MDNode *MDNode::getMostGenericFPMath(MDNode *A, MDNode *B) {
if (!A || !B)
return NULL;
APFloat AVal = cast<ConstantFP>(A->getOperand(0))->getValueAPF();
APFloat BVal = cast<ConstantFP>(B->getOperand(0))->getValueAPF();
if (AVal.compare(BVal) == APFloat::cmpLessThan)
return A;
return B;
}
// Walk forwards down the list of seen instructions, so we visit defs before
// uses.
void Float2IntPass::walkForwards() {
for (auto &It : reverse(SeenInsts)) {
if (It.second != unknownRange())
continue;
Instruction *I = It.first;
std::function<ConstantRange(ArrayRef<ConstantRange>)> Op;
switch (I->getOpcode()) {
// FIXME: Handle select and phi nodes.
default:
case Instruction::UIToFP:
case Instruction::SIToFP:
llvm_unreachable("Should have been handled in walkForwards!");
case Instruction::FAdd:
case Instruction::FSub:
case Instruction::FMul:
Op = [I](ArrayRef<ConstantRange> Ops) {
assert(Ops.size() == 2 && "its a binary operator!");
auto BinOp = (Instruction::BinaryOps) I->getOpcode();
return Ops[0].binaryOp(BinOp, Ops[1]);
};
break;
//
// Root-only instructions - we'll only see these if they're the
// first node in a walk.
//
case Instruction::FPToUI:
case Instruction::FPToSI:
Op = [I](ArrayRef<ConstantRange> Ops) {
assert(Ops.size() == 1 && "FPTo[US]I is a unary operator!");
// Note: We're ignoring the casts output size here as that's what the
// caller expects.
auto CastOp = (Instruction::CastOps)I->getOpcode();
return Ops[0].castOp(CastOp, MaxIntegerBW+1);
};
break;
case Instruction::FCmp:
Op = [](ArrayRef<ConstantRange> Ops) {
assert(Ops.size() == 2 && "FCmp is a binary operator!");
return Ops[0].unionWith(Ops[1]);
};
break;
}
bool Abort = false;
SmallVector<ConstantRange,4> OpRanges;
for (Value *O : I->operands()) {
if (Instruction *OI = dyn_cast<Instruction>(O)) {
assert(SeenInsts.find(OI) != SeenInsts.end() &&
"def not seen before use!");
OpRanges.push_back(SeenInsts.find(OI)->second);
} else if (ConstantFP *CF = dyn_cast<ConstantFP>(O)) {
// Work out if the floating point number can be losslessly represented
// as an integer.
// APFloat::convertToInteger(&Exact) purports to do what we want, but
// the exactness can be too precise. For example, negative zero can
// never be exactly converted to an integer.
//
// Instead, we ask APFloat to round itself to an integral value - this
// preserves sign-of-zero - then compare the result with the original.
//
const APFloat &F = CF->getValueAPF();
// First, weed out obviously incorrect values. Non-finite numbers
// can't be represented and neither can negative zero, unless
// we're in fast math mode.
if (!F.isFinite() ||
(F.isZero() && F.isNegative() && isa<FPMathOperator>(I) &&
!I->hasNoSignedZeros())) {
seen(I, badRange());
Abort = true;
break;
}
APFloat NewF = F;
auto Res = NewF.roundToIntegral(APFloat::rmNearestTiesToEven);
if (Res != APFloat::opOK || NewF.compare(F) != APFloat::cmpEqual) {
seen(I, badRange());
Abort = true;
break;
}
// OK, it's representable. Now get it.
APSInt Int(MaxIntegerBW+1, false);
bool Exact;
CF->getValueAPF().convertToInteger(Int,
APFloat::rmNearestTiesToEven,
&Exact);
OpRanges.push_back(ConstantRange(Int));
} else {
llvm_unreachable("Should have already marked this as badRange!");
}
}
// Reduce the operands' ranges to a single range and return.
if (!Abort)
seen(I, Op(OpRanges));
}
}