLink(symlinkSource, symlinkTarget);
-    }
-
-    ByteStream outputStream(allocator);
-    aarEncoder.encode(outputStream);
-    std::copy(outputStream.begin(), outputStream.end(), std::back_insert_iterator(atlasData));
-}
-
 void SharedCacheBuilder::computeCacheHeaders()
 {
     Timer::Scope timedScope(this->config, "computeCacheHeaders time");
 
-    // Content for all subcaches
+    for ( SubCache& subCache : this->subCaches )
+        subCache.writeCacheHeader(this->options, this->config, this->cacheDylibs);
+
+    // Content for the first (main) subCache only
     __block uint32_t osVersion                  = 0;
     __block uint32_t altPlatform                = 0;
     __block uint32_t altOsVersion               = 0;
-
-    // Content for the first (main) subCache only
     CacheVMAddress   dyldInCacheUnslidAddr      = CacheVMAddress(0ULL);
     CacheVMAddress   dyldInCacheEntryUnslidAddr = CacheVMAddress(0ULL);
-
     {
         // look for libdyld.dylib and record OS verson info into cache header
         for ( const CacheDylib& cacheDylib : this->cacheDylibs ) {
             if ( endsWith(cacheDylib.installName, "/libdyld.dylib") ) {
-                cacheDylib.inputHdr->platformAndVersions().unzip(^(mach_o::PlatformAndVersions pvs) {
-                    if ( pvs.platform == options.platform ) {
-                        osVersion = pvs.minOS.value();
+                cacheDylib.inputMF->forEachSupportedPlatform(^(dyld3::Platform platform, uint32_t minOS, uint32_t sdk) {
+                    if ( platform == options.platform ) {
+                        osVersion = minOS;
                     }
                     else {
-                        altPlatform = pvs.platform.value();
-                        altOsVersion = pvs.minOS.value();
+                        altPlatform  = (uint32_t)platform;
+                        altOsVersion = minOS;
                     }
                 });
             }
@@ -8679,17 +7977,13 @@
                 dyldInCacheUnslidAddr = cacheDylib.cacheLoadAddress;
                 uint64_t dyldEntryOffset;
                 bool     usesCRT;
-                if ( cacheDylib.cacheHdr->getEntry(dyldEntryOffset, usesCRT) ) {
+                if ( cacheDylib.cacheMF->getEntry(dyldEntryOffset, usesCRT) ) {
                     // the "pc" value in the LC_UNIXTHREAD was adjusted when dyld was placed in the cache
                     dyldInCacheEntryUnslidAddr = dyldInCacheUnslidAddr + VMOffset(dyldEntryOffset);
                 }
             }
         }
     }
-
-    for ( SubCache& subCache : this->subCaches )
-        subCache.writeCacheHeader(this->options, this->config, this->cacheDylibs,
-                                  osVersion, altPlatform, altOsVersion);
 
     // Fill in info for the main caches.  This must be after addCacheHeaderImageInfo().
     for ( SubCache& subCache : this->subCaches ) {
@@ -8697,11 +7991,11 @@
             subCache.addMainCacheHeaderInfo(this->options, this->config,
                                             this->cacheDylibs,
                                             this->totalVMSize, getMaxSlide(),
+                                            osVersion, altPlatform, altOsVersion,
                                             dyldInCacheUnslidAddr, dyldInCacheEntryUnslidAddr,
                                             this->dylibTrieOptimizer,
-                                            this->objcOptimizer, this->swiftOptimizer,
-                                            this->patchTableOptimizer, this->functionVariantsOptimizer,
-                                            this->prebuiltLoaderBuilder, this->prewarmingOptimizer);
+                                            this->objcOptimizer, this->swiftProtocolConformanceOptimizer,
+                                            this->patchTableOptimizer, this->prebuiltLoaderBuilder);
             continue;
         }
 
@@ -8789,7 +8083,7 @@
     return swiftPrespecializedDylibBuildError;
 }
 
-void SharedCacheBuilder::getResults(std::vector<CacheBuffer>& results, std::vector<std::byte>& atlas) const
+void SharedCacheBuilder::getResults(std::vector<CacheBuffer>& results) const
 {
     for ( const SubCache& subCache : this->subCaches ) {
         CacheBuffer buffer;
@@ -8797,8 +8091,6 @@
         buffer.bufferSize = subCache.bufferSize;
 
         buffer.cdHash = cdHashToString(subCache.cdHash);
-        if ( this->config.codeSign.mode == CodeSign::Mode::agile )
-            buffer.agilecdHash = cdHashToString(subCache.agilecdHash);
         buffer.uuid   = subCache.uuidString;
 
         buffer.cacheFileSuffix = subCache.fileSuffix;
@@ -8806,8 +8098,13 @@
         buffer.usedByCustomerConfig = subCache.shouldKeepCache(false, true);
         buffer.usedByDevelopmentConfig = subCache.shouldKeepCache(true, false);
 
