[X86] Twist shuffle mask when fold HOP(SHUFFLE(X,Y),SHUFFLE(X,Y)) -> SHUFFLE(HOP(X,Y))

This patch fixes PR50823.

The shuffle mask should be twisted twice before gotten the correct one due to the difference between inner HOP and outer.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D104903

Author: phoebewang

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -43709,9 +43709,10 @@ static SDValue combineHorizOpWithShuffle(SDNode *N, SelectionDAG &DAG,
         ShuffleVectorSDNode::commuteMask(ScaledMask1);
       }
       if ((Op00 == Op10) && (Op01 == Op11)) {
-        SmallVector<int, 4> ShuffleMask;
-        ShuffleMask.append(ScaledMask0.begin(), ScaledMask0.end());
-        ShuffleMask.append(ScaledMask1.begin(), ScaledMask1.end());
+        const int Map[4] = {0, 2, 1, 3};
+        SmallVector<int, 4> ShuffleMask(
+            {Map[ScaledMask0[0]], Map[ScaledMask1[0]], Map[ScaledMask0[1]],
+             Map[ScaledMask1[1]]});
         MVT ShufVT = VT.isFloatingPoint() ? MVT::v4f64 : MVT::v4i64;
         SDValue Res = DAG.getNode(Opcode, DL, VT, DAG.getBitcast(SrcVT, Op00),
                                   DAG.getBitcast(SrcVT, Op01));

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

@@ -1169,7 +1169,7 @@ define <4 x double> @PR34724_add_v4f64_u123(<4 x double> %0, <4 x double> %1) {
 ; AVX512-FAST:       # %bb.0:
 ; AVX512-FAST-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX512-FAST-NEXT:    vhaddpd %ymm1, %ymm0, %ymm0
-; AVX512-FAST-NEXT:    vpermpd {{.*#+}} ymm0 = ymm0[0,2,0,3]
+; AVX512-FAST-NEXT:    vpermpd {{.*#+}} ymm0 = ymm0[0,0,1,3]
 ; AVX512-FAST-NEXT:    retq
   %3 = shufflevector <4 x double> %0, <4 x double> %1, <2 x i32> <i32 2, i32 4>
   %4 = shufflevector <4 x double> %0, <4 x double> %1, <2 x i32> <i32 3, i32 5>
@@ -1270,7 +1270,7 @@ define <4 x double> @PR34724_add_v4f64_01u3(<4 x double> %0, <4 x double> %1) {
 ; AVX512-FAST-LABEL: PR34724_add_v4f64_01u3:
 ; AVX512-FAST:       # %bb.0:
 ; AVX512-FAST-NEXT:    vhaddpd %ymm1, %ymm0, %ymm0
-; AVX512-FAST-NEXT:    vpermpd {{.*#+}} ymm0 = ymm0[0,3,1,3]
+; AVX512-FAST-NEXT:    vpermpd {{.*#+}} ymm0 = ymm0[0,2,3,3]
 ; AVX512-FAST-NEXT:    retq
   %3 = shufflevector <4 x double> %0, <4 x double> undef, <2 x i32> <i32 0, i32 2>
   %4 = shufflevector <4 x double> %0, <4 x double> undef, <2 x i32> <i32 1, i32 3>

llvm/test/CodeGen/X86/packss.ll

@@ -370,7 +370,7 @@ define <32 x i8> @packsswb_icmp_zero_trunc_256(<16 x i16> %a0) {
 ; AVX2-NEXT:    vpxor %xmm1, %xmm1, %xmm1
 ; AVX2-NEXT:    vpcmpeqw %ymm1, %ymm0, %ymm0
 ; AVX2-NEXT:    vpacksswb %ymm0, %ymm1, %ymm0
-; AVX2-NEXT:    vpermq {{.*#+}} ymm0 = ymm0[0,0,2,3]
+; AVX2-NEXT:    vpermq {{.*#+}} ymm0 = ymm0[0,1,0,3]
 ; AVX2-NEXT:    ret{{[l|q]}}
   %1 = icmp eq <16 x i16> %a0, zeroinitializer
   %2 = sext <16 x i1> %1 to <16 x i16>

llvm/test/CodeGen/X86/pr50823.ll

@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown -mcpu=core-avx2 | FileCheck %s
+
+%v8_uniform_FVector3 = type { float, float, float }
+
+declare <8 x float> @llvm.x86.avx.hadd.ps.256(<8 x float>, <8 x float>)
+
+define void @foo(%v8_uniform_FVector3* %Out, float* %In, <8 x i32> %__mask) {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %allocas
+; CHECK-NEXT:    vmovups (%rsi), %xmm0
+; CHECK-NEXT:    vhaddps 32(%rsi), %xmm0, %xmm0
+; CHECK-NEXT:    vpermpd {{.*#+}} ymm0 = ymm0[0,0,1,1]
+; CHECK-NEXT:    vhaddps %ymm0, %ymm0, %ymm0
+; CHECK-NEXT:    vextractf128 $1, %ymm0, %xmm1
+; CHECK-NEXT:    vaddss %xmm1, %xmm0, %xmm0
+; CHECK-NEXT:    vmovss %xmm0, (%rdi)
+; CHECK-NEXT:    vzeroupper
+; CHECK-NEXT:    retq
+allocas:
+  %ptr_cast_for_load = bitcast float* %In to <8 x float>*
+  %ptr_masked_load74 = load <8 x float>, <8 x float>* %ptr_cast_for_load, align 4
+  %ptr8096 = getelementptr float, float* %In, i64 8
+  %ptr_cast_for_load81 = bitcast float* %ptr8096 to <8 x float>*
+  %ptr80_masked_load82 = load <8 x float>, <8 x float>* %ptr_cast_for_load81, align 4
+  %ret_7.i.i = shufflevector <8 x float> %ptr_masked_load74, <8 x float> %ptr80_masked_load82, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 10, i32 11>
+  %Out_load19 = getelementptr %v8_uniform_FVector3, %v8_uniform_FVector3* %Out, i64 0, i32 0
+  %v1.i.i100 = tail call <8 x float> @llvm.x86.avx.hadd.ps.256(<8 x float> %ret_7.i.i, <8 x float> %ret_7.i.i)
+  %v2.i.i101 = tail call <8 x float> @llvm.x86.avx.hadd.ps.256(<8 x float> %v1.i.i100, <8 x float> %v1.i.i100)
+  %scalar1.i.i102 = extractelement <8 x float> %v2.i.i101, i32 0
+  %scalar2.i.i103 = extractelement <8 x float> %v2.i.i101, i32 4
+  %sum.i.i104 = fadd float %scalar1.i.i102, %scalar2.i.i103
+  store float %sum.i.i104, float* %Out_load19, align 4
+  ret void
+}