[X86] combineVectorShiftImm - fold (shl (add X, X), C) -> (shl X, (C …

…+ 1)) Noticed while investigating the regressions in D106675
llvm · Aug 14, 2022 · 8b47e29 · 8b47e29
1 parent 0c90d5f
commit 8b47e29
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diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -47202,10 +47202,8 @@ static SDValue combineVectorShiftImm(SDNode *N, SelectionDAG &DAG,
     // result are all ones, not undef.
     return DAG.getConstant(-1, SDLoc(N), VT);
 
-  // (shift (shift X, C2), C1) -> (shift X, (C1 + C2))
-  if (Opcode == N0.getOpcode()) {
-    unsigned ShiftVal2 = cast<ConstantSDNode>(N0.getOperand(1))->getZExtValue();
-    unsigned NewShiftVal = ShiftVal + ShiftVal2;
+  auto MergeShifts = [&](SDValue X, uint64_t Amt0, uint64_t Amt1) {
+    unsigned NewShiftVal = Amt0 + Amt1;
     if (NewShiftVal >= NumBitsPerElt) {
       // Out of range logical bit shifts are guaranteed to be zero.
       // Out of range arithmetic bit shifts splat the sign bit.
@@ -47215,7 +47213,16 @@ static SDValue combineVectorShiftImm(SDNode *N, SelectionDAG &DAG,
     }
     return DAG.getNode(Opcode, SDLoc(N), VT, N0.getOperand(0),
                        DAG.getTargetConstant(NewShiftVal, SDLoc(N), MVT::i8));
-  }
+  };
+
+  // (shift (shift X, C2), C1) -> (shift X, (C1 + C2))
+  if (Opcode == N0.getOpcode())
+    return MergeShifts(N0.getOperand(0), ShiftVal, N0.getConstantOperandVal(1));
+
+  // (shl (add X, X), C) -> (shl X, (C + 1))
+  if (Opcode == X86ISD::VSHLI && N0.getOpcode() == ISD::ADD &&
+      N0.getOperand(0) == N0.getOperand(1))
+    return MergeShifts(N0.getOperand(0), ShiftVal, 1);
 
   // We can decode 'whole byte' logical bit shifts as shuffles.
   if (LogicalShift && (ShiftVal % 8) == 0) {

diff --git a/llvm/test/CodeGen/X86/pmul.ll b/llvm/test/CodeGen/X86/pmul.ll
@@ -1356,8 +1356,7 @@ define <2 x i64> @pmuldq_square(<2 x i64> %x) {
 ; SSE2-NEXT:    psrlq $32, %xmm0
 ; SSE2-NEXT:    pmuludq %xmm1, %xmm0
 ; SSE2-NEXT:    pmuludq %xmm1, %xmm1
-; SSE2-NEXT:    paddq %xmm0, %xmm0
-; SSE2-NEXT:    psllq $32, %xmm0
+; SSE2-NEXT:    psllq $33, %xmm0
 ; SSE2-NEXT:    paddq %xmm1, %xmm0
 ; SSE2-NEXT:    retq
 ;

