[PATCH] D103164: [SLP]Fix vectorization of insertelements with mutiple uses.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev created this revision.
ABataev added reviewers: RKSimon, spatel, rupprecht.
Herald added a subscriber: hiraditya.
ABataev requested review of this revision.
Herald added a project: LLVM.

SLP vectorizer should not consider in sertelements with multiple uses as
a part of high level build vector, it must be considered as
a terminating insertelement in the vector build, otherwise it may
produce incorrect code.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D103164

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/X86/insert-element-multiple-uses.ll


Index: llvm/test/Transforms/SLPVectorizer/X86/insert-element-multiple-uses.ll
===================================================================
--- llvm/test/Transforms/SLPVectorizer/X86/insert-element-multiple-uses.ll
+++ llvm/test/Transforms/SLPVectorizer/X86/insert-element-multiple-uses.ll
@@ -5,10 +5,14 @@
 ; CHECK-LABEL: @main(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[TMP0:%.*]] = load <2 x i64>, <2 x i64>* undef, align 16
-; CHECK-NEXT:    [[TMP1:%.*]] = add <2 x i64> [[TMP0]], <i64 1, i64 1>
-; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x i64> [[TMP1]], i32 0
-; CHECK-NEXT:    [[CMP_I:%.*]] = icmp eq i64 [[TMP2]], 0
-; CHECK-NEXT:    [[VEC_0_I:%.*]] = select i1 [[CMP_I]], <2 x i64> [[TMP1]], <2 x i64> [[TMP1]]
+; CHECK-NEXT:    [[VEC_0_VEC_EXTRACT_I:%.*]] = extractelement <2 x i64> [[TMP0]], i32 0
+; CHECK-NEXT:    [[ADD_I:%.*]] = add i64 [[VEC_0_VEC_EXTRACT_I]], 1
+; CHECK-NEXT:    [[VEC_0_VEC_INSERT_I:%.*]] = insertelement <2 x i64> [[TMP0]], i64 [[ADD_I]], i32 0
+; CHECK-NEXT:    [[CMP_I:%.*]] = icmp eq i64 [[ADD_I]], 0
+; CHECK-NEXT:    [[VEC_8_VEC_EXTRACT_I:%.*]] = extractelement <2 x i64> [[TMP0]], i32 1
+; CHECK-NEXT:    [[INC_I:%.*]] = add i64 [[VEC_8_VEC_EXTRACT_I]], 1
+; CHECK-NEXT:    [[VEC_8_VEC_INSERT_I:%.*]] = insertelement <2 x i64> [[VEC_0_VEC_INSERT_I]], i64 [[INC_I]], i32 1
+; CHECK-NEXT:    [[VEC_0_I:%.*]] = select i1 [[CMP_I]], <2 x i64> [[VEC_8_VEC_INSERT_I]], <2 x i64> [[VEC_0_VEC_INSERT_I]]
 ; CHECK-NEXT:    ret void
 ;
 entry:
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -7722,7 +7722,8 @@
     LastInsertInst = dyn_cast<Instruction>(LastInsertInst->getOperand(0));
   } while (LastInsertInst != nullptr &&
            (isa<InsertValueInst>(LastInsertInst) ||
-            isa<InsertElementInst>(LastInsertInst)));
+            isa<InsertElementInst>(LastInsertInst)) &&
+           LastInsertInst->hasOneUse());
   return true;
 }
 


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