[llvm] 8a0bfe4 - [SLP]Fix PR87630: wrong result for externally used vector value.

[Alexey Bataev via llvm-commits]

Author: Alexey Bataev
Date: 2024-04-04T12:03:28-07:00
New Revision: 8a0bfe490592de3df28d82c5dd69956e43c20f1d

URL: https://github.com/llvm/llvm-project/commit/8a0bfe490592de3df28d82c5dd69956e43c20f1d
DIFF: https://github.com/llvm/llvm-project/commit/8a0bfe490592de3df28d82c5dd69956e43c20f1d.diff

LOG: [SLP]Fix PR87630: wrong result for externally used vector value.

Need to check that the externally used value can be represented with the
BitWidth before applying it, otherwise need to keep wider type.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    llvm/test/Transforms/SLPVectorizer/X86/external-user-instruction-minbitwidth.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 79d146aec0c56d..bdd26acfd2f8b4 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -14141,6 +14141,16 @@ bool BoUpSLP::collectValuesToDemote(
       }))
     return FinalAnalysis();
 
+  if (!all_of(I->users(),
+              [=](User *U) {
+                return getTreeEntry(U) ||
+                       (UserIgnoreList && UserIgnoreList->contains(U)) ||
+                       (U->getType()->isSized() &&
+                        DL->getTypeSizeInBits(U->getType()) <= BitWidth);
+              }) &&
+      !IsPotentiallyTruncated(I, BitWidth))
+    return false;
+
   unsigned Start = 0;
   unsigned End = I->getNumOperands();
 

diff  --git a/llvm/test/Transforms/SLPVectorizer/X86/external-user-instruction-minbitwidth.ll b/llvm/test/Transforms/SLPVectorizer/X86/external-user-instruction-minbitwidth.ll
index 9d3d602d074322..84f7e219f50666 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/external-user-instruction-minbitwidth.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/external-user-instruction-minbitwidth.ll
@@ -14,17 +14,13 @@ define i8 @test() {
 ; CHECK-NEXT:    [[CONV1:%.*]] = zext i16 [[TMP1]] to i32
 ; CHECK-NEXT:    [[TMP2:%.*]] = insertelement <8 x i32> poison, i32 [[CONV]], i32 0
 ; CHECK-NEXT:    [[TMP3:%.*]] = shufflevector <8 x i32> [[TMP2]], <8 x i32> poison, <8 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP4:%.*]] = trunc <8 x i32> [[TMP3]] to <8 x i16>
-; CHECK-NEXT:    [[TMP5:%.*]] = or <8 x i16> [[TMP4]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 -32767>
+; CHECK-NEXT:    [[TMP4:%.*]] = or <8 x i32> [[TMP3]], <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 32769>
 ; CHECK-NEXT:    [[TMP6:%.*]] = insertelement <8 x i32> poison, i32 [[CONV1]], i32 0
 ; CHECK-NEXT:    [[TMP7:%.*]] = shufflevector <8 x i32> [[TMP6]], <8 x i32> poison, <8 x i32> zeroinitializer
-; CHECK-NEXT:    [[TMP8:%.*]] = trunc <8 x i32> [[TMP7]] to <8 x i16>
-; CHECK-NEXT:    [[TMP9:%.*]] = add <8 x i16> [[TMP5]], [[TMP8]]
-; CHECK-NEXT:    [[TMP10:%.*]] = call i16 @llvm.vector.reduce.or.v8i16(<8 x i16> [[TMP9]])
-; CHECK-NEXT:    [[TMP11:%.*]] = sext i16 [[TMP10]] to i32
+; CHECK-NEXT:    [[TMP8:%.*]] = add nsw <8 x i32> [[TMP4]], [[TMP7]]
+; CHECK-NEXT:    [[TMP11:%.*]] = call i32 @llvm.vector.reduce.or.v8i32(<8 x i32> [[TMP8]])
 ; CHECK-NEXT:    [[CONV4_30:%.*]] = trunc i32 [[TMP11]] to i8
-; CHECK-NEXT:    [[TMP12:%.*]] = extractelement <8 x i16> [[TMP5]], i32 7
-; CHECK-NEXT:    [[TMP13:%.*]] = sext i16 [[TMP12]] to i32
+; CHECK-NEXT:    [[TMP13:%.*]] = extractelement <8 x i32> [[TMP4]], i32 7
 ; CHECK-NEXT:    [[XOR_31:%.*]] = and i32 [[TMP13]], -2
 ; CHECK-NEXT:    store i32 [[XOR_31]], ptr @d, align 4
 ; CHECK-NEXT:    ret i8 [[CONV4_30]]