[asan] Turn -fsanitize-address-use-after-scope on by default [compiler-rt 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: 299175

1 files changed, 4 insertions, 0 deletions

diff --git a/compiler-rt/test/asan/TestCases/use-after-scope.cc b/compiler-rt/test/asan/TestCases/use-after-scope.cc
index d92dae6572c..4c5998abe20 100644
--- a/compiler-rt/test/asan/TestCases/use-after-scope.cc
+++ b/compiler-rt/test/asan/TestCases/use-after-scope.cc
@@ -1,6 +1,10 @@
 // RUN: %clangxx_asan -O1 -fsanitize-address-use-after-scope %s -o %t && \
 // RUN:     not %run %t 2>&1 | FileCheck %s
 
+// -fsanitize-address-use-after-scope is now on by default:
+// RUN: %clangxx_asan -O1 %s -o %t && \
+// RUN:     not %run %t 2>&1 | FileCheck %s
+
 volatile int *p = 0;
 
 int main() {