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[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi8 vectors #143106

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Merged
merged 1 commit into from
Jun 6, 2025
Merged

[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi8 vectors #143106

merged 1 commit into from
Jun 6, 2025

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RKSimon
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@RKSimon RKSimon commented Jun 6, 2025

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Fixes #130549

@RKSimon
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi8 vectors
c6f3800 
Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Fixes llvm#130549
@llvmbot
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llvmbot commented Jun 6, 2025

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

Changes

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Fixes #130549

Patch is 89.81 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/143106.diff

4 Files Affected:

  • (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+15-5)
  • (modified) llvm/test/CodeGen/X86/vector-idiv-sdiv-128.ll (+169-178)
  • (modified) llvm/test/CodeGen/X86/vector-idiv-sdiv-256.ll (+145-161)
  • (modified) llvm/test/CodeGen/X86/vector-idiv-sdiv-512.ll (+92-104)
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index e929dab429de5..6659050c7cd54 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -58113,13 +58113,14 @@ static SDValue combineAdd(SDNode *N, SelectionDAG &DAG,
     }
   }
 
-  // If vectors of i1 are legal, turn (add (zext (vXi1 X)), Y) into
-  // (sub Y, (sext (vXi1 X))).
-  // FIXME: We have the (sub Y, (zext (vXi1 X))) -> (add (sext (vXi1 X)), Y) in
-  // generic DAG combine without a legal type check, but adding this there
-  // caused regressions.
   if (VT.isVector()) {
     SDValue X, Y;
+
+    // If vectors of i1 are legal, turn (add (zext (vXi1 X)), Y) into
+    // (sub Y, (sext (vXi1 X))).
+    // FIXME: We have the (sub Y, (zext (vXi1 X))) -> (add (sext (vXi1 X)), Y)
+    // in generic DAG combine without a legal type check, but adding this there
+    // caused regressions.
     EVT BoolVT = EVT::getVectorVT(*DAG.getContext(), MVT::i1,
                                   VT.getVectorElementCount());
     if (DAG.getTargetLoweringInfo().isTypeLegal(BoolVT) &&
@@ -58128,6 +58129,15 @@ static SDValue combineAdd(SDNode *N, SelectionDAG &DAG,
       SDValue SExt = DAG.getNode(ISD::SIGN_EXTEND, DL, VT, X);
       return DAG.getNode(ISD::SUB, DL, VT, Y, SExt);
     }
+
+    // Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) to undo instcombine
+    // canonicalisation as we don't have good vXi8 shifts.
+    if (VT.getScalarType() == MVT::i8 &&
+        sd_match(N, m_Add(m_Value(X), m_Srl(m_Value(Y), m_SpecificInt(7))))) {
+      SDValue AShr = DAG.getNode(ISD::SRA, DL, VT, Y,
+                                 DAG.getShiftAmountConstant(7, VT, DL));
+      return DAG.getNode(ISD::SUB, DL, VT, X, AShr);
+    }
   }
 
   // Peephole for 512-bit VPDPBSSD on non-VLX targets.
diff --git a/llvm/test/CodeGen/X86/vector-idiv-sdiv-128.ll b/llvm/test/CodeGen/X86/vector-idiv-sdiv-128.ll
index 3cc17c1f2b86a..425cda1acb1fe 100644
--- a/llvm/test/CodeGen/X86/vector-idiv-sdiv-128.ll
+++ b/llvm/test/CodeGen/X86/vector-idiv-sdiv-128.ll
@@ -174,19 +174,18 @@ define <16 x i8> @test_div7_16i8(<16 x i8> %a) nounwind {
 ; SSE-NEXT:    movdqa {{.*#+}} xmm3 = [37632,37632,37632,37632,37632,37632,37632,37632]
 ; SSE-NEXT:    pmulhw %xmm3, %xmm2
 ; SSE-NEXT:    psrlw $8, %xmm2
-; SSE-NEXT:    punpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
-; SSE-NEXT:    pmulhw %xmm3, %xmm1
-; SSE-NEXT:    psrlw $8, %xmm1
-; SSE-NEXT:    packuswb %xmm2, %xmm1
-; SSE-NEXT:    paddb %xmm1, %xmm0
-; SSE-NEXT:    movdqa %xmm0, %xmm1
-; SSE-NEXT:    psrlw $2, %xmm1
-; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1
-; SSE-NEXT:    movdqa {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; SSE-NEXT:    pxor %xmm2, %xmm1
-; SSE-NEXT:    psrlw $7, %xmm0
+; SSE-NEXT:    pxor %xmm4, %xmm4
+; SSE-NEXT:    punpcklbw {{.*#+}} xmm4 = xmm4[0],xmm0[0],xmm4[1],xmm0[1],xmm4[2],xmm0[2],xmm4[3],xmm0[3],xmm4[4],xmm0[4],xmm4[5],xmm0[5],xmm4[6],xmm0[6],xmm4[7],xmm0[7]
+; SSE-NEXT:    pmulhw %xmm3, %xmm4
+; SSE-NEXT:    psrlw $8, %xmm4
+; SSE-NEXT:    packuswb %xmm2, %xmm4
+; SSE-NEXT:    paddb %xmm4, %xmm0
+; SSE-NEXT:    pcmpgtb %xmm0, %xmm1
+; SSE-NEXT:    psrlw $2, %xmm0
 ; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
-; SSE-NEXT:    paddb %xmm1, %xmm0
+; SSE-NEXT:    movdqa {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; SSE-NEXT:    pxor %xmm2, %xmm0
+; SSE-NEXT:    psubb %xmm1, %xmm0
 ; SSE-NEXT:    psubb %xmm2, %xmm0
 ; SSE-NEXT:    retq
 ;
@@ -197,18 +196,17 @@ define <16 x i8> @test_div7_16i8(<16 x i8> %a) nounwind {
 ; AVX1-NEXT:    vbroadcastss {{.*#+}} xmm3 = [37632,37632,37632,37632,37632,37632,37632,37632]
 ; AVX1-NEXT:    vpmulhw %xmm3, %xmm2, %xmm2
 ; AVX1-NEXT:    vpsrlw $8, %xmm2, %xmm2
-; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
-; AVX1-NEXT:    vpmulhw %xmm3, %xmm1, %xmm1
-; AVX1-NEXT:    vpsrlw $8, %xmm1, %xmm1
-; AVX1-NEXT:    vpackuswb %xmm2, %xmm1, %xmm1
-; AVX1-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
-; AVX1-NEXT:    vpsrlw $2, %xmm0, %xmm1
-; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
-; AVX1-NEXT:    vbroadcastss {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; AVX1-NEXT:    vpxor %xmm2, %xmm1, %xmm1
-; AVX1-NEXT:    vpsrlw $7, %xmm0, %xmm0
+; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm4 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
+; AVX1-NEXT:    vpmulhw %xmm3, %xmm4, %xmm3
+; AVX1-NEXT:    vpsrlw $8, %xmm3, %xmm3
+; AVX1-NEXT:    vpackuswb %xmm2, %xmm3, %xmm2
+; AVX1-NEXT:    vpaddb %xmm0, %xmm2, %xmm0
+; AVX1-NEXT:    vpcmpgtb %xmm0, %xmm1, %xmm1
+; AVX1-NEXT:    vpsrlw $2, %xmm0, %xmm0
 ; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX1-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
+; AVX1-NEXT:    vbroadcastss {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; AVX1-NEXT:    vpxor %xmm2, %xmm0, %xmm0
+; AVX1-NEXT:    vpsubb %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vpsubb %xmm2, %xmm0, %xmm0
 ; AVX1-NEXT:    retq
 ;
@@ -220,13 +218,13 @@ define <16 x i8> @test_div7_16i8(<16 x i8> %a) nounwind {
 ; AVX2NOBW-NEXT:    vextracti128 $1, %ymm1, %xmm2
 ; AVX2NOBW-NEXT:    vpackuswb %xmm2, %xmm1, %xmm1
 ; AVX2NOBW-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
-; AVX2NOBW-NEXT:    vpsrlw $2, %xmm0, %xmm1
-; AVX2NOBW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
