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launch-cache/update_dyld_shared_cache.cpp dyld-195.5 dyld-96.2
--- dyld/dyld-195.5/launch-cache/update_dyld_shared_cache.cpp
+++ dyld/dyld-96.2/launch-cache/update_dyld_shared_cache.cpp
@@ -1,6 +1,6 @@
 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*- 
  *
- * Copyright (c) 2006-2011 Apple Inc. All rights reserved.
+ * Copyright (c) 2006-2007 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  * 
@@ -26,7 +26,6 @@
 #include <sys/stat.h>
 #include <sys/mman.h>
 #include <mach/mach.h>
-#include <mach/mach_time.h>
 #include <limits.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -58,64 +57,29 @@
 #include "MachOBinder.hpp"
 #include "CacheFileAbstraction.hpp"
 
-#define SELOPT_WRITE
-#include <objc/objc-selopt.h>
-
-#define FIRST_DYLIB_TEXT_OFFSET 0x5000
-#define FIRST_DYLIB_DATA_OFFSET 0x1000
-
-#ifndef LC_FUNCTION_STARTS
-    #define LC_FUNCTION_STARTS 0x26
-#endif
+extern "C" { 
+	#include "dyld_shared_cache_server.h"
+}
+
 
 static bool							verbose = false;
-static bool							progress = false;
-static bool							iPhoneOS = false;
 static std::vector<const char*>		warnings;
 
 
-static void warn(const char *arch, const char *format, ...)
-{
-    char *msg;
-
-    va_list args;
-    va_start(args, format);
-    ::vasprintf(&msg, format, args);
-    va_end(args);
-    
-    warnings.push_back(msg);
-    
-    if ( verbose ) {
-        ::fprintf(::stderr, "update_dyld_shared_cache: warning: %s%s%s%s\n", 
-                  arch ? "for arch " : "", 
-                  arch ? arch : "", 
-                  arch ? ", " : "", 
-                  msg);
-    }
-}
-
-
 static uint64_t pageAlign(uint64_t addr) { return ( (addr + 4095) & (-4096) ); }
 
 class ArchGraph
 {
 public:
-	struct CStringEquals {
-		bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
-	};
-	typedef __gnu_cxx::hash_map<const char*, const char*, __gnu_cxx::hash<const char*>, CStringEquals> StringToString;
-
-	static void			addArchPair(ArchPair ap);
-	static void			addRoot(const char* vpath, const std::set<ArchPair>& archs);
-	static void			findSharedDylibs(ArchPair ap);
-	static ArchGraph*	graphForArchPair(ArchPair ap) { return fgPerArchGraph[ap]; }
-	static void			setFileSystemRoot(const char* root, bool usesOverlay) { fgFileSystemRoot = root; fgUsesOverlay = usesOverlay; }
-	static const char*	archName(ArchPair ap);
-	
-	ArchPair											getArchPair() { return fArchPair; }
+	static void			addArch(cpu_type_t arch);
+	static void			addRoot(const char* vpath, const std::set<cpu_type_t>& archs);
+	static void			findSharedDylibs(cpu_type_t arch);
+	static ArchGraph*	getArch(cpu_type_t arch) { return fgPerArchGraph[arch]; }
+	static void			setFileSystemRoot(const char* root) { fgFileSystemRoot = root; }
+	static const char*	archName(cpu_type_t arch);
+	
+	cpu_type_t											getArch() { return fArch; }
 	std::set<const class MachOLayoutAbstraction*>&		getSharedDylibs() { return fSharedDylibs; }
-	StringToString&										getDylibAliases() { return fAliasesMap; }
-	const char*											archName() { return archName(fArchPair); }
 	
 private:
 	
@@ -139,80 +103,68 @@
 		std::set<DependencyNode*>					fRootsDependentOnThis;
 	};
 
+	struct CStringEquals {
+		bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
+	};
 	typedef __gnu_cxx::hash_map<const char*, class DependencyNode*, __gnu_cxx::hash<const char*>, CStringEquals> PathToNode;
 
 
-								ArchGraph(ArchPair ap) : fArchPair(ap) {}
+								ArchGraph(cpu_type_t arch) : fArch(arch) {}
+	static void					addRootForArch(const char* path, const MachOLayoutAbstraction*);
 	void						addRoot(const char* path, const MachOLayoutAbstraction*);
 	DependencyNode*				getNode(const char* path);
 	DependencyNode*				getNodeForVirtualPath(const char* vpath);
-	static bool					canBeShared(const MachOLayoutAbstraction* layout, ArchPair ap, const std::set<const MachOLayoutAbstraction*>& possibleLibs, std::map<const MachOLayoutAbstraction*, bool>& shareableMap);
-	static bool					sharable(const MachOLayoutAbstraction* layout, ArchPair ap, char** msg);
-
-	static std::map<ArchPair, ArchGraph*>	fgPerArchGraph;
+	static bool					canBeShared(const MachOLayoutAbstraction* layout, cpu_type_t arch, const std::set<const MachOLayoutAbstraction*>& possibleLibs, std::map<const MachOLayoutAbstraction*, bool>& shareableMap);
+
+	static std::map<cpu_type_t, ArchGraph*>	fgPerArchGraph;
 	static const char*						fgFileSystemRoot;
-	static bool								fgUsesOverlay;
-	
-	ArchPair									fArchPair;
+	
+	cpu_type_t									fArch;
 	std::set<DependencyNode*>					fRoots;
 	PathToNode									fNodes;
 	std::set<const MachOLayoutAbstraction*>		fSharedDylibs;  // use set to avoid duplicates when installname!=realpath
-	StringToString								fAliasesMap;
 };
-std::map<ArchPair, ArchGraph*>		ArchGraph::fgPerArchGraph;
+std::map<cpu_type_t, ArchGraph*>	ArchGraph::fgPerArchGraph;
 const char*							ArchGraph::fgFileSystemRoot = "";
-bool								ArchGraph::fgUsesOverlay = false;
-
-void ArchGraph::addArchPair(ArchPair ap)
-{
-	//fprintf(stderr, "adding ArchPair 0x%08X,0x%08X\n", ap.arch, ap.subtype);
-	fgPerArchGraph[ap] = new ArchGraph(ap);
-}
-
-void ArchGraph::addRoot(const char* vpath, const std::set<ArchPair>& onlyArchs)
+
+void ArchGraph::addArch(cpu_type_t arch)
+{
+	//fprintf(stderr, "adding arch 0x%08X\n", arch);
+	fgPerArchGraph[arch] = new ArchGraph(arch);
+}
+
+void ArchGraph::addRoot(const char* vpath, const std::set<cpu_type_t>& archs)
 {
 	char completePath[strlen(fgFileSystemRoot)+strlen(vpath)+2];
-	const char* path = NULL;
+	const char* path;
 	if ( strlen(fgFileSystemRoot) == 0 ) {
 		path = vpath;
 	}
 	else {
 		strcpy(completePath, fgFileSystemRoot);
 		strcat(completePath, vpath);	// assumes vpath starts with '/'
-		if ( fgUsesOverlay ) {
-			// using -overlay means if /overlay/usr/lib exists use it, otherwise use original path
-			struct stat stat_buf;
-			if ( stat(completePath, &stat_buf) == 0 )
-				path = completePath;
-			else
-				path = vpath;
-		}
-		else {
-			// using -root means alway redirect /usr/lib to /rootpath/usr/lib
-			path = completePath;
-		}
+		path = completePath;
 	}
 	try {
-		const UniversalMachOLayout& uni = UniversalMachOLayout::find(path, &onlyArchs);
-		for(std::set<ArchPair>::iterator ait = onlyArchs.begin(); ait != onlyArchs.end(); ++ait) {
-			try {
-				const MachOLayoutAbstraction* layout = uni.getSlice(*ait);
-				if ( layout != NULL )
-					fgPerArchGraph[*ait]->addRoot(path, layout);
-			}
-			catch (const char* msg) {
-				if ( verbose ) 
-					fprintf(stderr, "update_dyld_shared_cache: warning for %s can't use root '%s': %s\n", fgPerArchGraph[*ait]->archName(), path, msg);
-			}
-			
-		}
+		const UniversalMachOLayout* uni = UniversalMachOLayout::find(path, &archs);
+		const std::vector<MachOLayoutAbstraction*>& layouts = uni->getArchs();
+		for(std::vector<MachOLayoutAbstraction*>::const_iterator it = layouts.begin(); it != layouts.end(); ++it) {
+			const MachOLayoutAbstraction* layout = *it;
+			if ( archs.count(layout->getArchitecture()) > 0 )
+				ArchGraph::addRootForArch(path, layout);
+		}
+		// don't delete uni, it is owned by UniversalMachOLayout cache
 	}
 	catch (const char* msg) {
-		fprintf(stderr, "update_dyld_shared_cache: warning can't use root '%s': %s\n", path, msg);
-	}
-}
-
-
+		fprintf(stderr, "update_dyld_shared_cache: warning can't use root %s: %s\n", path, msg);
+	}
+}
+
+void ArchGraph::addRootForArch(const char* path, const MachOLayoutAbstraction* layout)
+{
+	ArchGraph* graph = fgPerArchGraph[layout->getArchitecture()];
+	graph->addRoot(path, layout);
+}
 
 void ArchGraph::addRoot(const char* path, const MachOLayoutAbstraction* layout)
 {
@@ -230,7 +182,6 @@
 }
 
 // a virtual path does not have the fgFileSystemRoot prefix
-// a virtual path does not have the fgFileSystemRoot prefix
 ArchGraph::DependencyNode* ArchGraph::getNodeForVirtualPath(const char* vpath)
 {
 	if ( fgFileSystemRoot == NULL ) {
@@ -240,38 +191,7 @@
 		char completePath[strlen(fgFileSystemRoot)+strlen(vpath)+2];
 		strcpy(completePath, fgFileSystemRoot);
 		strcat(completePath, vpath);	// assumes vpath starts with '/'
-		if ( fgUsesOverlay ) {
-			// using -overlay means if /overlay/path/dylib exists use it, otherwise use /path/dylib
-			struct stat stat_buf;
-			if ( stat(completePath, &stat_buf) == 0 )
-				return this->getNode(completePath);
-			else {
-				// <rdar://problem/9279770> support when install name is a symlink
-				if ( (lstat(vpath, &stat_buf) == 0) && S_ISLNK(stat_buf.st_mode) ) {
-					// requested path did not exist in /overlay, but leaf of path is a symlink in /
-					char pathInSymLink[MAXPATHLEN];
-					size_t res = readlink(vpath, pathInSymLink, sizeof(pathInSymLink));
-					if ( res != -1 ) {
-						pathInSymLink[res] = '\0';
-						if ( pathInSymLink[0] != '/' ) {
-							char symFullPath[MAXPATHLEN];
-							strcpy(symFullPath, vpath);
-							char* lastSlash = strrchr(symFullPath, '/');
-							if ( lastSlash != NULL ) {
-								strcpy(lastSlash+1, pathInSymLink);
-								// (re)try looking for what symlink points to, but in /overlay
-								return this->getNodeForVirtualPath(symFullPath);
-							}
-						} 
-					}
-				}
-				return this->getNode(vpath);
-			}
-		}
-		else {
-			// using -root means always use /rootpath/usr/lib
-			return this->getNode(completePath);
-		}
+		return this->getNode(completePath);
 	}
 }
 
@@ -289,54 +209,21 @@
 	
 	// look up real path to see if node already exists
 	pos = fNodes.find(realPath);
-	if ( pos != fNodes.end() ) {
-		// update fAliasesMap with symlinks found
-		const char* aliasPath = path;
-		if ( (fgFileSystemRoot != NULL) && (strncmp(path, fgFileSystemRoot, strlen(fgFileSystemRoot)) == 0) ) {
-			aliasPath = &path[strlen(fgFileSystemRoot)];
-		}
-		if ( fAliasesMap.find(aliasPath) == fAliasesMap.end() ) {
-			if ( strcmp(aliasPath, pos->second->getLayout()->getID().name) != 0 ) {
-				fAliasesMap[strdup(aliasPath)] = pos->second->getLayout()->getID().name;
-				//fprintf(stderr, "getNode() %s: added alias %s -> %s\n", archName(fArchPair), aliasPath, fAliasesMap[aliasPath]);
-			}
-		}
+	if ( pos != fNodes.end() )
 		return pos->second;
-	}
 	
 	// still does not exist, so create a new node
-	const UniversalMachOLayout& uni = UniversalMachOLayout::find(realPath);
-	DependencyNode* node = new DependencyNode(this, realPath, uni.getSlice(fArchPair));
+	const UniversalMachOLayout* uni = UniversalMachOLayout::find(realPath);
+	DependencyNode* node = new DependencyNode(this, realPath, uni->getArch(fArch));
 	if ( node->getLayout() == NULL ) {
-		throwf("%s is missing arch %s", realPath, archName(fArchPair));
+		throwf("%s is missing arch %s", realPath, archName(fArch));
 	}
 	// add realpath to node map
 	fNodes[node->getPath()] = node;
 	// if install name is not real path, add install name to node map
 	if ( (node->getLayout()->getFileType() == MH_DYLIB) && (strcmp(realPath, node->getLayout()->getID().name) != 0) ) {
-		//fprintf(stderr, "adding %s node alias %s for %s\n", archName(fArchPair), node->getLayout()->getID().name, realPath);
-		pos = fNodes.find(node->getLayout()->getID().name);
-		if ( pos != fNodes.end() ) {
-			// <rdar://problem/8305479> warn if two dylib in cache have same install_name
-			char* msg;
-			asprintf(&msg, "update_dyld_shared_cache: warning, found two dylibs with same install path: %s\n\t%s\n\t%s\n", 
-									node->getLayout()->getID().name, pos->second->getPath(), node->getPath());
-			fprintf(stderr, "%s", msg);
-			warnings.push_back(msg);
-		}
-		else
-			fNodes[node->getLayout()->getID().name] = node;
-		// update fAliasesMap with symlinks found
-		const char* aliasPath = realPath;
-		if ( (fgFileSystemRoot != NULL) && (strncmp(realPath, fgFileSystemRoot, strlen(fgFileSystemRoot)) == 0) ) {
-			aliasPath = &realPath[strlen(fgFileSystemRoot)];
-		}
-		if ( fAliasesMap.find(aliasPath) == fAliasesMap.end() ) {
-			if ( strcmp(aliasPath, node->getLayout()->getID().name) != 0 ) {
-				fAliasesMap[strdup(aliasPath)] = node->getLayout()->getID().name;
-				//fprintf(stderr, "getNode() %s: added alias %s -> %s\n", archName(fArchPair), aliasPath, fAliasesMap[aliasPath]);
-			}
-		}
+		//fprintf(stderr, "adding node alias 0x%08X %s for %s\n", fArch, node->getLayout()->getID().name, realPath);
+		fNodes[node->getLayout()->getID().name] = node;
 	}
 	return node;
 }
@@ -357,13 +244,7 @@
 					// expand @executable_path path prefix
 					const char* executablePath = mainExecutableLayout->getFilePath();
 					char newPath[strlen(executablePath) + strlen(dependentPath)+2];
-					if ( (fgFileSystemRoot != NULL) && (strncmp(executablePath, fgFileSystemRoot, strlen(fgFileSystemRoot)) == 0) ) {
-						// executablePath already has rootPath prefix, need to remove that to get to base virtual path
-						strcpy(newPath, &executablePath[strlen(fgFileSystemRoot)]);
-					}
-					else {
-						strcpy(newPath, executablePath);
-					}
+					strcpy(newPath, executablePath);
 					char* addPoint = strrchr(newPath,'/');
 					if ( addPoint != NULL )
 						strcpy(&addPoint[1], &dependentPath[17]);
@@ -374,13 +255,7 @@
 				else if ( strncmp(dependentPath, "@loader_path/", 13) == 0 ) {
 					// expand @loader_path path prefix
 					char newPath[strlen(fPath) + strlen(dependentPath)+2];
-					if ( (fgFileSystemRoot != NULL) && (strncmp(fPath, fgFileSystemRoot, strlen(fgFileSystemRoot)) == 0) ) {
-						// fPath already has rootPath prefix, need to remove that to get to base virtual path
-						strcpy(newPath, &fPath[strlen(fgFileSystemRoot)]);
-					}
-					else {
-						strcpy(newPath, fPath);
-					}
+					strcpy(newPath, fPath);
 					char* addPoint = strrchr(newPath,'/');
 					if ( addPoint != NULL )
 						strcpy(&addPoint[1], &dependentPath[13]);
@@ -391,25 +266,11 @@
 				else if ( strncmp(dependentPath, "@rpath/", 7) == 0 ) {
 					throw "@rpath not supported in dyld shared cache";
 				}
-				// <rdar://problem/9161945> silently ignore dependents from main executables that can't be in shared cache
-				bool addDependent = true;
-				if ( fLayout->getFileType() == MH_EXECUTE ) {
-					if ( (strncmp(dependentPath, "/usr/lib/", 9) != 0) && (strncmp(dependentPath, "/System/Library/", 16) != 0) ) {
-						addDependent = false;
-					}
-				}
-				if ( addDependent )
-					fDependsOn.insert(fGraph->getNodeForVirtualPath(dependentPath));
+				fDependsOn.insert(fGraph->getNodeForVirtualPath(dependentPath));
 			}
 			catch (const char* msg) {
-				if ( it->weakImport && ! fLayout->hasSplitSegInfo() ) {
-					// ok to ignore missing weak imported dylibs from things that are
-					// not going to be in the dyld shared cache
-				}
-				else {
-					fprintf(stderr, "warning, could not bind %s because %s\n", fPath, msg);
-					fDependentMissing = true;
-				}
+				fprintf(stderr, "warning, could not bind %s because %s\n", fPath, msg);
+				fDependentMissing = true;
 			}
 		}
 		// recurse
@@ -436,94 +297,46 @@
 	//fprintf(stderr, "new DependencyNode(0x%08X, %s)\n", graph->fArch, path);
 }
 
-void ArchGraph::findSharedDylibs(ArchPair ap)
-{
-	const PathToNode& nodes = fgPerArchGraph[ap]->fNodes;
+void ArchGraph::findSharedDylibs(cpu_type_t arch)
+{
+	const PathToNode& nodes = fgPerArchGraph[arch]->fNodes;
 	std::set<const MachOLayoutAbstraction*> possibleLibs;
-	//fprintf(stderr, "shared for arch %s\n", archName(ap));
+	//fprintf(stderr, "shared for arch 0x%08X\n", arch);
 	for(PathToNode::const_iterator it = nodes.begin(); it != nodes.end(); ++it) {
 		DependencyNode* node = it->second;
-		// <rdar://problem/6127437> put all dylibs in shared cache - not just ones used by more than one app
-		if ( node->allDependentsFound() /*&& (node->useCount() > 1)*/ ) {
-			const MachOLayoutAbstraction* layout = node->getLayout();
-			if ( layout->isDylib() ) {
-				char* msg;
-				if ( sharable(layout, ap, &msg) ) {
-					possibleLibs.insert(layout);
-				}
-				else {
-					if ( layout->getID().name[0] == '@' ) {
-						// <rdar://problem/7770139> update_dyld_shared_cache should suppress warnings for embedded frameworks
-					}
-					else {
-						warnings.push_back(msg);
-						fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(ap), msg);
-					}
-				}
-			}
+		if ( node->allDependentsFound() && (node->useCount() > 1) ) {
+			if ( node->getLayout()->hasSplitSegInfo() ) 
+				possibleLibs.insert(node->getLayout());
+			//fprintf(stderr, "\t%s\n", it->first);
 		}
 	}
 	
 	// prune so that all shareable libs depend only on other shareable libs
-	std::set<const MachOLayoutAbstraction*>& sharedLibs = fgPerArchGraph[ap]->fSharedDylibs;
+	std::set<const MachOLayoutAbstraction*>& sharedLibs = fgPerArchGraph[arch]->fSharedDylibs;
 	std::map<const MachOLayoutAbstraction*,bool> shareableMap;
 	for (std::set<const MachOLayoutAbstraction*>::iterator lit = possibleLibs.begin(); lit != possibleLibs.end(); ++lit) {
-		if ( canBeShared(*lit, ap, possibleLibs, shareableMap) )
+		if ( canBeShared(*lit, arch, possibleLibs, shareableMap) )
 			sharedLibs.insert(*lit);
 	}
 }
 
-const char*	ArchGraph::archName(ArchPair ap)
-{
-	switch ( ap.arch ) {
+const char*	ArchGraph::archName(cpu_type_t arch)
+{
+	switch ( arch ) {
 		case CPU_TYPE_POWERPC:
 			return "ppc";
+		case CPU_TYPE_POWERPC64:
+			return "ppc64";
 		case CPU_TYPE_I386:
 			return "i386";
 		case CPU_TYPE_X86_64:
 			return "x86_64";
-		case CPU_TYPE_ARM:
-			switch ( ap.subtype ) {
-				case CPU_SUBTYPE_ARM_V4T:
-					return "armv4t";
-				case CPU_SUBTYPE_ARM_V6:
-					return "armv6";
-				case CPU_SUBTYPE_ARM_V5TEJ:
-					return "armv5";
-				case CPU_SUBTYPE_ARM_XSCALE:
-					return "arm-xscale";
-				case CPU_SUBTYPE_ARM_V7:
-					return "armv7";
-				default:
-					return "arm";
-			}
 		default:
 			return "unknown";
 	}
 }
 
