Fixed a bug in vectorizing GEP before gather/scatter intrinsic.

Vectorizing GEP was incorrect and broke SSA in some cases.
 
The patch fixes PR27997 https://llvm.org/bugs/show_bug.cgi?id=27997.

Differential revision: http://reviews.llvm.org/D22035

llvm-svn: 274735

1 files changed, 11 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index fbe042118de..38ddeede84a 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2786,24 +2786,27 @@ void InnerLoopVectorizer::vectorizeMemoryInstruction(Instruction *Instr) {
     // At this point we should vector version of GEP for Gather or Scatter
     assert(CreateGatherScatter && "The instruction should be scalarized");
     if (Gep) {
+      // Vectorizing GEP, across UF parts. We want to get a vector value for base
+      // and each index that's defined inside the loop, even if it is
+      // loop-invariant but wasn't hoisted out. Otherwise we want to keep them
+      // scalar.
       SmallVector<VectorParts, 4> OpsV;
-      // Vectorizing GEP, across UF parts, we want to keep each loop-invariant
-      // base or index of GEP scalar
       for (Value *Op : Gep->operands()) {
-        if (PSE.getSE()->isLoopInvariant(PSE.getSCEV(Op), OrigLoop))
-          OpsV.push_back(VectorParts(UF, Op));
-        else
+        Instruction *SrcInst = dyn_cast<Instruction>(Op);
+        if (SrcInst && OrigLoop->contains(SrcInst))
           OpsV.push_back(getVectorValue(Op));
+        else
+          OpsV.push_back(VectorParts(UF, Op));
       }
-
       for (unsigned Part = 0; Part < UF; ++Part) {
         SmallVector<Value *, 4> Ops;
         Value *GEPBasePtr = OpsV[0][Part];
         for (unsigned i = 1; i < Gep->getNumOperands(); i++)
           Ops.push_back(OpsV[i][Part]);
-        Value *NewGep =
-            Builder.CreateGEP(nullptr, GEPBasePtr, Ops, "VectorGep");
+        Value *NewGep =  Builder.CreateGEP(GEPBasePtr, Ops, "VectorGep");
+        cast<GetElementPtrInst>(NewGep)->setIsInBounds(Gep->isInBounds());
         assert(NewGep->getType()->isVectorTy() && "Expected vector GEP");
+
         NewGep =
             Builder.CreateBitCast(NewGep, VectorType::get(Ptr->getType(), VF));
         VectorGep.push_back(NewGep);