Fix PR16797 - Support PHINodes with multiple inputs from the same basic block.

Do not generate new vector values for the same entries because we know that the incoming values
from the same block must be identical.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188185 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 9312b4b..22a2519 100644
--- a/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -1187,10 +1187,21 @@ Value *BoUpSLP::vectorizeTree(TreeEntry *E) {
       PHINode *NewPhi = Builder.CreatePHI(VecTy, PH->getNumIncomingValues());
       E->VectorizedValue = NewPhi;
 
+      // PHINodes may have multiple entries from the same block. We want to
+      // visit every block once.
+      SmallSet<BasicBlock*, 4> VisitedBBs;
+
       for (unsigned i = 0, e = PH->getNumIncomingValues(); i < e; ++i) {
         ValueList Operands;
         BasicBlock *IBB = PH->getIncomingBlock(i);
 
+        if (VisitedBBs.count(IBB)) {
+          NewPhi->addIncoming(NewPhi->getIncomingValueForBlock(IBB), IBB);
+          continue;
+        }
+
+        VisitedBBs.insert(IBB);
+
         // Prepare the operand vector.
         for (unsigned j = 0; j < E->Scalars.size(); ++j)
           Operands.push_back(cast<PHINode>(E->Scalars[j])->