InstCombineCalls: fix annotateAnyAllocCallSite to report changes

[durin42]

Summary

Spotted during review of D123052.

[nikic]

LGTM

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

static IntrinsicInst *findInitTrampoline(Value *Callee) {
 
   if (IntrinsicInst *IT = findInitTrampolineFromAlloca(TrampMem))
     return IT;
   if (IntrinsicInst *IT = findInitTrampolineFromBB(AdjustTramp, TrampMem))
     return IT;
   return nullptr;
 }
 
-void InstCombinerImpl::annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI) {
+bool InstCombinerImpl::annotateAnyAllocSite(CallBase &Call,
+                                            const TargetLibraryInfo *TLI) {
   // Note: We only handle cases which can't be driven from generic attributes
   // here.  So, for example, nonnull and noalias (which are common properties
   // of some allocation functions) are expected to be handled via annotation
   // of the respective allocator declaration with generic attributes.
+  bool Changed = false;
 
   if (isAllocationFn(&Call, TLI)) {
     uint64_t Size;
     ObjectSizeOpts Opts;
     if (getObjectSize(&Call, Size, DL, TLI, Opts) && Size > 0) {
       // TODO: We really should just emit deref_or_null here and then
       // let the generic inference code combine that with nonnull.
-      if (Call.hasRetAttr(Attribute::NonNull))
+      if (Call.hasRetAttr(Attribute::NonNull)) {
+        Changed = !Call.hasRetAttr(Attribute::Dereferenceable);
         Call.addRetAttr(
             Attribute::getWithDereferenceableBytes(Call.getContext(), Size));
-      else
+      } else {
+        Changed = !Call.hasRetAttr(Attribute::DereferenceableOrNull);
         Call.addRetAttr(Attribute::getWithDereferenceableOrNullBytes(
             Call.getContext(), Size));
       }
     }
+  }
 
   // Add alignment attribute if alignment is a power of two constant.
   Value *Alignment = getAllocAlignment(&Call, TLI);
   if (!Alignment)
-    return;
+    return Changed;
 
   ConstantInt *AlignOpC = dyn_cast<ConstantInt>(Alignment);
   if (AlignOpC && AlignOpC->getValue().ult(llvm::Value::MaximumAlignment)) {
     uint64_t AlignmentVal = AlignOpC->getZExtValue();
     if (llvm::isPowerOf2_64(AlignmentVal)) {
       Align ExistingAlign = Call.getRetAlign().valueOrOne();
       Align NewAlign = Align(AlignmentVal);
       if (NewAlign > ExistingAlign) {
         Call.addRetAttr(
             Attribute::getWithAlignment(Call.getContext(), NewAlign));
+        Changed = true;
       }
     }
   }
+  return Changed;
 }
 
 /// Improvements for call, callbr and invoke instructions.
 Instruction *InstCombinerImpl::visitCallBase(CallBase &Call) {
-  annotateAnyAllocSite(Call, &TLI);
-
-  bool Changed = false;
+  bool Changed = annotateAnyAllocSite(Call, &TLI);
 
   // Mark any parameters that are known to be non-null with the nonnull
   // attribute.  This is helpful for inlining calls to functions with null
   // checks on their arguments.
   SmallVector<unsigned, 4> ArgNos;
   unsigned ArgNo = 0;
 
   for (Value *V : Call.args()) {

llvm/lib/Transforms/InstCombine/InstCombineInternal.h

public:
   /// Try to replace select with select operand SIOpd in SI-ICmp sequence.
   bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp,
                                  const unsigned SIOpd);
 
   LoadInst *combineLoadToNewType(LoadInst &LI, Type *NewTy,
                                  const Twine &Suffix = "");
 
 private:
-  void annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI);
+  bool annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI);
   bool isDesirableIntType(unsigned BitWidth) const;
   bool shouldChangeType(unsigned FromBitWidth, unsigned ToBitWidth) const;
   bool shouldChangeType(Type *From, Type *To) const;
   Value *dyn_castNegVal(Value *V) const;
 
   /// Classify whether a cast is worth optimizing.
   ///
   /// This is a helper to decide whether the simplification of