C++ (Cpp) ICmpInst::setOperand Examples

Example #1

File: LowerExpectIntrinsic.cpp Project: QuentinFiard/llvm

bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) {
  if (BI->isUnconditional())
    return false;

  // Handle non-optimized IR code like:
  //   %expval = call i64 @llvm.expect.i64(i64 %conv1, i64 1)
  //   %tobool = icmp ne i64 %expval, 0
  //   br i1 %tobool, label %if.then, label %if.end
  //
  // Or the following simpler case:
  //   %expval = call i1 @llvm.expect.i1(i1 %cmp, i1 1)
  //   br i1 %expval, label %if.then, label %if.end

  CallInst *CI;

  ICmpInst *CmpI = dyn_cast<ICmpInst>(BI->getCondition());
  if (!CmpI) {
    CI = dyn_cast<CallInst>(BI->getCondition());
  } else {
    if (CmpI->getPredicate() != CmpInst::ICMP_NE)
      return false;
    CI = dyn_cast<CallInst>(CmpI->getOperand(0));
  }

  if (!CI)
    return false;

  Function *Fn = CI->getCalledFunction();
  if (!Fn || Fn->getIntrinsicID() != Intrinsic::expect)
    return false;

  Value *ArgValue = CI->getArgOperand(0);
  ConstantInt *ExpectedValue = dyn_cast<ConstantInt>(CI->getArgOperand(1));
  if (!ExpectedValue)
    return false;

  MDBuilder MDB(CI->getContext());
  MDNode *Node;

  // If expect value is equal to 1 it means that we are more likely to take
  // branch 0, in other case more likely is branch 1.
  if (ExpectedValue->isOne())
    Node = MDB.createBranchWeights(LikelyBranchWeight, UnlikelyBranchWeight);
  else
    Node = MDB.createBranchWeights(UnlikelyBranchWeight, LikelyBranchWeight);

  BI->setMetadata(LLVMContext::MD_prof, Node);

  if (CmpI)
    CmpI->setOperand(0, ArgValue);
  else
    BI->setCondition(ArgValue);
  return true;
}

Example #2

bool LowerExpectIntrinsic::HandleIfExpect(BranchInst *BI) {
  if (BI->isUnconditional())
    return false;

  // Handle non-optimized IR code like:
  //   %expval = call i64 @llvm.expect.i64.i64(i64 %conv1, i64 1)
  //   %tobool = icmp ne i64 %expval, 0
  //   br i1 %tobool, label %if.then, label %if.end

  ICmpInst *CmpI = dyn_cast<ICmpInst>(BI->getCondition());
  if (!CmpI || CmpI->getPredicate() != CmpInst::ICMP_NE)
    return false;

  CallInst *CI = dyn_cast<CallInst>(CmpI->getOperand(0));
  if (!CI)
    return false;

  Function *Fn = CI->getCalledFunction();
  if (!Fn || Fn->getIntrinsicID() != Intrinsic::expect)
    return false;

  Value *ArgValue = CI->getArgOperand(0);
  ConstantInt *ExpectedValue = dyn_cast<ConstantInt>(CI->getArgOperand(1));
  if (!ExpectedValue)
    return false;

  LLVMContext &Context = CI->getContext();
  const Type *Int32Ty = Type::getInt32Ty(Context);
  bool Likely = ExpectedValue->isOne();

  // If expect value is equal to 1 it means that we are more likely to take
  // branch 0, in other case more likely is branch 1.
  Value *Ops[] = {
    MDString::get(Context, "branch_weights"),
    ConstantInt::get(Int32Ty, Likely ? LikelyBranchWeight : UnlikelyBranchWeight),
    ConstantInt::get(Int32Ty, Likely ? UnlikelyBranchWeight : LikelyBranchWeight)
  };

  MDNode *WeightsNode = MDNode::get(Context, Ops);
  BI->setMetadata(LLVMContext::MD_prof, WeightsNode);

  CmpI->setOperand(0, ArgValue);
  return true;
}