[asan] Turn -fsanitize-address-use-after-scope on by default [clang part]

AddressSanitizer has an optional compile-time flag, -fsanitize-address-use-after-scope, which enables detection of use-after-scope bugs. We'd like to have this feature on by default, because it is already very well tested, it's used in several projects already (LLVM automatically enables it when using -DLLVM_USE_SANITIZER=Address), it's low overhead and there are no known issues or incompatibilities.

This patch enables use-after-scope by default via the Clang driver, where we set true as the default value for AsanUseAfterScope. This also causes the lifetime markers to be generated whenever fsanitize=address is used. This has some nice consequences, e.g. we now have line numbers for all local variables.

Differential Revision: https://reviews.llvm.org/D31479

llvm-svn: 299174

diff --git a/clang/include/clang/Driver/SanitizerArgs.h b/clang/include/clang/Driver/SanitizerArgs.h
index 6206680..2df8077 100644 (file)
--- a/clang/include/clang/Driver/SanitizerArgs.h
+++ b/clang/include/clang/Driver/SanitizerArgs.h
@@ -34,7 +34,7 @@ class SanitizerArgs {
   bool CfiCrossDso = false;
   int AsanFieldPadding = 0;
   bool AsanSharedRuntime = false;
-  bool AsanUseAfterScope = false;
+  bool AsanUseAfterScope = true;
   bool LinkCXXRuntimes = false;
   bool NeedPIE = false;
   bool Stats = false;

diff --git a/clang/test/Driver/fsanitize.c b/clang/test/Driver/fsanitize.c
index c5a8e11..e8651d5 100644 (file)
--- a/clang/test/Driver/fsanitize.c
+++ b/clang/test/Driver/fsanitize.c
@@ -121,7 +121,7 @@
 // CHECK-USE-AFTER-SCOPE-BOTH-OFF-NOT: -cc1{{.*}}address-use-after-scope
 
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=address %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-WITHOUT-USE-AFTER-SCOPE
-// CHECK-ASAN-WITHOUT-USE-AFTER-SCOPE-NOT: -cc1{{.*}}address-use-after-scope
+// CHECK-ASAN-WITHOUT-USE-AFTER-SCOPE: -cc1{{.*}}address-use-after-scope
 
 // RUN: %clang -target x86_64-linux-gnu -fsanitize-memory-track-origins -pie %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ONLY-TRACK-ORIGINS
 // CHECK-ONLY-TRACK-ORIGINS: warning: argument unused during compilation: '-fsanitize-memory-track-origins'