-bool ArchGraph::sharable(const MachOLayoutAbstraction* layout, ArchPair ap, char** msg)
-{
-	if ( ! layout->isTwoLevelNamespace() ) 
-		asprintf(msg, "can't put %s in shared cache because it was built -flat_namespace", layout->getID().name);
-	else if ( ! layout->hasSplitSegInfo() ) 
-		asprintf(msg, "can't put %s in shared cache because it was not built for %s or later", layout->getID().name, (iPhoneOS ? "iPhoneOS 3.1" : "MacOSX 10.5"));
-	else if ( ! layout->isRootOwned() )
-		asprintf(msg, "can't put %s in shared cache because it is not owned by root", layout->getID().name);
-	else if ( ! layout->inSharableLocation() )
-		asprintf(msg, "can't put %s in shared cache because it is not in /usr/lib or /System/Library", layout->getID().name);
-	else if ( layout->hasDynamicLookupLinkage() )
-		asprintf(msg, "can't put %s in shared cache because it was built with '-undefined dynamic_lookup'", layout->getID().name);
-	else if ( layout->hasMainExecutableLookupLinkage() )
-		asprintf(msg, "can't put %s in shared cache because it was built with '-bundle_loader'", layout->getID().name);
-	//else if ( ! layout->hasDyldInfo() )
-	//	asprintf(msg, "can't put %s in shared cache because it was built for older OS", layout->getID().name);
-	else
-		return true;
-	return false;
-}
-
-bool ArchGraph::canBeShared(const MachOLayoutAbstraction* layout, ArchPair ap, const std::set<const MachOLayoutAbstraction*>& possibleLibs, std::map<const MachOLayoutAbstraction*, bool>& shareableMap)
+bool ArchGraph::canBeShared(const MachOLayoutAbstraction* layout, cpu_type_t arch, const std::set<const MachOLayoutAbstraction*>& possibleLibs, std::map<const MachOLayoutAbstraction*, bool>& shareableMap)
 {
 	// check map which is a cache of results
 	std::map<const MachOLayoutAbstraction*, bool>::iterator mapPos = shareableMap.find(layout);
@@ -534,42 +347,38 @@
 	if ( possibleLibs.count(layout) == 0 ) {
 		shareableMap[layout] = false;
 		char* msg;
-		if ( sharable(layout, ap, &msg) )
-			asprintf(&msg, "can't put %s in shared cache, unknown reason", layout->getID().name);
+		if ( ! layout->hasSplitSegInfo() )
+			asprintf(&msg, "can't put %s in shared cache because it was not built for 10.5", layout->getID().name);
+		else
+			asprintf(&msg, "can't put %s in shared cache", layout->getID().name);
 		warnings.push_back(msg);
 		if ( verbose )
-			fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(ap), msg);
+			fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(arch), msg);
 		return false;
 	}
 	// look recursively
 	shareableMap[layout] = true; // mark this shareable early in case of circular references
-	const PathToNode& nodes = fgPerArchGraph[ap]->fNodes;
+	const PathToNode& nodes = fgPerArchGraph[arch]->fNodes;
 	const std::vector<MachOLayoutAbstraction::Library>&	dependents = layout->getLibraries();
 	for (std::vector<MachOLayoutAbstraction::Library>::const_iterator dit = dependents.begin(); dit != dependents.end(); ++dit) {
 		PathToNode::const_iterator pos = nodes.find(dit->name);
 		if ( pos == nodes.end() ) {
-			// path from load command does not match any loaded dylibs, maybe there is a temp symlink
-			char realPath[MAXPATHLEN];
-			if ( realpath(dit->name, realPath) != NULL ) {
-				if ( nodes.find(realPath) != nodes.end() )
-					continue;
-			}
 			shareableMap[layout] = false;
 			char* msg;
 			asprintf(&msg, "can't put %s in shared cache because it depends on %s which can't be found", layout->getID().name, dit->name);
 			warnings.push_back(msg);
 			if ( verbose )
-				fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(ap), msg);
+				fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(arch), msg);
 			return false;
 		}
 		else {
-			if ( ! canBeShared(pos->second->getLayout(), ap, possibleLibs, shareableMap) ) {
+			if ( ! canBeShared(pos->second->getLayout(), arch, possibleLibs, shareableMap) ) {
 				shareableMap[layout] = false;
 				char* msg;
 				asprintf(&msg, "can't put %s in shared cache because it depends on %s which can't be in shared cache", layout->getID().name, dit->name);
 				warnings.push_back(msg);
 				if ( verbose )
-					fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(ap), msg);
+					fprintf(stderr, "update_dyld_shared_cache: for arch %s, %s\n", archName(arch), msg);
 				return false;
 			}
 		}
@@ -582,28 +391,16 @@
 class SharedCache
 {
 public:
-							SharedCache(ArchGraph* graph, const char* rootPath, const char* cacheDir, bool alphaSort, bool verify, bool optimize, bool overlay, uint64_t dyldBaseAddress);
-	bool					update(bool usesOverlay, bool force, bool optimize, bool deleteExistingFirst, int archIndex, 
-										int archCount, bool keepSignatures);
-	static const char*		cacheFileSuffix(bool optimized, const char* archName);
-
-    // vm address = address AS WRITTEN into the cache
-    // mapped address = address AS MAPPED into the update process only
-    // file offset = offset relative to start of cache file
-    void *					mappedAddressForVMAddress(uint64_t vmaddr);
-    uint64_t 				VMAddressForMappedAddress(const void *mapaddr);
-	uint64_t				cacheFileOffsetForVMAddress(uint64_t addr) const;
-	uint64_t				VMAddressForCacheFileOffset(uint64_t addr) const;
+							SharedCache(ArchGraph* graph, bool alphaSort, uint64_t dyldBaseAddress);
+	bool					update(const char* rootPath, const char* cacheDir, bool force, bool optimize, bool deleteExistingFirst, int archIndex, int archCount);
+	static const char*		filename(bool optimized);
 
 private:
-	typedef typename A::P			P;
-    typedef typename A::P::E		E;
-    typedef typename A::P::uint_t	pint_t;
-
-	bool					notUpToDate(const char* path, unsigned int aliasCount);
-	bool					notUpToDate(const void* cache, unsigned int aliasCount);
-	uint8_t*				optimizeLINKEDIT(bool keepSignatures);
-	void					optimizeObjC(std::vector<void*>& pointersInData);
+	typedef typename A::P::E	E;
+
+	bool					notUpToDate(const char* cachePath);
+	bool					notUpToDate(const void* cache);
+	uint8_t*				optimizeLINKEDIT();
 
 	static void				getSharedCacheBasAddresses(cpu_type_t arch, uint64_t* baseReadOnly, uint64_t* baseWritable);
 	static cpu_type_t		arch();
@@ -613,13 +410,13 @@
 	static uint64_t			sharedRegionReadOnlySize();
 	static uint64_t			sharedRegionWritableSize();
 	static uint64_t			getWritableSegmentNewAddress(uint64_t proposedNewAddress, uint64_t originalAddress, uint64_t executableSlide);
-	static bool				addCacheSlideInfo();
-	
-	void					assignNewBaseAddresses(bool verify);
+	
+	
+	void					assignNewBaseAddresses();
+	uint64_t				cacheFileOffsetForAddress(uint64_t addr);
 
 	struct LayoutInfo {
 		const MachOLayoutAbstraction*		layout;
-		std::vector<const char*>			aliases;
 		dyld_cache_image_info				info;
 	};
 	
@@ -628,217 +425,77 @@
 				{ return (strcmp(left.layout->getID().name, right.layout->getID().name) < 0); }
 	};
 
-    struct ByCStringSectionSizeSorter {
-        bool operator()(const LayoutInfo& left, const LayoutInfo& right) {
-            const std::vector<MachOLayoutAbstraction::Segment>& segs_l =
-                left.layout->getSegments();
-            const std::vector<MachOLayoutAbstraction::Segment>& segs_r = 
-                right.layout->getSegments();
-            if (segs_l.size() == 0  ||  segs_r.size() == 0) {
-                // one image has no segments
-                return segs_l.size() > segs_r.size();
-            }
-            const macho_header<P> *mh_l = (macho_header<P>*)segs_l[0].mappedAddress();
-            const macho_header<P> *mh_r = (macho_header<P>*)segs_r[0].mappedAddress();
-            const macho_section<P> *cstring_l = mh_l->getSection("__TEXT", "__cstring");
-            const macho_section<P> *cstring_r = mh_r->getSection("__TEXT", "__cstring");
-            if (!cstring_l  ||  !cstring_r) {
-                // one image has no cstrings
-                return cstring_l && !cstring_r;
-            }
-
-            return cstring_l->size() > cstring_r->size();
-        }
-    };
-
-	struct Sorter {
-		Sorter(std::map<const MachOLayoutAbstraction*, uint32_t>& map): fMap(map) {}
+	struct RandomSorter {
+		RandomSorter(const std::vector<LayoutInfo>& infos) {
+			for(typename std::vector<struct LayoutInfo>::const_iterator it = infos.begin(); it != infos.end(); ++it) 
+				fMap[it->layout] = arc4random();
+		}
 		bool operator()(const LayoutInfo& left, const LayoutInfo& right) {
 			return (fMap[left.layout] < fMap[right.layout]); 
 		}
 	private:
-		std::map<const MachOLayoutAbstraction*, uint32_t>& fMap;
+		std::map<const MachOLayoutAbstraction*, uint32_t> fMap;
 	};
 	
-	
+
 	ArchGraph*							fArchGraph;
-	const bool							fVerify;
-	bool								fExistingIsNotUpToDate;
-	bool								fCacheFileInFinalLocation;
-	const char*							fCacheFilePath;
-	uint8_t*							fExistingCacheForVerification;
 	std::vector<LayoutInfo>				fDylibs;
-	std::vector<LayoutInfo>				fDylibAliases;
 	std::vector<shared_file_mapping_np>	fMappings;
 	uint32_t							fHeaderSize;
-    uint8_t*							fInMemoryCache;
 	uint64_t							fDyldBaseAddress;
 	uint64_t							fLinkEditsTotalUnoptimizedSize;
 	uint64_t							fLinkEditsStartAddress;
 	MachOLayoutAbstraction::Segment*	fFirstLinkEditSegment;
-	uint32_t							fOffsetOfBindInfoInCombinedLinkedit;
-	uint32_t							fOffsetOfWeakBindInfoInCombinedLinkedit;
-	uint32_t							fOffsetOfLazyBindInfoInCombinedLinkedit;
-	uint32_t							fOffsetOfExportInfoInCombinedLinkedit;
-	uint32_t							fOffsetOfOldSymbolTableInfoInCombinedLinkedit;
-	uint32_t							fSizeOfOldSymbolTableInfoInCombinedLinkedit;
-	uint32_t							fOffsetOfOldExternalRelocationsInCombinedLinkedit;
-	uint32_t							fSizeOfOldExternalRelocationsInCombinedLinkedit;
-	uint32_t							fOffsetOfOldIndirectSymbolsInCombinedLinkedit;
-	uint32_t							fSizeOfOldIndirectSymbolsInCombinedLinkedit;
-	uint32_t							fOffsetOfOldStringPoolInCombinedLinkedit;
-	uint32_t							fSizeOfOldStringPoolInCombinedLinkedit;
-	uint32_t							fOffsetOfFunctionStartsInCombinedLinkedit;
-	uint32_t							fSizeOfFunctionStartsInCombinedLinkedit;
-	uint32_t							fLinkEditsTotalOptimizedSize;
 };
 
 
-// Access a section containing a list of pointers
-template <typename A, typename T>
-class PointerSection 
-{
-    typedef typename A::P P;
-    typedef typename A::P::uint_t pint_t;
-
-    SharedCache<A>* const			fCache;
-    const macho_section<P>* const	fSection;
-    pint_t * const					fBase;
-    uint64_t						fCount;
-
-public:
-    PointerSection(SharedCache<A>* cache, const macho_header<P>* header, 
-                   const char *segname, const char *sectname)
-        : fCache(cache)
-        , fSection(header->getSection(segname, sectname))
-        , fBase(fSection ? (pint_t *)cache->mappedAddressForVMAddress(fSection->addr()) : 0)
-        , fCount(fSection ? fSection->size() / sizeof(pint_t) : 0)
-    {
-    }
-
-    uint64_t count() const { return fCount; }
-
-    uint64_t getUnmapped(uint64_t index) const {
-        if (index >= fCount) throwf("index out of range");
-        return P::getP(fBase[index]);
-    }
-
-    T get(uint64_t index) const { 
-        return (T)fCache->mappedAddressForVMAddress(getUnmapped(index));
-    }
-
-    void set(uint64_t index, uint64_t value) {
-        if (index >= fCount) throwf("index out of range");
-        P::setP(fBase[index], value);
-    }
-	
-    void removeNulls() {
-        uint64_t shift = 0;
-        for (uint64_t i = 0; i < fCount; i++) {
-            pint_t value = fBase[i];
-            if (value) {
-                fBase[i-shift] = value;
-            } else {
-                shift++;
-            }
-        }
-        fCount -= shift;
-		const_cast<macho_section<P>*>(fSection)->set_size(fCount * sizeof(pint_t));
-    }
-};
-
-// Access a section containing an array of structures
-template <typename A, typename T>
-class ArraySection 
-{
-    typedef typename A::P P;
-
-    SharedCache<A>* const fCache;
-    const macho_section<P>* const fSection;
-    T * const fBase;
-    uint64_t const fCount;
-
-public:
-    ArraySection(SharedCache<A>* cache, const macho_header<P>* header, 
-                 const char *segname, const char *sectname)
-        : fCache(cache)
-        , fSection(header->getSection(segname, sectname))
-        , fBase(fSection ? (T *)cache->mappedAddressForVMAddress(fSection->addr()) : 0)
-        , fCount(fSection ? fSection->size() / sizeof(T) : 0)
-    {
-    }
-
-    uint64_t count() const { return fCount; }
-
-    T& get(uint64_t index) const { 
-        if (index >= fCount) throwf("index out of range");
-        return fBase[index];
-    }
-};
-
-
-// GrP fixme
-#include "ObjCLegacyAbstraction.hpp"
-#include "ObjCModernAbstraction.hpp"
-
 
 	
 template <>	 cpu_type_t	SharedCache<ppc>::arch()	{ return CPU_TYPE_POWERPC; }
+template <>	 cpu_type_t	SharedCache<ppc64>::arch()	{ return CPU_TYPE_POWERPC64; }
 template <>	 cpu_type_t	SharedCache<x86>::arch()	{ return CPU_TYPE_I386; }
 template <>	 cpu_type_t	SharedCache<x86_64>::arch()	{ return CPU_TYPE_X86_64; }
-template <>	 cpu_type_t	SharedCache<arm>::arch()	{ return CPU_TYPE_ARM; }
 
 template <>	 uint64_t	SharedCache<ppc>::sharedRegionReadOnlyStartAddress()	{ return 0x90000000; }
+template <>	 uint64_t	SharedCache<ppc64>::sharedRegionReadOnlyStartAddress()	{ return 0x7FFF80000000LL; }
 template <>	 uint64_t	SharedCache<x86>::sharedRegionReadOnlyStartAddress()	{ return 0x90000000; }
 template <>	 uint64_t	SharedCache<x86_64>::sharedRegionReadOnlyStartAddress()	{ return 0x7FFF80000000LL; }
-template <>	 uint64_t	SharedCache<arm>::sharedRegionReadOnlyStartAddress()	{ return 0x30000000; }
 
 template <>	 uint64_t	SharedCache<ppc>::sharedRegionWritableStartAddress()	{ return 0xA0000000; }
-template <>	 uint64_t	SharedCache<x86>::sharedRegionWritableStartAddress()	{ return 0xAC000000; }
+template <>	 uint64_t	SharedCache<ppc64>::sharedRegionWritableStartAddress()	{ return 0x7FFF70000000LL; }
+template <>	 uint64_t	SharedCache<x86>::sharedRegionWritableStartAddress()	{ return 0xA0000000; }
 template <>	 uint64_t	SharedCache<x86_64>::sharedRegionWritableStartAddress()	{ return 0x7FFF70000000LL; }
-template <>	 uint64_t	SharedCache<arm>::sharedRegionWritableStartAddress()	{ return 0x3E000000; }
 
 template <>	 uint64_t	SharedCache<ppc>::sharedRegionReadOnlySize()			{ return 0x10000000; }
-template <>	 uint64_t	SharedCache<x86>::sharedRegionReadOnlySize()			{ return 0x1C000000; }
-template <>	 uint64_t	SharedCache<x86_64>::sharedRegionReadOnlySize()			{ return 0x40000000; }
-template <>	 uint64_t	SharedCache<arm>::sharedRegionReadOnlySize()			{ return 0x0E000000; }
+template <>	 uint64_t	SharedCache<ppc64>::sharedRegionReadOnlySize()			{ return 0x7FE00000; }
+template <>	 uint64_t	SharedCache<x86>::sharedRegionReadOnlySize()			{ return 0x10000000; }
+template <>	 uint64_t	SharedCache<x86_64>::sharedRegionReadOnlySize()			{ return 0x7FE00000; }
 
 template <>	 uint64_t	SharedCache<ppc>::sharedRegionWritableSize()			{ return 0x10000000; }
-template <>	 uint64_t	SharedCache<x86>::sharedRegionWritableSize()			{ return 0x04000000; }
-template <>	 uint64_t	SharedCache<x86_64>::sharedRegionWritableSize()			{ return 0x10000000; }
-template <>	 uint64_t	SharedCache<arm>::sharedRegionWritableSize()			{ return 0x02000000; }
+template <>	 uint64_t	SharedCache<ppc64>::sharedRegionWritableSize()			{ return 0x20000000; }
+template <>	 uint64_t	SharedCache<x86>::sharedRegionWritableSize()			{ return 0x10000000; }
+template <>	 uint64_t	SharedCache<x86_64>::sharedRegionWritableSize()			{ return 0x20000000; }
 
 
 template <>	 const char*	SharedCache<ppc>::archName()	{ return "ppc"; }
+template <>	 const char*	SharedCache<ppc64>::archName()	{ return "ppc64"; }
 template <>	 const char*	SharedCache<x86>::archName()	{ return "i386"; }
 template <>	 const char*	SharedCache<x86_64>::archName()	{ return "x86_64"; }
-template <>	 const char*	SharedCache<arm>::archName()	{ return "arm"; }
-
-template <>	 const char*	SharedCache<ppc>::cacheFileSuffix(bool optimized, const char*)	{ return optimized ? "ppc" : "rosetta"; }
-template <>	 const char*	SharedCache<x86>::cacheFileSuffix(bool, const char* archName)	{ return archName; }
-template <>	 const char*	SharedCache<x86_64>::cacheFileSuffix(bool, const char* archName){ return archName; }
-template <>	 const char*	SharedCache<arm>::cacheFileSuffix(bool, const char* archName)	{ return archName; }
+
+template <>	 const char*	SharedCache<ppc>::filename(bool optimized)	{ return optimized ? "ppc" : "rosetta"; }
+template <>	 const char*	SharedCache<ppc64>::filename(bool)	{ return "ppc64"; }
+template <>	 const char*	SharedCache<x86>::filename(bool)	{ return "i386"; }
+template <>	 const char*	SharedCache<x86_64>::filename(bool)	{ return "x86_64"; }
 
 template <typename A>
-SharedCache<A>::SharedCache(ArchGraph* graph, const char* rootPath, const char* cacheDir, bool alphaSort, bool verify, bool optimize, bool overlay, uint64_t dyldBaseAddress) 
-  : fArchGraph(graph), fVerify(verify), fExistingIsNotUpToDate(true), 
-	fCacheFileInFinalLocation(rootPath[0] == '\0'), fCacheFilePath(NULL),
-	fExistingCacheForVerification(NULL), fDyldBaseAddress(dyldBaseAddress),
-	fOffsetOfBindInfoInCombinedLinkedit(0), fOffsetOfWeakBindInfoInCombinedLinkedit(0),
-	fOffsetOfLazyBindInfoInCombinedLinkedit(0), fOffsetOfExportInfoInCombinedLinkedit(0),
-	fOffsetOfOldSymbolTableInfoInCombinedLinkedit(0), fSizeOfOldSymbolTableInfoInCombinedLinkedit(0),
-	fOffsetOfOldExternalRelocationsInCombinedLinkedit(0), fSizeOfOldExternalRelocationsInCombinedLinkedit(0),
-	fOffsetOfOldIndirectSymbolsInCombinedLinkedit(0), fSizeOfOldIndirectSymbolsInCombinedLinkedit(0),
-	fOffsetOfOldStringPoolInCombinedLinkedit(0), fSizeOfOldStringPoolInCombinedLinkedit(0),
-	fOffsetOfFunctionStartsInCombinedLinkedit(0), fSizeOfFunctionStartsInCombinedLinkedit(0)
-{
-	if ( fArchGraph->getArchPair().arch != arch() )
-		throwf("SharedCache object is wrong architecture: 0x%08X vs 0x%08X", fArchGraph->getArchPair().arch, arch());
-		
+SharedCache<A>::SharedCache(ArchGraph* graph, bool alphaSort, uint64_t dyldBaseAddress) 
+  : fArchGraph(graph), fDyldBaseAddress(dyldBaseAddress)
+{
+	if ( fArchGraph->getArch() != arch() )
+		throw "wrong architecture";
+	
 	// build vector of all shared dylibs
-	unsigned int aliasCount = 0;
 	std::set<const MachOLayoutAbstraction*>& dylibs = fArchGraph->getSharedDylibs();
-	ArchGraph::StringToString& aliases = fArchGraph->getDylibAliases();
 	for(std::set<const MachOLayoutAbstraction*>::iterator it = dylibs.begin(); it != dylibs.end(); ++it) {
 		const MachOLayoutAbstraction* lib = *it;
 		LayoutInfo temp;
@@ -846,105 +503,27 @@
 		temp.info.address = 0;
 		temp.info.modTime = lib->getLastModTime();
 		temp.info.inode = lib->getInode();
-		temp.info.pathFileOffset = lib->getNameFileOffset();  // for now this is the offset within the dylib
-		for(ArchGraph::StringToString::iterator ait = aliases.begin(); ait != aliases.end(); ++ait) {
-			if ( strcmp(ait->second, lib->getID().name) == 0 ) {
-				temp.aliases.push_back(ait->first);
-				++aliasCount;
-			}
-		}
+		temp.info.pathFileOffset = lib->getNameFileOffset();
 		fDylibs.push_back(temp);
 	}
-
-	// create path to cache file
-	char cachePathNonOverlay[1024];
-	strcpy(cachePathNonOverlay, cacheDir);
-	if ( cachePathNonOverlay[strlen(cachePathNonOverlay)-1] != '/' )
-		strcat(cachePathNonOverlay, "/");
-	strcat(cachePathNonOverlay, DYLD_SHARED_CACHE_BASE_NAME);
-	strcat(cachePathNonOverlay, cacheFileSuffix(optimize, fArchGraph->archName()));
-	char cachePath[1024];
-	strcpy(cachePath, rootPath);
-	strcat(cachePath, "/");
-	strcat(cachePath, cachePathNonOverlay);
-	if ( !overlay && (rootPath[0] != '\0') )
-		fCacheFilePath = strdup(cachePathNonOverlay);
+	
+	// sort shared dylibs
+	if ( alphaSort )
+		std::sort(fDylibs.begin(), fDylibs.end(), ByNameSorter());
 	else
-		fCacheFilePath = strdup(cachePath);
-	if ( overlay ) {
-		// in overlay mode if there already is a cache file in the overlay
-		// check if it is up to date.  If there is no file, check if
-		// the one in the boot volume is up to date.
-		struct stat stat_buf;
-		if ( stat(fCacheFilePath, &stat_buf) == 0 ) 
-			fExistingIsNotUpToDate = this->notUpToDate(fCacheFilePath, aliasCount);
-		else
-			fExistingIsNotUpToDate = this->notUpToDate(cachePathNonOverlay, aliasCount);
-	}
-	else {
-		fExistingIsNotUpToDate = this->notUpToDate(fCacheFilePath, aliasCount);
-	}
-	
-	// sort shared dylibs
-	if ( verify ) {
-		// already sorted by notUpToDate()
-	}
-	else if ( alphaSort ) {
-		std::sort(fDylibs.begin(), fDylibs.end(), ByNameSorter());
-	}
-	else {
-		// random sort for Address Space Randomization
-		std::map<const MachOLayoutAbstraction*, uint32_t> map;
-		for(typename std::vector<struct LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) 
-			map[it->layout] = arc4random();
-		std::sort(fDylibs.begin(), fDylibs.end(), Sorter(map));
-	}
+		std::sort(fDylibs.begin(), fDylibs.end(), RandomSorter(fDylibs));
+		
 	
