Returns InstructionCost for getBranchMispredictPenalty().

Author: tianqingw

llvm/include/llvm/Analysis/TargetTransformInfo.h

@@ -419,10 +419,11 @@ class TargetTransformInfo {
   /// this factor, it is very likely to be predicted correctly.
   BranchProbability getPredictableBranchThreshold() const;
 
-  // Returns an integer indicating how aggressive the target wants for
-  // eliminating unpredictable branches. A zero return value means extra
-  // optimization applied to them should be minimal.
-  unsigned getBranchMispredictPenalty() const;
+  /// Returns estimated penalty of a branch misprediction in latency. Indicates
+  /// how aggressive the target wants for eliminating unpredictable branches. A
+  /// zero return value means extra optimization applied to them should be
+  /// minimal.
+  InstructionCost getBranchMispredictPenalty() const;
 
   /// Return true if branch divergence exists.
   ///
@@ -1837,7 +1838,7 @@ class TargetTransformInfo::Concept {
                                              ArrayRef<const Value *> Operands,
                                              TargetCostKind CostKind) = 0;
   virtual BranchProbability getPredictableBranchThreshold() = 0;
-  virtual unsigned getBranchMispredictPenalty() = 0;
+  virtual InstructionCost getBranchMispredictPenalty() = 0;
   virtual bool hasBranchDivergence(const Function *F = nullptr) = 0;
   virtual bool isSourceOfDivergence(const Value *V) = 0;
   virtual bool isAlwaysUniform(const Value *V) = 0;
@@ -2249,7 +2250,7 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
   BranchProbability getPredictableBranchThreshold() override {
     return Impl.getPredictableBranchThreshold();
   }
-  unsigned getBranchMispredictPenalty() override {
+  InstructionCost getBranchMispredictPenalty() override {
     return Impl.getBranchMispredictPenalty();
   }
   bool hasBranchDivergence(const Function *F = nullptr) override {

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -99,7 +99,7 @@ class TargetTransformInfoImplBase {
     return BranchProbability(99, 100);
   }
 
-  unsigned getBranchMispredictPenalty() const { return 0; }
+  InstructionCost getBranchMispredictPenalty() const { return 0; }
 
   bool hasBranchDivergence(const Function *F = nullptr) const { return false; }
 

llvm/lib/Analysis/TargetTransformInfo.cpp

@@ -279,7 +279,7 @@ BranchProbability TargetTransformInfo::getPredictableBranchThreshold() const {
              : TTIImpl->getPredictableBranchThreshold();
 }
 
-unsigned TargetTransformInfo::getBranchMispredictPenalty() const {
+InstructionCost TargetTransformInfo::getBranchMispredictPenalty() const {
   return TTIImpl->getBranchMispredictPenalty();
 }
 

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

@@ -6757,7 +6757,7 @@ InstructionCost X86TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
   return -1;
 }
 
-unsigned X86TTIImpl::getBranchMispredictPenalty() const {
+InstructionCost X86TTIImpl::getBranchMispredictPenalty() const {
   // TODO: Hook MispredictPenalty of SchedMachineModel into this.
   return 14;
 }

llvm/lib/Target/X86/X86TargetTransformInfo.h

@@ -294,7 +294,7 @@ class X86TTIImpl : public BasicTTIImplBase<X86TTIImpl> {
   bool supportsEfficientVectorElementLoadStore() const;
   bool enableInterleavedAccessVectorization();
 
-  unsigned getBranchMispredictPenalty() const;
+  InstructionCost getBranchMispredictPenalty() const;
 
 private:
   bool supportsGather() const;

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -3550,10 +3550,9 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
   // that need to be moved to the dominating block.
   SmallPtrSet<Instruction *, 4> AggressiveInsts;
   InstructionCost Cost = 0;
-  unsigned Threshold = TwoEntryPHINodeFoldingThreshold;
+  InstructionCost Budget = TwoEntryPHINodeFoldingThreshold * TargetTransformInfo::TCC_Basic;
   if (IsUnpredictable)
-    Threshold += TTI.getBranchMispredictPenalty();
-  InstructionCost Budget = Threshold * TargetTransformInfo::TCC_Basic;
+    Budget += TTI.getBranchMispredictPenalty();
 
   bool Changed = false;
   for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) {