[llvm] 4ea57b3 - [SLP]Fix detection of matching splat vector

[Alexey Bataev via llvm-commits]

Author: Alexey Bataev
Date: 2025-04-10T08:30:43-07:00
New Revision: 4ea57b3481c07fd8e19315752dfd0a03e1d7bd12

URL: https://github.com/llvm/llvm-project/commit/4ea57b3481c07fd8e19315752dfd0a03e1d7bd12
DIFF: https://github.com/llvm/llvm-project/commit/4ea57b3481c07fd8e19315752dfd0a03e1d7bd12.diff

LOG: [SLP]Fix detection of matching splat vector

Need to check, that the mask of the potentially matching splat node is
not less defined than the requested mask to avoid poison propagation and
incorrect code.

Fixes #135113

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    llvm/test/Transforms/SLPVectorizer/X86/identity-match-splat-less-defined.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 2efe107f03142..444bd08eac549 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -10617,7 +10617,11 @@ class BaseShuffleAnalysis {
                                /*IsStrict=*/true) ||
                 (Shuffle && Mask.size() == Shuffle->getShuffleMask().size() &&
                  Shuffle->isZeroEltSplat() &&
-                 ShuffleVectorInst::isZeroEltSplatMask(Mask, Mask.size())));
+                 ShuffleVectorInst::isZeroEltSplatMask(Mask, Mask.size()) &&
+                 all_of(enumerate(Mask), [&](const auto &P) {
+                   return P.value() == PoisonMaskElem ||
+                          Shuffle->getShuffleMask()[P.index()] == 0;
+                 })));
       }
       V = Op;
       return false;

diff  --git a/llvm/test/Transforms/SLPVectorizer/X86/identity-match-splat-less-defined.ll b/llvm/test/Transforms/SLPVectorizer/X86/identity-match-splat-less-defined.ll
index d6449c5ce4599..d6f0b7692bdd9 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/identity-match-splat-less-defined.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/identity-match-splat-less-defined.ll
@@ -7,7 +7,8 @@ define i32 @test() {
 ; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> poison, <4 x i32> <i32 0, i32 0, i32 0, i32 poison>
 ; CHECK-NEXT:    [[TMP3:%.*]] = or <4 x i32> [[TMP2]], <i32 0, i32 0, i32 0, i32 poison>
 ; CHECK-NEXT:    [[TMP4:%.*]] = shufflevector <4 x i32> [[TMP3]], <4 x i32> poison, <16 x i32> <i32 0, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2>
-; CHECK-NEXT:    [[TMP5:%.*]] = or <4 x i32> [[TMP2]], zeroinitializer
+; CHECK-NEXT:    [[TMP25:%.*]] = shufflevector <4 x i32> [[TMP2]], <4 x i32> poison, <4 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP5:%.*]] = or <4 x i32> [[TMP25]], zeroinitializer
 ; CHECK-NEXT:    [[TMP6:%.*]] = shufflevector <4 x i32> [[TMP5]], <4 x i32> poison, <24 x i32> <i32 0, i32 0, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 2, i32 3, i32 3, i32 3>
 ; CHECK-NEXT:    [[TMP7:%.*]] = shufflevector <4 x i32> [[TMP3]], <4 x i32> poison, <64 x i32> <i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
 ; CHECK-NEXT:    [[TMP8:%.*]] = shufflevector <4 x i32> [[TMP5]], <4 x i32> poison, <64 x i32> <i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 3, i32 3, i32 3, i32 3, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>