[LV] Teach vectorizer about variant value store into uniform address

Summary:
Teach vectorizer about vectorizing variant value stores to uniform
address. Similar to rL343028, we do not allow vectorization if we have
multiple stores to the same uniform address.

Cost model already has the change for considering the extract
instruction cost for a variant value store. See added test cases for how
vectorization is done.
The patch also contains changes to the ORE messages.

Reviewers: Ayal, mkuper, anemet, hsaito

Subscribers: rkruppe, llvm-commits

Differential Revision: https://reviews.llvm.org/D52656

llvm-svn: 344613

1 files changed, 6 insertions, 10 deletions

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index b43e290956d..4b8e8afdabb 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1869,13 +1869,9 @@ void LoopAccessInfo::analyzeLoop(AliasAnalysis *AA, LoopInfo *LI,
   for (StoreInst *ST : Stores) {
     Value *Ptr = ST->getPointerOperand();
 
-    if (isUniform(Ptr)) {
-      // Consider multiple stores to the same uniform address as a store of a
-      // variant value.
-      bool MultipleStoresToUniformPtr = !UniformStores.insert(Ptr).second;
-      HasVariantStoreToLoopInvariantAddress |=
-          (!isUniform(ST->getValueOperand()) || MultipleStoresToUniformPtr);
-    }
+    if (isUniform(Ptr))
+      HasMultipleStoresToLoopInvariantAddress |=
+          !UniformStores.insert(Ptr).second;
 
     // If we did *not* see this pointer before, insert it to  the read-write
     // list. At this phase it is only a 'write' list.
@@ -2276,7 +2272,7 @@ LoopAccessInfo::LoopAccessInfo(Loop *L, ScalarEvolution *SE,
       PtrRtChecking(llvm::make_unique<RuntimePointerChecking>(SE)),
       DepChecker(llvm::make_unique<MemoryDepChecker>(*PSE, L)), TheLoop(L),
       NumLoads(0), NumStores(0), MaxSafeDepDistBytes(-1), CanVecMem(false),
-      HasVariantStoreToLoopInvariantAddress(false) {
+      HasMultipleStoresToLoopInvariantAddress(false) {
   if (canAnalyzeLoop())
     analyzeLoop(AA, LI, TLI, DT);
 }
@@ -2308,8 +2304,8 @@ void LoopAccessInfo::print(raw_ostream &OS, unsigned Depth) const {
   PtrRtChecking->print(OS, Depth);
   OS << "\n";
 
-  OS.indent(Depth) << "Variant Store to invariant address was "
-                   << (HasVariantStoreToLoopInvariantAddress ? "" : "not ")
+  OS.indent(Depth) << "Multiple stores to invariant address were "
+                   << (HasMultipleStoresToLoopInvariantAddress ? "" : "not ")
                    << "found in loop.\n";
 
   OS.indent(Depth) << "SCEV assumptions:\n";