+        // The builder executable also passes back the fd.  This should typically be used instead of the data buffer
+#if !SUPPORT_CACHE_BUILDER_MEMORY_BUFFERS
+        buffer.fd       = subCache.fd;
+        buffer.tempPath = subCache.tempPath;
+#endif
+
         results.push_back(std::move(buffer));
-        atlas = std::move(this->atlasData);
     }
 }
 
@@ -8881,32 +8178,31 @@
 
     assert(mainSubCache.isMainCache());
 
-    json::Node cacheNode;
+    dyld3::json::Node cacheNode;
 
     cacheNode.map["version"].value = "1";
     cacheNode.map["disposition"].value = disposition;
-    cacheNode.map["arch"].value = this->options.arch.name();
-    cacheNode.map["platform"].value = mach_o::Platform(this->options.platform).name();
-    cacheNode.map["base-address"].value = json::hex(baseAddress);
+    cacheNode.map["base-address"].value = dyld3::json::hex(baseAddress);
     cacheNode.map["uuid"].value = mainSubCache.uuidString;
 
-    json::Node imagesNode;
+    dyld3::json::Node imagesNode;
     for ( const CacheDylib& cacheDylib : this->cacheDylibs ) {
-        json::Node imageNode;
+        dyld3::json::Node imageNode;
         imageNode.map["path"].value = cacheDylib.installName;
+        const dyld3::MachOFile* mf = cacheDylib.cacheMF;
         uuid_t uuid;
-        if ( cacheDylib.cacheHdr->getUuid(uuid) ) {
+        if ( mf->getUuid(uuid) ) {
             uuid_string_t uuidStr;
             uuid_unparse(uuid, uuidStr);
             imageNode.map["uuid"].value = uuidStr;
         }
 
-        __block json::Node segmentsNode;
-        cacheDylib.cacheHdr->forEachSegment(^(const Header::SegmentInfo &info, bool &stop) {
-            json::Node segmentNode;
-            segmentNode.map["name"].value = info.segmentName;
-            segmentNode.map["start-vmaddr"].value = json::hex(info.vmaddr);
-            segmentNode.map["end-vmaddr"].value = json::hex(info.vmaddr + info.vmsize);
+        __block dyld3::json::Node segmentsNode;
+        mf->forEachSegment(^(const dyld3::MachOAnalyzer::SegmentInfo &info, bool &stop) {
+            dyld3::json::Node segmentNode;
+            segmentNode.map["name"].value = info.segName;
+            segmentNode.map["start-vmaddr"].value = dyld3::json::hex(info.vmAddr);
+            segmentNode.map["end-vmaddr"].value = dyld3::json::hex(info.vmAddr + info.vmSize);
 
             // Add sections in verbose mode
             segmentsNode.array.push_back(segmentNode);
@@ -8987,9 +8283,9 @@
 {
     va_list list;
     va_start(list, format);
-    _SIMPLE_STRING buffer = _simple_salloc();
+    void* buffer = _simple_salloc();
     _simple_vsprintf(buffer, format, list);
-    this->warnings.push_back(_simple_string(buffer));
+    this->warnings.push_back((const char*)buffer);
     _simple_sfree(buffer);
     va_end(list);
 
