[sanitizer_common] [Darwin] Adopt _dyld_get_dyld_header (#182943)

ndrewh · c-rhodes · commit 7b6514cd3089 · 2026-03-31T08:27:08.000Z
(cherry picked from commit 2e7d07a)
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp
@@ -176,7 +176,7 @@ void MemoryMappingLayout::Reset() {
 // The dyld load address should be unchanged throughout process execution,
 // and it is expensive to compute once many libraries have been loaded,
 // so cache it here and do not reset.
-static mach_header *dyld_hdr = 0;
+static const mach_header* dyld_hdr = 0;
 static const char kDyldPath[] = "/usr/lib/dyld";
 static const int kDyldImageIdx = -1;
 
@@ -244,14 +244,18 @@ extern intptr_t _dyld_get_image_slide(const struct mach_header* mh);
 extern int dyld_shared_cache_iterate_text(
     const uuid_t cacheUuid,
     void (^callback)(const dyld_shared_cache_dylib_text_info *info));
+SANITIZER_WEAK_IMPORT const struct mach_header* _dyld_get_dyld_header(void);
 }  // extern "C"
 
-static mach_header *GetDyldImageHeaderViaSharedCache() {
+static const mach_header* GetDyldImageHeaderViaSharedCache() {
   uuid_t uuid;
   bool hasCache = _dyld_get_shared_cache_uuid(uuid);
   if (!hasCache)
     return nullptr;
 
+  if (&_dyld_get_dyld_header != nullptr)
+    return _dyld_get_dyld_header();
+
   size_t cacheLength;
   __block uptr cacheStart = (uptr)_dyld_get_shared_cache_range(&cacheLength);
   CHECK(cacheStart && cacheLength);
diff --git a/compiler-rt/lib/sanitizer_common/weak_symbols.txt b/compiler-rt/lib/sanitizer_common/weak_symbols.txt
@@ -10,3 +10,4 @@ ___sanitizer_symbolize_demangle
 ___sanitizer_symbolize_flush
 ___sanitizer_symbolize_set_demangle
 ___sanitizer_symbolize_set_inline_frames
+__dyld_get_dyld_header
diff --git a/compiler-rt/lib/tsan/go/buildgo.sh b/compiler-rt/lib/tsan/go/buildgo.sh
@@ -165,7 +165,7 @@ elif [ "$GOOS" = "netbsd" ]; then
 	"
 elif [ "$GOOS" = "darwin" ]; then
 	OSCFLAGS="-fPIC -Wno-unused-const-variable -Wno-unknown-warning-option -mmacosx-version-min=10.7"
-	OSLDFLAGS="-lpthread -fPIC -fpie -mmacosx-version-min=10.7"
+	OSLDFLAGS="-lpthread -fPIC -fpie -mmacosx-version-min=10.7 -Wl,-U,__dyld_get_dyld_header"
 	SRCS="
 		$SRCS
 		../rtl/tsan_platform_mac.cpp

Original file line number	Diff line number	Diff line change
`@@ -165,7 +165,7 @@ elif [ "$GOOS" = "netbsd" ]; then`
`165`	`165`	`"`
`166`	`166`	`elif [ "$GOOS" = "darwin" ]; then`
`167`	`167`	`OSCFLAGS="-fPIC -Wno-unused-const-variable -Wno-unknown-warning-option -mmacosx-version-min=10.7"`
`168`		`- OSLDFLAGS="-lpthread -fPIC -fpie -mmacosx-version-min=10.7"`
	`168`	`+ OSLDFLAGS="-lpthread -fPIC -fpie -mmacosx-version-min=10.7 -Wl,-U,__dyld_get_dyld_header"`
`169`	`169`	`SRCS="`
`170`	`170`	`$SRCS`
`171`	`171`	`../rtl/tsan_platform_mac.cpp`