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[X86] Ensure that bit reversals of byte vectors are properly lowered on pure GFNI targets #148304

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Merged
merged 6 commits into from
Jul 18, 2025
+313 −84
Merged

[X86] Ensure that bit reversals of byte vectors are properly lowered on pure GFNI targets #148304

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3a15c6a
Fix #148238
TDecking Jul 11, 2025
d4194ec
Update the test file
TDecking Jul 18, 2025
c097e12
Extend the optimization towards other vectors
TDecking Jul 18, 2025
718deea
Turn SSSE2 into SSSE3
TDecking Jul 18, 2025
4f27cd7
Formatting
TDecking Jul 18, 2025
aaf7f6d
Merge branch 'main' into bitrev
RKSimon Jul 18, 2025
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9 changes: 7 additions & 2 deletions llvm/lib/Target/X86/X86ISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1323,11 +1323,15 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
setOperationAction(ISD::STRICT_FDIV, MVT::v2f64, Legal);
}

if (Subtarget.hasGFNI()) {
if (!Subtarget.useSoftFloat() && Subtarget.hasGFNI()) {
setOperationAction(ISD::BITREVERSE, MVT::i8, Custom);
setOperationAction(ISD::BITREVERSE, MVT::i16, Custom);
setOperationAction(ISD::BITREVERSE, MVT::i32, Custom);
setOperationAction(ISD::BITREVERSE, MVT::i64, Custom);

for (auto VT : {MVT::v16i8, MVT::v8i16, MVT::v4i32, MVT::v2i64}) {
setOperationAction(ISD::BITREVERSE, VT, Custom);
}
}

if (!Subtarget.useSoftFloat() && Subtarget.hasSSSE3()) {
Expand Down Expand Up @@ -32694,7 +32698,8 @@ static SDValue LowerBITREVERSE(SDValue Op, const X86Subtarget &Subtarget,
if (Subtarget.hasXOP() && !VT.is512BitVector())
return LowerBITREVERSE_XOP(Op, DAG);

assert(Subtarget.hasSSSE3() && "SSSE3 required for BITREVERSE");
assert((Subtarget.hasSSSE3() || Subtarget.hasGFNI()) &&
"SSSE3 or GFNI required for BITREVERSE");

SDValue In = Op.getOperand(0);
SDLoc DL(Op);
Expand Down
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