[sancov] Don't instrument MSVC CRT stdio config helpers

They get called before initialization, which is a problem for winasan.

Test coming in compiler-rt.

llvm-svn: 286615

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index 93ca8668eaf..73881fa93ac 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -448,6 +448,11 @@ bool SanitizerCoverageModule::runOnFunction(Function &F) {
     return false; // Should not instrument sanitizer init functions.
   if (F.getName().startswith("__sanitizer_"))
     return false;  // Don't instrument __sanitizer_* callbacks.
+  // Don't instrument MSVC CRT configuration helpers. They may run before normal
+  // initialization.
+  if (F.getName() == "__local_stdio_printf_options" ||
+      F.getName() == "__local_stdio_scanf_options")
+    return false;
   // Don't instrument functions using SEH for now. Splitting basic blocks like
   // we do for coverage breaks WinEHPrepare.
   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.