[llvm] [SLP][REVEC] Fix insertelement has multiple uses. (PR #102329)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Han-Kuan Chen (HanKuanChen)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/102329.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp (+8) 
- (modified) llvm/test/Transforms/SLPVectorizer/revec.ll (+23) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 4186b17e644b0..7f098899311c0 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -6402,6 +6402,14 @@ BoUpSLP::TreeEntry::EntryState BoUpSLP::getScalarsVectorizationState(
       return TreeEntry::NeedToGather;
     }
 
+    if (any_of(VL, [&SourceVectors](Value *V) {
+          if (SourceVectors.contains(V))
+            return !V->hasOneUse();
+          // The last InsertElement can have multiple uses.
+          return false;
+        }))
+      return TreeEntry::NeedToGather;
+
     return TreeEntry::Vectorize;
   }
   case Instruction::Load: {
diff --git a/llvm/test/Transforms/SLPVectorizer/revec.ll b/llvm/test/Transforms/SLPVectorizer/revec.ll
index d6dd4128de9c7..d7c3ccd8c9ce8 100644
--- a/llvm/test/Transforms/SLPVectorizer/revec.ll
+++ b/llvm/test/Transforms/SLPVectorizer/revec.ll
@@ -124,3 +124,26 @@ entry:
   store <8 x i1> %6, ptr %7, align 1
   ret void
 }
+
+define void @test5(ptr %ptr0, ptr %ptr1) {
+; CHECK-LABEL: @test5(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[GETELEMENTPTR0:%.*]] = getelementptr i8, ptr null, i64 0
+; CHECK-NEXT:    [[TMP0:%.*]] = insertelement <4 x ptr> <ptr null, ptr null, ptr undef, ptr undef>, ptr [[GETELEMENTPTR0]], i32 2
+; CHECK-NEXT:    [[TMP1:%.*]] = insertelement <4 x ptr> [[TMP0]], ptr null, i32 3
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ult <4 x ptr> zeroinitializer, [[TMP1]]
+; CHECK-NEXT:    [[TMP3:%.*]] = insertelement <4 x ptr> <ptr poison, ptr null, ptr null, ptr null>, ptr [[PTR0:%.*]], i32 0
+; CHECK-NEXT:    [[TMP4:%.*]] = insertelement <4 x ptr> [[TMP1]], ptr [[PTR1:%.*]], i32 3
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp ult <4 x ptr> [[TMP3]], [[TMP4]]
+; CHECK-NEXT:    ret void
+;
+entry:
+  %getelementptr0 = getelementptr i8, ptr null, i64 0
+  %0 = insertelement <4 x ptr> <ptr null, ptr null, ptr undef, ptr undef>, ptr %getelementptr0, i32 2
+  %1 = insertelement <4 x ptr> %0, ptr null, i32 3
+  %2 = icmp ult <4 x ptr> zeroinitializer, %1
+  %3 = insertelement <4 x ptr> <ptr poison, ptr null, ptr null, ptr null>, ptr %ptr0, i32 0
+  %4 = insertelement <4 x ptr> %1, ptr %ptr1, i32 3
+  %5 = icmp ult <4 x ptr> %3, %4
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/102329