[DAG] Fold shuffle(bop(shuffle(x,y),shuffle(z,w)),undef) -> bop(shuffle'(x,y),shuffle'(z,w)

[RKSimon]

Summary

Followup to D96345, handle unary shuffles of binops (as well as binary shuffles) if we can merge the shuffle with inner operand shuffles.

[RKSimon]

any comments?

[pengfei]

I had a check on the tests, the changes should all be correct. LGTM.

llvm/test/CodeGen/X86/haddsub-shuf.ll

524

Though it's not related to this change, but should it be vphaddd %xmm1, %xmm1, %xmm1?

[pengfei]

llvm/test/CodeGen/X86/haddsub-shuf.ll

524

It's correct. Sorry for the noise.

[RKSimon]

llvm/test/CodeGen/X86/haddsub-shuf.ll

524

No worries - thanks for the review!

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

                                       SV0 ? SV0 : DAG.getUNDEF(VT),
                                       SV1 ? SV1 : DAG.getUNDEF(VT), Mask);
         }
       }
     }
 
     // Merge shuffles through binops if we are able to merge it with at least
     // one other shuffles.
+    // shuffle(bop(shuffle(x,y),shuffle(z,w)),undef)
     // shuffle(bop(shuffle(x,y),shuffle(z,w)),bop(shuffle(a,b),shuffle(c,d)))
     unsigned SrcOpcode = N0.getOpcode();
-    if (SrcOpcode == N1.getOpcode() && TLI.isBinOp(SrcOpcode) &&
-        N->isOnlyUserOf(N0.getNode()) && N->isOnlyUserOf(N1.getNode())) {
+    if (TLI.isBinOp(SrcOpcode) && N->isOnlyUserOf(N0.getNode()) &&
+        (N1.isUndef() ||
+         (SrcOpcode == N1.getOpcode() && N->isOnlyUserOf(N1.getNode())))) {
+      // Get binop source ops, or just pass on the undef.
       SDValue Op00 = N0.getOperand(0);
-      SDValue Op10 = N1.getOperand(0);
       SDValue Op01 = N0.getOperand(1);
-      SDValue Op11 = N1.getOperand(1);
+      SDValue Op10 = N1.isUndef() ? N1 : N1.getOperand(0);
+      SDValue Op11 = N1.isUndef() ? N1 : N1.getOperand(1);
       // TODO: We might be able to relax the VT check but we don't currently
       // have any isBinOp() that has different result/ops VTs so play safe until
       // we have test coverage.
       if (Op00.getValueType() == VT && Op10.getValueType() == VT &&
           Op01.getValueType() == VT && Op11.getValueType() == VT &&
           (Op00.getOpcode() == ISD::VECTOR_SHUFFLE ||
            Op10.getOpcode() == ISD::VECTOR_SHUFFLE ||
            Op01.getOpcode() == ISD::VECTOR_SHUFFLE ||

llvm/test/CodeGen/X86/haddsub-4.ll

; AVX2-NEXT:    retq
   %rhs = shufflevector <8 x float> %shuf0, <8 x float> %shuf1, <8 x i32> <i32 1, i32 3, i32 9, i32 11, i32 5, i32 7, i32 13, i32 15>
   %add = fadd <8 x float> %lhs, %rhs
   ret <8 x float> %add
 }
 