-; AVX2NOBW-NEXT:    vpbroadcastb {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; AVX2NOBW-NEXT:    vpxor %xmm2, %xmm1, %xmm1
-; AVX2NOBW-NEXT:    vpsrlw $7, %xmm0, %xmm0
+; AVX2NOBW-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; AVX2NOBW-NEXT:    vpcmpgtb %xmm0, %xmm1, %xmm1
+; AVX2NOBW-NEXT:    vpsrlw $2, %xmm0, %xmm0
 ; AVX2NOBW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX2NOBW-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
+; AVX2NOBW-NEXT:    vpbroadcastb {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; AVX2NOBW-NEXT:    vpxor %xmm2, %xmm0, %xmm0
+; AVX2NOBW-NEXT:    vpsubb %xmm1, %xmm0, %xmm0
 ; AVX2NOBW-NEXT:    vpsubb %xmm2, %xmm0, %xmm0
 ; AVX2NOBW-NEXT:    vzeroupper
 ; AVX2NOBW-NEXT:    retq
@@ -238,13 +236,13 @@ define <16 x i8> @test_div7_16i8(<16 x i8> %a) nounwind {
 ; AVX512BW-NEXT:    vpsrlw $8, %ymm1, %ymm1
 ; AVX512BW-NEXT:    vpmovwb %zmm1, %ymm1
 ; AVX512BW-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
-; AVX512BW-NEXT:    vpsrlw $2, %xmm0, %xmm1
-; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
-; AVX512BW-NEXT:    vpbroadcastb {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; AVX512BW-NEXT:    vpxor %xmm2, %xmm1, %xmm1
-; AVX512BW-NEXT:    vpsrlw $7, %xmm0, %xmm0
+; AVX512BW-NEXT:    vpxor %xmm1, %xmm1, %xmm1
+; AVX512BW-NEXT:    vpcmpgtb %xmm0, %xmm1, %xmm1
+; AVX512BW-NEXT:    vpsrlw $2, %xmm0, %xmm0
 ; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX512BW-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
+; AVX512BW-NEXT:    vpbroadcastb {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; AVX512BW-NEXT:    vpxor %xmm2, %xmm0, %xmm0
+; AVX512BW-NEXT:    vpsubb %xmm1, %xmm0, %xmm0
 ; AVX512BW-NEXT:    vpsubb %xmm2, %xmm0, %xmm0
 ; AVX512BW-NEXT:    vzeroupper
 ; AVX512BW-NEXT:    retq
@@ -264,26 +262,25 @@ define <16 x i8> @test_divconstant_16i8(<16 x i8> %a) nounwind {
 ; SSE-NEXT:    punpckhbw {{.*#+}} xmm2 = xmm2[8],xmm0[8],xmm2[9],xmm0[9],xmm2[10],xmm0[10],xmm2[11],xmm0[11],xmm2[12],xmm0[12],xmm2[13],xmm0[13],xmm2[14],xmm0[14],xmm2[15],xmm0[15]
 ; SSE-NEXT:    pmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2 # [37632,20224,11008,47872,26368,14592,14592,37632]
 ; SSE-NEXT:    psrlw $8, %xmm2
-; SSE-NEXT:    punpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
-; SSE-NEXT:    pmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1 # [37632,33024,14592,26368,47872,11008,20224,37632]
-; SSE-NEXT:    psrlw $8, %xmm1
-; SSE-NEXT:    packuswb %xmm2, %xmm1
+; SSE-NEXT:    pxor %xmm3, %xmm3
+; SSE-NEXT:    punpcklbw {{.*#+}} xmm3 = xmm3[0],xmm0[0],xmm3[1],xmm0[1],xmm3[2],xmm0[2],xmm3[3],xmm0[3],xmm3[4],xmm0[4],xmm3[5],xmm0[5],xmm3[6],xmm0[6],xmm3[7],xmm0[7]
+; SSE-NEXT:    pmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm3 # [37632,33024,14592,26368,47872,11008,20224,37632]
+; SSE-NEXT:    psrlw $8, %xmm3
+; SSE-NEXT:    packuswb %xmm2, %xmm3
 ; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
-; SSE-NEXT:    paddb %xmm1, %xmm0
-; SSE-NEXT:    movdqa %xmm0, %xmm1
-; SSE-NEXT:    punpckhbw {{.*#+}} xmm1 = xmm1[8],xmm0[8],xmm1[9],xmm0[9],xmm1[10],xmm0[10],xmm1[11],xmm0[11],xmm1[12],xmm0[12],xmm1[13],xmm0[13],xmm1[14],xmm0[14],xmm1[15],xmm0[15]
-; SSE-NEXT:    psraw $8, %xmm1
-; SSE-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1 # [32,64,128,32,64,128,128,64]
-; SSE-NEXT:    psrlw $8, %xmm1
+; SSE-NEXT:    paddb %xmm3, %xmm0
 ; SSE-NEXT:    movdqa %xmm0, %xmm2
-; SSE-NEXT:    punpcklbw {{.*#+}} xmm2 = xmm2[0],xmm0[0],xmm2[1],xmm0[1],xmm2[2],xmm0[2],xmm2[3],xmm0[3],xmm2[4],xmm0[4],xmm2[5],xmm0[5],xmm2[6],xmm0[6],xmm2[7],xmm0[7]