 	// assign segments in each dylib a new address
-	this->assignNewBaseAddresses(verify);
-	
-	// calculate where string pool offset will start
+	this->assignNewBaseAddresses();
+	
 	// calculate cache file header size
-	fHeaderSize = sizeof(dyld_cache_header) 
+	fHeaderSize = pageAlign(sizeof(dyld_cache_header) 
 							+ fMappings.size()*sizeof(shared_file_mapping_np) 
-							+ (fDylibs.size()+aliasCount)*sizeof(dyld_cache_image_info);
-	//fprintf(stderr, "aliasCount=%d, fHeaderSize=0x%08X\n", aliasCount, fHeaderSize);
-	// build list of aliases and compute where each ones path string will go
-	for(typename std::vector<struct LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
-		for(std::vector<const char*>::const_iterator ait = it->aliases.begin(); ait != it->aliases.end(); ++ait) {
-			LayoutInfo temp = *it;
-			// alias looks just like real dylib, but has a different name string
-			const char* aliasPath = *ait;
-			temp.aliases.clear();
-			temp.aliases.push_back(aliasPath);
-			temp.info.pathFileOffset = fHeaderSize; 
-			fDylibAliases.push_back(temp);
-			fHeaderSize += strlen(aliasPath)+1;
-		}
-	}
-	std::sort(fDylibAliases.begin(), fDylibAliases.end(), ByNameSorter());
-	//fprintf(stderr, "fHeaderSize=0x%08X, fDylibAliases.size()=%lu\n", fHeaderSize, fDylibAliases.size());
-	fHeaderSize = pageAlign(fHeaderSize);
-	
-	// check that cache we are about to create for verification purposes has same layout as existing cache
-	if ( verify ) {
-		// if no existing cache, say so
-		if ( fExistingCacheForVerification == NULL ) {
-			throwf("update_dyld_shared_cache[%u] for arch=%s, could not verify because cache file does not exist in /var/db/dyld/\n",
-			 getpid(), archName());
-		}
-		const dyldCacheHeader<E>* header = (dyldCacheHeader<E>*)fExistingCacheForVerification;
-		const dyldCacheImageInfo<E>* cacheEntry = (dyldCacheImageInfo<E>*)(fExistingCacheForVerification + header->imagesOffset());
-		for(typename std::vector<LayoutInfo>::iterator it = fDylibs.begin(); it != fDylibs.end(); ++it, ++cacheEntry) {
-			if ( cacheEntry->address() != it->layout->getSegments()[0].newAddress() ) {
-				throwf("update_dyld_shared_cache[%u] warning: for arch=%s, could not verify cache because start address of %s is 0x%llX in cache, but should be 0x%llX\n",
-							getpid(), archName(), it->layout->getID().name, cacheEntry->address(), it->layout->getSegments()[0].newAddress());
-			}
-		}
-	}
-	
-	
-	if ( fHeaderSize > FIRST_DYLIB_TEXT_OFFSET )
+							+ fDylibs.size()*sizeof(dyld_cache_image_info) );
+							//+ fDependencyPool.size()*sizeof(uint16_t));
+	
+	if ( fHeaderSize > 0x3000 )
 		throwf("header size miscalculation 0x%08X", fHeaderSize);
 }
 
@@ -958,54 +537,29 @@
 template <>
 uint64_t SharedCache<ppc>::getWritableSegmentNewAddress(uint64_t proposedNewAddress, uint64_t originalAddress, uint64_t executableSlide)
 {
-	// for ppc writable segments can only move in increments of 64K (so only hi16 instruction needs to be modified)
+	// for ppc64 writable segments can only move in increments of 64K (so only hi16 instruction needs to be modified)
 	return (((executableSlide & 0x000000000000F000ULL) - ((proposedNewAddress - originalAddress) & 0x000000000000F000ULL)) & 0x000000000000F000ULL) + proposedNewAddress;
 }
 
+template <>
+uint64_t SharedCache<ppc64>::getWritableSegmentNewAddress(uint64_t proposedNewAddress, uint64_t originalAddress, uint64_t executableSlide)
+{
+	// for ppc64 writable segments can only move in increments of 64K (so only hi16 instruction needs to be modified)
+	return (((executableSlide & 0x000000000000F000ULL) - ((proposedNewAddress - originalAddress) & 0x000000000000F000ULL)) & 0x000000000000F000ULL) + proposedNewAddress;
+}
+
 
 template <typename A>
-void SharedCache<A>::assignNewBaseAddresses(bool verify)
-{
-	uint64_t sharedCacheStartAddress = sharedRegionReadOnlyStartAddress();
-#if 0
-	if ( arch() == CPU_TYPE_X86_64 ) {
-		if ( verify ) {
-			if ( fExistingCacheForVerification == NULL ) {
-				throwf("update_dyld_shared_cache[%u] for arch=%s, could not verify because cache file does not exist in /var/db/dyld/\n",
-					   getpid(), archName());
-			}
-			const dyldCacheHeader<E>* header = (dyldCacheHeader<E>*)fExistingCacheForVerification;
-			const dyldCacheFileMapping<E>* mappings = (dyldCacheFileMapping<E>*)(fExistingCacheForVerification + header->mappingOffset());
-			sharedCacheStartAddress = mappings[0].address();
-		}
-		else {
-			// <rdar://problem/5274722> dyld shared cache can be more random
-			uint64_t readOnlySize = 0;
-			for(typename std::vector<LayoutInfo>::iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
-				if ( ! it->layout->hasSplitSegInfo() )
-					continue;
-				std::vector<MachOLayoutAbstraction::Segment>& segs = ((MachOLayoutAbstraction*)(it->layout))->getSegments();
-				for (int i=0; i < segs.size(); ++i) {
-					MachOLayoutAbstraction::Segment& seg = segs[i];
-					if ( ! seg.writable() )
-						readOnlySize += pageAlign(seg.size());
-				}
-			}
-			uint64_t maxSlide = sharedRegionReadOnlySize() - (readOnlySize + FIRST_DYLIB_TEXT_OFFSET);
-			sharedCacheStartAddress = sharedRegionReadOnlyStartAddress() + pageAlign(arc4random() % maxSlide);
-		}
-	}
-#endif
-	uint64_t currentExecuteAddress = sharedCacheStartAddress + FIRST_DYLIB_TEXT_OFFSET;	
-	uint64_t currentWritableAddress = sharedRegionWritableStartAddress() + FIRST_DYLIB_DATA_OFFSET;
-
-	// first layout TEXT and DATA for dylibs
+void SharedCache<A>::assignNewBaseAddresses()
+{
+	// first layout TEXT and DATA for split-seg (or can be split-seg) dylibs
+	uint64_t currentExecuteAddress = sharedRegionReadOnlyStartAddress() + 0x3000;	
+	uint64_t currentWritableAddress = sharedRegionWritableStartAddress();
 	for(typename std::vector<LayoutInfo>::iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
 		std::vector<MachOLayoutAbstraction::Segment>& segs = ((MachOLayoutAbstraction*)(it->layout))->getSegments();
 		MachOLayoutAbstraction::Segment* executableSegment = NULL;
 		for (int i=0; i < segs.size(); ++i) {
 			MachOLayoutAbstraction::Segment& seg = segs[i];
-			seg.reset();
 			if ( seg.writable() ) {
 				if ( seg.executable() && it->layout->hasSplitSegInfo() ) {
 					// skip __IMPORT segments in this pass
@@ -1034,6 +588,11 @@
 				}
 				else {
 					// skip read-only segments in this pass
+					// any non-LINKEDIT read-only segments leave a hole so that all R/W segment slide together
+					if ( (strcmp(seg.name(), "__LINKEDIT") != 0) && (i < (segs.size()-2)) ) {
+						fprintf(stderr, "update_dyld_shared_cache: warning %s segment in %s leaves a hole\n", seg.name(), it->layout->getID().name);
+						currentWritableAddress = pageAlign(currentWritableAddress + seg.size());
+					}
 				}
 			}
 		}
@@ -1056,6 +615,7 @@
 			else if ( seg.writable() && seg.executable() && it->layout->hasSplitSegInfo() ) {
 				// allocate IMPORT segments to end of writable shared region
 				seg.setNewAddress(currentWritableExecutableAddress);
+				seg.setWritable(false); // __IMPORT segments are not-writable in shared cache
 				currentWritableExecutableAddress += pageAlign(seg.size());
 			}
 		}
@@ -1079,19 +639,13 @@
 	}
 	fLinkEditsTotalUnoptimizedSize = (currentReadOnlyAddress - fLinkEditsStartAddress + 4095) & (-4096);
 
-    // <rdar://problem/9361288> i386 dyld shared cache overflows after adding libclh.dylib
-	if ( (currentReadOnlyAddress -  sharedRegionReadOnlyStartAddress()) > sharedRegionReadOnlySize() )
-		throwf("read-only slice of cache too big: %lluMB (max %lluMB)", 
-				(currentReadOnlyAddress -  sharedRegionReadOnlyStartAddress())/(1024*1024),
-			   sharedRegionReadOnlySize()/(1024*1024));
-		
 
 	// populate large mappings
 	uint64_t cacheFileOffset = 0;
-	if ( currentExecuteAddress > sharedCacheStartAddress + FIRST_DYLIB_TEXT_OFFSET ) {
+	if ( currentExecuteAddress > sharedRegionReadOnlyStartAddress() + 0x3000 ) {
 		shared_file_mapping_np  executeMapping;
-		executeMapping.sfm_address		= sharedCacheStartAddress;
-		executeMapping.sfm_size			= currentExecuteAddress - sharedCacheStartAddress;
+		executeMapping.sfm_address		= sharedRegionReadOnlyStartAddress();
+		executeMapping.sfm_size			= currentExecuteAddress - sharedRegionReadOnlyStartAddress();
 		executeMapping.sfm_file_offset	= cacheFileOffset;
 		executeMapping.sfm_max_prot		= VM_PROT_READ | VM_PROT_EXECUTE;
 		executeMapping.sfm_init_prot	= VM_PROT_READ | VM_PROT_EXECUTE;
@@ -1113,7 +667,8 @@
 			writableExecutableMapping.sfm_size		= currentWritableExecutableAddress - startWritableExecutableAddress;
 			writableExecutableMapping.sfm_file_offset= cacheFileOffset;
 			writableExecutableMapping.sfm_max_prot	= VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE;
-			writableExecutableMapping.sfm_init_prot	= VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE; 
+			// __IMPORT segments in shared cache are not writable 
+			writableExecutableMapping.sfm_init_prot	= VM_PROT_READ | VM_PROT_EXECUTE; 
 			fMappings.push_back(writableExecutableMapping);
 			cacheFileOffset += writableExecutableMapping.sfm_size;
 		}
@@ -1132,7 +687,7 @@
 		// empty cache
 		shared_file_mapping_np  cacheHeaderMapping;
 		cacheHeaderMapping.sfm_address		= sharedRegionWritableStartAddress();
-		cacheHeaderMapping.sfm_size			= FIRST_DYLIB_TEXT_OFFSET;
+		cacheHeaderMapping.sfm_size			= 0x3000;
 		cacheHeaderMapping.sfm_file_offset	= cacheFileOffset;
 		cacheHeaderMapping.sfm_max_prot		= VM_PROT_READ;
 		cacheHeaderMapping.sfm_init_prot	= VM_PROT_READ;
@@ -1143,174 +698,73 @@
 
 
 template <typename A>
-uint64_t SharedCache<A>::cacheFileOffsetForVMAddress(uint64_t vmaddr) const
-{
-	for(std::vector<shared_file_mapping_np>::const_iterator it = fMappings.begin(); it != fMappings.end(); ++it) {
-		if ( (it->sfm_address <= vmaddr) && (vmaddr < it->sfm_address+it->sfm_size) )
-			return it->sfm_file_offset + vmaddr - it->sfm_address;
-	}
-	throwf("address 0x%0llX is not in cache", vmaddr);
-}
+uint64_t SharedCache<A>::cacheFileOffsetForAddress(uint64_t addr)
+{
+	for(std::vector<shared_file_mapping_np>::iterator it = fMappings.begin(); it != fMappings.end(); ++it) {
+		if ( (it->sfm_address <= addr) && (addr < it->sfm_address+it->sfm_size) )
+			return it->sfm_file_offset + addr - it->sfm_address;
+	}
+	throwf("address 0x%0llX is not in cache", addr);
+}
+
 
 template <typename A>
-uint64_t SharedCache<A>::VMAddressForCacheFileOffset(uint64_t offset) const
-{
-    for(std::vector<shared_file_mapping_np>::const_iterator it = fMappings.begin(); it != fMappings.end(); ++it) {
-        if ( (it->sfm_file_offset <= offset) && (offset < it->sfm_file_offset+it->sfm_size) )
-            return it->sfm_address + offset - it->sfm_file_offset;
-    }
-    throwf("offset 0x%0llX is not in cache", offset);
-}
-
-template <typename A>
-void *SharedCache<A>::mappedAddressForVMAddress(uint64_t vmaddr)
-{
-    if (!vmaddr) return NULL;
-    else return fInMemoryCache + cacheFileOffsetForVMAddress(vmaddr);
-}
-
-template <typename A>
-uint64_t SharedCache<A>::VMAddressForMappedAddress(const void *mapaddr)
-{
-    if (!mapaddr) return 0;
-    uint64_t offset = (uint8_t *)mapaddr - (uint8_t *)fInMemoryCache;
-    return VMAddressForCacheFileOffset(offset);
-}
-
-
-template <typename A>
-bool SharedCache<A>::notUpToDate(const void* cache, unsigned int aliasCount)
+bool SharedCache<A>::notUpToDate(const void* cache)
 {
 	dyldCacheHeader<E>* header = (dyldCacheHeader<E>*)cache;
 	// not valid if header signature is wrong
-	const char* archPairName = fArchGraph->archName();
 	char temp[16];
 	strcpy(temp, "dyld_v1        ");
-	strcpy(&temp[15-strlen(archPairName)], archPairName);
-	if ( strcmp(header->magic(), temp) != 0 ) {
-		if ( fVerify ) {
-			fprintf(stderr, "update_dyld_shared_cache[%u] cannot verify %s because current cache file has invalid header\n", getpid(), archName());
-			return false;
-		}
-		else {
-			fprintf(stderr, "update_dyld_shared_cache[%u] updating cache because current cache file has invalid header\n", getpid());
-			return true;
-		}
-	}
+	strcpy(&temp[15-strlen(archName())], archName());
+	if ( strcmp(header->magic(), temp) != 0 ) 
+		return true;
 	// not valid if count of images does not match current images needed
-	if ( header->imagesCount() != (fDylibs.size()+aliasCount) ) {
-		if ( fVerify ) {
-			fprintf(stderr, "update_dyld_shared_cache[%u] cannot verify %s because current cache file contains a different set of dylibs\n", getpid(), archName());
-			return false;
-		}
-		else {
-			fprintf(stderr, "update_dyld_shared_cache[%u] updating %s cache because current cache file contains a different set of dylibs\n", getpid(), archName());
-			return true;
-		}
-	}
-	// get end of TEXT region
-	const dyldCacheFileMapping<E>* textMapping = (dyldCacheFileMapping<E>*)((uint8_t*)cache+sizeof(dyldCacheHeader<E>));
-	const uint32_t textSize = textMapping->size();
-	
+	if ( header->imagesCount() != fDylibs.size() )
+		return true;
 	// verify every dylib in constructed graph is in existing cache with same inode and modTime	
-	std::map<const MachOLayoutAbstraction*, uint32_t> sortingMap;
 	const dyldCacheImageInfo<E>* imagesStart = (dyldCacheImageInfo<E>*)((uint8_t*)cache + header->imagesOffset());
 	const dyldCacheImageInfo<E>* imagesEnd = &imagesStart[header->imagesCount()];
 	for(typename std::vector<LayoutInfo>::iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
 		bool found = false;
 		//fprintf(stderr, "inode=0x%llX, mTime=0x%llX, path=%s\n", it->info.inode, it->info.modTime, it->layout->getID().name);
 		for(const dyldCacheImageInfo<E>* cacheEntry = imagesStart; cacheEntry < imagesEnd; ++cacheEntry) {
-			if ( fVerify ) {
-				if ( cacheEntry->pathFileOffset() > textSize ) {
-					throwf("update_dyld_shared_cache[%u]: for arch=%s, image entries corrupt, bad path offset in %s\n", 
-								getpid(), archName(), it->layout->getID().name);
-				}
-				// in -verify mode, just match by path and warn if file looks different
-				if ( strcmp((char*)cache+cacheEntry->pathFileOffset(), it->layout->getID().name) == 0 ) {
-					found = true;
-					sortingMap[it->layout] = cacheEntry-imagesStart;
-					if ( (cacheEntry->inode() != it->info.inode) || (cacheEntry->modTime() != it->info.modTime) ) {
-						fprintf(stderr, "update_dyld_shared_cache[%u] warning: for arch=%s, %s has changed since cache was built\n", 
-								getpid(), archName(), it->layout->getID().name);
-					}
-					break;
-				}
-			}
-			else {
-				if ( cacheEntry->pathFileOffset() > textSize ) {
-					// cache corrupt, needs to be regenerated
-					return true;
-				}
-				// in normal update mode, everything has to match for cache to be up-to-date
-				if ( (cacheEntry->inode() == it->info.inode) 
-						&& (cacheEntry->modTime() == it->info.modTime) 
-						&& (strcmp((char*)cache+cacheEntry->pathFileOffset(), it->layout->getID().name) == 0) ) {
+			if ( (cacheEntry->inode() == it->info.inode) 
+			 && (cacheEntry->modTime() == it->info.modTime) 
+			 && (strcmp((char*)cache+cacheEntry->pathFileOffset(), it->layout->getID().name) == 0) ) {
 					found = true;
 					break;
-				}
 			}
 		}
 		if ( !found ) {
-			if ( fVerify ) {
-				throwf("update_dyld_shared_cache[%u] can't verify %s cache because %s is not in existing cache\n", getpid(), archName(), it->layout->getID().name);
-			}
-			else {
-				fprintf(stderr, "update_dyld_shared_cache[%u] updating %s cache because dylib at %s has changed\n", getpid(), archName(), it->layout->getID().name);
-				return true;
-			}
-		}
-	}
-	// all dylibs in existing cache file match those determined need to be in shared cache
-	if ( fVerify ) {
-		// sort fDylibs to match existing cache file so we can compare content
-		std::sort(fDylibs.begin(), fDylibs.end(), Sorter(sortingMap));
-		//fprintf(stderr, "dylibs sorted like existing cache:\n");
-		//for(typename std::vector<LayoutInfo>::iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
-		//	fprintf(stderr,"   %s\n", it->layout->getID().name);
-		//}
-		// do regenerate a new cache so we can compare content with existing
-		return true;
-	}
-	else {
-		// existing cache file is up-to-date, don't need to regenerate
-		return false;
-	}
+			fprintf(stderr, "update_dyld_shared_cache[%u] current cache invalid because %s has changed\n", getpid(), it->layout->getID().name);
+			return true;
+		}
+	}
+	return false;
 }
 
 
 template <typename A>
-bool SharedCache<A>::notUpToDate(const char* path, unsigned int aliasCount)
+bool SharedCache<A>::notUpToDate(const char* cachePath)
 {
 	// mmap existing cache file 
-	int fd = ::open(path, O_RDONLY);	
+	int fd = ::open(cachePath, O_RDONLY);	
 	if ( fd == -1 )
 		return true;
 	struct stat stat_buf;
 	::fstat(fd, &stat_buf);
-    uint32_t cacheFileSize = stat_buf.st_size;
-    uint32_t cacheAllocatedSize = (cacheFileSize + 4095) & (-4096);
-    uint8_t* mappingAddr = NULL;
-	if ( vm_allocate(mach_task_self(), (vm_address_t*)(&mappingAddr), cacheAllocatedSize, VM_FLAGS_ANYWHERE) != KERN_SUCCESS )
-        throwf("can't vm_allocate cache of size %u", cacheFileSize);
-    // <rdar://problem/8960832> update_dyld_shared_cache -verify finds differences
- 	(void)fcntl(fd, F_NOCACHE, 1);
-    ssize_t readResult = pread(fd, mappingAddr, cacheFileSize, 0);
-    if ( readResult != cacheFileSize )
-        throw "can't read existing cache file";
+	uint8_t* mappingAddr = (uint8_t*)mmap(NULL, stat_buf.st_size, PROT_READ , MAP_FILE | MAP_PRIVATE, fd, 0);
 	::close(fd);
+	if ( mappingAddr == (uint8_t*)(-1) )
+		return true;
 
