[msan] Do not insert check on volatile store.

Volatile bitfields can cause valid stores of uninitialized bits.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173153 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 618a6f0be472fae592e86567ae7e53be4a0cafbc..8bb8115012ae642eea03b3153fac3375a1f45665 100644 (file)
--- a/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/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);
   }

diff --git a/test/Instrumentation/MemorySanitizer/msan_basic.ll b/test/Instrumentation/MemorySanitizer/msan_basic.ll
index 641a3a26f4eb04c8e1c780b74ad58b9bd8513d7e..a3caa809bdce488d21df7265ed48d366abc424b9 100644 (file)
--- a/test/Instrumentation/MemorySanitizer/msan_basic.ll
+++ b/test/Instrumentation/MemorySanitizer/msan_basic.ll
@@ -563,3 +563,17 @@ define void @VACopy(i8* %p1, i8* %p2) nounwind uwtable {
 ; CHECK: @VACopy
 ; CHECK: call void @llvm.memset.p0i8.i64({{.*}}, i8 0, i64 24, i32 8, i1 false)
 ; CHECK: ret void
+
+
+; Test handling of volatile stores.
+; Check that MemorySanitizer does not add a check of the value being stored.
+
+define void @VolatileStore(i32* nocapture %p, i32 %x) nounwind uwtable {
+entry:
+  store volatile i32 %x, i32* %p, align 4
+  ret void
+}
+
+; CHECK: @VolatileStore
+; CHECK-NOT: @__msan_warning
+; CHECK: ret void