+; SSE-NEXT:    punpckhbw {{.*#+}} xmm2 = xmm2[8],xmm0[8],xmm2[9],xmm0[9],xmm2[10],xmm0[10],xmm2[11],xmm0[11],xmm2[12],xmm0[12],xmm2[13],xmm0[13],xmm2[14],xmm0[14],xmm2[15],xmm0[15]
 ; SSE-NEXT:    psraw $8, %xmm2
-; SSE-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2 # [64,64,128,64,32,128,64,32]
+; SSE-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2 # [32,64,128,32,64,128,128,64]
 ; SSE-NEXT:    psrlw $8, %xmm2
-; SSE-NEXT:    packuswb %xmm1, %xmm2
-; SSE-NEXT:    psrlw $7, %xmm0
-; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
-; SSE-NEXT:    paddb %xmm2, %xmm0
+; SSE-NEXT:    pcmpgtb %xmm0, %xmm1
+; SSE-NEXT:    punpcklbw {{.*#+}} xmm0 = xmm0[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
+; SSE-NEXT:    psraw $8, %xmm0
+; SSE-NEXT:    pmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0 # [64,64,128,64,32,128,64,32]
+; SSE-NEXT:    psrlw $8, %xmm0
+; SSE-NEXT:    packuswb %xmm2, %xmm0
+; SSE-NEXT:    psubb %xmm1, %xmm0
 ; SSE-NEXT:    retq
 ;
 ; AVX1-LABEL: test_divconstant_16i8:
@@ -292,24 +289,23 @@ define <16 x i8> @test_divconstant_16i8(<16 x i8> %a) nounwind {
 ; AVX1-NEXT:    vpunpckhbw {{.*#+}} xmm2 = xmm1[8],xmm0[8],xmm1[9],xmm0[9],xmm1[10],xmm0[10],xmm1[11],xmm0[11],xmm1[12],xmm0[12],xmm1[13],xmm0[13],xmm1[14],xmm0[14],xmm1[15],xmm0[15]
 ; AVX1-NEXT:    vpmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2 # [37632,20224,11008,47872,26368,14592,14592,37632]
 ; AVX1-NEXT:    vpsrlw $8, %xmm2, %xmm2
-; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
-; AVX1-NEXT:    vpmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1 # [37632,33024,14592,26368,47872,11008,20224,37632]
-; AVX1-NEXT:    vpsrlw $8, %xmm1, %xmm1
-; AVX1-NEXT:    vpackuswb %xmm2, %xmm1, %xmm1
+; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm3 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
+; AVX1-NEXT:    vpmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm3, %xmm3 # [37632,33024,14592,26368,47872,11008,20224,37632]
+; AVX1-NEXT:    vpsrlw $8, %xmm3, %xmm3
+; AVX1-NEXT:    vpackuswb %xmm2, %xmm3, %xmm2
 ; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX1-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
-; AVX1-NEXT:    vpunpckhbw {{.*#+}} xmm1 = xmm0[8,8,9,9,10,10,11,11,12,12,13,13,14,14,15,15]
-; AVX1-NEXT:    vpsraw $8, %xmm1, %xmm1
-; AVX1-NEXT:    vpmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1 # [32,64,128,32,64,128,128,64]
-; AVX1-NEXT:    vpsrlw $8, %xmm1, %xmm1
-; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm2 = xmm0[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
+; AVX1-NEXT:    vpaddb %xmm0, %xmm2, %xmm0
+; AVX1-NEXT:    vpunpckhbw {{.*#+}} xmm2 = xmm0[8,8,9,9,10,10,11,11,12,12,13,13,14,14,15,15]
 ; AVX1-NEXT:    vpsraw $8, %xmm2, %xmm2
-; AVX1-NEXT:    vpmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2 # [64,64,128,64,32,128,64,32]
+; AVX1-NEXT:    vpmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2 # [32,64,128,32,64,128,128,64]
 ; AVX1-NEXT:    vpsrlw $8, %xmm2, %xmm2
-; AVX1-NEXT:    vpackuswb %xmm1, %xmm2, %xmm1
-; AVX1-NEXT:    vpsrlw $7, %xmm0, %xmm0
-; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX1-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
+; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm3 = xmm0[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
+; AVX1-NEXT:    vpsraw $8, %xmm3, %xmm3
+; AVX1-NEXT:    vpmullw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm3, %xmm3 # [64,64,128,64,32,128,64,32]
+; AVX1-NEXT:    vpsrlw $8, %xmm3, %xmm3
+; AVX1-NEXT:    vpackuswb %xmm2, %xmm3, %xmm2