 	// validate it
-	bool result = this->notUpToDate(mappingAddr, aliasCount);
-	if ( fVerify ) {
-		// don't unmap yet, leave so it can be verified later
-		fExistingCacheForVerification = mappingAddr;
-	}
-	else {
-		// unmap
-        vm_deallocate(mach_task_self(), (vm_address_t)mappingAddr, cacheAllocatedSize);
-		if ( verbose && !result )
-			fprintf(stderr, "update_dyld_shared_cache: %s is up-to-date\n", path);
-	}
+	bool result = this->notUpToDate(mappingAddr);
+	// unmap
+	::munmap(mappingAddr, stat_buf.st_size);
+	if ( verbose && !result )
+		fprintf(stderr, "update_dyld_shared_cache: %s is up-to-date\n", cachePath);
+
 	return result;
 }
 
@@ -1340,7 +794,7 @@
 
 
 StringPool::StringPool() 
-	: fBufferUsed(0), fBufferAllocated(32*1024*1024)
+	: fBufferUsed(0), fBufferAllocated(4*1024*1024)
 {
 	fBuffer = (char*)malloc(fBufferAllocated);
 }
@@ -1350,7 +804,8 @@
 	uint32_t len = strlen(str);
 	if ( (fBufferUsed + len + 1) > fBufferAllocated ) {
 		// grow buffer
-		throw "string buffer exhausted";
+		fBufferAllocated = fBufferAllocated*2;
+		fBuffer = (char*)realloc(fBuffer, fBufferAllocated);
 	}
 	strcpy(&fBuffer[fBufferUsed], str);
 	uint32_t result = fBufferUsed;
@@ -1390,21 +845,16 @@
 class LinkEditOptimizer
 {
 public:
-											LinkEditOptimizer(const MachOLayoutAbstraction&, const SharedCache<A>&, uint8_t*, StringPool&);
+											LinkEditOptimizer(const MachOLayoutAbstraction&, uint8_t*, StringPool&);
 	virtual									~LinkEditOptimizer() {}
 
-		void								copyBindInfo(uint32_t&);
-		void								copyWeakBindInfo(uint32_t&);
-		void								copyLazyBindInfo(uint32_t&);
-		void								copyExportInfo(uint32_t&);
-		void								copyLocalSymbols(uint32_t symbolTableOffset, uint32_t&);
-		void								copyExportedSymbols(uint32_t symbolTableOffset, uint32_t&);
-		void								copyImportedSymbols(uint32_t symbolTableOffset, uint32_t&);
-		void								copyExternalRelocations(uint32_t& offset);
-		void								copyIndirectSymbolTable(uint32_t& offset);
-		void								copyFunctionStarts(uint32_t& offset);
-		void								updateLoadCommands(uint64_t newVMAddress, uint64_t size, uint32_t stringPoolOffset, 
-																uint32_t linkEditsFileOffset, bool keepSignatures);
+	static void								makeDummyLocalSymbol(uint32_t&, uint8_t*, StringPool&);
+		void								copyLocalSymbols();
+		void								copyExportedSymbols(uint32_t&);
+		void								copyImportedSymbols(uint32_t&);
+		void								copyExternalRelocations(uint32_t&);
+		void								copyIndirectSymbolTable(uint32_t&);
+		void								updateLoadCommands(uint64_t newVMAddress, uint64_t size, uint32_t stringPoolOffset);
 	
 
 protected:
@@ -1414,28 +864,16 @@
 			
 private:
 
-	const SharedCache<A>&						fSharedCache;
 	const macho_header<P>*						fHeader; 
 	uint8_t*									fNewLinkEditStart;	
 	uint8_t*									fLinkEditBase;		
 	const MachOLayoutAbstraction&				fLayout;
-	macho_dyld_info_command<P>*					fDyldInfo;
 	macho_dysymtab_command<P>*					fDynamicSymbolTable;
-	macho_linkedit_data_command<P>*				fFunctionStarts;
 	macho_symtab_command<P>*					fSymbolTableLoadCommand;
 	const macho_nlist<P>*						fSymbolTable;
 	const char*									fStrings;
 	StringPool&									fNewStringPool;
 	std::map<uint32_t,uint32_t>					fOldToNewSymbolIndexes;
-	uint32_t									fBindInfoOffsetIntoNewLinkEdit;
-	uint32_t									fBindInfoSizeInNewLinkEdit;
-	uint32_t									fWeakBindInfoOffsetIntoNewLinkEdit;
-	uint32_t									fWeakBindInfoSizeInNewLinkEdit;
-	uint32_t									fLazyBindInfoOffsetIntoNewLinkEdit;
-	uint32_t									fLazyBindInfoSizeInNewLinkEdit;
-	uint32_t									fExportInfoOffsetIntoNewLinkEdit;
-	uint32_t									fExportInfoSizeInNewLinkEdit;
-	uint32_t									fSymbolTableStartOffsetInNewLinkEdit;
 	uint32_t									fLocalSymbolsStartIndexInNewLinkEdit;
 	uint32_t									fLocalSymbolsCountInNewLinkEdit;
 	uint32_t									fExportedSymbolsStartIndexInNewLinkEdit;
@@ -1444,25 +882,20 @@
 	uint32_t									fImportedSymbolsCountInNewLinkEdit;
 	uint32_t									fExternalRelocationsOffsetIntoNewLinkEdit;
 	uint32_t									fIndirectSymbolTableOffsetInfoNewLinkEdit;
-	uint32_t									fFunctionStartsOffsetInNewLinkEdit;
+	static int32_t								fgLocalSymbolsStartIndexInNewLinkEdit;
 };
 
+template <typename A> int32_t LinkEditOptimizer<A>::fgLocalSymbolsStartIndexInNewLinkEdit = 0;
 
 
 template <typename A>
-LinkEditOptimizer<A>::LinkEditOptimizer(const MachOLayoutAbstraction& layout, const SharedCache<A>& sharedCache, uint8_t* newLinkEdit, StringPool& stringPool)
- : 	fSharedCache(sharedCache), fLayout(layout), fLinkEditBase(NULL), fNewLinkEditStart(newLinkEdit), fDyldInfo(NULL),
-	fDynamicSymbolTable(NULL), fFunctionStarts(NULL), fSymbolTableLoadCommand(NULL), fSymbolTable(NULL), fStrings(NULL), fNewStringPool(stringPool),
-	fBindInfoOffsetIntoNewLinkEdit(0), fBindInfoSizeInNewLinkEdit(0),
-	fWeakBindInfoOffsetIntoNewLinkEdit(0), fWeakBindInfoSizeInNewLinkEdit(0),
-	fLazyBindInfoOffsetIntoNewLinkEdit(0), fLazyBindInfoSizeInNewLinkEdit(0),
-	fExportInfoOffsetIntoNewLinkEdit(0), fExportInfoSizeInNewLinkEdit(0),
-	fSymbolTableStartOffsetInNewLinkEdit(0), 
+LinkEditOptimizer<A>::LinkEditOptimizer(const MachOLayoutAbstraction& layout, uint8_t* newLinkEdit, StringPool& stringPool)
+ : 	fLayout(layout), fLinkEditBase(NULL), fNewLinkEditStart(newLinkEdit), 
+	fDynamicSymbolTable(NULL), fSymbolTableLoadCommand(NULL), fSymbolTable(NULL), fStrings(NULL), fNewStringPool(stringPool),
 	fLocalSymbolsStartIndexInNewLinkEdit(0), fLocalSymbolsCountInNewLinkEdit(0),
 	fExportedSymbolsStartIndexInNewLinkEdit(0), fExportedSymbolsCountInNewLinkEdit(0),
 	fImportSymbolsStartIndexInNewLinkEdit(0), fImportedSymbolsCountInNewLinkEdit(0),
-	fExternalRelocationsOffsetIntoNewLinkEdit(0), fIndirectSymbolTableOffsetInfoNewLinkEdit(0),
-	fFunctionStartsOffsetInNewLinkEdit(0)
+	fExternalRelocationsOffsetIntoNewLinkEdit(0), fIndirectSymbolTableOffsetInfoNewLinkEdit(0)
 	
 {
 	fHeader = (const macho_header<P>*)fLayout.getSegments()[0].mappedAddress();
@@ -1491,13 +924,6 @@
 			case LC_DYSYMTAB:
 				fDynamicSymbolTable = (macho_dysymtab_command<P>*)cmd;
 				break;
-			case LC_DYLD_INFO:
-			case LC_DYLD_INFO_ONLY:
-				fDyldInfo = (macho_dyld_info_command<P>*)cmd;
-				break;
-			case LC_FUNCTION_STARTS:
-				fFunctionStarts = (macho_linkedit_data_command<P>*)cmd;
-				break;
 		}
 		cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
 	}	
@@ -1525,96 +951,51 @@
 
 
 template <typename A>
-void LinkEditOptimizer<A>::copyBindInfo(uint32_t& offset)
-{
-	if ( (fDyldInfo != NULL) && (fDyldInfo->bind_off() != 0) ) {
-		fBindInfoOffsetIntoNewLinkEdit = offset;
-		fBindInfoSizeInNewLinkEdit = fDyldInfo->bind_size();
-		memcpy(fNewLinkEditStart+offset, &fLinkEditBase[fDyldInfo->bind_off()], fDyldInfo->bind_size());
-		offset += fDyldInfo->bind_size();
-	}
+void LinkEditOptimizer<A>::makeDummyLocalSymbol(uint32_t& symbolIndex, uint8_t* storage, StringPool& pool)
+{
+	fgLocalSymbolsStartIndexInNewLinkEdit = symbolIndex;
+	macho_nlist<P>* newSymbolEntry = (macho_nlist<P>*)storage;
+	newSymbolEntry->set_n_strx(pool.add("__no_local_symbols_in_dyld_shared_cache"));
+	newSymbolEntry->set_n_type(N_SECT);
+	newSymbolEntry->set_n_sect(1);
+	newSymbolEntry->set_n_desc(0);
+	newSymbolEntry->set_n_value(0);
+	++symbolIndex;
 }
 
 template <typename A>
-void LinkEditOptimizer<A>::copyWeakBindInfo(uint32_t& offset)
-{
-	if ( (fDyldInfo != NULL) && (fDyldInfo->weak_bind_off() != 0) ) {
-		fWeakBindInfoOffsetIntoNewLinkEdit = offset;
-		fWeakBindInfoSizeInNewLinkEdit = fDyldInfo->weak_bind_size();
-		memcpy(fNewLinkEditStart+offset, &fLinkEditBase[fDyldInfo->weak_bind_off()], fDyldInfo->weak_bind_size());
-		offset += fDyldInfo->weak_bind_size();
-	}
-}
+void LinkEditOptimizer<A>::copyLocalSymbols()
+{
+	if ( fDynamicSymbolTable->nlocalsym() > 0 ) {
+		// if image has any local symbols, make cache look like it has one local symbol
+		// which is actually shared by all images
+		fLocalSymbolsCountInNewLinkEdit = 1; 
+		fLocalSymbolsStartIndexInNewLinkEdit = fgLocalSymbolsStartIndexInNewLinkEdit;
+	}
+}
+
 
 template <typename A>
-void LinkEditOptimizer<A>::copyLazyBindInfo(uint32_t& offset)
-{
-	if ( (fDyldInfo != NULL) && (fDyldInfo->lazy_bind_off() != 0) ) {
-		fLazyBindInfoOffsetIntoNewLinkEdit = offset;
-		fLazyBindInfoSizeInNewLinkEdit = fDyldInfo->lazy_bind_size();
-		memcpy(fNewLinkEditStart+offset, &fLinkEditBase[fDyldInfo->lazy_bind_off()], fDyldInfo->lazy_bind_size());
-		offset += fDyldInfo->lazy_bind_size();
-	}
-}
-
-template <typename A>
-void LinkEditOptimizer<A>::copyExportInfo(uint32_t& offset)
-{
-	if ( (fDyldInfo != NULL) && (fLayout.getDyldInfoExports() != NULL) ) {
-		fExportInfoOffsetIntoNewLinkEdit = offset;
-		fExportInfoSizeInNewLinkEdit = fDyldInfo->export_size();
-		memcpy(fNewLinkEditStart+offset, fLayout.getDyldInfoExports(), fDyldInfo->export_size());
-		offset += fDyldInfo->export_size();
-	}
-}
-
-
-
-template <typename A>
-void LinkEditOptimizer<A>::copyLocalSymbols(uint32_t symbolTableOffset, uint32_t& symbolIndex)
-{
-	fLocalSymbolsStartIndexInNewLinkEdit = symbolIndex;
-	fSymbolTableStartOffsetInNewLinkEdit = symbolTableOffset + symbolIndex*sizeof(macho_nlist<P>);
-	macho_nlist<P>* const newSymbolTableStart = (macho_nlist<P>*)(fNewLinkEditStart+symbolTableOffset);
-	const macho_nlist<P>* const firstLocal = &fSymbolTable[fDynamicSymbolTable->ilocalsym()];
-	const macho_nlist<P>* const lastLocal  = &fSymbolTable[fDynamicSymbolTable->ilocalsym()+fDynamicSymbolTable->nlocalsym()];
-	uint32_t oldIndex = fDynamicSymbolTable->ilocalsym();
-	for (const macho_nlist<P>* entry = firstLocal; entry < lastLocal; ++entry, ++oldIndex) {
-		if ( (entry->n_type() & N_TYPE) == N_SECT ) {
-			macho_nlist<P>* newSymbolEntry = &newSymbolTableStart[symbolIndex];
-			*newSymbolEntry = *entry;
-			newSymbolEntry->set_n_strx(fNewStringPool.addUnique(&fStrings[entry->n_strx()]));
-			++symbolIndex;
-		}
-	}
-	fLocalSymbolsCountInNewLinkEdit = symbolIndex - fLocalSymbolsStartIndexInNewLinkEdit;
-	//fprintf(stderr, "%u locals starting at %u for %s\n", fLocalSymbolsCountInNewLinkEdit, fLocalSymbolsStartIndexInNewLinkEdit, fLayout.getFilePath());
-}
-
-
-template <typename A>
-void LinkEditOptimizer<A>::copyExportedSymbols(uint32_t symbolTableOffset, uint32_t& symbolIndex)
+void LinkEditOptimizer<A>::copyExportedSymbols(uint32_t& symbolIndex)
 {
 	fExportedSymbolsStartIndexInNewLinkEdit = symbolIndex;
-	macho_nlist<P>* const newSymbolTableStart = (macho_nlist<P>*)(fNewLinkEditStart+symbolTableOffset);
 	const macho_nlist<P>* const firstExport = &fSymbolTable[fDynamicSymbolTable->iextdefsym()];
 	const macho_nlist<P>* const lastExport  = &fSymbolTable[fDynamicSymbolTable->iextdefsym()+fDynamicSymbolTable->nextdefsym()];
 	uint32_t oldIndex = fDynamicSymbolTable->iextdefsym();
 	for (const macho_nlist<P>* entry = firstExport; entry < lastExport; ++entry, ++oldIndex) {
-		if ( ((entry->n_type() & N_TYPE) == N_SECT) && (strncmp(&fStrings[entry->n_strx()], ".objc_", 6) != 0)
-						&& (strncmp(&fStrings[entry->n_strx()], "$ld$", 4) != 0) ) {
-			macho_nlist<P>* newSymbolEntry = &newSymbolTableStart[symbolIndex];
+		if ( ((entry->n_type() & N_TYPE) == N_SECT) && (strncmp(&fStrings[entry->n_strx()], ".objc_", 6) != 0) ) {
+			macho_nlist<P>* newSymbolEntry = &((macho_nlist<P>*)fNewLinkEditStart)[symbolIndex];
 			*newSymbolEntry = *entry;
-			newSymbolEntry->set_n_strx(fNewStringPool.addUnique(&fStrings[entry->n_strx()]));
-			fOldToNewSymbolIndexes[oldIndex] = symbolIndex-fLocalSymbolsStartIndexInNewLinkEdit;
+			newSymbolEntry->set_n_strx(fNewStringPool.add(&fStrings[entry->n_strx()]));
+			fOldToNewSymbolIndexes[oldIndex] = symbolIndex;
 			++symbolIndex;
 		}
 	}
 	fExportedSymbolsCountInNewLinkEdit = symbolIndex - fExportedSymbolsStartIndexInNewLinkEdit;
 	//fprintf(stderr, "%u exports starting at %u for %s\n", fExportedSymbolsCountInNewLinkEdit, fExportedSymbolsStartIndexInNewLinkEdit, fLayout.getFilePath());
 	// sort by name, so that dyld does not need a toc
-	macho_nlist<P>* newSymbolsStart = &newSymbolTableStart[fExportedSymbolsStartIndexInNewLinkEdit];
-	macho_nlist<P>* newSymbolsEnd = &newSymbolTableStart[fExportedSymbolsStartIndexInNewLinkEdit+fExportedSymbolsCountInNewLinkEdit];
+	macho_nlist<P>* newSymbolsStart = &((macho_nlist<P>*)fNewLinkEditStart)[fExportedSymbolsStartIndexInNewLinkEdit];
+	macho_nlist<P>* newSymbolsEnd = &((macho_nlist<P>*)fNewLinkEditStart)[fExportedSymbolsStartIndexInNewLinkEdit+fExportedSymbolsCountInNewLinkEdit];
 	std::sort(newSymbolsStart, newSymbolsEnd, SymbolSorter<A>(fNewStringPool));
 	//for (macho_nlist<P>* entry = newSymbolsStart; entry < newSymbolsEnd; ++entry)
 	//	fprintf(stderr, "\t%u\t %s\n", (entry-newSymbolsStart)+fExportedSymbolsStartIndexInNewLinkEdit, fNewStringPool.stringAtIndex(entry->n_strx()));
@@ -1622,19 +1003,18 @@
 
 
 template <typename A>
-void LinkEditOptimizer<A>::copyImportedSymbols(uint32_t symbolTableOffset, uint32_t& symbolIndex)
+void LinkEditOptimizer<A>::copyImportedSymbols(uint32_t& symbolIndex)
 {
 	fImportSymbolsStartIndexInNewLinkEdit = symbolIndex;
-	macho_nlist<P>* const newSymbolTableStart = (macho_nlist<P>*)(fNewLinkEditStart+symbolTableOffset);
 	const macho_nlist<P>* const firstImport = &fSymbolTable[fDynamicSymbolTable->iundefsym()];
 	const macho_nlist<P>* const lastImport  = &fSymbolTable[fDynamicSymbolTable->iundefsym()+fDynamicSymbolTable->nundefsym()];
 	uint32_t oldIndex = fDynamicSymbolTable->iundefsym();
 	for (const macho_nlist<P>* entry = firstImport; entry < lastImport; ++entry, ++oldIndex) {
 		if ( ((entry->n_type() & N_TYPE) == N_UNDF) && (strncmp(&fStrings[entry->n_strx()], ".objc_", 6) != 0) ) {
-			macho_nlist<P>* newSymbolEntry = &newSymbolTableStart[symbolIndex];
+			macho_nlist<P>* newSymbolEntry = &((macho_nlist<P>*)fNewLinkEditStart)[symbolIndex];
 			*newSymbolEntry = *entry;
 			newSymbolEntry->set_n_strx(fNewStringPool.addUnique(&fStrings[entry->n_strx()]));
-			fOldToNewSymbolIndexes[oldIndex] = symbolIndex-fLocalSymbolsStartIndexInNewLinkEdit;
+			fOldToNewSymbolIndexes[oldIndex] = symbolIndex;
 			++symbolIndex;
 		}
 	}
@@ -1661,16 +1041,6 @@
 		//	 &fStrings[fSymbolTable[reloc->r_symbolnum()].n_strx()], fLayout.getFilePath());
 		newReloc->set_r_symbolnum(newSymbolIndex);
 		offset += sizeof(macho_relocation_info<P>);
-	}
-}
-
-template <typename A>
-void LinkEditOptimizer<A>::copyFunctionStarts(uint32_t& offset)
-{	
-	if ( fFunctionStarts != NULL ) {
-		fFunctionStartsOffsetInNewLinkEdit = offset;
-		memcpy(&fNewLinkEditStart[offset], &fLinkEditBase[fFunctionStarts->dataoff()], fFunctionStarts->datasize());
-		offset += fFunctionStarts->datasize();
 	}
 }
 
@@ -1694,13 +1064,13 @@
 }
 
 template <typename A>
-void LinkEditOptimizer<A>::updateLoadCommands(uint64_t newVMAddress, uint64_t size, uint32_t stringPoolOffset, 
-												uint32_t linkEditsFileOffset, bool keepSignatures)
+void LinkEditOptimizer<A>::updateLoadCommands(uint64_t newVMAddress, uint64_t size, uint32_t stringPoolOffset)
 {
 	// set LINKEDIT segment commmand to new merged LINKEDIT
 	const macho_load_command<P>* const cmds = (macho_load_command<P>*)((uint8_t*)fHeader + sizeof(macho_header<P>));
 	const uint32_t cmd_count = fHeader->ncmds();
 	const macho_load_command<P>* cmd = cmds;
+	uint32_t linkEditStartFileOffset = 0;
 	for (uint32_t i = 0; i < cmd_count; ++i) {
 		if ( cmd->cmd() == macho_segment_command<P>::CMD ) {
 			macho_segment_command<P>* seg = (macho_segment_command<P>*)cmd;
@@ -1708,113 +1078,37 @@
 				seg->set_vmaddr(newVMAddress);
 				seg->set_vmsize(size);
 				seg->set_filesize(size);
-				seg->set_fileoff(linkEditsFileOffset);
-			}
-			// don't alter __TEXT until <rdar://problem/7022345> is fixed
-			else if ( strcmp(seg->segname(), "__TEXT") != 0 ) {
-				// update all other segments fileoff to be offset from start of cache file
-				pint_t oldFileOff = seg->fileoff();
-				seg->set_fileoff(fSharedCache.cacheFileOffsetForVMAddress(seg->vmaddr()));
-				pint_t fileOffsetDelta = seg->fileoff() - oldFileOff;
-				// update all sections in this segment
-				macho_section<P>* const sectionsStart = (macho_section<P>*)((char*)seg + sizeof(macho_segment_command<P>));
-				macho_section<P>* const sectionsEnd = &sectionsStart[seg->nsects()];
-				for(macho_section<P>* sect = sectionsStart; sect < sectionsEnd; ++sect) {
-					if ( sect->offset() != 0 )
-						sect->set_offset(sect->offset()+fileOffsetDelta);
-				}
+				linkEditStartFileOffset = seg->fileoff();
 			}
 		}
 		cmd = (const macho_load_command<P>*)(((uint8_t*)cmd)+cmd->cmdsize());
 	}	
-	
-	// update dyld_info with new offsets
-	if ( fDyldInfo != NULL ) {
-		fDyldInfo->set_rebase_off(0);
-		fDyldInfo->set_rebase_size(0);
-		fDyldInfo->set_bind_off(linkEditsFileOffset+fBindInfoOffsetIntoNewLinkEdit);
-		fDyldInfo->set_bind_size(fBindInfoSizeInNewLinkEdit);
-		fDyldInfo->set_weak_bind_off(linkEditsFileOffset+fWeakBindInfoOffsetIntoNewLinkEdit);
-		fDyldInfo->set_weak_bind_size(fWeakBindInfoSizeInNewLinkEdit);
-		fDyldInfo->set_lazy_bind_off(linkEditsFileOffset+fLazyBindInfoOffsetIntoNewLinkEdit);
-		fDyldInfo->set_lazy_bind_size(fLazyBindInfoSizeInNewLinkEdit);
-		fDyldInfo->set_export_off(linkEditsFileOffset+fExportInfoOffsetIntoNewLinkEdit);
-		fDyldInfo->set_export_size(fExportInfoSizeInNewLinkEdit);
 		
