[PATCH] D152604: [Driver] Default -fsanitize-address-globals-dead-stripping to true for ELF

[Fangrui Song via Phabricator via cfe-commits]

MaskRay created this revision.
MaskRay added reviewers: Sanitizers, aeubanks, rnk, eugenis, phosek, probinson.
Herald added a project: All.
MaskRay requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

-fsanitize-address-globals-dead-stripping is the default for non-ELF
platforms. For ELF, we disabled it to work around an ancient gold 2.26
bug. However, some platforms (Fuchsia and PS) default the option to
true.

This patch changes -fsanitize-address-globals-dead-stripping to true for all ELF
platforms. Without specifying -fdata-sections (non-default for most ELF
platforms), `asan_globals` can only be GCed if the monolithic .data/.bss section
is GCed, which makes it less effective.
However, I think this simplified rule is better than making the
-fsanitize-address-globals-dead-stripping default dependent on another option.

Close https://github.com/llvm/llvm-project/issues/63127


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D152604

Files:
  clang/lib/Driver/SanitizerArgs.cpp
  clang/test/Driver/fsanitize.c


Index: clang/test/Driver/fsanitize.c
===================================================================
--- clang/test/Driver/fsanitize.c
+++ clang/test/Driver/fsanitize.c
@@ -240,7 +240,7 @@
 // CHECK-ASAN-WITHOUT-POISON-CUSTOM-ARRAY-NEW-COOKIE-NOT: -cc1{{.*}}address-poison-custom-array-cookie
 
 // RUN: %clang --target=x86_64-linux-gnu -fsanitize=address -fsanitize-address-globals-dead-stripping %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-GLOBALS
-// RUN: %clang --target=x86_64-linux-gnu -fsanitize=address %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ASAN-GLOBALS
+// RUN: %clang --target=x86_64-linux-gnu -fsanitize=address %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-GLOBALS
 // RUN: %clang --target=x86_64-linux-gnu -fsanitize=address -fsanitize-address-globals-dead-stripping -fno-sanitize-address-globals-dead-stripping %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-NO-ASAN-GLOBALS
 // RUN: %clang_cl --target=x86_64-windows-msvc -fsanitize=address -fsanitize-address-globals-dead-stripping -### -- %s 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-GLOBALS
 // RUN: %clang_cl --target=x86_64-windows-msvc -fsanitize=address -### -- %s 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-GLOBALS
Index: clang/lib/Driver/SanitizerArgs.cpp
===================================================================
--- clang/lib/Driver/SanitizerArgs.cpp
+++ clang/lib/Driver/SanitizerArgs.cpp
@@ -928,14 +928,9 @@
                      options::OPT_fno_sanitize_address_outline_instrumentation,
                      AsanOutlineInstrumentation);
 
-    // As a workaround for a bug in gold 2.26 and earlier, dead stripping of
-    // globals in ASan is disabled by default on most ELF targets.
-    // See https://sourceware.org/bugzilla/show_bug.cgi?id=19002
     AsanGlobalsDeadStripping = Args.hasFlag(
         options::OPT_fsanitize_address_globals_dead_stripping,
-        options::OPT_fno_sanitize_address_globals_dead_stripping,
-        !TC.getTriple().isOSBinFormatELF() || TC.getTriple().isOSFuchsia() ||
-            TC.getTriple().isPS());
+        options::OPT_fno_sanitize_address_globals_dead_stripping, true);
 
     // Enable ODR indicators which allow better handling of mixed instrumented
     // and uninstrumented globals. Disable them for Windows where weak odr


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