[llvm] 520562c - Revert 412d59f0a510a05c08ed45545943dfd2f901bc5d "[DAG] combineShiftToMULH - handle zext nneg as sext"

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2024-10-01T10:52:27+01:00
New Revision: 520562c597a0a1d3056cf75b648c4192f77582ec

URL: https://github.com/llvm/llvm-project/commit/520562c597a0a1d3056cf75b648c4192f77582ec
DIFF: https://github.com/llvm/llvm-project/commit/520562c597a0a1d3056cf75b648c4192f77582ec.diff

LOG: Revert 412d59f0a510a05c08ed45545943dfd2f901bc5d "[DAG] combineShiftToMULH - handle zext nneg as sext"

Reverting until I can investigate a miscompilation reported by @mstorsjo

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/test/CodeGen/X86/pmulh.ll

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 65a620b70d8f0c..c6f6fc25080541 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -10287,10 +10287,8 @@ static SDValue combineShiftToMULH(SDNode *N, const SDLoc &DL, SelectionDAG &DAG,
   SDValue LeftOp = ShiftOperand.getOperand(0);
   SDValue RightOp = ShiftOperand.getOperand(1);
 
-  // Treat zext nneg as sext - we might need to support handling these as zext
-  // as well in the future, but for now just prefer sext.
-  bool IsSignExt = sd_match(LeftOp, m_SExtLike(m_Value()));
-  bool IsZeroExt = sd_match(LeftOp, m_ZExt(m_Value()));
+  bool IsSignExt = LeftOp.getOpcode() == ISD::SIGN_EXTEND;
+  bool IsZeroExt = LeftOp.getOpcode() == ISD::ZERO_EXTEND;
 
   if (!IsSignExt && !IsZeroExt)
     return SDValue();

diff  --git a/llvm/test/CodeGen/X86/pmulh.ll b/llvm/test/CodeGen/X86/pmulh.ll
index 4e9ce012aff219..300da68d9a3b34 100644
--- a/llvm/test/CodeGen/X86/pmulh.ll
+++ b/llvm/test/CodeGen/X86/pmulh.ll
@@ -953,15 +953,39 @@ define void @PR109790(ptr sret([32 x i8]) %ret, ptr %a) {
 ; SSE-NEXT:    movdqa %xmm0, 16(%rdi)
 ; SSE-NEXT:    retq
 ;
-; AVX-LABEL: PR109790:
-; AVX:       # %bb.0:
-; AVX-NEXT:    movq %rdi, %rax
-; AVX-NEXT:    vmovdqa (%rsi), %ymm0
-; AVX-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0
-; AVX-NEXT:    vpmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0 # [64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536]
-; AVX-NEXT:    vmovdqa %ymm0, (%rdi)
-; AVX-NEXT:    vzeroupper
-; AVX-NEXT:    retq
+; AVX2-LABEL: PR109790:
+; AVX2:       # %bb.0:
+; AVX2-NEXT:    movq %rdi, %rax
+; AVX2-NEXT:    vmovdqa (%rsi), %ymm0
+; AVX2-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0
+; AVX2-NEXT:    vpmulhw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0 # [64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536,64536]
+; AVX2-NEXT:    vmovdqa %ymm0, (%rdi)
+; AVX2-NEXT:    vzeroupper
+; AVX2-NEXT:    retq
+;
+; AVX512F-LABEL: PR109790:
+; AVX512F:       # %bb.0:
+; AVX512F-NEXT:    movq %rdi, %rax
+; AVX512F-NEXT:    vmovdqa (%rsi), %ymm0
+; AVX512F-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0
+; AVX512F-NEXT:    vpmovzxwd {{.*#+}} zmm0 = ymm0[0],zero,ymm0[1],zero,ymm0[2],zero,ymm0[3],zero,ymm0[4],zero,ymm0[5],zero,ymm0[6],zero,ymm0[7],zero,ymm0[8],zero,ymm0[9],zero,ymm0[10],zero,ymm0[11],zero,ymm0[12],zero,ymm0[13],zero,ymm0[14],zero,ymm0[15],zero
+; AVX512F-NEXT:    vpmulld {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to16}, %zmm0, %zmm0
+; AVX512F-NEXT:    vpsrld $16, %zmm0, %zmm0
+; AVX512F-NEXT:    vpmovdw %zmm0, (%rdi)
+; AVX512F-NEXT:    vzeroupper
+; AVX512F-NEXT:    retq
+;
+; AVX512BW-LABEL: PR109790:
+; AVX512BW:       # %bb.0:
+; AVX512BW-NEXT:    movq %rdi, %rax
+; AVX512BW-NEXT:    vmovdqa (%rsi), %ymm0
+; AVX512BW-NEXT:    vpand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %ymm0, %ymm0
+; AVX512BW-NEXT:    vpmovzxwd {{.*#+}} zmm0 = ymm0[0],zero,ymm0[1],zero,ymm0[2],zero,ymm0[3],zero,ymm0[4],zero,ymm0[5],zero,ymm0[6],zero,ymm0[7],zero,ymm0[8],zero,ymm0[9],zero,ymm0[10],zero,ymm0[11],zero,ymm0[12],zero,ymm0[13],zero,ymm0[14],zero,ymm0[15],zero
+; AVX512BW-NEXT:    vpmaddwd {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %zmm0, %zmm0 # [64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0,64536,0]
+; AVX512BW-NEXT:    vpsrld $16, %zmm0, %zmm0
+; AVX512BW-NEXT:    vpmovdw %zmm0, (%rdi)
+; AVX512BW-NEXT:    vzeroupper
+; AVX512BW-NEXT:    retq
   %load = load <16 x i16>, ptr %a, align 32
   %and = and <16 x i16> %load, <i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767, i16 32767>
   %ext = zext nneg <16 x i16> %and to <16 x i32>