[LV] Don't have fold-tail under optsize invalidate interleave-groups …

…when

masked-interleaving is enabled

Enable interleave-groups under fold-tail scenario for Opt for size compilation;
D50480 added support for vectorizing loops of arbitrary trip-count without a
remiander, which in turn makes everything in the loop conditional, including
interleave-groups if any. It therefore invalidated all interleave-groups
because we didn't have support for vectorizing predicated interleaved-groups
at the time. In the meantime, D53011 introduced this support, so we don't
have to invalidate interleave-groups when masked-interleaved support is enabled.

Reviewers: Ayal, hsaito, dcaballe, fhahn

Reviewed By: hsaito

Differential Revision: https://reviews.llvm.org/D53559

llvm-svn: 345115

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -6017,8 +6017,14 @@ LoopVectorizationPlanner::plan(bool OptForSize, unsigned UserVF) {
     return NoVectorization;
 
   // Invalidate interleave groups if all blocks of loop will be predicated.
-  if (CM.blockNeedsPredication(OrigLoop->getHeader()))
+  if (CM.blockNeedsPredication(OrigLoop->getHeader()) &&
+      !useMaskedInterleavedAccesses(*TTI)) {
+    LLVM_DEBUG(
+        dbgs()
+        << "LV: Invalidate all interleaved groups due to fold-tail by masking "
+           "which requires masked-interleaved support.\n");
     CM.InterleaveInfo.reset();
+  }
 
   if (UserVF) {
     LLVM_DEBUG(dbgs() << "LV: Using user VF " << UserVF << ".\n");