3 files changed, 15 insertions, 20 deletions

diff --git a/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp b/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
index f5b629846ae..11b4e7dc832 100644
--- a/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
+++ b/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
@@ -242,7 +242,7 @@ namespace {
 
     /// This function searches in the backward direction for an instruction that
     /// can be moved to the delay slot. Returns true on success.
-    bool searchBackward(MachineBasicBlock &MBB, Iter Slot) const;
+    bool searchBackward(MachineBasicBlock &MBB, MachineInstr &Slot) const;
 
     /// This function searches MBB in the forward direction for an instruction
     /// that can be moved to the delay slot. Returns true on success.
@@ -594,7 +594,7 @@ bool Filler::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
 
       if (MipsCompactBranchPolicy.getValue() != CB_Always ||
            !TII->getEquivalentCompactForm(I)) {
-        if (searchBackward(MBB, I)) {
+        if (searchBackward(MBB, *I)) {
           Filled = true;
         } else if (I->isTerminator()) {
           if (searchSuccBBs(MBB, I)) {
@@ -659,8 +659,6 @@ template<typename IterTy>
 bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
                          RegDefsUses &RegDU, InspectMemInstr& IM, Iter Slot,
                          IterTy &Filler) const {
-  bool IsReverseIter = std::is_convertible<IterTy, ReverseIter>::value;
-
   for (IterTy I = Begin; I != End;) {
     IterTy CurrI = I;
     ++I;
@@ -677,12 +675,6 @@ bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
 
     if (CurrI->isKill()) {
       CurrI->eraseFromParent();
-
-      // This special case is needed for reverse iterators, because when we
-      // erase an instruction, the iterators are updated to point to the next
-      // instruction.
-      if (IsReverseIter && I != End)
-        I = CurrI;
       continue;
     }
 
@@ -722,7 +714,7 @@ bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
   return false;
 }
 
-bool Filler::searchBackward(MachineBasicBlock &MBB, Iter Slot) const {
+bool Filler::searchBackward(MachineBasicBlock &MBB, MachineInstr &Slot) const {
   if (DisableBackwardSearch)
     return false;
 
@@ -731,14 +723,15 @@ bool Filler::searchBackward(MachineBasicBlock &MBB, Iter Slot) const {
   MemDefsUses MemDU(Fn->getDataLayout(), &Fn->getFrameInfo());
   ReverseIter Filler;
 
-  RegDU.init(*Slot);
+  RegDU.init(Slot);
 
-  if (!searchRange(MBB, ReverseIter(Slot), MBB.rend(), RegDU, MemDU, Slot,
+  MachineBasicBlock::iterator SlotI = Slot;
+  if (!searchRange(MBB, ++SlotI.getReverse(), MBB.rend(), RegDU, MemDU, Slot,
                    Filler))
     return false;
 
-  MBB.splice(std::next(Slot), &MBB, std::next(Filler).base());
-  MIBundleBuilder(MBB, Slot, std::next(Slot, 2));
+  MBB.splice(std::next(SlotI), &MBB, Filler.getReverse());
+  MIBundleBuilder(MBB, SlotI, std::next(SlotI, 2));
   ++UsefulSlots;
   return true;
 }
diff --git a/llvm/lib/Target/Mips/MipsInstrInfo.cpp b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
index 35ddbf221e8..1332258912a 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
@@ -147,14 +147,16 @@ unsigned MipsInstrInfo::InsertBranch(MachineBasicBlock &MBB,
 
 unsigned MipsInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
   MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
-  MachineBasicBlock::reverse_iterator FirstBr;
   unsigned removed;
 
   // Skip all the debug instructions.
   while (I != REnd && I->isDebugValue())
     ++I;
 
-  FirstBr = I;
+  if (I == REnd)
+    return 0;
+
+  MachineBasicBlock::iterator FirstBr = ++I.getReverse();
 
   // Up to 2 branches are removed.
   // Note that indirect branches are not removed.
@@ -162,7 +164,7 @@ unsigned MipsInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
     if (!getAnalyzableBrOpc(I->getOpcode()))
       break;
 
-  MBB.erase(I.base(), FirstBr.base());
+  MBB.erase((--I).getReverse(), FirstBr);
 
   return removed;
 }
diff --git a/llvm/lib/Target/Mips/MipsLongBranch.cpp b/llvm/lib/Target/Mips/MipsLongBranch.cpp
index dfb08101956..5eb3e7b01bb 100644
--- a/llvm/lib/Target/Mips/MipsLongBranch.cpp
+++ b/llvm/lib/Target/Mips/MipsLongBranch.cpp
@@ -157,7 +157,7 @@ void MipsLongBranch::splitMBB(MachineBasicBlock *MBB) {
   MBB->addSuccessor(Tgt);
   MF->insert(std::next(MachineFunction::iterator(MBB)), NewMBB);
 
-  NewMBB->splice(NewMBB->end(), MBB, (++LastBr).base(), MBB->end());
+  NewMBB->splice(NewMBB->end(), MBB, LastBr.getReverse(), MBB->end());
 }
 
 // Fill MBBInfos.
@@ -187,7 +187,7 @@ void MipsLongBranch::initMBBInfo() {
 
     if ((Br != End) && !Br->isIndirectBranch() &&
         (Br->isConditionalBranch() || (Br->isUnconditionalBranch() && IsPIC)))
-      MBBInfos[I].Br = &*(++Br).base();
+      MBBInfos[I].Br = &*Br;
   }
 }