[msan] Check return value of main().

llvm-svn: 190782

1 files changed, 13 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 075a72f78b1..9a67cfc5a75 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -427,6 +427,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
   bool LoadShadow;
   bool PoisonStack;
   bool PoisonUndef;
+  bool CheckReturnValue;
   OwningPtr<VarArgHelper> VAHelper;
 
   struct ShadowOriginAndInsertPoint {
@@ -449,6 +450,9 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     LoadShadow = SanitizeFunction;
     PoisonStack = SanitizeFunction && ClPoisonStack;
     PoisonUndef = SanitizeFunction && ClPoisonUndef;
+    // FIXME: Consider using SpecialCaseList to specify a list of functions that
+    // must always return fully initialized values. For now, we hardcode "main".
+    CheckReturnValue = SanitizeFunction && (F.getName() == "main");
 
     DEBUG(if (!InsertChecks)
           dbgs() << "MemorySanitizer is not inserting checks into '"
@@ -1686,12 +1690,17 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
 
   void visitReturnInst(ReturnInst &I) {
     IRBuilder<> IRB(&I);
-    if (Value *RetVal = I.getReturnValue()) {
-      // Set the shadow for the RetVal.
+    Value *RetVal = I.getReturnValue();
+    if (!RetVal) return;
+    Value *ShadowPtr = getShadowPtrForRetval(RetVal, IRB);
+    if (CheckReturnValue) {
+      insertCheck(RetVal, &I);
+      Value *Shadow = getCleanShadow(RetVal);
+      IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment);
+    } else {
       Value *Shadow = getShadow(RetVal);
-      Value *ShadowPtr = getShadowPtrForRetval(RetVal, IRB);
-      DEBUG(dbgs() << "Return: " << *Shadow << "\n" << *ShadowPtr << "\n");
       IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment);
+      // FIXME: make it conditional if ClStoreCleanOrigin==0
       if (MS.TrackOrigins)
         IRB.CreateStore(getOrigin(RetVal), getOriginPtrForRetval(IRB));
     }