1 files changed, 17 insertions, 6 deletions

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 7a7ea69..7557979 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -42,6 +42,7 @@
 using namespace llvm;
 
 STATISTIC(NumSpills  , "Number of register spills");
+STATISTIC(NumIdCopies, "Number of identity moves eliminated after rewriting");
 
 //===----------------------------------------------------------------------===//
 //  VirtRegMap implementation
@@ -260,6 +261,8 @@ void VirtRegMap::rewrite(SlotIndexes *Indexes) {
                << "********** Function: "
                << MF->getFunction()->getName() << '\n');
   DEBUG(dump());
+  SmallVector<unsigned, 8> SuperDeads;
+  SmallVector<unsigned, 8> SuperDefs;
   SmallVector<unsigned, 8> SuperKills;
 
   for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
@@ -283,12 +286,13 @@ void VirtRegMap::rewrite(SlotIndexes *Indexes) {
         if (MO.getSubReg()) {
           // A virtual register kill refers to the whole register, so we may
           // have to add <imp-use,kill> operands for the super-register.
-          if (MO.isUse() && MO.isKill() && !MO.isUndef())
-            SuperKills.push_back(PhysReg);
-
-          // We don't have to deal with sub-register defs because
-          // LiveIntervalAnalysis already added the necessary <imp-def>
-          // operands.
+          if (MO.isUse()) {
+            if (MO.isKill() && !MO.isUndef())
+              SuperKills.push_back(PhysReg);
+          } else if (MO.isDead())
+            SuperDeads.push_back(PhysReg);
+          else
+            SuperDefs.push_back(PhysReg);
 
           // PhysReg operands cannot have subregister indexes.
           PhysReg = TRI->getSubReg(PhysReg, MO.getSubReg());
@@ -305,10 +309,17 @@ void VirtRegMap::rewrite(SlotIndexes *Indexes) {
       while (!SuperKills.empty())
         MI->addRegisterKilled(SuperKills.pop_back_val(), TRI, true);
 
+      while (!SuperDeads.empty())
+        MI->addRegisterDead(SuperDeads.pop_back_val(), TRI, true);
+
+      while (!SuperDefs.empty())
+        MI->addRegisterDefined(SuperDefs.pop_back_val(), TRI);
+
       DEBUG(dbgs() << "> " << *MI);
 
       // Finally, remove any identity copies.
       if (MI->isIdentityCopy()) {
+        ++NumIdCopies;
         if (MI->getNumOperands() == 2) {
           DEBUG(dbgs() << "Deleting identity copy.\n");
           RemoveMachineInstrFromMaps(MI);