 define <8 x float> @hadd_reverse3_v8f32(<8 x float> %a0, <8 x float> %a1) {
 ; SSE-LABEL: hadd_reverse3_v8f32:
 ; SSE:       # %bb.0:
-; SSE-NEXT:    movaps %xmm0, %xmm4
-; SSE-NEXT:    haddps %xmm2, %xmm4
-; SSE-NEXT:    haddps %xmm3, %xmm1
-; SSE-NEXT:    shufps {{.*#+}} xmm1 = xmm1[3,2,1,0]
-; SSE-NEXT:    shufps {{.*#+}} xmm4 = xmm4[3,2,1,0]
-; SSE-NEXT:    movaps %xmm1, %xmm0
-; SSE-NEXT:    movaps %xmm4, %xmm1
+; SSE-NEXT:    haddps %xmm1, %xmm3
+; SSE-NEXT:    shufps {{.*#+}} xmm3 = xmm3[1,0,3,2]
+; SSE-NEXT:    haddps %xmm0, %xmm2
+; SSE-NEXT:    shufps {{.*#+}} xmm2 = xmm2[1,0,3,2]
+; SSE-NEXT:    movaps %xmm3, %xmm0
+; SSE-NEXT:    movaps %xmm2, %xmm1
 ; SSE-NEXT:    retq
 ;
 ; AVX1-LABEL: hadd_reverse3_v8f32:
 ; AVX1:       # %bb.0:
-; AVX1-NEXT:    vhaddps %ymm1, %ymm0, %ymm0
+; AVX1-NEXT:    vhaddps %ymm0, %ymm1, %ymm0
 ; AVX1-NEXT:    vperm2f128 {{.*#+}} ymm0 = ymm0[2,3,0,1]
-; AVX1-NEXT:    vpermilps {{.*#+}} ymm0 = ymm0[3,2,1,0,7,6,5,4]
+; AVX1-NEXT:    vpermilps {{.*#+}} ymm0 = ymm0[1,0,3,2,5,4,7,6]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: hadd_reverse3_v8f32:
 ; AVX2:       # %bb.0:
-; AVX2-NEXT:    vhaddps %ymm1, %ymm0, %ymm0
-; AVX2-NEXT:    vpermilps {{.*#+}} ymm0 = ymm0[3,2,1,0,7,6,5,4]
+; AVX2-NEXT:    vhaddps %ymm0, %ymm1, %ymm0
+; AVX2-NEXT:    vpermilps {{.*#+}} ymm0 = ymm0[1,0,3,2,5,4,7,6]
 ; AVX2-NEXT:    vpermpd {{.*#+}} ymm0 = ymm0[2,3,0,1]
 ; AVX2-NEXT:    retq
   %shuf0 = shufflevector <8 x float> %a0, <8 x float> %a1, <8 x i32> <i32 0, i32 2, i32 8, i32 10, i32 4, i32 6, i32 12, i32 14>
   %shuf1 = shufflevector <8 x float> %a0, <8 x float> %a1, <8 x i32> <i32 1, i32 3, i32 9, i32 11, i32 5, i32 7, i32 13, i32 15>
   %add = fadd <8 x float> %shuf0, %shuf1
   %shuf2 = shufflevector <8 x float> %add, <8 x float> poison, <8 x i32> <i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
   ret <8 x float> %shuf2
 }

llvm/test/CodeGen/X86/haddsub-shuf.ll

 ; SSSE3-LABEL: hadd_v8i32b:
 ; SSSE3:       # %bb.0:
 ; SSSE3-NEXT:    phaddd %xmm0, %xmm0
 ; SSSE3-NEXT:    phaddd %xmm1, %xmm1
 ; SSSE3-NEXT:    retq
 ;
 ; AVX1-LABEL: hadd_v8i32b:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vphaddd %xmm0, %xmm0, %xmm1
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX1-NEXT:    vphaddd %xmm0, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm1, %ymm0
-; AVX1-NEXT:    vmovddup {{.*#+}} ymm0 = ymm0[0,0,2,2]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: hadd_v8i32b:
 ; AVX2:       # %bb.0:
 ; AVX2-NEXT:    vphaddd %ymm0, %ymm0, %ymm0
 ; AVX2-NEXT:    retq
   %a0 = shufflevector <8 x i32> %a, <8 x i32> undef, <8 x i32> <i32 0, i32 2, i32 undef, i32 undef, i32 4, i32 6, i32 undef, i32 undef>
   %a1 = shufflevector <8 x i32> %a, <8 x i32> undef, <8 x i32> <i32 1, i32 3, i32 undef, i32 undef, i32 5, i32 7, i32 undef, i32 undef>