-//		fprintf(stderr, "dylib %s\n", fLayout.getFilePath());
-//		fprintf(stderr, "  bind_off=0x%08X\n", fDyldInfo->bind_off());
-//		fprintf(stderr, "  export_off=0x%08X\n", fDyldInfo->export_off());
-//		fprintf(stderr, "  export_size=%d\n", fDyldInfo->export_size());
-		
-	}	
-	
 	// update symbol table and dynamic symbol table with new offsets
-	fSymbolTableLoadCommand->set_symoff(linkEditsFileOffset+fSymbolTableStartOffsetInNewLinkEdit);
-	fSymbolTableLoadCommand->set_nsyms(fLocalSymbolsCountInNewLinkEdit+fExportedSymbolsCountInNewLinkEdit+fImportedSymbolsCountInNewLinkEdit);
-	fSymbolTableLoadCommand->set_stroff(linkEditsFileOffset+stringPoolOffset);
+	fSymbolTableLoadCommand->set_symoff(linkEditStartFileOffset);
+	fSymbolTableLoadCommand->set_nsyms(fExportedSymbolsCountInNewLinkEdit+fImportedSymbolsCountInNewLinkEdit);
+	fSymbolTableLoadCommand->set_stroff(linkEditStartFileOffset+stringPoolOffset);
 	fSymbolTableLoadCommand->set_strsize(fNewStringPool.size());
-	fDynamicSymbolTable->set_ilocalsym(0);
+	fDynamicSymbolTable->set_ilocalsym(fLocalSymbolsStartIndexInNewLinkEdit);
 	fDynamicSymbolTable->set_nlocalsym(fLocalSymbolsCountInNewLinkEdit);
-	fDynamicSymbolTable->set_iextdefsym(fExportedSymbolsStartIndexInNewLinkEdit-fLocalSymbolsStartIndexInNewLinkEdit);
+	fDynamicSymbolTable->set_iextdefsym(fExportedSymbolsStartIndexInNewLinkEdit);
 	fDynamicSymbolTable->set_nextdefsym(fExportedSymbolsCountInNewLinkEdit);
-	fDynamicSymbolTable->set_iundefsym(fImportSymbolsStartIndexInNewLinkEdit-fLocalSymbolsStartIndexInNewLinkEdit);
+	fDynamicSymbolTable->set_iundefsym(fImportSymbolsStartIndexInNewLinkEdit);
 	fDynamicSymbolTable->set_nundefsym(fImportedSymbolsCountInNewLinkEdit);
 	fDynamicSymbolTable->set_tocoff(0);
 	fDynamicSymbolTable->set_ntoc(0);
 	fDynamicSymbolTable->set_modtaboff(0);
 	fDynamicSymbolTable->set_nmodtab(0);
-	fDynamicSymbolTable->set_indirectsymoff(linkEditsFileOffset+fIndirectSymbolTableOffsetInfoNewLinkEdit);
-	fDynamicSymbolTable->set_extreloff(linkEditsFileOffset+fExternalRelocationsOffsetIntoNewLinkEdit);
+	fDynamicSymbolTable->set_indirectsymoff(linkEditStartFileOffset+fIndirectSymbolTableOffsetInfoNewLinkEdit);
+	fDynamicSymbolTable->set_extreloff(linkEditStartFileOffset+fExternalRelocationsOffsetIntoNewLinkEdit);
 	fDynamicSymbolTable->set_locreloff(0);
 	fDynamicSymbolTable->set_nlocrel(0);
-
-	// update function starts
-	if ( fFunctionStarts != NULL ) {
-		fFunctionStarts->set_dataoff(linkEditsFileOffset+fFunctionStartsOffsetInNewLinkEdit);
-	}
-	
-	// now remove load commands no longer needed
-	const macho_load_command<P>* srcCmd = cmds;
-	macho_load_command<P>* dstCmd = (macho_load_command<P>*)cmds;
-	int32_t newCount = 0;
-	for (uint32_t i = 0; i < cmd_count; ++i) {	
-		uint32_t cmdSize = srcCmd->cmdsize();
-		switch ( srcCmd->cmd() ) {
-			case LC_SEGMENT_SPLIT_INFO:
-				// don't copy
-				break;
-			case LC_CODE_SIGNATURE:
-				if ( !keepSignatures )
-					break;
-				// otherwise fall into copy case
-			default:
-				memmove(dstCmd, srcCmd, cmdSize);
-				dstCmd = (macho_load_command<P>*)(((uint8_t*)dstCmd)+cmdSize);
-				++newCount;
-				break;
-		}
-		srcCmd = (const macho_load_command<P>*)(((uint8_t*)srcCmd)+cmdSize);
-	}
-	// zero out stuff removed
-	bzero(dstCmd, (uint8_t*)srcCmd - (uint8_t*)dstCmd);
-	
-	// update mach_header
-	macho_header<P>* writableHeader = (macho_header<P>*)fHeader; 
-	writableHeader->set_ncmds(newCount);
-	writableHeader->set_sizeofcmds((uint8_t*)dstCmd - ((uint8_t*)fHeader + sizeof(macho_header<P>)));
-	
-	// this invalidates some ivars
-	fDynamicSymbolTable = NULL;
-	fSymbolTableLoadCommand = NULL;
-	fDyldInfo = NULL;
-	fSymbolTable = NULL;
-	fStrings = NULL;
 }
 
 
 
 template <typename A>
-uint8_t* SharedCache<A>::optimizeLINKEDIT(bool keepSignatures)
+uint8_t* SharedCache<A>::optimizeLINKEDIT()
 {
 	// allocate space for optimized LINKEDIT area
 	uint8_t* newLinkEdit = new uint8_t[fLinkEditsTotalUnoptimizedSize];
@@ -1826,88 +1120,58 @@
 	// create optimizer object for each LINKEDIT segment
 	std::vector<LinkEditOptimizer<A>*> optimizers;
 	for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
-		optimizers.push_back(new LinkEditOptimizer<A>(*it->layout, *this, newLinkEdit, stringPool));
-	}
-
-	// rebase info is not copied because images in shared cache are never rebased
-	
-	// copy weak bind info
-	uint32_t offset = 0;
-	fOffsetOfWeakBindInfoInCombinedLinkedit = offset;
+		optimizers.push_back(new LinkEditOptimizer<A>(*it->layout, newLinkEdit, stringPool));
+	}
+
+	// copy local symbol table entries
+	uint32_t symbolTableIndex = 0;
+	LinkEditOptimizer<A>::makeDummyLocalSymbol(symbolTableIndex, newLinkEdit, stringPool);
 	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyWeakBindInfo(offset);
-	}
-	
-	// copy export info
-	fOffsetOfExportInfoInCombinedLinkedit = offset;
+		(*it)->copyLocalSymbols();
+	}
+
+	// copy exported symbol table entries
 	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyExportInfo(offset);
-	}
-
-	// copy bind info
-	fOffsetOfBindInfoInCombinedLinkedit = offset;
+		(*it)->copyExportedSymbols(symbolTableIndex);
+	}
+	//fprintf(stderr, "%u exported symbols, with %d bytes of strings\n", symbolTableIndex, stringPool.size());
+	//uint32_t importStart = symbolTableIndex;
+	//uint32_t importPoolStart =  stringPool.size();
+	
+	// copy imported symbol table entries
 	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyBindInfo(offset);
-	}
-	
-	// copy lazy bind info
-	fOffsetOfLazyBindInfoInCombinedLinkedit = offset;
+		(*it)->copyImportedSymbols(symbolTableIndex);
+	}
+	//fprintf(stderr, "%u imported symbols, with %d bytes of strings\n", symbolTableIndex-importStart, stringPool.size()-importPoolStart);
+	
+	// copy external relocations, 8-byte aligned after end of symbol table
+	uint32_t externalRelocsOffset = (symbolTableIndex * sizeof(macho_nlist<typename A::P>) + 7) & (-8);
+	//uint32_t externalRelocsStartOffset = externalRelocsOffset;
 	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyLazyBindInfo(offset);
-	}
-
-	// copy symbol table entries
-	fOffsetOfOldSymbolTableInfoInCombinedLinkedit = offset;
-	uint32_t symbolTableOffset = offset;
-	uint32_t symbolTableIndex = 0;
+		(*it)->copyExternalRelocations(externalRelocsOffset);
+	}
+	//fprintf(stderr, "%u bytes of external relocs\n", externalRelocsOffset-externalRelocsStartOffset);
+	
+	// copy indirect symbol tables
+	uint32_t indirectSymbolTableOffset = externalRelocsOffset;
 	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyLocalSymbols(symbolTableOffset, symbolTableIndex);
-		(*it)->copyExportedSymbols(symbolTableOffset, symbolTableIndex);
-		(*it)->copyImportedSymbols(symbolTableOffset, symbolTableIndex);
-	}
-	fSizeOfOldSymbolTableInfoInCombinedLinkedit =  symbolTableIndex * sizeof(macho_nlist<typename A::P>);
-	offset = symbolTableOffset + fSizeOfOldSymbolTableInfoInCombinedLinkedit & (-8);
-	
-	// copy external relocations, 8-byte aligned after end of symbol table
-	fOffsetOfOldExternalRelocationsInCombinedLinkedit = offset;
-	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyExternalRelocations(offset);
-	}
-	fSizeOfOldExternalRelocationsInCombinedLinkedit = offset - fOffsetOfOldExternalRelocationsInCombinedLinkedit;
-	
-	// copy function starts
-	fOffsetOfFunctionStartsInCombinedLinkedit = offset;
-	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyFunctionStarts(offset);
-	}
-	fSizeOfFunctionStartsInCombinedLinkedit = offset - fOffsetOfFunctionStartsInCombinedLinkedit;
-
-	// copy indirect symbol tables
-	fOffsetOfOldIndirectSymbolsInCombinedLinkedit = offset;
-	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->copyIndirectSymbolTable(offset);
-	}
-	fSizeOfOldIndirectSymbolsInCombinedLinkedit = offset - fOffsetOfOldIndirectSymbolsInCombinedLinkedit;
-		
+		(*it)->copyIndirectSymbolTable(indirectSymbolTableOffset);
+	}
+	
 	// copy string pool
-	fOffsetOfOldStringPoolInCombinedLinkedit = offset;
-	memcpy(&newLinkEdit[offset], stringPool.getBuffer(), stringPool.size());
-	fSizeOfOldStringPoolInCombinedLinkedit = stringPool.size();
-	
-	// total new size round up to page size
-	fLinkEditsTotalOptimizedSize = (fOffsetOfOldStringPoolInCombinedLinkedit + fSizeOfOldStringPoolInCombinedLinkedit + 4095) & (-4096);
-	
-	// choose new linkedit file offset 
-	uint32_t linkEditsFileOffset = cacheFileOffsetForVMAddress(fLinkEditsStartAddress);
-//	uint32_t linkEditsFileOffset = fLinkEditsStartAddress - sharedRegionReadOnlyStartAddress();	
-
+	uint32_t stringPoolOffset = indirectSymbolTableOffset;
+	memcpy(&newLinkEdit[stringPoolOffset], stringPool.getBuffer(), stringPool.size());
+	
+	// find new size
+	uint32_t linkEditsTotalOptimizedSize = (stringPoolOffset + stringPool.size() + 4095) & (-4096);
+	
 	// update load commands so that all dylibs shared different areas of the same LINKEDIT segment
 	for(typename std::vector<LinkEditOptimizer<A>*>::iterator it = optimizers.begin(); it != optimizers.end(); ++it) {
-		(*it)->updateLoadCommands(fLinkEditsStartAddress, fLinkEditsTotalUnoptimizedSize, fOffsetOfOldStringPoolInCombinedLinkedit, linkEditsFileOffset, keepSignatures);
-	}
-
-	//fprintf(stderr, "fLinkEditsTotalUnoptimizedSize=%llu, fLinkEditsTotalOptimizedSize=%u\n", fLinkEditsTotalUnoptimizedSize, fLinkEditsTotalOptimizedSize);
-	//printf(stderr, "mega link edit mapped starting at: %p\n", fFirstLinkEditSegment->mappedAddress());
+		(*it)->updateLoadCommands(fLinkEditsStartAddress, fLinkEditsTotalUnoptimizedSize, stringPoolOffset);
+	}
+
+	//fprintf(stderr, "fLinkEditsTotalUnoptimizedSize=%llu, linkEditsTotalOptimizedSize=%u\n", fLinkEditsTotalUnoptimizedSize, linkEditsTotalOptimizedSize);
+	//fprintf(stderr, "mega link edit mapped starting at: %p\n", fFirstLinkEditSegment->mappedAddress());
 
 	// overwrite mapped LINKEDIT area with new optimized LINKEDIT segment
 	memcpy(fFirstLinkEditSegment->mappedAddress(), newLinkEdit, fLinkEditsTotalUnoptimizedSize);
@@ -1920,198 +1184,15 @@
 			if ( !seg.writable() && !seg.executable() && (strcmp(seg.name(), "__LINKEDIT") == 0) ) {
 				seg.setNewAddress(fLinkEditsStartAddress);
 				seg.setMappedAddress(fFirstLinkEditSegment->mappedAddress());
-				seg.setSize(fLinkEditsTotalOptimizedSize);
-				seg.setFileSize(fLinkEditsTotalOptimizedSize);
-				seg.setFileOffset(linkEditsFileOffset);
+				seg.setSize(linkEditsTotalOptimizedSize);
+				seg.setFileSize(linkEditsTotalOptimizedSize);
+				//seg.setFileOffset(0);
 			}
 		}
 	}
 	
 	// return new end of cache
-	return (uint8_t*)fFirstLinkEditSegment->mappedAddress() + fLinkEditsTotalOptimizedSize;
-}
-
-
-
-template <typename A>
-class ObjCSelectorUniquer
-{
-private:
-    objc_opt::string_map fSelectorStrings;
-    SharedCache<A> *fCache;
-    size_t fCount;
-
-public:
-
-    ObjCSelectorUniquer(SharedCache<A> *newCache)
-        : fSelectorStrings()
-        , fCache(newCache)
-        , fCount(0)
-    { }
-
-    typename A::P::uint_t visit(typename A::P::uint_t oldValue) 
-    {
-        fCount++;
-        const char *s = (const char *)
-            fCache->mappedAddressForVMAddress(oldValue);
-        objc_opt::string_map::iterator element = 
-            fSelectorStrings.insert(objc_opt::string_map::value_type(s, oldValue)).first;
-        return (typename A::P::uint_t)element->second;
-    }
-
-    objc_opt::string_map& strings() { 
-        return fSelectorStrings;
-    }
-
-    size_t count() const { return fCount; }
-};
-
-template <typename A>
-void SharedCache<A>::optimizeObjC(std::vector<void*>& pointersInData)
-{
-    const char *err;
-    size_t headerSize = sizeof(objc_opt::objc_opt_t);
-
-    if ( verbose ) {
-        fprintf(stderr, "update_dyld_shared_cache: for %s, optimizing objc metadata\n", archName());
-    }
-
-    // Find libobjc's empty sections to fill in
-    const macho_section<P> *optROSection = NULL;
-    const macho_section<P> *optRWSection = NULL;
-	for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
-        if ( strstr(it->layout->getFilePath(), "libobjc") != NULL ) {
-			const macho_header<P>* mh = (const macho_header<P>*)(*it->layout).getSegments()[0].mappedAddress();
-			optROSection = mh->getSection("__TEXT", "__objc_opt_ro");
-			// __objc_selopt is old name for __objc_opt_ro
-			if ( optROSection == NULL )
-				optROSection = mh->getSection("__TEXT", "__objc_selopt");
-			optRWSection = mh->getSection("__DATA", "__objc_opt_rw");
-			break;
-		}
-	}
-    
-	if ( optROSection == NULL ) {
-		warn(archName(), "libobjc's read-only section missing (metadata not optimized)");
-		return;
-	}
-	
-	objc_opt::objc_opt_t* optROHeader = (objc_opt::objc_opt_t*)mappedAddressForVMAddress(optROSection->addr());
-	if (optROSection->size() < headerSize) {
-		warn(archName(), "libobjc's read-only section is too small (metadata not optimized)");
-		return;
-	}
-
-	if (E::get32(optROHeader->version) != objc_opt::VERSION) {
-		warn(archName(), "libobjc's read-only section version is unrecognized (metadata not optimized)");
-		return;
-	}
-
-    // Update selector references and build selector list
-
-    // This is SAFE: if we run out of room for the selector table, 
-    // the modified binaries are still usable.
-
-    // Heuristic: choose selectors from libraries with more cstring data first.
-    // This tries to localize selector cstring memory.
-    ObjCSelectorUniquer<A> uniq(this);
-    std::vector<LayoutInfo> sortedDylibs = fDylibs;
-    std::sort(sortedDylibs.begin(), sortedDylibs.end(), ByCStringSectionSizeSorter());
-
-    SelectorOptimizer<A, ObjCSelectorUniquer<A> > selOptimizer(uniq);
-	for(typename std::vector<LayoutInfo>::const_iterator it = sortedDylibs.begin(); it != sortedDylibs.end(); ++it) {
-        const macho_header<P> *mh = (const macho_header<P>*)(*it->layout).getSegments()[0].mappedAddress();
-        LegacySelectorUpdater<A, ObjCSelectorUniquer<A> >::update(this, mh, uniq);
-        selOptimizer.optimize(this, mh);
-	}
-
-    if ( verbose ) {
-        fprintf(stderr, "update_dyld_shared_cache: for %s, found %zu unique objc selectors\n", archName(), uniq.strings().size());
-    }
-
-    // Write selector table in read-only data.
-    size_t selTableOffset = P::round_up(headerSize);
-    size_t selTableSize;
-    objc_opt::objc_selopt_t *seloptData = (objc_opt::objc_selopt_t *)
-        mappedAddressForVMAddress(optROSection->addr() + selTableOffset);
-    err = objc_opt::write_selopt(seloptData, 
-                                 optROSection->addr() + selTableOffset, 
-                                 optROSection->size() - selTableOffset, 
-                                 uniq.strings(), 
-                                 E::little_endian, &selTableSize);
-    if (err) {
-        warn(archName(), err);
-        return;
-    }
-
-    if ( verbose ) {
-        size_t totalSize = headerSize + selTableSize;
-        fprintf(stderr, "update_dyld_shared_cache: for %s, %zu/%llu bytes "
-                "(%d%%) used in libobjc read-only optimization section\n", 
-                archName(), totalSize, optROSection->size(), 
-                (int)(totalSize / (double)optROSection->size() * 100));
-        fprintf(stderr, "update_dyld_shared_cache: for %s, "
-                "updated %zu selector references\n", 
-                archName(), uniq.count());
-        fprintf(stderr, "update_dyld_shared_cache: for %s, "
-                "wrote objc metadata optimization version %d\n", 
-                archName(), objc_opt::VERSION);
-    }
-
-	// if r/w section exists in libojc attempt to optimize categories into classes
-	if ( optRWSection != NULL ) {
-		// Attach categories to classes in the same framework. 
-		// Build aggregated (but unsorted) method lists in read-write data.
-
-		// This is SAFE: if we run out of room while attaching categories in 
-		// a binary then previously-edited binaries are still valid. (This assumes 
-		// each binary is processed all-or-nothing, which CategoryAttacher does.)
-		// This must be done AFTER uniquing selectors.
-		// This must be done BEFORE sorting method lists.
-		
-		size_t categoryOffset = 0;
-		uint8_t *categoryData = (uint8_t*)mappedAddressForVMAddress(optRWSection->addr() + categoryOffset);
-		CategoryAttacher<A> categoryAttacher(categoryData, optRWSection->size() - categoryOffset);
-		for(typename std::vector<LayoutInfo>::const_iterator it = sortedDylibs.begin(); it != sortedDylibs.end(); ++it) {
-			macho_header<P> *mh = (macho_header<P>*)(*it->layout).getSegments()[0].mappedAddress();
-			err = categoryAttacher.optimize(this, mh, pointersInData);
-			if (err) {
-				warn(archName(), err);
-				return;
-			}
-		}    
-		size_t categorySize = categoryAttacher.bytesUsed();
-
-
-		// Sort method lists.
-		
-		// This is SAFE: modified binaries are still usable as unsorted lists.
-		// This must be done AFTER uniquing selectors.
-		// This must be done AFTER attaching categories.
-
-		MethodListSorter<A> methodSorter;
-		for(typename std::vector<LayoutInfo>::const_iterator it = sortedDylibs.begin(); it != sortedDylibs.end(); ++it) {
-			macho_header<P> *mh = (macho_header<P>*)(*it->layout).getSegments()[0].mappedAddress();
-			methodSorter.optimize(this, mh);
-		}
-
-		if ( verbose ) {
-			size_t totalRWSize = categorySize;
-			fprintf(stderr, "update_dyld_shared_cache: for %s, %zu/%llu bytes "
-                "(%d%%) used in libobjc read-write optimization section\n", 
-                archName(), totalRWSize, optRWSection->size(), 
-                (int)(totalRWSize / (double)optRWSection->size() * 100));
-			fprintf(stderr, "update_dyld_shared_cache: for %s, "
-                "attached %zu categories (%zd bytes used)\n", 
-                archName(), categoryAttacher.count(), 
-                categoryAttacher.bytesUsed());
-		}
-	}
-
-    // Success. Update RO header last
-    E::set32(optROHeader->selopt_offset, headerSize);
-
-    return;
+	return (uint8_t*)fFirstLinkEditSegment->mappedAddress() + linkEditsTotalOptimizedSize;
 }
 
