Don't sink the instruction if TargetRegisterInfo::isSafeToMoveRegClassDefs doesn't think it's safe. This works around PR1911.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63994 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index 87114396f9..a85a41fbae 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -167,6 +167,10 @@ bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
     } else {
       // Virtual register uses are always safe to sink.
       if (MO.isUse()) continue;
+
+      // If it's not safe to move defs of the register class, then abort.
+      if (!TII->isSafeToMoveRegClassDefs(RegInfo->getRegClass(Reg)))
+        return false;
       
       // FIXME: This picks a successor to sink into based on having one
       // successor that dominates all the uses.  However, there are cases where