[MemorySSA] Update last_access_in_block check.

The check for "was there an access in this block" should be: is the last
access in this block and is it not a newly inserted phi.
Resolves new test in PR43438.

Also fix a typo when simplifying trivial Phis to match the comment.

llvm-svn: 373380

1 files changed, 7 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
index b62cf08eb4c..315037bcc04 100644
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -303,7 +303,12 @@ void MemorySSAUpdater::insertDef(MemoryDef *MD, bool RenameUses) {
 
   // See if we had a local def, and if not, go hunting.
   MemoryAccess *DefBefore = getPreviousDef(MD);
-  bool DefBeforeSameBlock = DefBefore->getBlock() == MD->getBlock();
+  bool DefBeforeSameBlock = false;
+  if (DefBefore->getBlock() == MD->getBlock() &&
+      !(isa<MemoryPhi>(DefBefore) &&
+        std::find(InsertedPHIs.begin(), InsertedPHIs.end(), DefBefore) !=
+            InsertedPHIs.end()))
+    DefBeforeSameBlock = true;
 
   // There is a def before us, which means we can replace any store/phi uses
   // of that thing with us, since we are in the way of whatever was there
@@ -628,7 +633,7 @@ void MemorySSAUpdater::updatePhisWhenInsertingUniqueBackedgeBlock(
 
   // If NewMPhi is a trivial phi, remove it. Its use in the header MPhi will be
   // replaced with the unique value.
-  tryRemoveTrivialPhi(MPhi);
+  tryRemoveTrivialPhi(NewMPhi);
 }
 
 void MemorySSAUpdater::updateForClonedLoop(const LoopBlocksRPO &LoopBlocks,