 ; SSSE3-NEXT:    retq
 ;
 ; AVX1-LABEL: hsub_v8i32b:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vphsubd %xmm0, %xmm0, %xmm1
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX1-NEXT:    vphsubd %xmm0, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm1, %ymm0
-; AVX1-NEXT:    vmovddup {{.*#+}} ymm0 = ymm0[0,0,2,2]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: hsub_v8i32b:
 ; AVX2:       # %bb.0:
 ; AVX2-NEXT:    vphsubd %ymm0, %ymm0, %ymm0
 ; AVX2-NEXT:    retq
   %a0 = shufflevector <8 x i32> %a, <8 x i32> undef, <8 x i32> <i32 0, i32 2, i32 undef, i32 undef, i32 4, i32 6, i32 undef, i32 undef>
   %a1 = shufflevector <8 x i32> %a, <8 x i32> undef, <8 x i32> <i32 1, i32 3, i32 undef, i32 undef, i32 5, i32 7, i32 undef, i32 undef>

 ; SSSE3-NEXT:    retq
 ;
 ; AVX1-LABEL: hadd_v16i16b:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vphaddw %xmm0, %xmm0, %xmm1
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX1-NEXT:    vphaddw %xmm0, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm1, %ymm0
-; AVX1-NEXT:    vmovddup {{.*#+}} ymm0 = ymm0[0,0,2,2]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: hadd_v16i16b:
 ; AVX2:       # %bb.0:
 ; AVX2-NEXT:    vphaddw %ymm0, %ymm0, %ymm0
 ; AVX2-NEXT:    retq
   %a0 = shufflevector <16 x i16> %a, <16 x i16> undef, <16 x i32> <i32 0, i32 2, i32 4, i32 6, i32 undef, i32 undef, i32 undef, i32 undef, i32 8, i32 10, i32 12, i32 14, i32 undef, i32 undef, i32 undef, i32 undef>
   %a1 = shufflevector <16 x i16> %a, <16 x i16> undef, <16 x i32> <i32 1, i32 3, i32 5, i32 7, i32 undef, i32 undef, i32 undef, i32 undef, i32 9, i32 11, i32 13, i32 15, i32 undef, i32 undef, i32 undef, i32 undef>

 ; SSSE3-NEXT:    retq
 ;
 ; AVX1-LABEL: hsub_v16i16b:
 ; AVX1:       # %bb.0:
 ; AVX1-NEXT:    vphsubw %xmm0, %xmm0, %xmm1
 ; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX1-NEXT:    vphsubw %xmm0, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm1, %ymm0
-; AVX1-NEXT:    vmovddup {{.*#+}} ymm0 = ymm0[0,0,2,2]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: hsub_v16i16b:
 ; AVX2:       # %bb.0:
 ; AVX2-NEXT:    vphsubw %ymm0, %ymm0, %ymm0
 ; AVX2-NEXT:    retq
   %a0 = shufflevector <16 x i16> %a, <16 x i16> undef, <16 x i32> <i32 0, i32 2, i32 4, i32 6, i32 undef, i32 undef, i32 undef, i32 undef, i32 8, i32 10, i32 12, i32 14, i32 undef, i32 undef, i32 undef, i32 undef>
   %a1 = shufflevector <16 x i16> %a, <16 x i16> undef, <16 x i32> <i32 1, i32 3, i32 5, i32 7, i32 undef, i32 undef, i32 undef, i32 undef, i32 9, i32 11, i32 13, i32 15, i32 undef, i32 undef, i32 undef, i32 undef>

llvm/test/CodeGen/X86/known-signbits-vector.ll

; X64-AVX2-NEXT:    retq
   ret <4 x float> %6
 }
 
 define <4 x i32> @signbits_mask_ashr_smax(<4 x i32> %a0, <4 x i32> %a1) {
 ; X86-LABEL: signbits_mask_ashr_smax:
 ; X86:       # %bb.0:
 ; X86-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X86-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X86-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpmaxsd %xmm1, %xmm0, %xmm0
+; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpand {{\.LCPI.*}}, %xmm0, %xmm0
 ; X86-NEXT:    retl
 ;
 ; X64-AVX1-LABEL: signbits_mask_ashr_smax:
 ; X64-AVX1:       # %bb.0:
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpmaxsd %xmm1, %xmm0, %xmm0
+; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpand {{.*}}(%rip), %xmm0, %xmm0
 ; X64-AVX1-NEXT:    retq
 ;
 ; X64-AVX2-LABEL: signbits_mask_ashr_smax:
 ; X64-AVX2:       # %bb.0:
 ; X64-AVX2-NEXT:    vmovdqa {{.*#+}} xmm2 = [25,26,27,0]
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm0, %xmm0
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm1, %xmm1

