Index: lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
===================================================================
--- lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
+++ lib/Target/AMDGPU/SILoadStoreOptimizer.cpp
@@ -141,10 +141,12 @@
   }
 }
 
-static void addDefsToList(const MachineInstr &MI,
-                          SmallVectorImpl<const MachineOperand *> &Defs) {
+static void addDefsToList(const MachineInstr &MI, DenseSet<unsigned> &Defs) {
+  // XXX: Should this be looking for implicit defs?
   for (const MachineOperand &Def : MI.defs()) {
-    Defs.push_back(&Def);
+    bool Inserted = Defs.insert(Def.getReg()).second;
+    (void)Inserted;
+    assert(Inserted);
   }
 }
 
@@ -152,25 +154,25 @@
                                       MachineBasicBlock::iterator B,
                                       const SIInstrInfo *TII,
                                       AliasAnalysis * AA) {
-  return (TII->areMemAccessesTriviallyDisjoint(*A, *B, AA) ||
-    // RAW or WAR - cannot reorder
-    // WAW - cannot reorder
-    // RAR - safe to reorder
-    !(A->mayStore() || B->mayStore()));
+  // RAW or WAR - cannot reorder
+  // WAW - cannot reorder
+  // RAR - safe to reorder
+  return !(A->mayStore() || B->mayStore()) ||
+    TII->areMemAccessesTriviallyDisjoint(*A, *B, AA);
 }
 
 // Add MI and its defs to the lists if MI reads one of the defs that are
 // already in the list. Returns true in that case.
 static bool
 addToListsIfDependent(MachineInstr &MI,
-                      SmallVectorImpl<const MachineOperand *> &Defs,
+                      DenseSet<unsigned> &Defs,
                       SmallVectorImpl<MachineInstr*> &Insts) {
-  for (const MachineOperand *Def : Defs) {
-    bool ReadDef = MI.readsVirtualRegister(Def->getReg());
-    // If ReadDef is true, then there is a use of Def between I
-    // and the instruction that I will potentially be merged with. We
-    // will need to move this instruction after the merged instructions.
-    if (ReadDef) {
+  for (MachineOperand &Use : MI.operands()) {
+    // If one of the defs is read, then there is a use of Def between I and the
+    // instruction that I will potentially be merged with. We will need to move
+    // this instruction after the merged instructions.
+
+    if (Use.isReg() && Use.readsReg() && Defs.count(Use.getReg())) {
       Insts.push_back(&MI);
       addDefsToList(MI, Defs);
       return true;
@@ -248,8 +250,10 @@
   return false;
 }
 
+
 bool SILoadStoreOptimizer::findMatchingDSInst(CombineInfo &CI) {
-  MachineBasicBlock::iterator E = CI.I->getParent()->end();
+  MachineBasicBlock *MBB = CI.I->getParent();
+  MachineBasicBlock::iterator E = MBB->end();
   MachineBasicBlock::iterator MBBI = CI.I;
 
   int AddrIdx = AMDGPU::getNamedOperandIdx(CI.I->getOpcode(),
@@ -258,12 +262,13 @@
 
   // We only ever merge operations with the same base address register, so don't
   // bother scanning forward if there are no other uses.
-  if (MRI->hasOneNonDBGUse(AddrReg0.getReg()))
+  if (TargetRegisterInfo::isPhysicalRegister(AddrReg0.getReg()) ||
+      MRI->hasOneNonDBGUse(AddrReg0.getReg()))
     return false;
 
   ++MBBI;
 
-  SmallVector<const MachineOperand *, 8> DefsToMove;
+  DenseSet<unsigned> DefsToMove;
   addDefsToList(*CI.I, DefsToMove);
 
   for ( ; MBBI != E; ++MBBI) {