1 files changed, 42 insertions, 7 deletions

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 0d506d646659..c8946010e9d1 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -167,6 +167,7 @@ class VirtRegRewriter : public MachineFunctionPass {
   bool readsUndefSubreg(const MachineOperand &MO) const;
   void addLiveInsForSubRanges(const LiveInterval &LI, unsigned PhysReg) const;
   void handleIdentityCopy(MachineInstr &MI) const;
+  void expandCopyBundle(MachineInstr &MI) const;
 
 public:
   static char ID;
@@ -367,11 +368,41 @@ void VirtRegRewriter::handleIdentityCopy(MachineInstr &MI) const {
   }
 
   if (Indexes)
-    Indexes->removeMachineInstrFromMaps(MI);
-  MI.eraseFromParent();
+    Indexes->removeSingleMachineInstrFromMaps(MI);
+  MI.eraseFromBundle();
   DEBUG(dbgs() << "  deleted.\n");
 }
 
+/// The liverange splitting logic sometimes produces bundles of copies when
+/// subregisters are involved. Expand these into a sequence of copy instructions
+/// after processing the last in the bundle. Does not update LiveIntervals
+/// which we shouldn't need for this instruction anymore.
+void VirtRegRewriter::expandCopyBundle(MachineInstr &MI) const {
+  if (!MI.isCopy())
+    return;
+
+  if (MI.isBundledWithPred() && !MI.isBundledWithSucc()) {
+    // Only do this when the complete bundle is made out of COPYs.
+    MachineBasicBlock &MBB = *MI.getParent();
+    for (MachineBasicBlock::reverse_instr_iterator I =
+         std::next(MI.getReverseIterator()), E = MBB.instr_rend();
+         I != E && I->isBundledWithSucc(); ++I) {
+      if (!I->isCopy())
+        return;
+    }
+
+    for (MachineBasicBlock::reverse_instr_iterator I = MI.getReverseIterator();
+         I->isBundledWithPred(); ) {
+      MachineInstr &MI = *I;
+      ++I;
+
+      MI.unbundleFromPred();
+      if (Indexes)
+        Indexes->insertMachineInstrInMaps(MI);
+    }
+  }
+}
+
 void VirtRegRewriter::rewrite() {
   bool NoSubRegLiveness = !MRI->subRegLivenessEnabled();
   SmallVector<unsigned, 8> SuperDeads;
@@ -431,12 +462,14 @@ void VirtRegRewriter::rewrite() {
             }
           }
 
-          // The <def,undef> flag only makes sense for sub-register defs, and
-          // we are substituting a full physreg.  An <imp-use,kill> operand
-          // from the SuperKills list will represent the partial read of the
-          // super-register.
-          if (MO.isDef())
+          // The <def,undef> and <def,internal> flags only make sense for
+          // sub-register defs, and we are substituting a full physreg.  An
+          // <imp-use,kill> operand from the SuperKills list will represent the
+          // partial read of the super-register.
+          if (MO.isDef()) {
             MO.setIsUndef(false);
+            MO.setIsInternalRead(false);
+          }
 
           // PhysReg operands cannot have subregister indexes.
           PhysReg = TRI->getSubReg(PhysReg, SubReg);
@@ -461,6 +494,8 @@ void VirtRegRewriter::rewrite() {
 
       DEBUG(dbgs() << "> " << *MI);
 
+      expandCopyBundle(*MI);
+
       // We can remove identity copies right now.
       handleIdentityCopy(*MI);
     }