[CodeGen] Skip over dbg-instr in twoaddr pass

A DBG_VALUE between a two-address instruction and a following COPY
would prevent rescheduleMIBelowKill optimization inside
TwoAddressInstructionPass.

Differential Revision: https://reviews.llvm.org/D55987

llvm-svn: 350289

1 files changed, 6 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
index 2e2fe72e539..4b72f6a84ca 100644
--- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -929,9 +929,12 @@ rescheduleMIBelowKill(MachineBasicBlock::iterator &mi,
   MachineBasicBlock::iterator Begin = MI;
   MachineBasicBlock::iterator AfterMI = std::next(Begin);
   MachineBasicBlock::iterator End = AfterMI;
-  while (End->isCopy() &&
-         regOverlapsSet(Defs, End->getOperand(1).getReg(), TRI)) {
-    Defs.push_back(End->getOperand(0).getReg());
+  while (End != MBB->end()) {
+    End = skipDebugInstructionsForward(End, MBB->end());
+    if (End->isCopy() && regOverlapsSet(Defs, End->getOperand(1).getReg(), TRI))
+      Defs.push_back(End->getOperand(0).getReg());
+    else
+      break;
     ++End;
   }