C++ (Cpp) CallInst::copyFastMathFlags Examples

Example #1

File: IRBuilder.cpp Project: jamezhetianswang/llvm

static CallInst *createCallHelper(Value *Callee, ArrayRef<Value *> Ops,
                                  IRBuilderBase *Builder,
                                  const Twine &Name = "",
                                  Instruction *FMFSource = nullptr) {
  CallInst *CI = CallInst::Create(Callee, Ops, Name);
  if (FMFSource)
    CI->copyFastMathFlags(FMFSource);
  Builder->GetInsertBlock()->getInstList().insert(Builder->GetInsertPoint(),CI);
  Builder->SetInstDebugLocation(CI);
  return CI;  
}

Example #2

File: AMDGPUCodeGenPrepare.cpp Project: bkaradzic/SwiftShader

// The fractional part of a float is enough to accurately represent up to
// a 24-bit signed integer.
Value* AMDGPUCodeGenPrepare::expandDivRem24(IRBuilder<> &Builder,
                                            BinaryOperator &I,
                                            Value *Num, Value *Den,
                                            bool IsDiv, bool IsSigned) const {
  assert(Num->getType()->isIntegerTy(32));

  const DataLayout &DL = Mod->getDataLayout();
  unsigned LHSSignBits = ComputeNumSignBits(Num, DL, 0, AC, &I);
  if (LHSSignBits < 9)
    return nullptr;

  unsigned RHSSignBits = ComputeNumSignBits(Den, DL, 0, AC, &I);
  if (RHSSignBits < 9)
    return nullptr;


  unsigned SignBits = std::min(LHSSignBits, RHSSignBits);
  unsigned DivBits = 32 - SignBits;
  if (IsSigned)
    ++DivBits;

  Type *Ty = Num->getType();
  Type *I32Ty = Builder.getInt32Ty();
  Type *F32Ty = Builder.getFloatTy();
  ConstantInt *One = Builder.getInt32(1);
  Value *JQ = One;

  if (IsSigned) {
    // char|short jq = ia ^ ib;
    JQ = Builder.CreateXor(Num, Den);

    // jq = jq >> (bitsize - 2)
    JQ = Builder.CreateAShr(JQ, Builder.getInt32(30));

    // jq = jq | 0x1
    JQ = Builder.CreateOr(JQ, One);
  }

  // int ia = (int)LHS;
  Value *IA = Num;

  // int ib, (int)RHS;
  Value *IB = Den;

  // float fa = (float)ia;
  Value *FA = IsSigned ? Builder.CreateSIToFP(IA, F32Ty)
                       : Builder.CreateUIToFP(IA, F32Ty);

  // float fb = (float)ib;
  Value *FB = IsSigned ? Builder.CreateSIToFP(IB,F32Ty)
                       : Builder.CreateUIToFP(IB,F32Ty);

  Value *RCP = Builder.CreateFDiv(ConstantFP::get(F32Ty, 1.0), FB);
  Value *FQM = Builder.CreateFMul(FA, RCP);

  // fq = trunc(fqm);
  CallInst* FQ = Builder.CreateIntrinsic(Intrinsic::trunc, { FQM });
  FQ->copyFastMathFlags(Builder.getFastMathFlags());

  // float fqneg = -fq;
  Value *FQNeg = Builder.CreateFNeg(FQ);

  // float fr = mad(fqneg, fb, fa);
  Value *FR = Builder.CreateIntrinsic(Intrinsic::amdgcn_fmad_ftz,
                                      { FQNeg, FB, FA }, FQ);

  // int iq = (int)fq;
  Value *IQ = IsSigned ? Builder.CreateFPToSI(FQ, I32Ty)
                       : Builder.CreateFPToUI(FQ, I32Ty);

  // fr = fabs(fr);
  FR = Builder.CreateIntrinsic(Intrinsic::fabs, { FR }, FQ);

  // fb = fabs(fb);
  FB = Builder.CreateIntrinsic(Intrinsic::fabs, { FB }, FQ);

  // int cv = fr >= fb;
  Value *CV = Builder.CreateFCmpOGE(FR, FB);

  // jq = (cv ? jq : 0);
  JQ = Builder.CreateSelect(CV, JQ, Builder.getInt32(0));

  // dst = iq + jq;
  Value *Div = Builder.CreateAdd(IQ, JQ);

  Value *Res = Div;
  if (!IsDiv) {
    // Rem needs compensation, it's easier to recompute it
    Value *Rem = Builder.CreateMul(Div, Den);
    Res = Builder.CreateSub(Num, Rem);
  }

  // Truncate to number of bits this divide really is.
  if (IsSigned) {
    Res = Builder.CreateTrunc(Res, Builder.getIntNTy(DivBits));
    Res = Builder.CreateSExt(Res, Ty);
  } else {
    ConstantInt *TruncMask = Builder.getInt32((UINT64_C(1) << DivBits) - 1);
    Res = Builder.CreateAnd(Res, TruncMask);
  }

  return Res;
}