diff --git a/llvm/test/CodeGen/X86/udiv_fix_sat.ll b/llvm/test/CodeGen/X86/udiv_fix_sat.ll
@@ -311,73 +311,69 @@ define <4 x i32> @vec(<4 x i32> %x, <4 x i32> %y) nounwind {
 ; X64-LABEL: vec:
 ; X64:       # %bb.0:
 ; X64-NEXT:    pxor %xmm9, %xmm9
-; X64-NEXT:    movdqa %xmm1, %xmm2
-; X64-NEXT:    punpckhdq {{.*#+}} xmm2 = xmm2[2],xmm9[2],xmm2[3],xmm9[3]
-; X64-NEXT:    movq %xmm2, %rcx
-; X64-NEXT:    movdqa %xmm0, %xmm2
-; X64-NEXT:    punpckhdq {{.*#+}} xmm2 = xmm2[2],xmm9[2],xmm2[3],xmm9[3]
-; X64-NEXT:    paddq %xmm2, %xmm2
-; X64-NEXT:    psllq $31, %xmm2
-; X64-NEXT:    movq %xmm2, %rax
+; X64-NEXT:    pxor %xmm3, %xmm3
+; X64-NEXT:    punpckhdq {{.*#+}} xmm3 = xmm3[2],xmm0[2],xmm3[3],xmm0[3]
+; X64-NEXT:    movq %xmm3, %rax
+; X64-NEXT:    movdqa %xmm1, %xmm4
+; X64-NEXT:    punpckhdq {{.*#+}} xmm4 = xmm4[2],xmm9[2],xmm4[3],xmm9[3]
+; X64-NEXT:    movq %xmm4, %rcx
 ; X64-NEXT:    xorl %edx, %edx
 ; X64-NEXT:    divq %rcx
 ; X64-NEXT:    movq %rax, %xmm6
-; X64-NEXT:    pshufd {{.*#+}} xmm2 = xmm2[2,3,2,3]
-; X64-NEXT:    movq %xmm2, %rax
-; X64-NEXT:    movdqa %xmm1, %xmm2
-; X64-NEXT:    psrldq {{.*#+}} xmm2 = xmm2[12,13,14,15],zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero
-; X64-NEXT:    movq %xmm2, %rcx
+; X64-NEXT:    pshufd {{.*#+}} xmm3 = xmm3[2,3,2,3]
+; X64-NEXT:    movq %xmm3, %rax
+; X64-NEXT:    movdqa %xmm1, %xmm3
+; X64-NEXT:    psrldq {{.*#+}} xmm3 = xmm3[12,13,14,15],zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero
+; X64-NEXT:    movq %xmm3, %rcx
 ; X64-NEXT:    xorl %edx, %edx
 ; X64-NEXT:    divq %rcx
-; X64-NEXT:    movq %rax, %xmm2
-; X64-NEXT:    punpcklqdq {{.*#+}} xmm6 = xmm6[0],xmm2[0]
+; X64-NEXT:    movq %rax, %xmm3
+; X64-NEXT:    punpcklqdq {{.*#+}} xmm6 = xmm6[0],xmm3[0]
 ; X64-NEXT:    movdqa {{.*#+}} xmm10 = [9223372039002259456,9223372039002259456]
-; X64-NEXT:    movdqa %xmm6, %xmm2
-; X64-NEXT:    pxor %xmm10, %xmm2
-; X64-NEXT:    pshufd {{.*#+}} xmm7 = xmm2[1,1,3,3]
+; X64-NEXT:    movdqa %xmm6, %xmm3
+; X64-NEXT:    pxor %xmm10, %xmm3
+; X64-NEXT:    pshufd {{.*#+}} xmm7 = xmm3[1,1,3,3]
 ; X64-NEXT:    movdqa {{.*#+}} xmm8 = [2147483649,2147483649,2147483649,2147483649]
 ; X64-NEXT:    pcmpeqd %xmm8, %xmm7
-; X64-NEXT:    movdqa {{.*#+}} xmm4 = [9223372043297226751,9223372043297226751]
-; X64-NEXT:    movdqa %xmm4, %xmm5
-; X64-NEXT:    pcmpgtd %xmm2, %xmm5
-; X64-NEXT:    pshufd {{.*#+}} xmm3 = xmm5[0,0,2,2]
-; X64-NEXT:    pand %xmm7, %xmm3
-; X64-NEXT:    pshufd {{.*#+}} xmm2 = xmm5[1,1,3,3]
