[AMDGPU] Return better Changed status from AMDGPUAnnotateUniformValues

[piotr]

LGTM

llvm/lib/Target/AMDGPU/AMDGPUAnnotateUniformValues.cpp

 namespace {
 
 class AMDGPUAnnotateUniformValues : public FunctionPass,
                        public InstVisitor<AMDGPUAnnotateUniformValues> {
   LegacyDivergenceAnalysis *DA;
   MemorySSA *MSSA;
   AliasAnalysis *AA;
   bool isEntryFunc;
+  bool Changed;
+
+  void setUniformMetadata(Instruction *I) {
+    I->setMetadata("amdgpu.uniform", MDNode::get(I->getContext(), {}));
+    Changed = true;
+  }
+
+  void setNoClobberMetadata(Instruction *I) {
+    I->setMetadata("amdgpu.noclobber", MDNode::get(I->getContext(), {}));
+    Changed = true;
+  }
 
 public:
   static char ID;
   AMDGPUAnnotateUniformValues() :
     FunctionPass(ID) { }
   bool doInitialization(Module &M) override;
   bool runOnFunction(Function &F) override;
   StringRef getPassName() const override {

 INITIALIZE_PASS_DEPENDENCY(LegacyDivergenceAnalysis)
 INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 INITIALIZE_PASS_END(AMDGPUAnnotateUniformValues, DEBUG_TYPE,
                     "Add AMDGPU uniform metadata", false, false)
 
 char AMDGPUAnnotateUniformValues::ID = 0;
 
-static void setUniformMetadata(Instruction *I) {
-  I->setMetadata("amdgpu.uniform", MDNode::get(I->getContext(), {}));
-}
-static void setNoClobberMetadata(Instruction *I) {
-  I->setMetadata("amdgpu.noclobber", MDNode::get(I->getContext(), {}));
-}
-
 void AMDGPUAnnotateUniformValues::visitBranchInst(BranchInst &I) {
   if (DA->isUniform(&I))
     setUniformMetadata(&I);
 }
 
 void AMDGPUAnnotateUniformValues::visitLoadInst(LoadInst &I) {
   Value *Ptr = I.getPointerOperand();
   if (!DA->isUniform(Ptr))
bool AMDGPUAnnotateUniformValues::runOnFunction(Function &F) {
   if (skipFunction(F))
     return false;
 
   DA = &getAnalysis<LegacyDivergenceAnalysis>();
   MSSA = &getAnalysis<MemorySSAWrapperPass>().getMSSA();
   AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
   isEntryFunc = AMDGPU::isEntryFunctionCC(F.getCallingConv());
 
+  Changed = false;
   visit(F);
-  return true;
+  return Changed;
 }
 
 FunctionPass *
 llvm::createAMDGPUAnnotateUniformValues() {
   return new AMDGPUAnnotateUniformValues();
 }