General definition for weak functions

In this diff, I define a general macro for defining weak functions
with a default implementation: "SANITIZER_INTERFACE_WEAK_DEF()".
This way, we simplify the implementation for different platforms.

For example, we cannot define weak functions on Windows, but we can
use linker pragmas to create an alias to a default implementation.
All of these implementation details are hidden in the new macro.

Also, as I modify the name for exported weak symbols on Windows, I
needed to temporarily disable "dll_host" test for asan, which checks
the list of functions included in asan_win_dll_thunk.

Differential Revision: https://reviews.llvm.org/D28596

llvm-svn: 293419

1 files changed, 3 insertions, 4 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sancov_flags.cc b/compiler-rt/lib/sanitizer_common/sancov_flags.cc
index 08fd2a4366a..9abb5b5c598 100644
--- a/compiler-rt/lib/sanitizer_common/sancov_flags.cc
+++ b/compiler-rt/lib/sanitizer_common/sancov_flags.cc
@@ -15,10 +15,9 @@
 #include "sanitizer_flag_parser.h"
 #include "sanitizer_platform.h"
 
-#if !SANITIZER_LINUX
-// other platforms do not have weak symbols out of the box.
-extern "C" const char* __sancov_default_options() { return ""; }
-#endif
+SANITIZER_INTERFACE_WEAK_DEF(const char*, __sancov_default_options, void) {
+  return "";
+}
 
 using namespace __sanitizer;