Clear kill flags before propagating a copy.

The live range of the source register may be extended when a redundant
copy is eliminated. Make sure any kill flags between the two copies are
cleared.

This fixes PR11765.

llvm-svn: 149069

1 files changed, 6 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index c82f81b..f96c869 100644
--- a/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -142,7 +142,12 @@ bool MachineCopyPropagation::CopyPropagateBlock(MachineBasicBlock &MBB) {
           // %RSP<def> = COPY %RAX
           // CALL
           // %RAX<def> = COPY %RSP
-          CopyMI->getOperand(1).setIsKill(false);
+
+          // Clear any kills of Def between CopyMI and MI. This extends the
+          // live range.
+          for (MachineBasicBlock::iterator I = CopyMI, E = MI; I != E; ++I)
+            I->clearRegisterKills(Def, TRI);
+
           MI->eraseFromParent();
           Changed = true;
           ++NumDeletes;