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[AMDGPU] Common up some unsafe fexp lowering. NFC. #170841

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Merged
jayfoad merged 1 commit into from
Dec 8, 2025
Merged

[AMDGPU] Common up some unsafe fexp lowering. NFC. #170841

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21 changes: 7 additions & 14 deletions llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3072,14 +3072,14 @@ SDValue AMDGPUTargetLowering::lowerFEXP(SDValue Op, SelectionDAG &DAG) const {
SDNodeFlags Flags = Op->getFlags();
const bool IsExp10 = Op.getOpcode() == ISD::FEXP10;

if (VT.getScalarType() == MVT::f16) {
// v_exp_f16 (fmul x, log2e)

if (allowApproxFunc(DAG, Flags)) { // TODO: Does this really require fast?
return IsExp10 ? lowerFEXP10Unsafe(X, SL, DAG, Flags)
: lowerFEXPUnsafe(X, SL, DAG, Flags);
}
// TODO: Interpret allowApproxFunc as ignoring DAZ. This is currently copying
// library behavior. Also, is known-not-daz source sufficient?
if (allowApproxFunc(DAG, Flags)) { // TODO: Does this really require fast?
return IsExp10 ? lowerFEXP10Unsafe(X, SL, DAG, Flags)
: lowerFEXPUnsafe(X, SL, DAG, Flags);
}

if (VT.getScalarType() == MVT::f16) {
if (VT.isVector())
return SDValue();

Expand All @@ -3098,13 +3098,6 @@ SDValue AMDGPUTargetLowering::lowerFEXP(SDValue Op, SelectionDAG &DAG) const {

assert(VT == MVT::f32);

// TODO: Interpret allowApproxFunc as ignoring DAZ. This is currently copying
// library behavior. Also, is known-not-daz source sufficient?
if (allowApproxFunc(DAG, Flags)) {
return IsExp10 ? lowerFEXP10Unsafe(X, SL, DAG, Flags)
: lowerFEXPUnsafe(X, SL, DAG, Flags);
}

// Algorithm:
//
// e^x = 2^(x/ln(2)) = 2^(x*(64/ln(2))/64)
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