[MemorySSA] Moving at the end often means before terminator.

Moving accesses in MemorySSA at InsertionPlace::End, when an instruction is
moved into a block, almost always means insert at the end of the block, but
before the block terminator. This matters when the block terminator is a
MemoryAccess itself (an invoke), and the insertion must be done before
the terminator for the update to be correct.

Insert an additional position: InsertionPlace:BeforeTerminator and update
current usages where this applies.

Resolves PR44027.

2 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/LoopInfo.cpp b/llvm/lib/Analysis/LoopInfo.cpp
index 663b42c55f1..3e3303cbb02 100644
--- a/llvm/lib/Analysis/LoopInfo.cpp
+++ b/llvm/lib/Analysis/LoopInfo.cpp
@@ -106,7 +106,8 @@ bool Loop::makeLoopInvariant(Instruction *I, bool &Changed,
   I->moveBefore(InsertPt);
   if (MSSAU)
     if (auto *MUD = MSSAU->getMemorySSA()->getMemoryAccess(I))
-      MSSAU->moveToPlace(MUD, InsertPt->getParent(), MemorySSA::End);
+      MSSAU->moveToPlace(MUD, InsertPt->getParent(),
+                         MemorySSA::BeforeTerminator);
 
   // There is possibility of hoisting this instruction above some arbitrary
   // condition. Any metadata defined on it can be control dependent on this
diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
index f2d56b05d96..473268982f2 100644
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -1159,7 +1159,13 @@ void MemorySSAUpdater::moveAfter(MemoryUseOrDef *What, MemoryUseOrDef *Where) {
 
 void MemorySSAUpdater::moveToPlace(MemoryUseOrDef *What, BasicBlock *BB,
                                    MemorySSA::InsertionPlace Where) {
-  return moveTo(What, BB, Where);
+  if (Where != MemorySSA::InsertionPlace::BeforeTerminator)
+    return moveTo(What, BB, Where);
+
+  if (auto *Where = MSSA->getMemoryAccess(BB->getTerminator()))
+    return moveBefore(What, Where);
+  else
+    return moveTo(What, BB, MemorySSA::InsertionPlace::End);
 }
 
 // All accesses in To used to be in From. Move to end and update access lists.