[msan] Do not insert check on volatile store.

Volatile bitfields can cause valid stores of uninitialized bits.

llvm-svn: 173153

1 files changed, 1 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 618a6f0be47..8bb8115012a 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -451,9 +451,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
         IRB.CreateAlignedStore(Shadow, ShadowPtr, I.getAlignment());
       DEBUG(dbgs() << "  STORE: " << *NewSI << "\n");
       (void)NewSI;
-      // If the store is volatile, add a check.
-      if (I.isVolatile())
-        insertCheck(Val, &I);
+
       if (ClCheckAccessAddress)
         insertCheck(Addr, &I);
 
@@ -847,7 +845,6 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
   ///
   /// Stores the corresponding shadow and (optionally) origin.
   /// Optionally, checks that the store address is fully defined.
-  /// Volatile stores check that the value being stored is fully defined.
   void visitStoreInst(StoreInst &I) {
     StoreList.push_back(&I);
   }