[Pipeliner] Drop memrefs instead of creating ones with size UINT64_MAX

Absence of memory operands is treated as "aliasing everything", so
dropping them is sufficient.

Recommit r326256 with a fixed testcase.

llvm-svn: 326262

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 3cce7b3649b..7ee4a99437e 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -3099,8 +3099,10 @@ void SwingSchedulerDAG::updateMemOperands(MachineInstr &NewMI,
       int64_t AdjOffset = Delta * Num;
       NewMemRefs[Refs++] =
           MF.getMachineMemOperand(MMO, AdjOffset, MMO->getSize());
-    } else
-      NewMemRefs[Refs++] = MF.getMachineMemOperand(MMO, 0, UINT64_MAX);
+    } else {
+      NewMI.dropMemRefs();
+      return;
+    }
   }
   NewMI.setMemRefs(NewMemRefs, NewMemRefs + NumRefs);
 }