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X86: disable AVX512 truncate with saturation instructions

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These are not very useful in RPCS3.
However, pessimizations occur.
This commit is contained in:
Nekotekina 2021-11-16 13:45:26 +03:00
parent 747fc0efaa
commit 610c27aa1c
1 changed files with 1 additions and 41 deletions
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42
lib/Target/X86/X86ISelLowering.cpp
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@ -45741,11 +45741,7 @@ static SDValue combineTruncateWithSat(SDValue In, EVT VT, const SDLoc &DL,
// FIXME: We could widen truncates to 512 to remove the VLX restriction.
// If the result type is 256-bits or larger and we have disable 512-bit
// registers, we should go ahead and use the pack instructions if possible.
bool PreferAVX512 = ((Subtarget.hasAVX512() && InSVT == MVT::i32) ||
(Subtarget.hasBWI() && InSVT == MVT::i16)) &&
(InVT.getSizeInBits() > 128) &&
(Subtarget.hasVLX() || InVT.getSizeInBits() > 256) &&
!(!Subtarget.useAVX512Regs() && VT.getSizeInBits() >= 256);
bool PreferAVX512 = false;
if (isPowerOf2_32(VT.getVectorNumElements()) && !PreferAVX512 &&
VT.getSizeInBits() >= 64 &&
@ -45773,42 +45769,6 @@ static SDValue combineTruncateWithSat(SDValue In, EVT VT, const SDLoc &DL,
Subtarget);
}
const TargetLowering &TLI = DAG.getTargetLoweringInfo();
if (TLI.isTypeLegal(InVT) && InVT.isVector() && SVT != MVT::i1 &&
Subtarget.hasAVX512() && (InSVT != MVT::i16 || Subtarget.hasBWI()) &&
(SVT == MVT::i32 || SVT == MVT::i16 || SVT == MVT::i8)) {
unsigned TruncOpc = 0;
SDValue SatVal;
if (auto SSatVal = detectSSatPattern(In, VT)) {
SatVal = SSatVal;
TruncOpc = X86ISD::VTRUNCS;
} else if (auto USatVal = detectUSatPattern(In, VT, DAG, DL)) {
SatVal = USatVal;
TruncOpc = X86ISD::VTRUNCUS;
}
if (SatVal) {
unsigned ResElts = VT.getVectorNumElements();
// If the input type is less than 512 bits and we don't have VLX, we need
// to widen to 512 bits.
if (!Subtarget.hasVLX() && !InVT.is512BitVector()) {
unsigned NumConcats = 512 / InVT.getSizeInBits();
ResElts *= NumConcats;
SmallVector<SDValue, 4> ConcatOps(NumConcats, DAG.getUNDEF(InVT));
ConcatOps[0] = SatVal;
InVT = EVT::getVectorVT(*DAG.getContext(), InSVT,
NumConcats * InVT.getVectorNumElements());
SatVal = DAG.getNode(ISD::CONCAT_VECTORS, DL, InVT, ConcatOps);
}
// Widen the result if its narrower than 128 bits.
if (ResElts * SVT.getSizeInBits() < 128)
ResElts = 128 / SVT.getSizeInBits();
EVT TruncVT = EVT::getVectorVT(*DAG.getContext(), SVT, ResElts);
SDValue Res = DAG.getNode(TruncOpc, DL, TruncVT, SatVal);
return DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, Res,
DAG.getIntPtrConstant(0, DL));
}
}
return SDValue();
}