[llvm] [X86] Widden binary shuffle to unary for i8/i16 (PR #96414)
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Sat Jun 22 21:25:21 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-x86
Author: Phoebe Wang (phoebewang)
<details>
<summary>Changes</summary>
VPERM[I,T]2[B,W] are 3 uops on Skylake and Icelake so we try to use VPERMV.
---
Full diff: https://github.com/llvm/llvm-project/pull/96414.diff
2 Files Affected:
- (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+19-1)
- (modified) llvm/test/CodeGen/X86/shuffle-vs-trunc-512.ll (+1-2)
``````````diff
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 82d2b301d854e..c4d08206593f0 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -14123,7 +14123,25 @@ static SDValue lowerShuffleWithPERMV(const SDLoc &DL, MVT VT,
MVT MaskVT = VT.changeTypeToInteger();
SDValue MaskNode;
MVT ShuffleVT = VT;
- if (!VT.is512BitVector() && !Subtarget.hasVLX()) {
+ MVT ElementVT = VT.getVectorElementType();
+ // VPERM[I,T]2[B,W] are 3 uops on Skylake and Icelake so we try to use VPERMV.
+ if (Subtarget.hasVBMI() && !V2.isUndef() &&
+ (VT.is128BitVector() ||
+ (VT.is256BitVector() && Subtarget.hasEVEX512())) &&
+ (ElementVT == MVT::i8 || ElementVT == MVT::i16) &&
+ V1.getOpcode() == ISD::EXTRACT_SUBVECTOR &&
+ V1.getConstantOperandVal(1) == 0 &&
+ V2.getOpcode() == ISD::EXTRACT_SUBVECTOR &&
+ V2.getConstantOperandVal(1) == VT.getVectorNumElements() &&
+ V1.getOperand(0) == V2.getOperand(0)) {
+ SmallVector<int, 32> AdjustedMask(Mask);
+ AdjustedMask.resize(VT.getVectorNumElements() * 2, SM_SentinelUndef);
+ ShuffleVT = VT.getDoubleNumVectorElementsVT();
+ V1 = V1.getOperand(0);
+ V2 = DAG.getUNDEF(ShuffleVT);
+ MaskNode = getConstVector(
+ AdjustedMask, MaskVT.getDoubleNumVectorElementsVT(), DAG, DL, true);
+ } else if (!VT.is512BitVector() && !Subtarget.hasVLX()) {
V1 = widenSubVector(V1, false, Subtarget, DAG, DL, 512);
V2 = widenSubVector(V2, false, Subtarget, DAG, DL, 512);
ShuffleVT = V1.getSimpleValueType();
diff --git a/llvm/test/CodeGen/X86/shuffle-vs-trunc-512.ll b/llvm/test/CodeGen/X86/shuffle-vs-trunc-512.ll
index a481aaef4257d..95e249984e184 100644
--- a/llvm/test/CodeGen/X86/shuffle-vs-trunc-512.ll
+++ b/llvm/test/CodeGen/X86/shuffle-vs-trunc-512.ll
@@ -348,8 +348,7 @@ define <16 x i8> @trunc_shuffle_v64i8_01_05_09_13_17_21_25_29_33_37_41_45_49_53_
; AVX512VBMIVL-LABEL: trunc_shuffle_v64i8_01_05_09_13_17_21_25_29_33_37_41_45_49_53_57_62:
; AVX512VBMIVL: # %bb.0:
; AVX512VBMIVL-NEXT: vmovdqa {{.*#+}} xmm1 = [1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,62]
-; AVX512VBMIVL-NEXT: vextracti64x4 $1, %zmm0, %ymm2
-; AVX512VBMIVL-NEXT: vpermt2b %ymm2, %ymm1, %ymm0
+; AVX512VBMIVL-NEXT: vpermb %zmm0, %zmm1, %zmm0
; AVX512VBMIVL-NEXT: # kill: def $xmm0 killed $xmm0 killed $zmm0
; AVX512VBMIVL-NEXT: vzeroupper
; AVX512VBMIVL-NEXT: retq
``````````
</details>
https://github.com/llvm/llvm-project/pull/96414
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