 
@@ -2128,24 +1209,20 @@
 }
 
 
-
-template <>	 bool	SharedCache<x86_64>::addCacheSlideInfo(){ return true; }
-template <>	 bool	SharedCache<arm>::addCacheSlideInfo()	{ return true; }
-template <>	 bool	SharedCache<x86>::addCacheSlideInfo()	{ return false; }
-template <>	 bool	SharedCache<ppc>::addCacheSlideInfo()	{ return false; }
-
-
-
 template <typename A>
-bool SharedCache<A>::update(bool usesOverlay, bool force, bool optimize, bool deleteExistingFirst, int archIndex,
-								int archCount, bool keepSignatures)
+bool SharedCache<A>::update(const char* rootPath, const char* cacheDir, bool force, bool optimize, bool deleteExistingFirst, int archIndex, int archCount)
 {
 	bool didUpdate = false;
+	char cachePath[1024];
+	strcpy(cachePath, rootPath);
+	strcat(cachePath, cacheDir);
+	strcat(cachePath, DYLD_SHARED_CACHE_BASE_NAME);
+	strcat(cachePath, filename(optimize));
 	
 	// already up to date?
-	if ( force || fExistingIsNotUpToDate ) {
+	if ( force || this->notUpToDate(cachePath) ) {
 		if ( verbose )
-			fprintf(stderr, "update_dyld_shared_cache: regenerating %s\n", fCacheFilePath);
+			fprintf(stderr, "update_dyld_shared_cache: regenerating %s\n", cachePath);
 		if ( fDylibs.size() == 0 ) {
 			fprintf(stderr, "update_dyld_shared_cache: warning, empty cache not generated for arch %s\n", archName());
 			return false;
@@ -2153,41 +1230,37 @@
 		// delete existing cache while building the new one
 		// this is a flag to dyld to stop pinging update_dyld_shared_cache
 		if ( deleteExistingFirst )
-			::unlink(fCacheFilePath);
+			::unlink(cachePath);
 		uint8_t* inMemoryCache = NULL;
 		uint32_t allocatedCacheSize = 0;
-		char tempCachePath[strlen(fCacheFilePath)+16];
-		sprintf(tempCachePath, "%s.tmp%u", fCacheFilePath, getpid());
+		char tempCachePath[strlen(cachePath)+16];
+		sprintf(tempCachePath, "%s.tmp%u", cachePath, getpid());
 		try {
 			// allocate a memory block to hold cache
 			uint32_t cacheFileSize = 0;
 			for(std::vector<shared_file_mapping_np>::iterator it = fMappings.begin(); it != fMappings.end(); ++it) {
 				uint32_t end = it->sfm_file_offset + it->sfm_size;
-				if ( end > cacheFileSize ) 
+				if ( end > cacheFileSize )
 					cacheFileSize = end;
 			}
 			if ( vm_allocate(mach_task_self(), (vm_address_t*)(&inMemoryCache), cacheFileSize, VM_FLAGS_ANYWHERE) != KERN_SUCCESS )
 				throwf("can't vm_allocate cache of size %u", cacheFileSize);
 			allocatedCacheSize = cacheFileSize;
-            fInMemoryCache = inMemoryCache;
 			
 			// fill in header
 			dyldCacheHeader<E>* header = (dyldCacheHeader<E>*)inMemoryCache;
-			const char* archPairName = fArchGraph->archName();
 			char temp[16];
 			strcpy(temp, "dyld_v1        ");
-			strcpy(&temp[15-strlen(archPairName)], archPairName);
+			strcpy(&temp[15-strlen(archName())], archName());
 			header->set_magic(temp);
 			//header->set_architecture(arch());
 			header->set_mappingOffset(sizeof(dyldCacheHeader<E>)); 
 			header->set_mappingCount(fMappings.size());
 			header->set_imagesOffset(header->mappingOffset() + fMappings.size()*sizeof(dyldCacheFileMapping<E>));	
-			header->set_imagesCount(fDylibs.size()+fDylibAliases.size());
+			header->set_imagesCount(fDylibs.size());
 			header->set_dyldBaseAddress(fDyldBaseAddress);
-			header->set_codeSignatureOffset(cacheFileSize);
-			header->set_codeSignatureSize(0);
-			header->set_slideInfoOffset(0);
-			header->set_slideInfoSize(0);
+			//header->set_dependenciesOffset(sizeof(dyldCacheHeader<E>) + fMappings.size()*sizeof(dyldCacheFileMapping<E>) + fDylibs.size()*sizeof(dyldCacheImageInfo<E>));	
+			//header->set_dependenciesCount(fDependencyPool.size());
 			
 			// fill in mappings
 			dyldCacheFileMapping<E>* mapping = (dyldCacheFileMapping<E>*)&inMemoryCache[sizeof(dyldCacheHeader<E>)];
@@ -2209,38 +1282,20 @@
 				image->set_address(it->info.address);
 				image->set_modTime(it->info.modTime);
 				image->set_inode(it->info.inode);
-				image->set_pathFileOffset(cacheFileOffsetForVMAddress(it->info.address+it->info.pathFileOffset));
-				++image;
-			}
-			
-			// add aliases to end of image table
-			for(typename std::vector<LayoutInfo>::iterator it = fDylibAliases.begin(); it != fDylibAliases.end(); ++it) {
-				image->set_address(it->info.address);
-				image->set_modTime(it->info.modTime);
-				image->set_inode(it->info.inode);
-				image->set_pathFileOffset(it->info.pathFileOffset);
-				strcpy((char*)inMemoryCache+it->info.pathFileOffset, it->aliases[0]);
-				//fprintf(stderr, "adding alias to offset 0x%08X %s\n", it->info.pathFileOffset, it->aliases[0]);
+				image->set_pathFileOffset(cacheFileOffsetForAddress(it->info.address+it->info.pathFileOffset));
+				//image->set_dependenciesStartOffset(it->info.dependenciesStartOffset);
 				++image;
 			}
 						
 			// copy each segment to cache buffer
-			const int dylibCount = fDylibs.size();
 			int dylibIndex = 0;
-			int progressIndex = 0;
 			for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it, ++dylibIndex) {
 				const char* path = it->layout->getFilePath();
-				int src = ::open(path, O_RDONLY, 0);
+				int src = ::open(path, O_RDONLY, 0);	
 				if ( src == -1 )
 					throwf("can't open file %s, errnor=%d", it->layout->getID().name, errno);
 				// mark source as "don't cache"
 				(void)fcntl(src, F_NOCACHE, 1);
-				// verify file has not changed since dependency analysis
-				struct stat stat_buf;
-				if ( fstat(src, &stat_buf) == -1)
-					throwf("can't stat open file %s, errno=%d", path, errno);
-				if ( (it->layout->getInode() != stat_buf.st_ino) || (it->layout->getLastModTime() != stat_buf.st_mtime) )
-					throwf("file modified during cache creation: %s", path);
 
 				if ( verbose )
 					fprintf(stderr, "update_dyld_shared_cache: copying %s to cache\n", it->layout->getID().name);
@@ -2253,15 +1308,9 @@
 						if ( seg.size() > 0 ) {
 							const uint64_t segmentSrcStartOffset = it->layout->getOffsetInUniversalFile()+seg.fileOffset();
 							const uint64_t segmentSize = seg.fileSize();
-							const uint64_t segmentDstStartOffset = cacheFileOffsetForVMAddress(seg.newAddress());
-							ssize_t readResult = ::pread(src, &inMemoryCache[segmentDstStartOffset], segmentSize, segmentSrcStartOffset);
-							if ( readResult != segmentSize ) {
-								if ( readResult == -1 )
-									throwf("read failure copying dylib errno=%d for %s", errno, it->layout->getID().name);
-								else
-									throwf("read failure copying dylib. Read of %lld bytes at file offset %lld returned %ld for %s", 
-											segmentSize, segmentSrcStartOffset, readResult, it->layout->getID().name);
-							}
+							const uint64_t segmentDstStartOffset = cacheFileOffsetForAddress(seg.newAddress());
+							if ( ::pread(src, &inMemoryCache[segmentDstStartOffset], segmentSize, segmentSrcStartOffset) != segmentSize )
+								throwf("read failure copying dylib errno=%d for %s", errno, it->layout->getID().name);
 						}
 					}
 				}
@@ -2269,13 +1318,6 @@
 					throwf("%s while copying %s to shared cache", msg, it->layout->getID().name);
 				}
 				::close(src);
-				if ( progress ) {
-					// assuming read takes 40% of time
-					int nextProgressIndex = archIndex*100+(40*dylibIndex)/dylibCount;
-					if ( nextProgressIndex != progressIndex )
-						fprintf(stdout, "%3u/%u\n", nextProgressIndex, archCount*100);
-					progressIndex = nextProgressIndex;
-				}
 			}
 						
 			// set mapped address for each segment
@@ -2284,30 +1326,36 @@
 				for (int i=0; i < segs.size(); ++i) {
 					MachOLayoutAbstraction::Segment& seg = segs[i];
 					if ( seg.size() > 0 )
-						seg.setMappedAddress(inMemoryCache + cacheFileOffsetForVMAddress(seg.newAddress()));
+						seg.setMappedAddress(inMemoryCache + cacheFileOffsetForAddress(seg.newAddress()));
 					//fprintf(stderr, "%s at %p to %p for %s\n", seg.name(), seg.mappedAddress(), (char*)seg.mappedAddress()+ seg.size(), it->layout->getID().name);
 				}
 			}
-	
-			// also construct list of all pointers in cache to other things in cache
-			std::vector<void*> pointersInData;
-			pointersInData.reserve(1024);
-			
-			// add pointer in start of __DATA to start of __TEXT to remain compatible with previous dylds
-			pint_t* dataStartPtr = (pint_t*)(&inMemoryCache[fMappings[1].sfm_file_offset]);
-			P::setP(*dataStartPtr, fMappings[0].sfm_address);
 
 			// rebase each dylib in shared cache
 			for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
 				try {
 					Rebaser<A> r(*it->layout);
-					r.rebase(pointersInData);
+					r.rebase();
 					//if ( verbose )
 					//	fprintf(stderr, "update_dyld_shared_cache: for %s, rebasing dylib into cache for %s\n", archName(), it->layout->getID().name);
 				}
 				catch (const char* msg) {
 					throwf("%s in %s", msg, it->layout->getID().name);
 				}
+			}
+			
+			// merge/optimize all LINKEDIT segments
+			if ( optimize ) {
+				//fprintf(stderr, "update_dyld_shared_cache: original cache file size %uMB\n", cacheFileSize/(1024*1024));
+				cacheFileSize = (this->optimizeLINKEDIT() - inMemoryCache);
+				//fprintf(stderr, "update_dyld_shared_cache: optimized cache file size %uMB\n", cacheFileSize/(1024*1024));
+				// update header to reduce mapping size
+				dyldCacheHeader<E>* cacheHeader = (dyldCacheHeader<E>*)inMemoryCache;
+				dyldCacheFileMapping<E>* mappings = (dyldCacheFileMapping<E>*)&inMemoryCache[sizeof(dyldCacheHeader<E>)];
+				dyldCacheFileMapping<E>* lastMapping = &mappings[cacheHeader->mappingCount()-1];
+				lastMapping->set_size(cacheFileSize-lastMapping->file_offset());
+				// update fMappings so .map file will print correctly
+				fMappings.back().sfm_size = cacheFileSize-fMappings.back().sfm_file_offset;
 			}
 			
 			if ( verbose )
@@ -2323,7 +1371,6 @@
 				if ( it->layout->getID().name != NULL )
 					map[it->layout->getID().name] = binder;
 			}
-  			
 			// tell each Binder about the others
 			for(typename std::vector<Binder<A>*>::iterator it = binders.begin(); it != binders.end(); ++it) {
 				(*it)->setDependentBinders(map);
@@ -2333,16 +1380,7 @@
 				if ( verbose )
 					fprintf(stderr, "update_dyld_shared_cache: for %s, updating binding information in cache for %s\n", archName(), (*it)->getDylibID());
 				try {
-					(*it)->bind(pointersInData);
-				}
-				catch (const char* msg) {
-					throwf("%s in %s", msg, (*it)->getDylibID());
-				}
-			}
-			// optimize binding
-			for(typename std::vector<Binder<A>*>::iterator it = binders.begin(); it != binders.end(); ++it) {
-				try {
-					(*it)->optimize();
+					(*it)->bind();
 				}
 				catch (const char* msg) {
 					throwf("%s in %s", msg, (*it)->getDylibID());
@@ -2353,356 +1391,93 @@
 				delete *it;
 			}
 	
-			// merge/optimize all LINKEDIT segments
-			if ( optimize ) {
-				//fprintf(stderr, "update_dyld_shared_cache: original cache file size %uMB\n", cacheFileSize/(1024*1024));
-				cacheFileSize = (this->optimizeLINKEDIT(keepSignatures) - inMemoryCache);
-				//fprintf(stderr, "update_dyld_shared_cache: optimized cache file size %uMB\n", cacheFileSize/(1024*1024));
-				// update header to reduce mapping size
-				dyldCacheHeader<E>* cacheHeader = (dyldCacheHeader<E>*)inMemoryCache;
-				dyldCacheFileMapping<E>* mappings = (dyldCacheFileMapping<E>*)&inMemoryCache[sizeof(dyldCacheHeader<E>)];
-				dyldCacheFileMapping<E>* lastMapping = &mappings[cacheHeader->mappingCount()-1];
-				lastMapping->set_size(cacheFileSize-lastMapping->file_offset());
-				// update fMappings so .map file will print correctly
-				fMappings.back().sfm_size = cacheFileSize-fMappings.back().sfm_file_offset;
-				// update header
-				//fprintf(stderr, "update_dyld_shared_cache: changing end of cache address from 0x%08llX to 0x%08llX\n", 
-				//		header->codeSignatureOffset(), fMappings.back().sfm_address + fMappings.back().sfm_size);
-				header->set_codeSignatureOffset(fMappings.back().sfm_file_offset + fMappings.back().sfm_size);
-			}
+			// install signal handlers to delete temp file if program is killed 
+			sCleanupFile = tempCachePath;
+			::signal(SIGINT, cleanup);
+			::signal(SIGBUS, cleanup);
+			::signal(SIGSEGV, cleanup);
 			
