[llvm] b8b5e87 - [X86][AVX] Handle vperm2x128 shuffling of a subvector splat.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2021-01-20T18:16:33Z
New Revision: b8b5e87e6b8102d77e4e6beccf4e0f0237acc897

URL: https://github.com/llvm/llvm-project/commit/b8b5e87e6b8102d77e4e6beccf4e0f0237acc897
DIFF: https://github.com/llvm/llvm-project/commit/b8b5e87e6b8102d77e4e6beccf4e0f0237acc897.diff

LOG: [X86][AVX] Handle vperm2x128 shuffling of a subvector splat.

We already handle "vperm2x128 (ins ?, X, C1), (ins ?, X, C1), 0x31" for shuffling of the upper subvectors, but we weren't dealing with the case when we were splatting the upper subvector from a single source.

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp
    llvm/test/CodeGen/X86/avx-vperm2x128.ll
    llvm/test/CodeGen/X86/vector-shuffle-256-v8.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 0b52b2021c73..852078a299b9 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -37324,6 +37324,14 @@ static SDValue combineTargetShuffle(SDValue N, SelectionDAG &DAG,
     SDValue Ins1 = peekThroughBitcasts(N.getOperand(1));
     unsigned Imm = N.getConstantOperandVal(2);
 
+    // Handle subvector splat by tweaking values to match binary concat.
+    // vperm2x128 (ins ?, X, C1), undef, 0x11 ->
+    // vperm2x128 (ins ?, X, C1), (ins ?, X, C1), 0x31 -> concat X, X
+    if (Imm == 0x11 && Ins1.isUndef()) {
+      Imm = 0x31;
+      Ins1 = Ins0;
+    }
+
     if (!(Imm == 0x31 &&
           Ins0.getOpcode() == ISD::INSERT_SUBVECTOR &&
           Ins1.getOpcode() == ISD::INSERT_SUBVECTOR &&

diff  --git a/llvm/test/CodeGen/X86/avx-vperm2x128.ll b/llvm/test/CodeGen/X86/avx-vperm2x128.ll
index a519f55aaafe..bfab2f186bf5 100644
--- a/llvm/test/CodeGen/X86/avx-vperm2x128.ll
+++ b/llvm/test/CodeGen/X86/avx-vperm2x128.ll
@@ -130,7 +130,6 @@ define <32 x i8> @shuffle_v32i8_2323_domain(<32 x i8> %a, <32 x i8> %b) nounwind
 ; AVX1-NEXT:    vpcmpeqd %xmm1, %xmm1, %xmm1
 ; AVX1-NEXT:    vpsubb %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm0, %ymm0
-; AVX1-NEXT:    vperm2f128 {{.*#+}} ymm0 = ymm0[2,3,2,3]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2-LABEL: shuffle_v32i8_2323_domain:

diff  --git a/llvm/test/CodeGen/X86/vector-shuffle-256-v8.ll b/llvm/test/CodeGen/X86/vector-shuffle-256-v8.ll
index f1af4faf67e2..5f2a3cd72b71 100644
--- a/llvm/test/CodeGen/X86/vector-shuffle-256-v8.ll
+++ b/llvm/test/CodeGen/X86/vector-shuffle-256-v8.ll
@@ -3098,14 +3098,13 @@ entry:
 define <8 x i32> @add_v8i32_02468ACE_13579BDF(<8 x i32> %a, <8 x i32> %b) {
 ; AVX1-LABEL: add_v8i32_02468ACE_13579BDF:
 ; AVX1:       # %bb.0: # %entry
-; AVX1-NEXT:    vphaddd %xmm1, %xmm0, %xmm2
+; AVX1-NEXT:    vextractf128 $1, %ymm1, %xmm2
+; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm3
+; AVX1-NEXT:    vphaddd %xmm2, %xmm3, %xmm2
 ; AVX1-NEXT:    vinsertf128 $1, %xmm2, %ymm2, %ymm2
-; AVX1-NEXT:    vextractf128 $1, %ymm1, %xmm1
-; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX1-NEXT:    vphaddd %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm0, %ymm0
-; AVX1-NEXT:    vperm2f128 {{.*#+}} ymm0 = ymm0[2,3,2,3]
-; AVX1-NEXT:    vshufpd {{.*#+}} ymm0 = ymm2[0],ymm0[0],ymm2[3],ymm0[3]
+; AVX1-NEXT:    vshufpd {{.*#+}} ymm0 = ymm0[0],ymm2[0],ymm0[3],ymm2[3]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2OR512VL-LABEL: add_v8i32_02468ACE_13579BDF:
@@ -3123,14 +3122,13 @@ entry:
 define <8 x i32> @add_v8i32_8ACE0246_9BDF1357(<8 x i32> %a, <8 x i32> %b) {
 ; AVX1-LABEL: add_v8i32_8ACE0246_9BDF1357:
 ; AVX1:       # %bb.0: # %entry
-; AVX1-NEXT:    vphaddd %xmm1, %xmm0, %xmm2
+; AVX1-NEXT:    vextractf128 $1, %ymm1, %xmm2
+; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm3
+; AVX1-NEXT:    vphaddd %xmm2, %xmm3, %xmm2
 ; AVX1-NEXT:    vinsertf128 $1, %xmm2, %ymm2, %ymm2
-; AVX1-NEXT:    vextractf128 $1, %ymm1, %xmm1
-; AVX1-NEXT:    vextractf128 $1, %ymm0, %xmm0
 ; AVX1-NEXT:    vphaddd %xmm1, %xmm0, %xmm0
 ; AVX1-NEXT:    vinsertf128 $1, %xmm0, %ymm0, %ymm0
-; AVX1-NEXT:    vperm2f128 {{.*#+}} ymm0 = ymm0[2,3,2,3]
-; AVX1-NEXT:    vshufpd {{.*#+}} ymm0 = ymm2[1],ymm0[1],ymm2[2],ymm0[2]
+; AVX1-NEXT:    vshufpd {{.*#+}} ymm0 = ymm0[1],ymm2[1],ymm0[2],ymm2[2]
 ; AVX1-NEXT:    retq
 ;
 ; AVX2OR512VL-LABEL: add_v8i32_8ACE0246_9BDF1357: