- Turn copies of implicit_def into implicit_def instructions.

- Be smarter about coalescing copies from implicit_def.

llvm-svn: 49168

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SimpleRegisterCoalescing.h b/llvm/lib/CodeGen/SimpleRegisterCoalescing.h
index cfac126607c..453760a7e7b 100644
--- a/llvm/lib/CodeGen/SimpleRegisterCoalescing.h
+++ b/llvm/lib/CodeGen/SimpleRegisterCoalescing.h
@@ -190,6 +190,12 @@ namespace llvm {
     bool RemoveCopyByCommutingDef(LiveInterval &IntA, LiveInterval &IntB,
                                   MachineInstr *CopyMI);
 
+    /// TurnCopyIntoImpDef - If source of the specified copy is an implicit def,
+    /// turn the copy into an implicit def.
+    bool TurnCopyIntoImpDef(MachineBasicBlock::iterator &I,
+                            MachineBasicBlock *MBB,
+                            unsigned DstReg, unsigned SrcReg);
+
     /// isBackEdgeCopy - Returns true if CopyMI is a back edge copy.
     ///
     bool isBackEdgeCopy(MachineInstr *CopyMI, unsigned DstReg);