release/22.x: [sanitizer_common] [Darwin] Adopt _dyld_get_dyld_header (#182943)

[llvmbot]

Backport 2e7d07a

Requested by: @ndrewh

[llvmbot]

@DanBlackwell What do you think about merging this PR to the release branch?

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: llvmbot

Changes

Backport 2e7d07a

Requested by: @ndrewh

---

Full diff: https://github.com/llvm/llvm-project/pull/188913.diff

3 Files Affected:

• (modified) compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp (+6-2)
• (modified) compiler-rt/lib/sanitizer_common/weak_symbols.txt (+1)
• (modified) compiler-rt/lib/tsan/go/buildgo.sh (+1-1)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_mac.cpp
index 979729f15aa16..93d3929033a86 100644
--- 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
index 77e7b5d9f702e..600ab8a7c649c 100644
--- 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
index d9e56402ad48f..1340071819fcb 100755
--- 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

[ndrewh]

I think we should cherry-pick this to make sure that clang 22 supports ASAN on macOS 26.4.

[dyung]

Is this a regression? If so, when was the regression introduced?

[DanBlackwell]

Is this a regression? If so, when was the regression introduced?

This is a regression caused by an OS change in macOS 26.4; any runtimes without this change will not run on macOS 26.4+. Any runtimes built with this patch can run on both pre- and post-macOS 26.4 OSes.

[c-rhodes]

@DanBlackwell sounds reasonable, please accept if you're happy. Also adding sanitizer maintainer for visibility.