+; AVX1-NEXT:    vpcmpgtb %xmm0, %xmm1, %xmm0
+; AVX1-NEXT:    vpsubb %xmm0, %xmm2, %xmm0
 ; AVX1-NEXT:    retq
 ;
 ; AVX2NOBW-LABEL: test_divconstant_16i8:
@@ -326,9 +322,9 @@ define <16 x i8> @test_divconstant_16i8(<16 x i8> %a) nounwind {
 ; AVX2NOBW-NEXT:    vpsrlw $8, %ymm1, %ymm1
 ; AVX2NOBW-NEXT:    vextracti128 $1, %ymm1, %xmm2
 ; AVX2NOBW-NEXT:    vpackuswb %xmm2, %xmm1, %xmm1
-; AVX2NOBW-NEXT:    vpsrlw $7, %xmm0, %xmm0
-; AVX2NOBW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX2NOBW-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
+; AVX2NOBW-NEXT:    vpxor %xmm2, %xmm2, %xmm2
+; AVX2NOBW-NEXT:    vpcmpgtb %xmm0, %xmm2, %xmm0
+; AVX2NOBW-NEXT:    vpsubb %xmm0, %xmm1, %xmm0
 ; AVX2NOBW-NEXT:    vzeroupper
 ; AVX2NOBW-NEXT:    retq
 ;
@@ -344,9 +340,9 @@ define <16 x i8> @test_divconstant_16i8(<16 x i8> %a) nounwind {
 ; AVX512BW-NEXT:    vpmovsxbw %xmm0, %ymm2
 ; AVX512BW-NEXT:    vpsravw %zmm1, %zmm2, %zmm1
 ; AVX512BW-NEXT:    vpmovwb %zmm1, %ymm1
-; AVX512BW-NEXT:    vpsrlw $7, %xmm0, %xmm0
-; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0, %xmm0
-; AVX512BW-NEXT:    vpaddb %xmm0, %xmm1, %xmm0
+; AVX512BW-NEXT:    vpxor %xmm2, %xmm2, %xmm2
+; AVX512BW-NEXT:    vpcmpgtb %xmm0, %xmm2, %xmm0
+; AVX512BW-NEXT:    vpsubb %xmm0, %xmm1, %xmm0
 ; AVX512BW-NEXT:    vzeroupper
 ; AVX512BW-NEXT:    retq
   %res = sdiv <16 x i8> %a, <i8 7, i8 8, i8 9, i8 10,i8 11, i8 12, i8 13, i8 14, i8 14, i8 13, i8 12, i8 11, i8 10, i8 9,i8 9, i8 7>
@@ -568,25 +564,24 @@ define <16 x i8> @test_rem7_16i8(<16 x i8> %a) nounwind {
 ; SSE-NEXT:    movdqa {{.*#+}} xmm3 = [37632,37632,37632,37632,37632,37632,37632,37632]
 ; SSE-NEXT:    pmulhw %xmm3, %xmm2
 ; SSE-NEXT:    psrlw $8, %xmm2
-; SSE-NEXT:    punpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
-; SSE-NEXT:    pmulhw %xmm3, %xmm1
-; SSE-NEXT:    psrlw $8, %xmm1
-; SSE-NEXT:    packuswb %xmm2, %xmm1
-; SSE-NEXT:    paddb %xmm0, %xmm1
-; SSE-NEXT:    movdqa %xmm1, %xmm2
-; SSE-NEXT:    psrlw $2, %xmm2
-; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2
-; SSE-NEXT:    movdqa {{.*#+}} xmm3 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; SSE-NEXT:    pxor %xmm3, %xmm2
-; SSE-NEXT:    psrlw $7, %xmm1
+; SSE-NEXT:    pxor %xmm4, %xmm4
+; SSE-NEXT:    punpcklbw {{.*#+}} xmm4 = xmm4[0],xmm0[0],xmm4[1],xmm0[1],xmm4[2],xmm0[2],xmm4[3],xmm0[3],xmm4[4],xmm0[4],xmm4[5],xmm0[5],xmm4[6],xmm0[6],xmm4[7],xmm0[7]
+; SSE-NEXT:    pmulhw %xmm3, %xmm4
+; SSE-NEXT:    psrlw $8, %xmm4
+; SSE-NEXT:    packuswb %xmm2, %xmm4
+; SSE-NEXT:    paddb %xmm0, %xmm4
+; SSE-NEXT:    pcmpgtb %xmm4, %xmm1
+; SSE-NEXT:    psrlw $2, %xmm4
+; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm4
+; SSE-NEXT:    movdqa {{.*#+}} xmm2 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; SSE-NEXT:    pxor %xmm2, %xmm4
+; SSE-NEXT:    psubb %xmm1, %xmm4
+; SSE-NEXT:    psubb %xmm2, %xmm4
+; SSE-NEXT:    movdqa %xmm4, %xmm1
+; SSE-NEXT:    psllw $3, %xmm1
 ; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1
-; SSE-NEXT:    paddb %xmm2, %xmm1
-; SSE-NEXT:    psubb %xmm3, %xmm1
-; SSE-NEXT:    movdqa %xmm1, %xmm2
-; SSE-NEXT:    psllw $3, %xmm2
-; SSE-NEXT:    pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2
-; SSE-NEXT:    psubb %xmm2, %xmm1
-; SSE-NEXT:    paddb %xmm1, %xmm0
+; SSE-NEXT:    psubb %xmm1, %xmm4
+; SSE-NEXT:    paddb %xmm4, %xmm0
 ; SSE-NEXT:    retq
 ;
 ; AVX1-LABEL: test_rem7_16i8:
@@ -596,18 +591,17 @@ define <16 x i8> @test_rem7_16i8(<16 x i8> %a) nounwind {
 ; AVX1-NEXT:    vbroadcastss {{.*#+}} xmm3 = [37632,37632,37632,37632,37632,37632,37632,37632]
 ; AVX1-NEXT:    vpmulhw %xmm3, %xmm2, %xmm2