@@ -9013,219 +8309,3 @@
 
     fprintf(stderr, "Didn't find a dylib with install name: %s\n", installName);
 }
-
-// This name is used only to create a placeholder input file and determine the library order.
-const std::string_view swiftPrespecializedDylibInstallName = "/usr/lib/libswiftPrespecialized.dylib";
-
-bool SharedCacheBuilder::shouldBuildSwiftPrespecializedDylib()
-{
-    if ( options.platform == Platform::driverKit )
-        return false;
-
-    if ( options.platform.isExclaveKit() )
-        return false;
-
-    // build the dylib, only if the order file is defined
-    if ( options.swiftGenericMetadataFile.empty() )
-        return false;
-
-    // check if the metadata builder is available
-#if !BUILDING_CACHE_BUILDER_UNIT_TESTS && !BUILDING_SIM_CACHE_BUILDER
-    if ( swift_externalMetadataBuilder_create == nullptr )
-        return false;
-#endif // !BUILDING_CACHE_BUILDER_UNIT_TESTS
-
-    return true;
-}
-
-Error SharedCacheBuilder::buildSwiftPrespecializedDylibJSON()
-{
-#if !BUILDING_CACHE_BUILDER_UNIT_TESTS && !BUILDING_SIM_CACHE_BUILDER
-    Timer::Scope timedScope(this->config, "buildSwiftPrespecializedDylibJSON time");
-
-    SwiftExternalMetadataBuilder* builder = swift_externalMetadataBuilder_create(options.platform.value(), options.arch.name());
-    if ( !builder )
-        return Error("swift_externalMetadataBuilder_create failed");
-
-    for ( const CacheDylib& dylib : this->cacheDylibs ) {
-        if ( dylib.inputHdr == nullptr ) continue;
-
-        // TODO: rdar://132262275 (dyld shared cache builder should tell Swift Metadata builder also about dyld)
-        if ( dylib.inputHdr->isDylinker() ) continue;
-
-        if ( const char* err = swift_externalMetadataBuilder_addDylib(builder, dylib.inputHdr->installName(),
-                (const struct mach_header*)dylib.inputHdr, dylib.inputFile->size) )
-            return Error("swift_externalMetadataBuilder_addDylib failed: %s", err);
-    }
-
-    if ( const char* err = swift_externalMetadataBuilder_readNamesJSON(builder, options.swiftGenericMetadataFile.c_str()) )
-        return Error("swift_externalMetadataBuilder_readNamesJSON failed: %s", err);
-
-    if ( const char* err = swift_externalMetadataBuilder_buildMetadata(builder) )
-        return Error("swift_externalMetadataBuilder_buildMetadata failed: %s", err);
-
-    if ( const char* json = swift_externalMetadataBuilder_getMetadataJSON(builder) )
-        swiftPrespecializedDylibJSON = json;
-    else
-        return Error("swift_externalMetadataBuilder_getMetadataJSON returned an empty JSON");
-
-    const std::string_view placeholderVersion = R"("platformVersion": "1.0")";
-    // Patch platformVersion if it's 1.0 until rdar://122585868 is fixed
-    if ( auto pos = swiftPrespecializedDylibJSON.find(placeholderVersion);
-            pos != swiftPrespecializedDylibJSON.npos ) {
-
-        __block mach_o::Version32 newMinOS;
-        // determine new deployment target based on dyld's version
-        for ( const InputFile& inputFile : allInputFiles ) {
-            if ( !inputFile.mf )
-                continue;
-
-            if ( !endsWith(inputFile.path, "dyld") )
-                continue;
-
-            ((Header*)inputFile.mf)->platformAndVersions().unzip(^(mach_o::PlatformAndVersions pvs) {
-                if ( pvs.platform == options.platform )
-                    newMinOS = pvs.minOS;
-            });
-            break;
-        }
-
-        if ( newMinOS > mach_o::Version32(1, 0) ) {
-            char verStr[32];
-            newMinOS.toString(verStr);
-            std::string newVersion = "\"platformVersion\": \"";
-            newVersion += verStr;
-            newVersion += "\"";
-
-            swiftPrespecializedDylibJSON.replace(pos, placeholderVersion.size(), newVersion);
-        }
-    }
-
-    swift_externalMetadataBuilder_destroy(builder);
-
-    if ( options.debug ) {
-        std::string path;
-        if ( const char* dir = getenv("TMPDIR") )
-            path = dir;
-        if ( path.empty() )
-            path = "/tmp";
-        path += "/swift-prespecialized.json-XXXXXX";
-
-        int outFileFd = mkstemp(path.data());
-        if ( outFileFd != -1 ) {
-            write(outFileFd, swiftPrespecializedDylibJSON.data(), swiftPrespecializedDylibJSON.size());
-        }
-    }
-#endif // !BUILDING_CACHE_BUILDER_UNIT_TESTS
-
-    return Error::none();
-}
-
