From c738c9651925e67ea3153bb651eebb9105d2bad5 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Wed, 16 Mar 2011 22:56:13 +0000
Subject: [PATCH] Erase virtual registers that are unused after DCE.

llvm-svn: 127773
---
 llvm/lib/CodeGen/LiveRangeEdit.cpp | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 0769f95262dc..e994d8c32d49 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -174,13 +174,21 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
         if (!TargetRegisterInfo::isVirtualRegister(Reg))
           continue;
         LiveInterval &LI = LIS.getInterval(Reg);
-        // Remove defined value.
-        if (MOI->isDef())
-          if (VNInfo *VNI = LI.getVNInfoAt(Idx))
-            LI.removeValNo(VNI);
+
         // Shrink read registers.
         if (MI->readsVirtualRegister(Reg))
           ToShrink.insert(&LI);
+
+        // Remove defined value.
+        if (MOI->isDef()) {
+          if (VNInfo *VNI = LI.getVNInfoAt(Idx)) {
+            LI.removeValNo(VNI);
+            if (LI.empty()) {
+              ToShrink.remove(&LI);
+              eraseVirtReg(Reg, LIS);
+            }
+          }
+        }
       }
 
       if (delegate_)