[llvm] [X86] combineConcatVectorOps - convert PSHUFB/PSADBW/VPMADDUBSW/VPMADDUBSW concatenation to use combineConcatVectorOps recursion (PR #130592)
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Mon Mar 10 05:37:15 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-x86
Author: Simon Pilgrim (RKSimon)
<details>
<summary>Changes</summary>
Only concatenate nodes if at least one operand is beneficial to concatenate
---
Full diff: https://github.com/llvm/llvm-project/pull/130592.diff
3 Files Affected:
- (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+7-3)
- (modified) llvm/test/CodeGen/X86/combine-pmadd.ll (+7-11)
- (modified) llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll (+4-6)
``````````diff
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index ccd7f2418fcd1..3bfd902b7a83b 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -58095,9 +58095,13 @@ static SDValue combineConcatVectorOps(const SDLoc &DL, MVT VT,
MVT SrcVT = Op0.getOperand(0).getSimpleValueType();
SrcVT = MVT::getVectorVT(SrcVT.getScalarType(),
NumOps * SrcVT.getVectorNumElements());
- return DAG.getNode(Op0.getOpcode(), DL, VT,
- ConcatSubOperand(SrcVT, Ops, 0),
- ConcatSubOperand(SrcVT, Ops, 1));
+ SDValue Concat0 = CombineSubOperand(SrcVT, Ops, 0);
+ SDValue Concat1 = CombineSubOperand(SrcVT, Ops, 1);
+ if (Concat0 || Concat1)
+ return DAG.getNode(
+ Op0.getOpcode(), DL, VT,
+ Concat0 ? Concat0 : ConcatSubOperand(SrcVT, Ops, 0),
+ Concat1 ? Concat1 : ConcatSubOperand(SrcVT, Ops, 1));
}
break;
case X86ISD::VPERMV:
diff --git a/llvm/test/CodeGen/X86/combine-pmadd.ll b/llvm/test/CodeGen/X86/combine-pmadd.ll
index 242dfb030d2f8..d9283aa8591fc 100644
--- a/llvm/test/CodeGen/X86/combine-pmadd.ll
+++ b/llvm/test/CodeGen/X86/combine-pmadd.ll
@@ -51,11 +51,9 @@ define <8 x i32> @combine_pmaddwd_concat(<8 x i16> %a0, <8 x i16> %a1, <8 x i16>
;
; AVX2-LABEL: combine_pmaddwd_concat:
; AVX2: # %bb.0:
-; AVX2-NEXT: # kill: def $xmm1 killed $xmm1 def $ymm1
-; AVX2-NEXT: # kill: def $xmm0 killed $xmm0 def $ymm0
-; AVX2-NEXT: vinserti128 $1, %xmm3, %ymm1, %ymm1
-; AVX2-NEXT: vinserti128 $1, %xmm2, %ymm0, %ymm0
-; AVX2-NEXT: vpmaddwd %ymm1, %ymm0, %ymm0
+; AVX2-NEXT: vpmaddwd %xmm1, %xmm0, %xmm0
+; AVX2-NEXT: vpmaddwd %xmm3, %xmm2, %xmm1
+; AVX2-NEXT: vinserti128 $1, %xmm1, %ymm0, %ymm0
; AVX2-NEXT: retq
%1 = call <4 x i32> @llvm.x86.sse2.pmadd.wd(<8 x i16> %a0, <8 x i16> %a1)
%2 = call <4 x i32> @llvm.x86.sse2.pmadd.wd(<8 x i16> %a2, <8 x i16> %a3)
@@ -209,7 +207,7 @@ define <16 x i16> @combine_pmaddubsw_concat(<32 x i8> %a0, <32 x i8> %a1) {
ret <16 x i16> %res
}
-; TODO: Not beneficial to concatenate both inputs just to create a 256-bit pmaddubsw
+; Not beneficial to concatenate both inputs just to create a 256-bit pmaddubsw
define <16 x i16> @combine_pmaddubsw_concat_unecessary(<16 x i8> %a0, <16 x i8> %a1, <16 x i8> %a2, <16 x i8> %a3) {
; SSE-LABEL: combine_pmaddubsw_concat_unecessary:
; SSE: # %bb.0:
@@ -227,11 +225,9 @@ define <16 x i16> @combine_pmaddubsw_concat_unecessary(<16 x i8> %a0, <16 x i8>
;
; AVX2-LABEL: combine_pmaddubsw_concat_unecessary:
; AVX2: # %bb.0:
-; AVX2-NEXT: # kill: def $xmm1 killed $xmm1 def $ymm1
-; AVX2-NEXT: # kill: def $xmm0 killed $xmm0 def $ymm0
-; AVX2-NEXT: vinserti128 $1, %xmm3, %ymm1, %ymm1
-; AVX2-NEXT: vinserti128 $1, %xmm2, %ymm0, %ymm0
-; AVX2-NEXT: vpmaddubsw %ymm1, %ymm0, %ymm0
+; AVX2-NEXT: vpmaddubsw %xmm1, %xmm0, %xmm0
+; AVX2-NEXT: vpmaddubsw %xmm3, %xmm2, %xmm1
+; AVX2-NEXT: vinserti128 $1, %xmm1, %ymm0, %ymm0
; AVX2-NEXT: retq
%1 = call <8 x i16> @llvm.x86.ssse3.pmadd.ub.sw.128(<16 x i8> %a0, <16 x i8> %a1)
%2 = call <8 x i16> @llvm.x86.ssse3.pmadd.ub.sw.128(<16 x i8> %a2, <16 x i8> %a3)
diff --git a/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll b/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll
index 65358c3ac7a3c..b18a32d7d0459 100644
--- a/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll
+++ b/llvm/test/CodeGen/X86/vector-shuffle-combining-avx2.ll
@@ -806,15 +806,13 @@ define <32 x i8> @concat_packsr_unnecessary(<8 x i16> %a0, <8 x i16> %a1, <8 x i
}
declare <16 x i8> @llvm.x86.sse2.packsswb.128(<8 x i16>, <8 x i16>)
-; TODO: Not beneficial to concatenate both inputs just to create a 256-bit pshufb
+; Not beneficial to concatenate both inputs just to create a 256-bit pshufb
define <32 x i8> @concat_pshufb_unnecessary(<16 x i8> %a0, <16 x i8> %a1, <16 x i8> %a2) nounwind {
; CHECK-LABEL: concat_pshufb_unnecessary:
; CHECK: # %bb.0:
-; CHECK-NEXT: # kill: def $xmm1 killed $xmm1 def $ymm1
-; CHECK-NEXT: # kill: def $xmm0 killed $xmm0 def $ymm0
-; CHECK-NEXT: vinserti128 $1, %xmm2, %ymm1, %ymm1
-; CHECK-NEXT: vinserti128 $1, %xmm0, %ymm0, %ymm0
-; CHECK-NEXT: vpshufb %ymm1, %ymm0, %ymm0
+; CHECK-NEXT: vpshufb %xmm1, %xmm0, %xmm1
+; CHECK-NEXT: vpshufb %xmm2, %xmm0, %xmm0
+; CHECK-NEXT: vinserti128 $1, %xmm0, %ymm1, %ymm0
; CHECK-NEXT: ret{{[l|q]}}
%lo = tail call <16 x i8> @llvm.x86.ssse3.pshuf.b.128(<16 x i8> %a0, <16 x i8> %a1)
%hi = tail call <16 x i8> @llvm.x86.ssse3.pshuf.b.128(<16 x i8> %a0, <16 x i8> %a2)
``````````
</details>
https://github.com/llvm/llvm-project/pull/130592
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