/// foldFMulConst() is a helper routine of InstCombiner::visitFMul().
/// The input \p FMulOrDiv is a FMul/FDiv with one and only one operand
/// being a constant (i.e. isFMulOrFDivWithConstant(FMulOrDiv) == true).
/// This function is to simplify "FMulOrDiv * C" and returns the
/// resulting expression. Note that this function could return NULL in
/// case the constants cannot be folded into a normal floating-point.
///
Value *InstCombiner::foldFMulConst(Instruction *FMulOrDiv, Constant *C,
Instruction *InsertBefore) {
assert(isFMulOrFDivWithConstant(FMulOrDiv) && "V is invalid");
Value *Opnd0 = FMulOrDiv->getOperand(0);
Value *Opnd1 = FMulOrDiv->getOperand(1);
Constant *C0 = dyn_cast<Constant>(Opnd0);
Constant *C1 = dyn_cast<Constant>(Opnd1);
BinaryOperator *R = nullptr;
// (X * C0) * C => X * (C0*C)
if (FMulOrDiv->getOpcode() == Instruction::FMul) {
Constant *F = ConstantExpr::getFMul(C1 ? C1 : C0, C);
if (isNormalFp(F))
R = BinaryOperator::CreateFMul(C1 ? Opnd0 : Opnd1, F);
} else {
if (C0) {
// (C0 / X) * C => (C0 * C) / X
if (FMulOrDiv->hasOneUse()) {
// It would otherwise introduce another div.
Constant *F = ConstantExpr::getFMul(C0, C);
if (isNormalFp(F))
R = BinaryOperator::CreateFDiv(F, Opnd1);
}
} else {
// (X / C1) * C => X * (C/C1) if C/C1 is not a denormal
Constant *F = ConstantExpr::getFDiv(C, C1);
if (isNormalFp(F)) {
R = BinaryOperator::CreateFMul(Opnd0, F);
} else {
// (X / C1) * C => X / (C1/C)
Constant *F = ConstantExpr::getFDiv(C1, C);
if (isNormalFp(F))
R = BinaryOperator::CreateFDiv(Opnd0, F);
}
}
}
if (R) {
R->setHasUnsafeAlgebra(true);
InsertNewInstWith(R, *InsertBefore);
}
return R;
}
