[IAI,LV] Avoid creating interleave-groups for predicated accesse

This patch fixes PR39099.

When strided loads are predicated, each of them will form an interleaved-group
(with gaps). However, subsequent stages of vectorization (planning and
transformation) assume that if a load is part of an Interleave-Group it is not
predicated, resulting in wrong code - unmasked wide loads are created.

The Interleaving Analysis does take care not to have conditional interleave
groups of size > 1, but until we extend the planning and transformation stages
to support masked-interleave-groups we should also avoid having them for
size == 1.

Reviewers: Ayal, hsaito, dcaballe, fhahn

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D52682

llvm-svn: 343931

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/VectorUtils.cpp b/llvm/lib/Analysis/VectorUtils.cpp
index c639f36c512..272c665ace1 100644
--- a/llvm/lib/Analysis/VectorUtils.cpp
+++ b/llvm/lib/Analysis/VectorUtils.cpp
@@ -712,7 +712,9 @@ void InterleavedAccessInfo::analyzeInterleaving() {
     // create a group for B, we continue with the bottom-up algorithm to ensure
     // we don't break any of B's dependences.
     InterleaveGroup *Group = nullptr;
-    if (isStrided(DesB.Stride)) {
+    // TODO: Ignore B if it is in a predicated block. This restriction can be 
+    // relaxed in the future once we handle masked interleaved groups.
+    if (isStrided(DesB.Stride) && !isPredicated(B->getParent())) {
       Group = getInterleaveGroup(B);
       if (!Group) {
         LLVM_DEBUG(dbgs() << "LV: Creating an interleave group with:" << *B