 }
 declare <4 x i32> @llvm.smax.v4i32(<4 x i32>, <4 x i32>) nounwind readnone
 
 define <4 x i32> @signbits_mask_ashr_smin(<4 x i32> %a0, <4 x i32> %a1) {
 ; X86-LABEL: signbits_mask_ashr_smin:
 ; X86:       # %bb.0:
 ; X86-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X86-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X86-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpminsd %xmm1, %xmm0, %xmm0
+; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpand {{\.LCPI.*}}, %xmm0, %xmm0
 ; X86-NEXT:    retl
 ;
 ; X64-AVX1-LABEL: signbits_mask_ashr_smin:
 ; X64-AVX1:       # %bb.0:
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpminsd %xmm1, %xmm0, %xmm0
+; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpand {{.*}}(%rip), %xmm0, %xmm0
 ; X64-AVX1-NEXT:    retq
 ;
 ; X64-AVX2-LABEL: signbits_mask_ashr_smin:
 ; X64-AVX2:       # %bb.0:
 ; X64-AVX2-NEXT:    vmovdqa {{.*#+}} xmm2 = [25,26,27,0]
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm0, %xmm0
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm1, %xmm1

 }
 declare <4 x i32> @llvm.smin.v4i32(<4 x i32>, <4 x i32>) nounwind readnone
 
 define <4 x i32> @signbits_mask_ashr_umax(<4 x i32> %a0, <4 x i32> %a1) {
 ; X86-LABEL: signbits_mask_ashr_umax:
 ; X86:       # %bb.0:
 ; X86-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X86-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X86-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpmaxud %xmm1, %xmm0, %xmm0
+; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpand {{\.LCPI.*}}, %xmm0, %xmm0
 ; X86-NEXT:    retl
 ;
 ; X64-AVX1-LABEL: signbits_mask_ashr_umax:
 ; X64-AVX1:       # %bb.0:
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpmaxud %xmm1, %xmm0, %xmm0
+; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpand {{.*}}(%rip), %xmm0, %xmm0
 ; X64-AVX1-NEXT:    retq
 ;
 ; X64-AVX2-LABEL: signbits_mask_ashr_umax:
 ; X64-AVX2:       # %bb.0:
 ; X64-AVX2-NEXT:    vmovdqa {{.*#+}} xmm2 = [25,26,27,0]
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm0, %xmm0
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm1, %xmm1

 }
 declare <4 x i32> @llvm.umax.v4i32(<4 x i32>, <4 x i32>) nounwind readnone
 
 define <4 x i32> @signbits_mask_ashr_umin(<4 x i32> %a0, <4 x i32> %a1) {
 ; X86-LABEL: signbits_mask_ashr_umin:
 ; X86:       # %bb.0:
 ; X86-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X86-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X86-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpminud %xmm1, %xmm0, %xmm0
+; X86-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X86-NEXT:    vpand {{\.LCPI.*}}, %xmm0, %xmm0
 ; X86-NEXT:    retl
 ;
 ; X64-AVX1-LABEL: signbits_mask_ashr_umin:
 ; X64-AVX1:       # %bb.0:
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm0, %xmm0
 ; X64-AVX1-NEXT:    vpsrad $25, %xmm1, %xmm1
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm1 = xmm1[0,0,0,0]
-; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpminud %xmm1, %xmm0, %xmm0
+; X64-AVX1-NEXT:    vpshufd {{.*#+}} xmm0 = xmm0[0,0,0,0]
 ; X64-AVX1-NEXT:    vpand {{.*}}(%rip), %xmm0, %xmm0
 ; X64-AVX1-NEXT:    retq
 ;
 ; X64-AVX2-LABEL: signbits_mask_ashr_umin:
 ; X64-AVX2:       # %bb.0:
 ; X64-AVX2-NEXT:    vmovdqa {{.*#+}} xmm2 = [25,26,27,0]
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm0, %xmm0
 ; X64-AVX2-NEXT:    vpsravd %xmm2, %xmm1, %xmm1