[LV] Scalarize instructions marked scalar after vectorization

This patch ensures that we actually scalarize instructions marked scalar after
vectorization. Previously, such instructions may have been vectorized instead.

Differential Revision: https://reviews.llvm.org/D23889

llvm-svn: 282418

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 0b5d7351b60..06413546619 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4506,6 +4506,15 @@ static bool mayDivideByZero(Instruction &I) {
 void InnerLoopVectorizer::vectorizeBlockInLoop(BasicBlock *BB, PhiVector *PV) {
   // For each instruction in the old loop.
   for (Instruction &I : *BB) {
+
+    // Scalarize instructions that should remain scalar after vectorization.
+    if (!(isa<BranchInst>(&I) || isa<PHINode>(&I) ||
+          isa<DbgInfoIntrinsic>(&I)) &&
+        Legal->isScalarAfterVectorization(&I)) {
+      scalarizeInstruction(&I);
+      continue;
+    }
+
     switch (I.getOpcode()) {
     case Instruction::Br:
       // Nothing to do for PHIs and BR, since we already took care of the