 ; AVX1-NEXT:    vpsrlw $8, %xmm2, %xmm2
-; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
-; AVX1-NEXT:    vpmulhw %xmm3, %xmm1, %xmm1
-; AVX1-NEXT:    vpsrlw $8, %xmm1, %xmm1
-; AVX1-NEXT:    vpackuswb %xmm2, %xmm1, %xmm1
-; AVX1-NEXT:    vpaddb %xmm0, %xmm1, %xmm1
-; AVX1-NEXT:    vpsrlw $2, %xmm1, %xmm2
+; AVX1-NEXT:    vpunpcklbw {{.*#+}} xmm4 = xmm1[0],xmm0[0],xmm1[1],xmm0[1],xmm1[2],xmm0[2],xmm1[3],xmm0[3],xmm1[4],xmm0[4],xmm1[5],xmm0[5],xmm1[6],xmm0[6],xmm1[7],xmm0[7]
+; AVX1-NEXT:    vpmulhw %xmm3, %xmm4, %xmm3
+; AVX1-NEXT:    vpsrlw $8, %xmm3, %xmm3
+; AVX1-NEXT:    vpackuswb %xmm2, %xmm3, %xmm2
+; AVX1-NEXT:    vpaddb %xmm0, %xmm2, %xmm2
+; AVX1-NEXT:    vpcmpgtb %xmm2, %xmm1, %xmm1
+; AVX1-NEXT:    vpsrlw $2, %xmm2, %xmm2
 ; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2
 ; AVX1-NEXT:    vbroadcastss {{.*#+}} xmm3 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
 ; AVX1-NEXT:    vpxor %xmm3, %xmm2, %xmm2
-; AVX1-NEXT:    vpsrlw $7, %xmm1, %xmm1
-; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
-; AVX1-NEXT:    vpaddb %xmm1, %xmm2, %xmm1
+; AVX1-NEXT:    vpsubb %xmm1, %xmm2, %xmm1
 ; AVX1-NEXT:    vpsubb %xmm3, %xmm1, %xmm1
 ; AVX1-NEXT:    vpsllw $3, %xmm1, %xmm2
 ; AVX1-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2
@@ -623,13 +617,13 @@ define <16 x i8> @test_rem7_16i8(<16 x i8> %a) nounwind {
 ; AVX2NOBW-NEXT:    vextracti128 $1, %ymm1, %xmm2
 ; AVX2NOBW-NEXT:    vpackuswb %xmm2, %xmm1, %xmm1
 ; AVX2NOBW-NEXT:    vpaddb %xmm0, %xmm1, %xmm1
-; AVX2NOBW-NEXT:    vpsrlw $2, %xmm1, %xmm2
-; AVX2NOBW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2
-; AVX2NOBW-NEXT:    vpbroadcastb {{.*#+}} xmm3 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; AVX2NOBW-NEXT:    vpxor %xmm3, %xmm2, %xmm2
-; AVX2NOBW-NEXT:    vpsrlw $7, %xmm1, %xmm1
+; AVX2NOBW-NEXT:    vpxor %xmm2, %xmm2, %xmm2
+; AVX2NOBW-NEXT:    vpcmpgtb %xmm1, %xmm2, %xmm2
+; AVX2NOBW-NEXT:    vpsrlw $2, %xmm1, %xmm1
 ; AVX2NOBW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
-; AVX2NOBW-NEXT:    vpaddb %xmm1, %xmm2, %xmm1
+; AVX2NOBW-NEXT:    vpbroadcastb {{.*#+}} xmm3 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; AVX2NOBW-NEXT:    vpxor %xmm3, %xmm1, %xmm1
+; AVX2NOBW-NEXT:    vpsubb %xmm2, %xmm1, %xmm1
 ; AVX2NOBW-NEXT:    vpsubb %xmm3, %xmm1, %xmm1
 ; AVX2NOBW-NEXT:    vpsllw $3, %xmm1, %xmm2
 ; AVX2NOBW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2
@@ -645,13 +639,13 @@ define <16 x i8> @test_rem7_16i8(<16 x i8> %a) nounwind {
 ; AVX512BW-NEXT:    vpsrlw $8, %ymm1, %ymm1
 ; AVX512BW-NEXT:    vpmovwb %zmm1, %ymm1
 ; AVX512BW-NEXT:    vpaddb %xmm0, %xmm1, %xmm1
-; AVX512BW-NEXT:    vpsrlw $2, %xmm1, %xmm2
-; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2
-; AVX512BW-NEXT:    vpbroadcastb {{.*#+}} xmm3 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
-; AVX512BW-NEXT:    vpxor %xmm3, %xmm2, %xmm2
-; AVX512BW-NEXT:    vpsrlw $7, %xmm1, %xmm1
+; AVX512BW-NEXT:    vpxor %xmm2, %xmm2, %xmm2
+; AVX512BW-NEXT:    vpcmpgtb %xmm1, %xmm2, %xmm2
+; AVX512BW-NEXT:    vpsrlw $2, %xmm1, %xmm1
 ; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm1, %xmm1
-; AVX512BW-NEXT:    vpaddb %xmm1, %xmm2, %xmm1
+; AVX512BW-NEXT:    vpbroadcastb {{.*#+}} xmm3 = [32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32]
+; AVX512BW-NEXT:    vpxor %xmm3, %xmm1, %xmm1
+; AVX512BW-NEXT:    vpsubb %xmm2, %xmm1, %xmm1
 ; AVX512BW-NEXT:    vpsubb %xmm3, %xmm1, %xmm1
 ; AVX512BW-NEXT:    vpsllw $3, %xmm1, %xmm2
 ; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2, %xmm2
@@ -675,27 +669...
[truncated]

