[CostModel] Add more realistic SK_ExtractSubvector generic costs.

Instead of defaulting to a cost = 1, expand to element extract/insert like we do for other shuffles.

This exposes an issue in LoopVectorize which could call SK_ExtractSubvector with a scalar subvector type.

llvm-svn: 346656

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index c9c70b5c536..17191a19a3f 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -5826,9 +5826,10 @@ unsigned LoopVectorizationCostModel::getInstructionCost(Instruction *I,
     auto *Phi = cast<PHINode>(I);
 
     // First-order recurrences are replaced by vector shuffles inside the loop.
+    // NOTE: Don't use ToVectorTy as SK_ExtractSubvector expects a vector type.
     if (VF > 1 && Legal->isFirstOrderRecurrence(Phi))
       return TTI.getShuffleCost(TargetTransformInfo::SK_ExtractSubvector,
-                                VectorTy, VF - 1, ToVectorTy(RetTy, 1));
+                                VectorTy, VF - 1, VectorType::get(RetTy, 1));
 
     // Phi nodes in non-header blocks (not inductions, reductions, etc.) are
     // converted into select instructions. We require N - 1 selects per phi