-; X64-NEXT:    por %xmm3, %xmm2
+; X64-NEXT:    movdqa {{.*#+}} xmm2 = [9223372043297226751,9223372043297226751]
+; X64-NEXT:    movdqa %xmm2, %xmm5
+; X64-NEXT:    pcmpgtd %xmm3, %xmm5
+; X64-NEXT:    pshufd {{.*#+}} xmm4 = xmm5[0,0,2,2]
+; X64-NEXT:    pand %xmm7, %xmm4
+; X64-NEXT:    pshufd {{.*#+}} xmm3 = xmm5[1,1,3,3]
+; X64-NEXT:    por %xmm4, %xmm3
 ; X64-NEXT:    movdqa {{.*#+}} xmm7 = [8589934591,8589934591]
-; X64-NEXT:    pand %xmm2, %xmm6
-; X64-NEXT:    pandn %xmm7, %xmm2
-; X64-NEXT:    por %xmm6, %xmm2
-; X64-NEXT:    psrlq $1, %xmm2
-; X64-NEXT:    punpckldq {{.*#+}} xmm0 = xmm0[0],xmm9[0],xmm0[1],xmm9[1]
-; X64-NEXT:    paddq %xmm0, %xmm0
-; X64-NEXT:    psllq $31, %xmm0
-; X64-NEXT:    movq %xmm0, %rax
+; X64-NEXT:    pand %xmm3, %xmm6
+; X64-NEXT:    pandn %xmm7, %xmm3
+; X64-NEXT:    por %xmm6, %xmm3
+; X64-NEXT:    psrlq $1, %xmm3
+; X64-NEXT:    punpckldq {{.*#+}} xmm9 = xmm9[0],xmm0[0],xmm9[1],xmm0[1]
+; X64-NEXT:    movq %xmm9, %rax
 ; X64-NEXT:    movd %xmm1, %ecx
 ; X64-NEXT:    xorl %edx, %edx
 ; X64-NEXT:    divq %rcx
-; X64-NEXT:    movq %rax, %xmm3
-; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[2,3,2,3]
+; X64-NEXT:    movq %rax, %xmm4
+; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm9[2,3,2,3]
 ; X64-NEXT:    movq %xmm0, %rax
 ; X64-NEXT:    psrlq $32, %xmm1
 ; X64-NEXT:    movq %xmm1, %rcx
 ; X64-NEXT:    xorl %edx, %edx
 ; X64-NEXT:    divq %rcx
 ; X64-NEXT:    movq %rax, %xmm0
-; X64-NEXT:    punpcklqdq {{.*#+}} xmm3 = xmm3[0],xmm0[0]
-; X64-NEXT:    pxor %xmm3, %xmm10
+; X64-NEXT:    punpcklqdq {{.*#+}} xmm4 = xmm4[0],xmm0[0]
+; X64-NEXT:    pxor %xmm4, %xmm10
 ; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm10[1,1,3,3]
 ; X64-NEXT:    pcmpeqd %xmm8, %xmm0
-; X64-NEXT:    pcmpgtd %xmm10, %xmm4
-; X64-NEXT:    pshufd {{.*#+}} xmm1 = xmm4[0,0,2,2]
+; X64-NEXT:    pcmpgtd %xmm10, %xmm2
+; X64-NEXT:    pshufd {{.*#+}} xmm1 = xmm2[0,0,2,2]
 ; X64-NEXT:    pand %xmm0, %xmm1
-; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm4[1,1,3,3]
+; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm2[1,1,3,3]
 ; X64-NEXT:    por %xmm1, %xmm0
-; X64-NEXT:    pand %xmm0, %xmm3
+; X64-NEXT:    pand %xmm0, %xmm4
 ; X64-NEXT:    pandn %xmm7, %xmm0
-; X64-NEXT:    por %xmm3, %xmm0
+; X64-NEXT:    por %xmm4, %xmm0
 ; X64-NEXT:    psrlq $1, %xmm0
-; X64-NEXT:    shufps {{.*#+}} xmm0 = xmm0[0,2],xmm2[0,2]
+; X64-NEXT:    shufps {{.*#+}} xmm0 = xmm0[0,2],xmm3[0,2]
 ; X64-NEXT:    retq
 ;
 ; X86-LABEL: vec: