--- /dev/null
+++ dyld/dyld-1235.2/mach_o/FunctionStarts.cpp
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2021 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "FunctionStarts.h"
+#include "Misc.h"
+
+
+namespace mach_o {
+
+
+FunctionStarts::FunctionStarts(const uint8_t* start, size_t size)
+  : _funcStartsBegin(start), _funcStartsEnd(start+size)
+{
+}
+
+Error FunctionStarts::valid(uint64_t maxFuncOffset) const
+{
+    uint64_t runtimeOffset = 0;
+    for (const uint8_t* p=_funcStartsBegin; p < _funcStartsEnd; ) {
+        bool malformed;
+        uint64_t value = read_uleb128(p, _funcStartsEnd, malformed);
+        if ( malformed )
+            return Error("malformed uleb128 in function-starts data");
+        // a delta of zero marks end of functionStarts stream
+        if ( value == 0 ) {
+            while ( p < _funcStartsEnd ) {
+                if ( *p++ != 0 )
+                    return Error("padding at end of function-starts not all zeros");
+            }
+            return Error::none();
+        }
+        runtimeOffset += value;
+        if ( runtimeOffset > maxFuncOffset )
+            return Error("functions-starts has entry beyond end of TEXT");
+    };
+    return Error("functions-starts not zero terminated");
+}
+
+void FunctionStarts::forEachFunctionStart(uint64_t loadAddr, void (^callback)(uint64_t funcAddr)) const
+{
+    uint64_t runtimeOffset = 0;
+    for (const uint8_t* p=_funcStartsBegin; p < _funcStartsEnd; ) {
+        bool malformed;
+        uint64_t value = read_uleb128(p, _funcStartsEnd, malformed);
+        // a delta of zero marks end of functionStarts stream
+        if ( malformed || (value == 0) )
+            return;
+        runtimeOffset += value;
+        callback(loadAddr+runtimeOffset);
+    };
+}
+
+
+#if BUILDING_MACHO_WRITER
+FunctionStarts::FunctionStarts(uint64_t prefLoadAddr, std::span<const uint64_t> functionAddresses)
+{
+    uint64_t lastAddr = prefLoadAddr;
+    for (uint64_t addr : functionAddresses) {
+        assert(addr >= lastAddr && "function addresses not sorted");
+        // <rdar://problem/10422823> filter out zero-length atoms, so LC_FUNCTION_STARTS address can't spill into next section
+        if ( addr == lastAddr)
+            continue;
+        // FIXME: for 32-bit arm need to check thumbness
+        uint64_t delta = addr - lastAddr;
+        append_uleb128(delta);
+        lastAddr = addr;
+    }
+    // terminate delta encoded list
+    _bytes.push_back(0);
+    // 8-byte align
+    while ( (_bytes.size() % 8) != 0 )
+        _bytes.push_back(0);
+
+    // set up pointers to data can be parsed
+    _funcStartsBegin = &_bytes[0];
+    _funcStartsEnd   = &_bytes[_bytes.size()];
+}
+
+void FunctionStarts::append_uleb128(uint64_t value)
+{
+    uint8_t byte;
+    do {
+        byte = value & 0x7F;
+        value &= ~0x7F;
+        if ( value != 0 )
+            byte |= 0x80;
+        _bytes.push_back(byte);
+        value = value >> 7;
+    } while( byte >= 0x80 );
+}
+
+#endif // BUILDING_MACHO_WRITER
+
+
+
+
+} // namespace mach_o