1 files changed, 28 insertions, 13 deletions

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 734b87e..226b78f 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -259,7 +259,9 @@ void VirtRegMap::rewrite(SlotIndexes *Indexes) {
   DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n"
                << "********** 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 +285,13 @@ 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());
@@ -305,16 +308,28 @@ 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()) {
-        DEBUG(dbgs() << "Deleting identity copy.\n");
-        RemoveMachineInstrFromMaps(MI);
-        if (Indexes)
-          Indexes->removeMachineInstrFromMaps(MI);
-        // It's safe to erase MI because MII has already been incremented.
-        MI->eraseFromParent();
+        if (MI->getNumOperands() == 2) {
+          DEBUG(dbgs() << "Deleting identity copy.\n");
+          RemoveMachineInstrFromMaps(MI);
+          if (Indexes)
+            Indexes->removeMachineInstrFromMaps(MI);
+          // It's safe to erase MI because MII has already been incremented.
+          MI->eraseFromParent();
+        } else {
+          // Transform identity copy to a KILL to deal with subregisters.
+          MI->setDesc(TII->get(TargetOpcode::KILL));
+          DEBUG(dbgs() << "Identity copy: " << *MI);
+        }
       }
     }
   }