phoebewang
phoebewang approved these changes Jun 6, 2025
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LGTM.

@RKSimon RKSimon merged commit 4e676a1 into llvm:main Jun 6, 2025
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@RKSimon RKSimon deleted the x86-add-srl-sra branch June 6, 2025 12:33
@RKSimon RKSimon mentioned this pull request Jun 8, 2025
Merged
RKSimon added a commit that referenced this pull request Jun 8, 2025
@RKSimon
Revert "[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi…
e0b33c9 
…8 vectors" (#143303)

Reverts #143106 as this is causing infinite loops in
#143238
@RKSimon RKSimon mentioned this pull request Jun 8, 2025
Closed
llvm-sync bot pushed a commit to arm/arm-toolchain that referenced this pull request Jun 8, 2025
@RKSimon @github-actions
Automerge: Revert "[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y,…
e3b00f8 
… 7)) on vXi8 vectors" (#143303)

Reverts llvm/llvm-project#143106 as this is causing infinite loops in
#143238
omkar-mohanty pushed a commit to omkar-mohanty/llvm-project that referenced this pull request Jun 8, 2025
@RKSimon @omkar-mohanty
Revert "[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi…
8a44abb 
…8 vectors" (llvm#143303)

Reverts llvm#143106 as this is causing infinite loops in
llvm#143238
RKSimon added a commit to RKSimon/llvm-project that referenced this pull request Jun 9, 2025
@RKSimon
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (icmp_sgt 0, Y)) on vXi8 ve…
365cb80 
…ctors