-			// unique objc selectors and update other objc metadata
-            if ( optimize ) {
-				optimizeObjC(pointersInData);
-				if ( progress ) {
-					// assuming objc optimizations takes 15% of time
-					fprintf(stdout, "%3u/%u\n", (archIndex+1)*55, archCount*100);
-				}
-			}
-
-			if ( addCacheSlideInfo() ) {
-				// build bitmap of which pointers need sliding
-				uint8_t* const dataStart = &inMemoryCache[fMappings[1].sfm_file_offset]; // R/W mapping is always second
-				uint8_t* const dataEnd   = &inMemoryCache[fMappings[1].sfm_file_offset+fMappings[1].sfm_size];
-				const int bitmapSize = (dataEnd - dataStart)/(4*8);
-				uint8_t* bitmap = (uint8_t*)calloc(bitmapSize, 1);
-				void* lastPointer = inMemoryCache;
-				for(std::vector<void*>::iterator pit=pointersInData.begin(); pit != pointersInData.end(); ++pit) {
-					if ( *pit != lastPointer ) {
-						void* p = *pit;
-						if ( (p < dataStart) || ( p > dataEnd) )
-							throwf("DATA pointer for sliding, out of range 0x%08lX\n", (long)((uint8_t*)p-inMemoryCache));
-						long offset = (long)((uint8_t*)p - dataStart);
-						if ( (offset % 4) != 0 )
-							throwf("pointer not 4-byte aligned in DATA offset 0x%08lX\n", offset);
-						long byteIndex = offset / (4*8);
-						long bitInByte =  (offset % 32) >> 2;
-						bitmap[byteIndex] |= (1 << bitInByte);
-						lastPointer = p;
+			// create temp file for cache
+			int fd = ::open(tempCachePath, O_CREAT | O_RDWR | O_TRUNC, 0644);	
+			if ( fd == -1 )
+				throwf("can't create temp file %s, errnor=%d", tempCachePath, errno);
+				
+			// try to allocate whole cache file contiguously
+			fstore_t fcntlSpec = { F_ALLOCATECONTIG|F_ALLOCATEALL, F_PEOFPOSMODE, 0, cacheFileSize, 0 };
+			::fcntl(fd, F_PREALLOCATE, &fcntlSpec);
+
+			// write out cache file
+			if ( verbose )
+				fprintf(stderr, "update_dyld_shared_cache: writing cache to disk\n");
+			if ( ::pwrite(fd, inMemoryCache, cacheFileSize, 0) != cacheFileSize )
+				throwf("write() failure creating cache file, errno=%d", errno);
+			
+			// flush to disk and close
+			int result = ::fcntl(fd, F_FULLFSYNC, NULL);
+			if ( result == -1 ) 
+				fprintf(stderr, "update_dyld_shared_cache: warning, fcntl(F_FULLFSYNC) failed with errno=%d for %s\n", errno, tempCachePath);
+			result = ::close(fd);
+			if ( result != 0 ) 
+				fprintf(stderr, "update_dyld_shared_cache: warning, close() failed with errno=%d for %s\n", errno, tempCachePath);
+			
+			// atomically swap in new cache file, do this after F_FULLFSYNC
+			result = ::rename(tempCachePath, cachePath);
+			if ( result != 0 ) 
+				throwf("can't swap newly create dyld shared cache file: rename(%s,%s) returned errno=%d", tempCachePath, cachePath, errno);
+				
+			// flush everything to disk to assure rename() gets recorded
+			::sync();
+			didUpdate = true;
+			
+			// restore default signal handlers
+			::signal(SIGINT, SIG_DFL);
+			::signal(SIGBUS, SIG_DFL);
+			::signal(SIGSEGV, SIG_DFL);
+
+			// generate human readable "map" file that shows the layout of the cache file
+			if ( verbose )
+				fprintf(stderr, "update_dyld_shared_cache: writing .map file to disk\n");
+			sprintf(tempCachePath, "%s.map", cachePath);// re-use path buffer
+			FILE* fmap = ::fopen(tempCachePath, "w");	
+			if ( fmap == NULL ) {
+				fprintf(stderr, "can't create map file %s, errnor=%d", tempCachePath, errno);
+			}
+			else {
+				for(std::vector<shared_file_mapping_np>::iterator it = fMappings.begin(); it != fMappings.end(); ++it) {
+					const char* prot = "RW";
+					if ( it->sfm_init_prot == (VM_PROT_EXECUTE|VM_PROT_READ) )
+						prot = "EX";
+					else if ( it->sfm_init_prot == VM_PROT_READ )
+						prot = "RO";
+					else if ( it->sfm_init_prot == (VM_PROT_EXECUTE|VM_PROT_WRITE|VM_PROT_READ) )
+						prot = "WX";
+					if ( it->sfm_size > 1024*1024 )
+						fprintf(fmap, "mapping %s %4lluMB 0x%0llX -> 0x%0llX\n", prot, it->sfm_size/(1024*1024),
+															it->sfm_address, it->sfm_address+it->sfm_size);
+					else
+						fprintf(fmap, "mapping %s %4lluKB 0x%0llX -> 0x%0llX\n", prot, it->sfm_size/1024,
+															it->sfm_address, it->sfm_address+it->sfm_size);
+				}
+				for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
+					fprintf(fmap, "%s\n", it->layout->getID().name);
+					const std::vector<MachOLayoutAbstraction::Segment>&	segs = it->layout->getSegments();
+					for (int i=0; i < segs.size(); ++i) {
+						const MachOLayoutAbstraction::Segment& seg = segs[i];
+						fprintf(fmap, "\t%16s 0x%0llX -> 0x%0llX\n", seg.name(), seg.newAddress(), seg.newAddress()+seg.size());
 					}
 				}
-
-				// allocate worst case size block of all slide info
-				const int entry_size = 4096/(8*4); // 8 bits per byte, possible pointer every 4 bytes.
-				const int toc_count = bitmapSize/entry_size;
-				int slideInfoSize = sizeof(dyldCacheSlideInfo<E>) + 2*toc_count + entry_size*(toc_count+1);
-				dyldCacheSlideInfo<E>* slideInfo = (dyldCacheSlideInfo<E>*)calloc(slideInfoSize, 1);
-				slideInfo->set_version(1);
-				slideInfo->set_toc_offset(sizeof(dyldCacheSlideInfo<E>));
-				slideInfo->set_toc_count(toc_count);
-				slideInfo->set_entries_offset((slideInfo->toc_offset()+2*toc_count+127)&(-128));
-				slideInfo->set_entries_count(0);
-				slideInfo->set_entries_size(entry_size);
-				// append each unique entry 
-				const dyldCacheSlideInfoEntry* bitmapAsEntries = (dyldCacheSlideInfoEntry*)bitmap;
-				dyldCacheSlideInfoEntry* const entriesInSlidInfo = (dyldCacheSlideInfoEntry*)((char*)slideInfo+slideInfo->entries_offset());
-				int entry_count = 0;
-				for (int i=0; i < toc_count; ++i) {
-					const dyldCacheSlideInfoEntry* thisEntry = &bitmapAsEntries[i];
-					// see if it is same as one already added
-					bool found = false;
-					for (int j=0; j < entry_count; ++j) {
-						if ( memcmp(thisEntry, &entriesInSlidInfo[j], entry_size) == 0 ) {
-							//fprintf(stderr, "toc[%d] optimized to %d\n", i, j);
-							slideInfo->set_toc(i, j);
-							found = true;
-							break;
-						}	
+				if ( warnings.size() > 0 ) {
+					fprintf(fmap, "# Warnings:\n");
+					for (std::vector<const char*>::iterator it=warnings.begin(); it != warnings.end(); ++it) {
+						fprintf(fmap, "# %s\n", *it);
 					}
-					if ( ! found ) {
-						// append to end
-						memcpy(&entriesInSlidInfo[entry_count], thisEntry, entry_size);
-						slideInfo->set_toc(i, entry_count++);
-					}
-				}
-				slideInfo->set_entries_count(entry_count);
-	
-				int slideInfoPageSize = (slideInfo->entries_offset() + entry_count*entry_size + 4095) & (-4096);
-				cacheFileSize += slideInfoPageSize;
-			
-				// update mappings to increase RO size
-				dyldCacheHeader<E>* cacheHeader = (dyldCacheHeader<E>*)inMemoryCache;
-				dyldCacheFileMapping<E>* mappings = (dyldCacheFileMapping<E>*)&inMemoryCache[sizeof(dyldCacheHeader<E>)];
-				dyldCacheFileMapping<E>* lastMapping = &mappings[cacheHeader->mappingCount()-1];
-				lastMapping->set_size(lastMapping->size()+slideInfoPageSize);
-				
-				// update header to show location of slidePointers
-				cacheHeader->set_slideInfoOffset(cacheHeader->codeSignatureOffset());
-				cacheHeader->set_slideInfoSize(slideInfoPageSize);
-				cacheHeader->set_codeSignatureOffset(cacheHeader->codeSignatureOffset()+slideInfoPageSize);
-				
-				// update fMappings so .map file will print correctly
-				fMappings.back().sfm_size = cacheFileSize-fMappings.back().sfm_file_offset;
-				
-				// copy compressed into into buffer
-				memcpy(&inMemoryCache[cacheHeader->slideInfoOffset()], slideInfo, slideInfoPageSize);	
-			}
-			
-			
-			if ( fVerify ) {
-				// if no existing cache, say so
-				if ( fExistingCacheForVerification == NULL ) {
-					throwf("update_dyld_shared_cache[%u] for arch=%s, could not verify because cache file does not exist in /var/db/dyld/\n",
-					 getpid(), archName());
-				}
-				// new cache is built, compare header entries
-				const dyldCacheHeader<E>* newHeader = (dyldCacheHeader<E>*)inMemoryCache;
-				const dyldCacheHeader<E>* oldHeader = (dyldCacheHeader<E>*)fExistingCacheForVerification;
-				if ( newHeader->mappingCount() != oldHeader->mappingCount() ) {
-					throwf("update_dyld_shared_cache[%u] for arch=%s, could not verify cache because caches have a different number of mappings\n",
-					 getpid(), archName());
-				}
-				const dyldCacheFileMapping<E>* newMappings = (dyldCacheFileMapping<E>*)&inMemoryCache[newHeader->mappingOffset()];
-				const dyldCacheFileMapping<E>* oldMappings = (dyldCacheFileMapping<E>*)&fExistingCacheForVerification[oldHeader->mappingOffset()];
-				for (int i=0; i < newHeader->mappingCount(); ++i) {
-					if ( newMappings[i].address() != oldMappings[i].address() ) {
-						throwf("update_dyld_shared_cache[%u] for arch=%s, could not verify cache because mapping %d starts at a different address 0x%0llX vs 0x%0llX\n", 
-							getpid(), archName(), i, newMappings[i].address(), oldMappings[i].address() );
-					}
-					if ( newMappings[i].size() != oldMappings[i].size() ) {
-						throwf("update_dyld_shared_cache[%u] for arch=%s, could not verify cache because mapping %d has a different size\n",
-						 getpid(), archName(), i);
-					}
-				}
-				
-				//fprintf(stderr, "%s existing cache = %p\n", archName(), fExistingCacheForVerification);
-				//fprintf(stderr, "%s new cache = %p\n", archName(), inMemoryCache);
-				// compare content to existing cache page by page
-				for (int offset=0; offset < cacheFileSize; offset += 4096) {
-					if ( memcmp(&inMemoryCache[offset], &fExistingCacheForVerification[offset], 4096) != 0 ) {
-						fprintf(stderr, "verifier found differences on page offset 0x%08X for %s:\n", offset, archName());
-						for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it, ++dylibIndex) {
-							const std::vector<MachOLayoutAbstraction::Segment>& segs = it->layout->getSegments();
-							for(std::vector<MachOLayoutAbstraction::Segment>::const_iterator sit = segs.begin(); sit != segs.end(); ++sit) {
-								const MachOLayoutAbstraction::Segment& seg = *sit;
-								if ( (seg.mappedAddress() <= &inMemoryCache[offset]) && (&inMemoryCache[offset] < ((uint8_t*)seg.mappedAddress() + seg.fileSize())) ) {
-									// all LINKEDITs point to the same region, so just print one
-									if ( strcmp(seg.name(), "__LINKEDIT") == 0 ) 
-										fprintf(stderr, "  in merged LINKEDIT segment\n");
-									else
-										fprintf(stderr, "  in segment %s of dylib %s\n", seg.name(), it->layout->getID().name);
-									break;
-								}
-							}
-						}
-						for (int po=0; po < 4096; po += 16) {
-							if ( memcmp(&inMemoryCache[offset+po], &fExistingCacheForVerification[offset+po], 16) != 0 ) {
-								fprintf(stderr, "   existing: 0x%08X: ", offset+po);
-								for ( int j=0; j < 16; ++j)
-									fprintf(stderr, " 0x%02X", fExistingCacheForVerification[offset+po+j]);
-								fprintf(stderr, "\n");
-								fprintf(stderr, "  should be: 0x%08X: ", offset+po);
-								for ( int j=0; j < 16; ++j)
-									fprintf(stderr, " 0x%02X", inMemoryCache[offset+po+j]);
-								fprintf(stderr, "\n");
-							}
-						}
-					}
-				}
-			}
-			else {
-				// install signal handlers to delete temp file if program is killed 
-				sCleanupFile = tempCachePath;
-				::signal(SIGINT, cleanup);
-				::signal(SIGBUS, cleanup);
-				::signal(SIGSEGV, cleanup);
-				
-				// create var/db/dyld dirs if needed
-				char dyldDirs[1024];
-				strcpy(dyldDirs, fCacheFilePath);
-				char* lastSlash = strrchr(dyldDirs, '/');
-				if ( lastSlash != NULL )
-					lastSlash[1] = '\0';
-				struct stat stat_buf;
-				if ( stat(dyldDirs, &stat_buf) != 0 ) {
-					const char* afterSlash = &dyldDirs[1];
-					char* slash;
-					while ( (slash = strchr(afterSlash, '/')) != NULL ) {
-						*slash = '\0';
-						::mkdir(dyldDirs, S_IRWXU | S_IRGRP|S_IXGRP | S_IROTH|S_IXOTH);
-						*slash = '/';
-						afterSlash = slash+1;
-					}
-				}
-				
-				// create temp file for cache
-				int fd = ::open(tempCachePath, O_CREAT | O_RDWR | O_TRUNC, 0644);	
-				if ( fd == -1 )
-					throwf("can't create temp file %s, errnor=%d", tempCachePath, errno);
-					
-				// try to allocate whole cache file contiguously
-				fstore_t fcntlSpec = { F_ALLOCATECONTIG|F_ALLOCATEALL, F_PEOFPOSMODE, 0, cacheFileSize, 0 };
-				::fcntl(fd, F_PREALLOCATE, &fcntlSpec);
-
-				// write out cache file
-				if ( verbose )
-					fprintf(stderr, "update_dyld_shared_cache: writing cache to disk\n");
-				if ( ::pwrite(fd, inMemoryCache, cacheFileSize, 0) != cacheFileSize )
-					throwf("write() failure creating cache file, errno=%d", errno);
-				if ( progress ) {
-					// assuming write takes 35% of time
-					fprintf(stdout, "%3u/%u\n", (archIndex+1)*90, archCount*100);
-				}
-				
-				// flush to disk and close
-				int result = ::fcntl(fd, F_FULLFSYNC, NULL);
-				if ( result == -1 ) 
-					fprintf(stderr, "update_dyld_shared_cache: warning, fcntl(F_FULLFSYNC) failed with errno=%d for %s\n", errno, tempCachePath);
-				result = ::close(fd);
-				if ( result != 0 ) 
-					fprintf(stderr, "update_dyld_shared_cache: warning, close() failed with errno=%d for %s\n", errno, tempCachePath);
-				
-				// <rdar://problem/7901042> Make life easier for the kernel at shutdown.
-				// If we just move the new cache file over the old, the old file
-				// may need to exist in the open-unlink state.  But because it
-				// may be mapped into the shared region, it cannot be deleted
-				// until all user processes are terminated.  That leaves are
-				// small to non-existent window for the kernel to delete the
-				// old cache file.
-				if ( fCacheFileInFinalLocation ) {
-					char tmpDirPath[64];
-					const char* pathLastSlash = strrchr(fCacheFilePath, '/');
-					if ( pathLastSlash != NULL ) {
-						sprintf(tmpDirPath, "/var/run%s.old.%u", pathLastSlash, getpid());
-						// move existing cache file to /var/run to be clean up next boot
-						result = ::rename(fCacheFilePath, tmpDirPath);
-						if ( result != 0 ) {
-							if ( errno != ENOENT )
-								fprintf(stderr, "update_dyld_shared_cache: warning, unable to move existing cache to %s errno=%d for %s\n", tmpDirPath, errno, fCacheFilePath);
-						}
-					}
-				}
-				
-				// move new cache file to correct location for use after reboot
-				result = ::rename(tempCachePath, fCacheFilePath);
-				if ( result != 0 ) 
-					throwf("can't swap newly create dyld shared cache file: rename(%s,%s) returned errno=%d", tempCachePath, fCacheFilePath, errno);
-				
-				
-				// flush everything to disk to assure rename() gets recorded
-				::sync();
-				didUpdate = true;
-				
-				// restore default signal handlers
-				::signal(SIGINT, SIG_DFL);
-				::signal(SIGBUS, SIG_DFL);
-				::signal(SIGSEGV, SIG_DFL);
-
-				// generate human readable "map" file that shows the layout of the cache file
-				if ( verbose )
-					fprintf(stderr, "update_dyld_shared_cache: writing .map file to disk\n");
-				char mapFilePath[strlen(fCacheFilePath)+16];
-				sprintf(mapFilePath, "%s.map", fCacheFilePath);
-				char tempMapFilePath[strlen(fCacheFilePath)+32];
-				sprintf(tempMapFilePath, "%s.map%u", fCacheFilePath, getpid());
-				FILE* fmap = ::fopen(tempMapFilePath, "w");	
-				if ( fmap == NULL ) {
-					fprintf(stderr, "can't create map file %s, errnor=%d", tempCachePath, errno);
-				}
-				else {
-					for(std::vector<shared_file_mapping_np>::iterator it = fMappings.begin(); it != fMappings.end(); ++it) {
-						const char* prot = "RW";
-						if ( it->sfm_init_prot == (VM_PROT_EXECUTE|VM_PROT_READ) )
-							prot = "EX";
-						else if ( it->sfm_init_prot == VM_PROT_READ )
-							prot = "RO";
-						else if ( it->sfm_init_prot == (VM_PROT_EXECUTE|VM_PROT_WRITE|VM_PROT_READ) )
-							prot = "WX";
-						if ( it->sfm_size > 1024*1024 )
-							fprintf(fmap, "mapping %s %4lluMB 0x%0llX -> 0x%0llX\n", prot, it->sfm_size/(1024*1024),
-																it->sfm_address, it->sfm_address+it->sfm_size);
-						else
-							fprintf(fmap, "mapping %s %4lluKB 0x%0llX -> 0x%0llX\n", prot, it->sfm_size/1024,
-																it->sfm_address, it->sfm_address+it->sfm_size);
-					}
-
-					fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX weak binding info\n",		
-								(fOffsetOfExportInfoInCombinedLinkedit-fOffsetOfWeakBindInfoInCombinedLinkedit)/1024,
-								fLinkEditsStartAddress+fOffsetOfWeakBindInfoInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfExportInfoInCombinedLinkedit);
-					fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX export info\n",		
-								(fOffsetOfBindInfoInCombinedLinkedit-fOffsetOfExportInfoInCombinedLinkedit)/1024,
-								fLinkEditsStartAddress+fOffsetOfExportInfoInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfBindInfoInCombinedLinkedit);
-					fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX binding info\n",		
-								(fOffsetOfLazyBindInfoInCombinedLinkedit-fOffsetOfBindInfoInCombinedLinkedit)/1024,
-								fLinkEditsStartAddress+fOffsetOfBindInfoInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfLazyBindInfoInCombinedLinkedit);
-					fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX lazy binding info\n",		
-								(fOffsetOfOldSymbolTableInfoInCombinedLinkedit-fOffsetOfLazyBindInfoInCombinedLinkedit)/1024,
-								fLinkEditsStartAddress+fOffsetOfLazyBindInfoInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfOldSymbolTableInfoInCombinedLinkedit);
-					fprintf(fmap, "linkedit   %4uMB 0x%0llX -> 0x%0llX non-dyld symbol table size\n",		
-								(fSizeOfOldSymbolTableInfoInCombinedLinkedit)/(1024*1024),
-								fLinkEditsStartAddress+fOffsetOfOldSymbolTableInfoInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfOldSymbolTableInfoInCombinedLinkedit+fSizeOfOldSymbolTableInfoInCombinedLinkedit);				
-					if ( fSizeOfFunctionStartsInCombinedLinkedit != 0 )
-						fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX non-dyld functions starts size\n",		
-								fSizeOfFunctionStartsInCombinedLinkedit/1024,
-								fLinkEditsStartAddress+fOffsetOfFunctionStartsInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfFunctionStartsInCombinedLinkedit+fSizeOfFunctionStartsInCombinedLinkedit);				
-					if ( fSizeOfOldExternalRelocationsInCombinedLinkedit != 0 )
-						fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX non-dyld external relocs size\n",		
-								fSizeOfOldExternalRelocationsInCombinedLinkedit/1024,
-								fLinkEditsStartAddress+fOffsetOfOldExternalRelocationsInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfOldExternalRelocationsInCombinedLinkedit+fSizeOfOldExternalRelocationsInCombinedLinkedit);				
-					fprintf(fmap, "linkedit   %4uKB 0x%0llX -> 0x%0llX non-dyld indirect symbol table size\n",		
-								fSizeOfOldIndirectSymbolsInCombinedLinkedit/1024,
-								fLinkEditsStartAddress+fOffsetOfOldIndirectSymbolsInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfOldIndirectSymbolsInCombinedLinkedit+fSizeOfOldIndirectSymbolsInCombinedLinkedit);				
-					fprintf(fmap, "linkedit   %4uMB 0x%0llX -> 0x%0llX non-dyld string pool\n",		
-								(fSizeOfOldStringPoolInCombinedLinkedit)/(1024*1024),
-								fLinkEditsStartAddress+fOffsetOfOldStringPoolInCombinedLinkedit,
-								fLinkEditsStartAddress+fOffsetOfOldStringPoolInCombinedLinkedit+fSizeOfOldStringPoolInCombinedLinkedit);				
-					
-					for(typename std::vector<LayoutInfo>::const_iterator it = fDylibs.begin(); it != fDylibs.end(); ++it) {
-						fprintf(fmap, "%s\n", it->layout->getID().name);
-						for (std::vector<const char*>::const_iterator ait = it->aliases.begin(); ait != it->aliases.end(); ++ait) 
-							fprintf(fmap, "%s\n", *ait);
-						const std::vector<MachOLayoutAbstraction::Segment>&	segs = it->layout->getSegments();
-						for (int i=0; i < segs.size(); ++i) {
-							const MachOLayoutAbstraction::Segment& seg = segs[i];
-							fprintf(fmap, "\t%16s 0x%0llX -> 0x%0llX\n", seg.name(), seg.newAddress(), seg.newAddress()+seg.size());
-						}
-					}
-					if ( warnings.size() > 0 ) {
-						fprintf(fmap, "# Warnings:\n");
-						for (std::vector<const char*>::iterator it=warnings.begin(); it != warnings.end(); ++it) {
-							fprintf(fmap, "# %s\n", *it);
-						}
-					}
-					fclose(fmap);
-					result = ::rename(tempMapFilePath, mapFilePath);
-				}
+				}
+				fclose(fmap);
 			}
 			
 			// free in memory cache
 			vm_deallocate(mach_task_self(), (vm_address_t)inMemoryCache, allocatedCacheSize);
 			inMemoryCache = NULL;
-			if ( progress ) {
-				// finished
-				fprintf(stdout, "%3u/%u\n", (archIndex+1)*100, archCount*100);
-			}
 		}
 		catch (...){
 			// remove temp cache file
@@ -2771,15 +1546,7 @@
 						*last = '\0';
 						--last;
 					}
-					// <rdar://problem/8305479> images in shared cache are bound against different IOKit than found at runtime
-					// HACK:  Just ignore the known bad IOKit
-					if ( strcmp(symbolStart, "/System/Library/Frameworks/IOKit.framework/IOKit") == 0 ) {
-						fprintf(stderr, "update_dyld_shared_cache: warning, ignoring /System/Library/Frameworks/IOKit.framework/IOKit\n");
-						warnings.push_back("update_dyld_shared_cache: warning, ignoring /System/Library/Frameworks/IOKit.framework/IOKit\n");
-					}
-					else {
-						paths.push_back(symbolStart);
-					}
+					paths.push_back(symbolStart);
 					symbolStart = NULL;
 					state = lineStart;
 				}
@@ -2794,32 +1561,10 @@
 }
 
 
-
-static void setSharedDylibs(const char* rootPath, bool usesOverlay, const std::set<ArchPair>& onlyArchs, std::vector<const char*> rootsPaths)
-{
-	// set file system root
-	ArchGraph::setFileSystemRoot(rootPath, usesOverlay);
-
-	// initialize all architectures requested
-	for(std::set<ArchPair>::iterator a = onlyArchs.begin(); a != onlyArchs.end(); ++a)
-		ArchGraph::addArchPair(*a);
-
-	// add roots to graph
-	for(std::vector<const char*>::const_iterator it = rootsPaths.begin(); it != rootsPaths.end(); ++it) 
-		ArchGraph::addRoot(*it, onlyArchs);
-
-	// determine shared dylibs
-	for(std::set<ArchPair>::iterator a = onlyArchs.begin(); a != onlyArchs.end(); ++a)
-		ArchGraph::findSharedDylibs(*a);
-}
-
-
-static void scanForSharedDylibs(const char* rootPath, bool usesOverlay, const char* dirOfPathFiles, const std::set<ArchPair>& onlyArchs)
+static void scanForSharedDylibs(const char* rootPath, const char* dirOfPathFiles, const std::set<cpu_type_t>& onlyArchs)
 {
 	char rootDirOfPathFiles[strlen(rootPath)+strlen(dirOfPathFiles)+2];
-	// in -overlay mode, still look for roots in /var/db/dyld
-	// in -root mode, look for roots in /rootpath/var/db/dyld
-	if ( !usesOverlay && (strlen(rootPath) != 0) ) {
+	if ( strlen(rootPath) != 0 ) {
 		strcpy(rootDirOfPathFiles, rootPath);
 		strcat(rootDirOfPathFiles, dirOfPathFiles);
 		dirOfPathFiles = rootDirOfPathFiles;
@@ -2833,23 +1578,14 @@
 	if ( dir == NULL )
 		throwf("%s does not exist, errno=%d\n", dirOfPathFiles, errno);
 	for (dirent* entry = ::readdir(dir); entry != NULL; entry = ::readdir(dir)) {
-		if ( entry->d_type == DT_REG || entry->d_type == DT_UNKNOWN ) {
-			// only look at regular files ending in .paths
+		if ( entry->d_type == DT_REG ) {
+			// only look at files ending in .paths
 			if ( strcmp(&entry->d_name[entry->d_namlen-6], ".paths") == 0 ) {
-				struct stat tmpStatPathsFile;
 				char fullPath[strlen(dirOfPathFiles)+entry->d_namlen+2];
 				strcpy(fullPath, dirOfPathFiles);
 				strcat(fullPath, "/");
 				strcat(fullPath, entry->d_name);
-				if ( lstat(fullPath, &tmpStatPathsFile) == -1 ) {
-					fprintf(stderr, "update_dyld_shared_cache: can't access %s\n", fullPath);
-				} 
-				else if ( S_ISREG(tmpStatPathsFile.st_mode) ) {
-					parsePathsFile(fullPath, rootsPaths);
-				} 
-				else {
-					fprintf(stderr, "update_dyld_shared_cache: wrong file type for %s\n", fullPath);
-				}
+				parsePathsFile(fullPath, rootsPaths);
 			}
 			else {
 				fprintf(stderr, "update_dyld_shared_cache: warning, ignore file with wrong extension: %s\n", entry->d_name);
@@ -2857,17 +1593,24 @@
 		}
 	}
 	::closedir(dir);
+
+	// set file system root
+	ArchGraph::setFileSystemRoot(rootPath);
+
+	// initialize all architectures requested
+	for(std::set<cpu_type_t>::iterator a = onlyArchs.begin(); a != onlyArchs.end(); ++a)
+		ArchGraph::addArch(*a);
+
+	// add roots to graph
+	for(std::vector<const char*>::iterator it = rootsPaths.begin(); it != rootsPaths.end(); ++it) 
+		ArchGraph::addRoot(*it, onlyArchs);
+
+	// determine shared dylibs
+	for(std::set<cpu_type_t>::iterator a = onlyArchs.begin(); a != onlyArchs.end(); ++a)
+		ArchGraph::findSharedDylibs(*a);
 	
 	if ( rootsPaths.size() == 0 )
 		fprintf(stderr, "update_dyld_shared_cache: warning, no entries found in shared_region_roots\n");
-	setSharedDylibs(rootPath, usesOverlay, onlyArchs, rootsPaths);
-}
-
-static void setSharedDylibs(const char* rootPath, bool usesOverlay, const char* pathsFile, const std::set<ArchPair>& onlyArchs)
-{
-	std::vector<const char*> rootsPaths;
-	parsePathsFile(pathsFile, rootsPaths);
-	setSharedDylibs(rootPath, usesOverlay, onlyArchs, rootsPaths);
 }
 
