Immediately erase trivially useless copies.

There is no need for these instructions to stick around since they are
known to be not dead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157102 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 84fd590f26..0dbc7b6c65 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -1070,15 +1070,17 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
 
   // If they are already joined we continue.
   if (CP.getSrcReg() == CP.getDstReg()) {
-    markAsJoined(CopyMI);
     DEBUG(dbgs() << "\tCopy already coalesced.\n");
+    LIS->RemoveMachineInstrFromMaps(CopyMI);
+    CopyMI->eraseFromParent();
     return false;  // Not coalescable.
   }
 
   // Eliminate undefs.
   if (!CP.isPhys() && eliminateUndefCopy(CopyMI, CP)) {
-    markAsJoined(CopyMI);
     DEBUG(dbgs() << "\tEliminated copy of <undef> value.\n");
+    LIS->RemoveMachineInstrFromMaps(CopyMI);
+    CopyMI->eraseFromParent();
     return false;  // Not coalescable.
   }