[MSan] fix the types of RegSaveAreaPtrPtr and OverflowArgAreaPtrPtr

[glider]

Summary

Despite their names, RegSaveAreaPtrPtr and OverflowArgAreaPtrPtr used to be i8* instead of i8**.
This is important, because these pointers are dereferenced twice (first in CreateLoad(), then in getShadowOriginPtr()), but for some reason MSan allowed this - most certainly because it was possible to optimize getShadowOriginPtr() away at compile time.

llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp

void finalizeInstrumentation() override {
     for (size_t i = 0, n = VAStartInstrumentationList.size(); i < n; i++) {
       CallInst *OrigInst = VAStartInstrumentationList[i];
       IRBuilder<> IRB(OrigInst->getNextNode());
       Value *VAListTag = OrigInst->getArgOperand(0);
 
       Value *RegSaveAreaPtrPtr = IRB.CreateIntToPtr(
           IRB.CreateAdd(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy),
                         ConstantInt::get(MS.IntptrTy, 16)),
-          Type::getInt64PtrTy(*MS.C));
+          PointerType::get(Type::getInt64PtrTy(*MS.C), 0));
       Value *RegSaveAreaPtr = IRB.CreateLoad(RegSaveAreaPtrPtr);
       Value *RegSaveAreaShadowPtr, *RegSaveAreaOriginPtr;
       unsigned Alignment = 16;
       std::tie(RegSaveAreaShadowPtr, RegSaveAreaOriginPtr) =
           MSV.getShadowOriginPtr(RegSaveAreaPtr, IRB, IRB.getInt8Ty(),
                                  Alignment);
       IRB.CreateMemCpy(RegSaveAreaShadowPtr, Alignment, VAArgTLSCopy, Alignment,
                        AMD64FpEndOffset);
       Value *OverflowArgAreaPtrPtr = IRB.CreateIntToPtr(
           IRB.CreateAdd(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy),
                         ConstantInt::get(MS.IntptrTy, 8)),
-          Type::getInt64PtrTy(*MS.C));
+          PointerType::get(Type::getInt64PtrTy(*MS.C), 0));
       Value *OverflowArgAreaPtr = IRB.CreateLoad(OverflowArgAreaPtrPtr);
       Value *OverflowArgAreaShadowPtr, *OverflowArgAreaOriginPtr;
       std::tie(OverflowArgAreaShadowPtr, OverflowArgAreaOriginPtr) =
           MSV.getShadowOriginPtr(OverflowArgAreaPtr, IRB, IRB.getInt8Ty(),
                                  Alignment);
       Value *SrcPtr = IRB.CreateConstGEP1_32(IRB.getInt8Ty(), VAArgTLSCopy,
                                              AMD64FpEndOffset);
       IRB.CreateMemCpy(OverflowArgAreaShadowPtr, Alignment, SrcPtr, Alignment,
void finalizeInstrumentation() override {
 
     // Instrument va_start.
     // Copy va_list shadow from the backup copy of the TLS contents.
     for (size_t i = 0, n = VAStartInstrumentationList.size(); i < n; i++) {
       CallInst *OrigInst = VAStartInstrumentationList[i];
       IRBuilder<> IRB(OrigInst->getNextNode());
       Value *VAListTag = OrigInst->getArgOperand(0);
       Value *RegSaveAreaPtrPtr =
           IRB.CreateIntToPtr(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy),
-                        Type::getInt64PtrTy(*MS.C));
+                             PointerType::get(Type::getInt64PtrTy(*MS.C), 0));
       Value *RegSaveAreaPtr = IRB.CreateLoad(RegSaveAreaPtrPtr);
       Value *RegSaveAreaShadowPtr, *RegSaveAreaOriginPtr;
       unsigned Alignment = 8;
       std::tie(RegSaveAreaShadowPtr, RegSaveAreaOriginPtr) =
           MSV.getShadowOriginPtr(RegSaveAreaPtr, IRB, IRB.getInt8Ty(),
                                  Alignment);
       IRB.CreateMemCpy(RegSaveAreaShadowPtr, Alignment, VAArgTLSCopy, Alignment,
                        CopySize);
void finalizeInstrumentation() override {
 
     // Instrument va_start.
     // Copy va_list shadow from the backup copy of the TLS contents.
     for (size_t i = 0, n = VAStartInstrumentationList.size(); i < n; i++) {
       CallInst *OrigInst = VAStartInstrumentationList[i];
       IRBuilder<> IRB(OrigInst->getNextNode());
       Value *VAListTag = OrigInst->getArgOperand(0);
       Value *RegSaveAreaPtrPtr =
           IRB.CreateIntToPtr(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy),
-                        Type::getInt64PtrTy(*MS.C));
+                             PointerType::get(Type::getInt64PtrTy(*MS.C), 0));
       Value *RegSaveAreaPtr = IRB.CreateLoad(RegSaveAreaPtrPtr);
       Value *RegSaveAreaShadowPtr, *RegSaveAreaOriginPtr;
       unsigned Alignment = 8;
       std::tie(RegSaveAreaShadowPtr, RegSaveAreaOriginPtr) =
           MSV.getShadowOriginPtr(RegSaveAreaPtr, IRB, IRB.getInt8Ty(),
                                  Alignment);
       IRB.CreateMemCpy(RegSaveAreaShadowPtr, Alignment, VAArgTLSCopy, Alignment,
                        CopySize);