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Alternative to llvm#143106 which could cause infinite loops between srl/sra conversions

Fixes llvm#130549
@RKSimon RKSimon mentioned this pull request Jun 9, 2025
Merged
RKSimon added a commit that referenced this pull request Jun 9, 2025
@RKSimon
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (icmp_sgt 0, Y)) on vXi8 ve…
66911b7 
…ctors (#143359)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift
support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Alternative to #143106 which could cause infinite loops between srl/sra
conversions

Fixes #130549
rorth pushed a commit to rorth/llvm-project that referenced this pull request Jun 11, 2025
@RKSimon @rorth
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi8 vectors (
80882b0 
llvm#143106)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Fixes llvm#130549
rorth pushed a commit to rorth/llvm-project that referenced this pull request Jun 11, 2025
@RKSimon @rorth
Revert "[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi…
c1cb750 
…8 vectors" (llvm#143303)

Reverts llvm#143106 as this is causing infinite loops in
llvm#143238
rorth pushed a commit to rorth/llvm-project that referenced this pull request Jun 11, 2025
@RKSimon @rorth
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (icmp_sgt 0, Y)) on vXi8 ve…
4315bf5 
…ctors (llvm#143359)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift
support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Alternative to llvm#143106 which could cause infinite loops between srl/sra
conversions

Fixes llvm#130549
DhruvSrivastavaX pushed a commit to DhruvSrivastavaX/lldb-for-aix that referenced this pull request Jun 12, 2025
@RKSimon @DhruvSrivastavaX
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi8 vectors (
5733a65 
llvm#143106)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Fixes llvm#130549
DhruvSrivastavaX pushed a commit to DhruvSrivastavaX/lldb-for-aix that referenced this pull request Jun 12, 2025
@RKSimon @DhruvSrivastavaX
Revert "[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi…
018c4f7 
…8 vectors" (llvm#143303)

Reverts llvm#143106 as this is causing infinite loops in
llvm#143238
DhruvSrivastavaX pushed a commit to DhruvSrivastavaX/lldb-for-aix that referenced this pull request Jun 12, 2025
@RKSimon @DhruvSrivastavaX
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (icmp_sgt 0, Y)) on vXi8 ve…
a0f172c 
…ctors (llvm#143359)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift
support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Alternative to llvm#143106 which could cause infinite loops between srl/sra
conversions

Fixes llvm#130549
tomtor pushed a commit to tomtor/llvm-project that referenced this pull request Jun 14, 2025
@RKSimon @tomtor
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi8 vectors (
c1b62f1 
llvm#143106)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Fixes llvm#130549
tomtor pushed a commit to tomtor/llvm-project that referenced this pull request Jun 14, 2025
@RKSimon @tomtor
Revert "[X86] Fold (add X, (srl Y, 7)) -> (sub X, (ashr Y, 7)) on vXi…
6ff1eb9 
…8 vectors" (llvm#143303)

Reverts llvm#143106 as this is causing infinite loops in
llvm#143238
tomtor pushed a commit to tomtor/llvm-project that referenced this pull request Jun 14, 2025
@RKSimon @tomtor
[X86] Fold (add X, (srl Y, 7)) -> (sub X, (icmp_sgt 0, Y)) on vXi8 ve…
a5f856b 
…ctors (llvm#143359)

Undo the vectorcombine canonicalisation as SSE has awful vXi8 shift
support, but can easily splat the MSB using the PCMPGTB(0,x) trick.

Alternative to llvm#143106 which could cause infinite loops between srl/sra
conversions

Fixes llvm#130549
@RKSimon RKSimon mentioned this pull request Jun 24, 2025
Closed
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@phoebewang phoebewang phoebewang approved these changes

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[X86] acc -= val < 0 converted to less efficient acc += (val >> 7) & 1
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@RKSimon @llvmbot @phoebewang