[ASan] Make ASan instrument variable-masked loads and stores

[filcab]

Summary

Previously we only supported constant-masked loads and stores.

[filcab]

I just noticed I forgot to include the tests changes.
I will add these soon, but feel free to start reviewing the code :-) (or wait)

[vitalybuka]

LGTM with tests

[filcab]

Added tests.

[RKSimon]

LGTM

lib/Transforms/Instrumentation/AddressSanitizer.cpp

Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
                                    uint64_t *TypeSize, unsigned *Alignment,
                                    Value **MaybeMask = nullptr);
   void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
                      bool UseCalls, const DataLayout &DL);
   void instrumentPointerComparisonOrSubtraction(Instruction *I);
   void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
                          Value *Addr, uint32_t TypeSize, bool IsWrite,
                          Value *SizeArgument, bool UseCalls, uint32_t Exp);
-  void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
+  void instrumentUnusualSizeOrAlignment(Instruction *I,
+                                        Instruction *InsertBefore, Value *Addr,
                                         uint32_t TypeSize, bool IsWrite,
                                         Value *SizeArgument, bool UseCalls,
                                         uint32_t Exp);
   Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
                            Value *ShadowValue, uint32_t TypeSize);
   Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
                                  bool IsWrite, size_t AccessSizeIndex,
                                  Value *SizeArgument, uint32_t Exp);
if (F && (F->getName().startswith("llvm.masked.load.") ||
         // Masked store has an initial operand for the value.
         OpOffset = 1;
         *IsWrite = true;
       } else {
         if (!ClInstrumentReads)
           return nullptr;
         *IsWrite = false;
       }
-      // Only instrument if the mask is constant for now.
-      if (isa<ConstantVector>(CI->getOperand(2 + OpOffset))) {
-        auto BasePtr = CI->getOperand(0 + OpOffset);
-        auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
-        *TypeSize = DL.getTypeStoreSizeInBits(Ty);
-        if (auto AlignmentConstant =
-                dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
-          *Alignment = (unsigned)AlignmentConstant->getZExtValue();
-        else
-          *Alignment = 1; // No alignment guarantees. We probably got Undef
-        if (MaybeMask)
-          *MaybeMask = CI->getOperand(2 + OpOffset);
-        PtrOperand = BasePtr;
-      }
-    }
-  }
+
 
   // Do not instrument acesses from different address spaces; we cannot deal
   // with them.
   if (PtrOperand) {
     Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
     if (PtrTy->getPointerAddressSpace() != 0)
       return nullptr;
   }
void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
   for (Value *&i : Param) {
     if (i->getType()->isPointerTy())
       i = IRB.CreatePointerCast(i, IntptrTy);
   }
   IRB.CreateCall(F, Param);
 }
 
 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
-                                Value *Addr, unsigned Alignment,
-                                unsigned Granularity, uint32_t TypeSize,
-                                bool IsWrite, Value *SizeArgument,
-                                bool UseCalls, uint32_t Exp) {
+                                Instruction *InsertBefore, Value *Addr,
+                                unsigned Alignment, unsigned Granularity,
+                                uint32_t TypeSize, bool IsWrite,
+                                Value *SizeArgument, bool UseCalls,
+                                uint32_t Exp) {
   // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
   // if the data is properly aligned.
   if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
        TypeSize == 128) &&
       (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
-    return Pass->instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr,
-                                   UseCalls, Exp);
-  Pass->instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
-                                         UseCalls, Exp);
+    return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
+                                   nullptr, UseCalls, Exp);
+  Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
+                                         IsWrite, nullptr, UseCalls, Exp);
 }
 
 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
                                         const DataLayout &DL, Type *IntptrTy,
-                                        ConstantVector *Mask, Instruction *I,
+                                        Value *Mask, Instruction *I,
                                         Value *Addr, unsigned Alignment,
                                         unsigned Granularity, uint32_t TypeSize,
                                         bool IsWrite, Value *SizeArgument,
                                         bool UseCalls, uint32_t Exp) {
   auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
   uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
   unsigned Num = VTy->getVectorNumElements();
   auto Zero = ConstantInt::get(IntptrTy, 0);
   for (unsigned Idx = 0; Idx < Num; ++Idx) {
+    Value *InstrumentedAddress = nullptr;
+    Instruction *InsertBefore = I;
+    if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
       // dyn_cast as we might get UndefValue
-    auto Masked = dyn_cast<ConstantInt>(Mask->getOperand(Idx));
-    if (Masked && Masked->isAllOnesValue()) {
+      if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
+        if (Masked->isNullValue())
+          // Mask is constant false, so no instrumentation needed.
+          continue;
+        // If we have a true or undef value, fall through to doInstrumentAddress
+        // with InsertBefore == I
+      }
+    } else {
       IRBuilder<> IRB(I);
-      auto InstrumentedAddress =
-          IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
-      doInstrumentAddress(Pass, I, InstrumentedAddress, Alignment, Granularity,
-                          ElemTypeSize, IsWrite, SizeArgument, UseCalls, Exp);
+      Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
+      TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
+      InsertBefore = ThenTerm;
     }
+
+    IRBuilder<> IRB(InsertBefore);
+    InstrumentedAddress =
+        IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
+    doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
+                        Granularity, ElemTypeSize, IsWrite, SizeArgument,
+                        UseCalls, Exp);
   }
 }
 
 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
                                      Instruction *I, bool UseCalls,
                                      const DataLayout &DL) {
   bool IsWrite = false;
   unsigned Alignment = 0;
void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
 
   if (IsWrite)
     NumInstrumentedWrites++;
   else
     NumInstrumentedReads++;
 
   unsigned Granularity = 1 << Mapping.Scale;
   if (MaybeMask) {
-    auto Mask = cast<ConstantVector>(MaybeMask);
-    instrumentMaskedLoadOrStore(this, DL, IntptrTy, Mask, I, Addr, Alignment,
-                                Granularity, TypeSize, IsWrite, nullptr,
-                                UseCalls, Exp);
+    instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
+                                Alignment, Granularity, TypeSize, IsWrite,
+                                nullptr, UseCalls, Exp);
   } else {
-    doInstrumentAddress(this, I, Addr, Alignment, Granularity, TypeSize,
+    doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
                         IsWrite, nullptr, UseCalls, Exp);
   }
 }
 
 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
                                                  Value *Addr, bool IsWrite,
                                                  size_t AccessSizeIndex,
                                                  Value *SizeArgument,
void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
   Crash->setDebugLoc(OrigIns->getDebugLoc());
 }
 
 // Instrument unusual size or unusual alignment.
 // We can not do it with a single check, so we do 1-byte check for the first
 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
 // to report the actual access size.
 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
-    Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
-    Value *SizeArgument, bool UseCalls, uint32_t Exp) {
-  IRBuilder<> IRB(I);
+    Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
+    bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
+  IRBuilder<> IRB(InsertBefore);
   Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
   Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
   if (UseCalls) {
     if (Exp == 0)
       IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
                      {AddrLong, Size});
     else
       IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
                      {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
   } else {
     Value *LastByte = IRB.CreateIntToPtr(
         IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
         Addr->getType());
-    instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
-    instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
+    instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
+    instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
   }
 }
 
 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
                                                   GlobalValue *ModuleName) {
   // Set up the arguments to our poison/unpoison functions.
   IRBuilder<> IRB(&GlobalInit.front(),
                   GlobalInit.front().getFirstInsertionPt());