[CostModel] Add SK_ExtractSubvector handling to getInstructionThroughput (PR39368)

Add ShuffleVectorInst::isExtractSubvectorMask helper to match shuffle masks.

llvm-svn: 346510

1 files changed, 8 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/TargetTransformInfo.cpp b/llvm/lib/Analysis/TargetTransformInfo.cpp
index 6e4eb8ff0cd..a6a1a872b65 100644
--- a/llvm/lib/Analysis/TargetTransformInfo.cpp
+++ b/llvm/lib/Analysis/TargetTransformInfo.cpp
@@ -1108,14 +1108,20 @@ int TargetTransformInfo::getInstructionThroughput(const Instruction *I) const {
   }
   case Instruction::ShuffleVector: {
     const ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
-    // TODO: Identify and add costs for insert/extract subvector, etc.
+    Type *Ty = Shuffle->getType();
+    Type *SrcTy = Shuffle->getOperand(0)->getType();
+
+    // TODO: Identify and add costs for insert subvector, etc.
+    int SubIndex;
+    if (Shuffle->isExtractSubvectorMask(SubIndex))
+      return TTIImpl->getShuffleCost(SK_ExtractSubvector, Ty, SubIndex, SrcTy);
+
     if (Shuffle->changesLength())
       return -1;
 
     if (Shuffle->isIdentity())
       return 0;
 
-    Type *Ty = Shuffle->getType();
     if (Shuffle->isReverse())
       return TTIImpl->getShuffleCost(SK_Reverse, Ty, 0, nullptr);