 
@@ -2878,15 +1621,15 @@
 // creation time was before the last restart of this machine.
 static void deleteOrphanTempCacheFiles()
 {
-	DIR* dir = ::opendir(MACOSX_DYLD_SHARED_CACHE_DIR);
+	DIR* dir = ::opendir(DYLD_SHARED_CACHE_DIR);
 	if ( dir != NULL ) {
 		std::vector<const char*> filesToDelete;
 		for (dirent* entry = ::readdir(dir); entry != NULL; entry = ::readdir(dir)) {
 			if ( entry->d_type == DT_REG ) {
 				// only look at files with .tmp in name
 				if ( strstr(entry->d_name, ".tmp") != NULL ) {
-					char fullPath[strlen(MACOSX_DYLD_SHARED_CACHE_DIR)+entry->d_namlen+2];
-					strcpy(fullPath, MACOSX_DYLD_SHARED_CACHE_DIR);
+					char fullPath[strlen(DYLD_SHARED_CACHE_DIR)+entry->d_namlen+2];
+					strcpy(fullPath, DYLD_SHARED_CACHE_DIR);
 					strcat(fullPath, "/");
 					strcat(fullPath, entry->d_name);
 					struct stat tmpFileStatInfo;
@@ -2914,67 +1657,54 @@
 
 
 
-static bool updateSharedeCacheFile(const char* rootPath, bool usesOverlay, const char* cacheDir, const std::set<ArchPair>& onlyArchs, 
-									bool force, bool alphaSort, bool optimize, bool deleteExistingFirst, bool verify, bool keepSignatures)
+static bool updateSharedeCacheFile(const char* rootPath, const char* cacheDir, const std::set<cpu_type_t>& onlyArchs, 
+									bool force, bool alphaSort, bool optimize, bool deleteExistingFirst)
 {
 	bool didUpdate = false;
 	// get dyld load address info
-	UniversalMachOLayout* dyldLayout = NULL;
-	char dyldPath[1024];
-	strlcpy(dyldPath, rootPath, 1024);
-	strlcat(dyldPath, "/usr/lib/dyld", 1024);
-	struct stat stat_buf;
-	if ( stat(dyldPath, &stat_buf) == 0 ) {
-		dyldLayout = new UniversalMachOLayout(dyldPath, &onlyArchs);
-	}
-	else {
-		dyldLayout = new UniversalMachOLayout("/usr/lib/dyld", &onlyArchs);
-	}
+	UniversalMachOLayout* dyldLayout = new UniversalMachOLayout("/usr/lib/dyld", &onlyArchs);
+
 	const int archCount = onlyArchs.size();
 	int index = 0;
-	for(std::set<ArchPair>::iterator a = onlyArchs.begin(); a != onlyArchs.end(); ++a, ++index) {
-		const MachOLayoutAbstraction* dyldLayoutForArch = dyldLayout->getSlice(*a);
-		uint64_t dyldBaseAddress = 0;
-		if ( dyldLayoutForArch != NULL )
-			dyldBaseAddress = dyldLayoutForArch->getBaseAddress();
-		else
-			fprintf(stderr, "update_dyld_shared_cache: warning, dyld not available for specified architectures\n");
-		switch ( a->arch ) {
+	for(std::set<cpu_type_t>::iterator a = onlyArchs.begin(); a != onlyArchs.end(); ++a, ++index) {
+		const MachOLayoutAbstraction* dyldLayoutForArch = dyldLayout->getArch(*a);
+		if ( dyldLayoutForArch == NULL )
+			throw "dyld not avaiable for specified architecture";
+		uint64_t dyldBaseAddress = dyldLayoutForArch->getBaseAddress();
+		switch ( *a ) {
 			case CPU_TYPE_POWERPC:
 				{
-		#if __i386__ || __x86_64__
+					SharedCache<ppc> cache(ArchGraph::getArch(*a), alphaSort, dyldBaseAddress);
+		#if __i386__
 					// <rdar://problem/5217377> Rosetta does not work with optimized dyld shared cache
-					SharedCache<ppc> cache(ArchGraph::graphForArchPair(*a), rootPath, cacheDir, alphaSort, verify, false, usesOverlay, dyldBaseAddress);
-					didUpdate |= cache.update(usesOverlay, force, false, deleteExistingFirst, index, archCount, keepSignatures);
+					didUpdate |= cache.update(rootPath, cacheDir, force, false, deleteExistingFirst, index, archCount);
 		#else
-					SharedCache<ppc> cache(ArchGraph::graphForArchPair(*a), rootPath, cacheDir, alphaSort, verify, optimize, usesOverlay, dyldBaseAddress);
-					didUpdate |= cache.update(usesOverlay, force, optimize, deleteExistingFirst, index, archCount, keepSignatures);
+					didUpdate |= cache.update(rootPath, cacheDir, force, optimize, deleteExistingFirst, index, archCount);
 		#endif
+				}
+				break;
+			case CPU_TYPE_POWERPC64:
+				{
+					SharedCache<ppc64> cache(ArchGraph::getArch(*a), alphaSort, dyldBaseAddress);
+					didUpdate |= cache.update(rootPath, cacheDir, force, optimize, deleteExistingFirst, index, archCount);
 				}
 				break;
 			case CPU_TYPE_I386:
 				{
-					SharedCache<x86> cache(ArchGraph::graphForArchPair(*a), rootPath, cacheDir, alphaSort, verify, optimize, usesOverlay, dyldBaseAddress);
-					didUpdate |= cache.update(usesOverlay, force, optimize, deleteExistingFirst, index, archCount, keepSignatures);
+					SharedCache<x86> cache(ArchGraph::getArch(*a), alphaSort, dyldBaseAddress);
+					didUpdate |= cache.update(rootPath, cacheDir, force, optimize, deleteExistingFirst, index, archCount);
 				}
 				break;
 			case CPU_TYPE_X86_64:
 				{
-					SharedCache<x86_64> cache(ArchGraph::graphForArchPair(*a), rootPath, cacheDir, alphaSort, verify, optimize, usesOverlay, dyldBaseAddress);
-					didUpdate |= cache.update(usesOverlay, force, optimize, deleteExistingFirst, index, archCount, keepSignatures);
+					SharedCache<x86_64> cache(ArchGraph::getArch(*a), alphaSort, dyldBaseAddress);
+					didUpdate |= cache.update(rootPath, cacheDir, force, optimize, deleteExistingFirst, index, archCount);
 				}
 				break;
-			case CPU_TYPE_ARM:
-				{
-					SharedCache<arm> cache(ArchGraph::graphForArchPair(*a), rootPath, cacheDir, alphaSort, verify, optimize, usesOverlay, dyldBaseAddress);
-					didUpdate |= cache.update(usesOverlay, force, optimize, deleteExistingFirst, index, archCount, keepSignatures);
-				}
-				break;
-		}
-	}
-	
-	if ( !iPhoneOS )
-		deleteOrphanTempCacheFiles();
+		}
+	}
+	
+	deleteOrphanTempCacheFiles();
 	
 	return didUpdate;
 }
@@ -2982,186 +1712,191 @@
 
 static void usage()
 {
-	fprintf(stderr, "update_dyld_shared_cache [-force] [-root dir] [-overlay dir] [-arch arch] [-debug]\n");
+	fprintf(stderr, "update_dyld_shared_cache [-force] [-root dir] [-arch arch] [-debug]\n");
+}
+
+// flag so that we only update cache once per invocation
+static bool doNothingAndDrainQueue = false;
+
+static kern_return_t do_update_cache(cpu_type_t arch, bool deleteExistingCacheFileFirst)
+{
+	if ( !doNothingAndDrainQueue ) {
+		std::set<cpu_type_t> onlyArchs;
+		onlyArchs.insert(arch);
+		try {
+			scanForSharedDylibs("", "/var/db/dyld/shared_region_roots/", onlyArchs);
+			if ( updateSharedeCacheFile("", DYLD_SHARED_CACHE_DIR, onlyArchs, false, false, true, deleteExistingCacheFileFirst) )
+				fprintf(stderr, "update_dyld_shared_cache[%u] regenerated cache for arch=%s\n", getpid(), ArchGraph::archName(arch));
+		}
+		catch (const char* msg) {
+			fprintf(stderr, "update_dyld_shared_cache[%u] for arch=%s failed: %s\n", getpid(), ArchGraph::archName(arch), msg);
+			return KERN_FAILURE;
+		}
+	}
+	return KERN_SUCCESS;
+}
+
+
+
+kern_return_t do_dyld_shared_cache_missing(mach_port_t dyld_port, cpu_type_t arch)
+{
+	return do_update_cache(arch, false);
+}
+
+
+kern_return_t do_dyld_shared_cache_out_of_date(mach_port_t dyld_port, cpu_type_t arch)
+{
+	// If cache exists but is out of date, delete the file while building the new one.
+	// This will stop dyld from pinging update_dyld_share_cache while the cache is being built.
+	return do_update_cache(arch, true);
 }
 
 
 int main(int argc, const char* argv[])
 {
-	std::set<ArchPair> onlyArchs;
-	const char* rootPath = "";
-	const char* dylibListFile = NULL;
-	bool force = false;
-	bool alphaSort = false;
-	bool optimize = true;
-	bool hasRoot = false;
-	bool hasOverlay = false;
-	bool verify = false;
-	bool keepSignatures = false;
-	const char* cacheDir = NULL;
-	
-	try {
-		// parse command line options
-		for(int i=1; i < argc; ++i) {
-			const char* arg = argv[i];
-			if ( arg[0] == '-' ) {
-				if ( strcmp(arg, "-debug") == 0 ) {
-					verbose = true;
-				}
-				else if ( strcmp(arg, "-force") == 0 ) {
-					force = true;
-				}
-				else if ( strcmp(arg, "-verify") == 0 ) {
-					verify = true;
-				}
-				else if ( strcmp(arg, "-sort_by_name") == 0 ) {
-					alphaSort = true;
-				}
-				else if ( strcmp(arg, "-progress") == 0 ) {
-					progress = true;
-				}
-				else if ( strcmp(arg, "-opt") == 0 ) {
-					optimize = true;
-				}
-				else if ( strcmp(arg, "-no_opt") == 0 ) {
-					optimize = false;
-				}
-				else if ( strcmp(arg, "-iPhone") == 0 ) {
-					iPhoneOS = true;
-				}
-				else if ( strcmp(arg, "-dylib_list") == 0 ) {
-					dylibListFile = argv[++i];
-					if ( dylibListFile == NULL )
-						throw "-dylib_list missing path argument";
-				}
-				else if ( (strcmp(arg, "-root") == 0) || (strcmp(arg, "--root") == 0) ) {
-					if ( hasOverlay )
-						throw "cannot use both -root and -overlay";
-					rootPath = argv[++i];
-					if ( rootPath == NULL )
-						throw "-root missing path argument";
-					hasRoot = true;
-				}
-				else if ( strcmp(arg, "-overlay") == 0 ) {
-					if ( hasRoot )
-						throw "cannot use both -root and -overlay";
-					rootPath = argv[++i];
-					if ( rootPath == NULL )
-						throw "-root missing path argument";
-					hasOverlay = true;
-				}
-				else if ( strcmp(arg, "-cache_dir") == 0 ) {
-					cacheDir = argv[++i];
-					if ( cacheDir == NULL )
-						throw "-cache_dir missing path argument";
-				}
-				else if ( strcmp(arg, "-arch") == 0 ) {
-					const char* arch = argv[++i];
-					if ( strcmp(arch, "ppc") == 0 ) 
-						onlyArchs.insert(ArchPair(CPU_TYPE_POWERPC, CPU_SUBTYPE_POWERPC_ALL));
-					else if ( strcmp(arch, "i386") == 0 )
-						onlyArchs.insert(ArchPair(CPU_TYPE_I386, CPU_SUBTYPE_I386_ALL));
-					else if ( strcmp(arch, "x86_64") == 0 )
-						onlyArchs.insert(ArchPair(CPU_TYPE_X86_64, CPU_SUBTYPE_X86_64_ALL));
-					else if ( strcmp(arch, "armv4t") == 0 )
-						onlyArchs.insert(ArchPair(CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V4T));
-					else if ( strcmp(arch, "armv5") == 0 )
-						onlyArchs.insert(ArchPair(CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V5TEJ));
-					else if ( strcmp(arch, "armv6") == 0 )
-						onlyArchs.insert(ArchPair(CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V6));
-					else if ( strcmp(arch, "armv7") == 0 )
-						onlyArchs.insert(ArchPair(CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V7));
-					else 
-						throwf("unknown architecture %s", arch);
-				}
-				else if ( strcmp(arg, "-universal_boot") == 0 ) {
-			#if __ppc__
-					throwf("universal_boot option can only be used on Intel machines");
-			#endif
-					onlyArchs.insert(ArchPair(CPU_TYPE_X86_64, CPU_SUBTYPE_X86_64_ALL));
-					onlyArchs.insert(ArchPair(CPU_TYPE_I386, CPU_SUBTYPE_I386_ALL));
+	mach_port_t mp;
+	if ( bootstrap_check_in(bootstrap_port, "com.apple.dyld", &mp) == KERN_SUCCESS ) {
+		// started by launchd
+		mach_msg_size_t mxmsgsz = sizeof(union __RequestUnion__do_dyld_server_subsystem) + MAX_TRAILER_SIZE;
+		doNothingAndDrainQueue = false;
+		while ( mach_msg_server(dyld_server_server, mxmsgsz, mp, MACH_RCV_TIMEOUT) == KERN_SUCCESS ) {
+			// keep processing messages
+			doNothingAndDrainQueue = true;
+			// but set flag so work is no longer done.
+			// This is because the rest of the tool leaks and processing more than once
+			// can hog system resources: <rdar://problem/5392427> 9A516 - Keep getting disk full errors
+			// We drain the queue of messages because there is usually are a couple of duplicate messages.
+			// It is ok to miss some messages.  If the cache is out of date or missing, some new process
+			// will discover it and send another message.  
+		}
+		return 0;
+	}
+	else {
+		// started as command line tool
+		std::set<cpu_type_t> onlyArchs;
+		const char* rootPath = "";
+		bool force = false;
+		bool alphaSort = false;
+		bool optimize = true;
+		bool makeSymLink = false;
+	
+		try {
+			// parse command line options
+			for(int i=1; i < argc; ++i) {
+				const char* arg = argv[i];
+				if ( arg[0] == '-' ) {
+					if ( strcmp(arg, "-debug") == 0 ) {
+						verbose = true;
+					}
+					else if ( strcmp(arg, "-force") == 0 ) {
+						force = true;
+					}
+					else if ( strcmp(arg, "-sort_by_name") == 0 ) {
+						alphaSort = true;
+					}
+					else if ( strcmp(arg, "-opt") == 0 ) {
+						optimize = true;
+					}
+					else if ( strcmp(arg, "-no_opt") == 0 ) {
+						optimize = false;
+					}
+					else if ( (strcmp(arg, "-root") == 0) || (strcmp(arg, "--root") == 0) ) {
+						rootPath = argv[++i];
+						if ( rootPath == NULL )
+							throw "-root missing path argument";
+						// strip tailing slashes
+						int len = strlen(rootPath)-1;
+						if (  rootPath[len] == '/' ) {
+							char* newRootPath = strdup(rootPath);
+							while ( newRootPath[len] == '/' )	
+								newRootPath[len--] = '\0';
+							rootPath = newRootPath;
+						}
+					}
+					else if ( strcmp(arg, "-arch") == 0 ) {
+						const char* arch = argv[++i];
+						if ( strcmp(arch, "ppc") == 0 ) 
+							onlyArchs.insert(CPU_TYPE_POWERPC);
+						else if ( strcmp(arch, "ppc64") == 0 )
+							onlyArchs.insert(CPU_TYPE_POWERPC64);
+						else if ( strcmp(arch, "i386") == 0 )
+							onlyArchs.insert(CPU_TYPE_I386);
+						else if ( strcmp(arch, "x86_64") == 0 )
+							onlyArchs.insert(CPU_TYPE_X86_64);
+						else 
+							throwf("unknown architecture %s", arch);
+					}
+					else if ( strcmp(arg, "-universal_boot") == 0 ) {
+				#if __ppc__
+						throwf("universal_boot option can only be used on Intel machines");
+				#endif
+						onlyArchs.insert(CPU_TYPE_POWERPC);
+						onlyArchs.insert(CPU_TYPE_I386);
+						makeSymLink = true;
+					}
+					else {
+						usage();
+						throwf("unknown option: %s\n", arg);
+					}
 				}
 				else {
 					usage();
 					throwf("unknown option: %s\n", arg);
 				}
 			}
-			else {
-				usage();
-				throwf("unknown option: %s\n", arg);
-			}
-		}
-				
-		// strip tailing slashes on -root or -overlay
-		// make it a real path so as to not make all dylibs look like symlink aliases
-		if ( rootPath[0] != '\0' ) {
-			char realRootPath[MAXPATHLEN];
-			if ( realpath(rootPath, realRootPath) == NULL )
-				throwf("realpath() failed on %s\n", rootPath);
-			rootPath = strdup(realRootPath);
-		}
-		
-		// set location to write cache dir
-		if ( cacheDir == NULL ) {
-			if ( (rootPath[0] == '\0') || hasOverlay ) {
-				cacheDir =  (iPhoneOS ? IPHONE_DYLD_SHARED_CACHE_DIR : MACOSX_DYLD_SHARED_CACHE_DIR);
-			}
-			else {
-				asprintf((char**)&cacheDir, "%s/%s", rootPath, (iPhoneOS ? IPHONE_DYLD_SHARED_CACHE_DIR : MACOSX_DYLD_SHARED_CACHE_DIR));
-			}
-		}
-
-		// if no restrictions specified, use architectures that work on this machine
-		if ( onlyArchs.size() == 0 ) {
-			if ( iPhoneOS ) {
-				onlyArchs.insert(ArchPair(CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V6));
-				onlyArchs.insert(ArchPair(CPU_TYPE_ARM, CPU_SUBTYPE_ARM_V7));
-			}
-			else {
+					
+			// if no restrictions specified, use architectures that work on this machine
+			if ( onlyArchs.size() == 0 ) {
 				int available;
 				size_t len = sizeof(int);
-			#if __i386__ || __x86_64__
-				onlyArchs.insert(ArchPair(CPU_TYPE_I386, CPU_SUBTYPE_I386_ALL));
-				// check rosetta is installed
-				char rosettaPath[1024];
-				strlcpy(rosettaPath, rootPath, 1024);
-				strlcat(rosettaPath, "/usr/libexec/oah/translate", 1024);
-				struct stat stat_buf;
-				if ( stat(rosettaPath, &stat_buf) == 0 ) {
-					onlyArchs.insert(ArchPair(CPU_TYPE_POWERPC, CPU_SUBTYPE_POWERPC_ALL));
-				}
-				else if ( hasOverlay ) {
-					// in overlay mode, rosetta may be installed on base system, but is not in update root
-					if ( stat("/usr/libexec/oah/translate", &stat_buf) == 0 ) 
-						onlyArchs.insert(ArchPair(CPU_TYPE_POWERPC, CPU_SUBTYPE_POWERPC_ALL));
-				}
-				// check system is capable of running 64-bit programs
+			#if __ppc__	
+				onlyArchs.insert(CPU_TYPE_POWERPC);
+				if ( (sysctlbyname("hw.optional.64bitops", &available, &len, NULL, 0) == 0) && available )
+					onlyArchs.insert(CPU_TYPE_POWERPC64);
+			#elif __i386__
+				onlyArchs.insert(CPU_TYPE_I386);
+				onlyArchs.insert(CPU_TYPE_POWERPC);	// assume rosetta always available
 				if ( (sysctlbyname("hw.optional.x86_64", &available, &len, NULL, 0) == 0) && available )
-					onlyArchs.insert(ArchPair(CPU_TYPE_X86_64, CPU_SUBTYPE_X86_64_ALL));
+					onlyArchs.insert(CPU_TYPE_X86_64);
 			#else
-				#error unsupported architecture
+				#error unknown architecture
 			#endif
 			}
+			
+			if ( geteuid() != 0 )
+				throw "you must be root to run this tool";
+			
+			// build list of shared dylibs
+			scanForSharedDylibs(rootPath, "/var/db/dyld/shared_region_roots/", onlyArchs);
+			updateSharedeCacheFile(rootPath, DYLD_SHARED_CACHE_DIR, onlyArchs, force, alphaSort, optimize, false);
+			
+			// To make a universal bootable image with dyld caches,
+			// build the rosetta cache and symlink ppc to point to it.
+			// A rosetta cache is just an unoptimized ppc cache, so ppc machine can use it too.
+			// rdar://problem/5498469
+			if ( makeSymLink ) {
+				char symLinkLocation[1024];
+				strcpy(symLinkLocation, rootPath);
+				strcat(symLinkLocation, DYLD_SHARED_CACHE_DIR);
+				strcat(symLinkLocation, DYLD_SHARED_CACHE_BASE_NAME);
+				strcat(symLinkLocation, SharedCache<ppc>::filename(true));
+				char symLinkTarget[1024];
+				strcpy(symLinkTarget, DYLD_SHARED_CACHE_BASE_NAME);
+				strcat(symLinkTarget, SharedCache<ppc>::filename(false));
+				if ( symlink(symLinkTarget, symLinkLocation) == -1 ) {
+					if ( errno != EEXIST )
+						throwf("symlink() returned errno=%d", errno);
+				}
+			}
+		}
+		catch (const char* msg) {
+			fprintf(stderr, "update_dyld_shared_cache failed: %s\n", msg);
+			return 1;
 		}
 		
-		if ( !verify && (geteuid() != 0) )
-			throw "you must be root to run this tool";
-		
-		// build list of shared dylibs
-		if ( dylibListFile != NULL )
-			setSharedDylibs(rootPath, hasOverlay, dylibListFile, onlyArchs);
-		else
-			scanForSharedDylibs(rootPath, hasOverlay, "/var/db/dyld/shared_region_roots/", onlyArchs);
-		updateSharedeCacheFile(rootPath, hasOverlay, cacheDir, onlyArchs, force, alphaSort, optimize, 
-								false, verify, keepSignatures);
-	}
-	catch (const char* msg) {
-		fprintf(stderr, "update_dyld_shared_cache failed: %s\n", msg);
-		return 1;
-	}
-	
-	return 0;
-}
-
-
-
+		return 0;
+	}
+}
+
+
+