-bool SharedCacheBuilder::reserveSwiftPrespecializedInputFile()
-{
-    if ( !shouldBuildSwiftPrespecializedDylib() )
-        return false;
-
-    InputFile inputFile;
-    inputFile.mf = nullptr;
-    inputFile.inode = 0;
-    inputFile.mtime = 0;
-    inputFile.path = swiftPrespecializedDylibInstallName;
-    allInputFiles.push_back(std::move(inputFile));
-    cacheDylibs.push_back(CacheDylib(swiftPrespecializedDylibInstallName));
-    return true;
-}
-
-Error SharedCacheBuilder::createSwiftPrespecializedDylib()
-{
-    if ( !shouldBuildSwiftPrespecializedDylib() )
-        return Error::none();
-
-    if ( Error err = buildSwiftPrespecializedDylibJSON() )
-        return err;
-
-    Timer::Scope timedScope(this->config, "createSwiftPrespecializedDylib time");
-
-    InputFile* inputFile = nullptr;
-    if ( allInputFiles.empty() || allInputFiles.back().path != swiftPrespecializedDylibInstallName )
-        return Error("missing input file placeholder for Swift prespecialized dylib");
-    inputFile = &allInputFiles.back();
-
-    std::vector<const char*> dylibsList;
-    // the dylib list needs to be in order of objc dylibs
-    for ( const CacheDylib* dylib : this->objcOptimizer.objcDylibs )
-        dylibsList.push_back(CString::dup(dylib->installName).c_str());
-
-    // TODO: support in-memory file buffer
-    std::string path;
-    if ( const char* dir = getenv("TMPDIR") )
-        path = dir;
-    if ( path.empty() )
-        path = "/tmp";
-    path += "/libswiftPrespecialized.dylib-XXXXXX";
-
-    int outFileFd = mkstemp(path.data());
-    if ( outFileFd == -1 )
-        return Error("couldn't create a temporary file for Swift prespecialized dylib: %s", (const char*)strerror(errno));
-
-    close(outFileFd);
-    if ( const char* err = ldMakeDylibFromJSON(swiftPrespecializedDylibJSON, dylibsList, path.c_str()) )
-        return Error("%s", err);
-
-    // cleanup dylibs list
-    for ( const char* str : dylibsList )
-        free((void*)str);
-
-    // re-open output file
-    outFileFd = open(path.c_str(), O_RDONLY);
-    if ( outFileFd < 0 )
-        return Error("could not open swift dylib file because: %s", (const char*)strerror(errno));
-
-    struct stat stat_buf;
-    if (  fstat(outFileFd, &stat_buf) == -1 )
-        return Error("could not stat swift dylib file because: %s", (const char*)strerror(errno));
-
-    vm_size_t bufferSize = stat_buf.st_size;
-    void* buffer = mmap(nullptr, bufferSize, PROT_READ, MAP_FILE | MAP_SHARED, outFileFd, 0);
-    if ( buffer == MAP_FAILED ) {
-        // Failed to mmap the file
-        return Error("could not mmap swift dylib file because: %s", (const char*)strerror(errno));
-    }
-
-    Diagnostics diag;
-    uint64_t    sliceOffset = 0;
-    inputFile->mf = MachOFile::compatibleSlice(diag, sliceOffset, inputFile->size, buffer, bufferSize, path.data(),
-                                               this->options.platform, /* isOSBinary */ false,
-                                               this->options.gradedArchs);
-    if ( diag.hasError() )
-        return Error("%s", diag.errorMessageCStr());
-
-    // recreate cache dylib at the reserved slot
-    auto cacheDylibIt = std::find_if(cacheDylibs.begin(), cacheDylibs.end(), [](CacheDylib& dylib) {
-            return dylib.inputHdr == nullptr && dylib.installName == swiftPrespecializedDylibInstallName;
-    });
-    if ( cacheDylibIt == cacheDylibs.end() )
-        return Error("missing cache dylib slot for Swift prespecialized dylib");
-
-    // save previously computed cache index
-    uint32_t index = cacheDylibIt->cacheIndex;
-    // recreate cache dylib with the updated input file
-    *cacheDylibIt = CacheDylib(*inputFile);
-    cacheDylibIt->cacheIndex = index;
-    // rdar://122906481 (Shared cache builder - explicitly model dylibs without a need for a patch table)
-    cacheDylibIt->needsPatchTable = false;
-    this->swiftPrespecializedDylib = &*cacheDylibIt;
-
-    // sanity check Swift dylib compatibility
-    __block Error err = Error::none();
-    inputFile->mf->withFileLayout(diag, ^(const mach_o::Layout& layout) {
-        mach_o::SplitSeg splitSeg(layout);
-
-        if ( !splitSeg.isV2() )
-            err = Error("Swift prespecialized dylib must use split seg V2");
-    });
-    if ( !inputFile->mf->hasChainedFixups() )
-        err = Error("Swift prespecialized dylib must use chained fixups");
-
-    return std::move(err);
-}