MISched: Fix moving stores across barriers

This fixes an issue with ScheduleDAGInstrs::buildSchedGraph
where stores without an underlying object would not be added
as a predecessor to the current BarrierChain.

llvm-svn: 223717

1 files changed, 7 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp b/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
index d8d8422f0ed..dece643c0d2 100644
--- a/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/llvm/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -920,6 +920,13 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA,
       AliasMemDefs.clear();
       AliasMemUses.clear();
     } else if (MI->mayStore()) {
+      // Add dependence on barrier chain, if needed.
+      // There is no point to check aliasing on barrier event. Even if
+      // SU and barrier _could_ be reordered, they should not. In addition,
+      // we have lost all RejectMemNodes below barrier.
+      if (BarrierChain)
+        BarrierChain->addPred(SDep(SU, SDep::Barrier));
+
       UnderlyingObjectsVector Objs;
       getUnderlyingObjectsForInstr(MI, MFI, Objs);
 
@@ -989,12 +996,6 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA,
         adjustChainDeps(AA, MFI, SU, &ExitSU, RejectMemNodes,
                         TrueMemOrderLatency);
       }
-      // Add dependence on barrier chain, if needed.
-      // There is no point to check aliasing on barrier event. Even if
-      // SU and barrier _could_ be reordered, they should not. In addition,
-      // we have lost all RejectMemNodes below barrier.
-      if (BarrierChain)
-        BarrierChain->addPred(SDep(SU, SDep::Barrier));
     } else if (MI->mayLoad()) {
       bool MayAlias = true;
       if (MI->isInvariantLoad(AA)) {