PR18060 - When we RAUW values with ExtractElement instructions in some cases

we generate PHI nodes with multiple entries from the same basic block but
with different values. Enabling CSE on ExtractElement instructions make sure
that all of the RAUWed instructions are the same.

llvm-svn: 195773

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index f2a099ac691..78caab3b50a 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -1591,6 +1591,8 @@ Value *BoUpSLP::vectorizeTree() {
     if (PHINode *PN = dyn_cast<PHINode>(Vec)) {
       Builder.SetInsertPoint(PN->getParent()->getFirstInsertionPt());
       Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+      if (Instruction *Ins = dyn_cast<Instruction>(Ex))
+        GatherSeq.insert(Ins);
       User->replaceUsesOfWith(Scalar, Ex);
     } else if (isa<Instruction>(Vec)){
       if (PHINode *PH = dyn_cast<PHINode>(User)) {
@@ -1598,17 +1600,23 @@ Value *BoUpSLP::vectorizeTree() {
           if (PH->getIncomingValue(i) == Scalar) {
             Builder.SetInsertPoint(PH->getIncomingBlock(i)->getTerminator());
             Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+            if (Instruction *Ins = dyn_cast<Instruction>(Ex))
+              GatherSeq.insert(Ins);
             PH->setOperand(i, Ex);
           }
         }
       } else {
         Builder.SetInsertPoint(cast<Instruction>(User));
         Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+        if (Instruction *Ins = dyn_cast<Instruction>(Ex))
+          GatherSeq.insert(Ins);
         User->replaceUsesOfWith(Scalar, Ex);
      }
     } else {
       Builder.SetInsertPoint(F->getEntryBlock().begin());
       Value *Ex = Builder.CreateExtractElement(Vec, Lane);
+      if (Instruction *Ins = dyn_cast<Instruction>(Ex))
+        GatherSeq.insert(Ins);
       User->replaceUsesOfWith(Scalar, Ex);
     }