[llvm] r312846 - RegAllocFast: Cleanup; NFC

Matthias Braun via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 8 17:52:46 PDT 2017


Author: matze
Date: Fri Sep  8 17:52:46 2017
New Revision: 312846

URL: http://llvm.org/viewvc/llvm-project?rev=312846&view=rev
Log:
RegAllocFast: Cleanup; NFC

- Use range based for
- Variable names should start with upper case
- Add `const`
- Change class name to match filename
- Fix doxygen comments
- Use MCPhysReg instead of unsigned
- Use references instead of pointers where things cannot be nullptr
- Misc coding style improvements

Modified:
    llvm/trunk/include/llvm/InitializePasses.h
    llvm/trunk/lib/CodeGen/CodeGen.cpp
    llvm/trunk/lib/CodeGen/RegAllocFast.cpp

Modified: llvm/trunk/include/llvm/InitializePasses.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=312846&r1=312845&r2=312846&view=diff
==============================================================================
--- llvm/trunk/include/llvm/InitializePasses.h (original)
+++ llvm/trunk/include/llvm/InitializePasses.h Fri Sep  8 17:52:46 2017
@@ -304,7 +304,7 @@ void initializeProfileSummaryInfoWrapper
 void initializePromoteLegacyPassPass(PassRegistry&);
 void initializePruneEHPass(PassRegistry&);
 void initializeRABasicPass(PassRegistry&);
-void initializeRAFastPass(PassRegistry&);
+void initializeRegAllocFastPass(PassRegistry&);
 void initializeRAGreedyPass(PassRegistry&);
 void initializeReassociateLegacyPassPass(PassRegistry&);
 void initializeRegBankSelectPass(PassRegistry&);

Modified: llvm/trunk/lib/CodeGen/CodeGen.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGen.cpp?rev=312846&r1=312845&r2=312846&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGen.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGen.cpp Fri Sep  8 17:52:46 2017
@@ -78,7 +78,7 @@ void llvm::initializeCodeGen(PassRegistr
   initializePreISelIntrinsicLoweringLegacyPassPass(Registry);
   initializeProcessImplicitDefsPass(Registry);
   initializeRABasicPass(Registry);
-  initializeRAFastPass(Registry);
+  initializeRegAllocFastPass(Registry);
   initializeRAGreedyPass(Registry);
   initializeRegisterCoalescerPass(Registry);
   initializeRenameIndependentSubregsPass(Registry);

Modified: llvm/trunk/lib/CodeGen/RegAllocFast.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocFast.cpp?rev=312846&r1=312845&r2=312846&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocFast.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocFast.cpp Fri Sep  8 17:52:46 2017
@@ -7,8 +7,9 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This register allocator allocates registers to a basic block at a time,
-// attempting to keep values in registers and reusing registers as appropriate.
+/// \file This register allocator allocates registers to a basic block at a
+/// time, attempting to keep values in registers and reusing registers as
+/// appropriate.
 //
 //===----------------------------------------------------------------------===//
 
@@ -45,33 +46,31 @@ static RegisterRegAlloc
   fastRegAlloc("fast", "fast register allocator", createFastRegisterAllocator);
 
 namespace {
-  class RAFast : public MachineFunctionPass {
+  class RegAllocFast : public MachineFunctionPass {
   public:
     static char ID;
-    RAFast() : MachineFunctionPass(ID), StackSlotForVirtReg(-1),
-               isBulkSpilling(false) {}
+    RegAllocFast() : MachineFunctionPass(ID), StackSlotForVirtReg(-1) {}
 
   private:
-    MachineFunction *MF;
+    MachineFrameInfo *MFI;
     MachineRegisterInfo *MRI;
     const TargetRegisterInfo *TRI;
     const TargetInstrInfo *TII;
     RegisterClassInfo RegClassInfo;
 
-    // Basic block currently being allocated.
+    /// Basic block currently being allocated.
     MachineBasicBlock *MBB;
 
-    // StackSlotForVirtReg - Maps virtual regs to the frame index where these
-    // values are spilled.
+    /// Maps virtual regs to the frame index where these values are spilled.
     IndexedMap<int, VirtReg2IndexFunctor> StackSlotForVirtReg;
 
-    // Everything we know about a live virtual register.
+    /// Everything we know about a live virtual register.
     struct LiveReg {
-      MachineInstr *LastUse;    // Last instr to use reg.
-      unsigned VirtReg;         // Virtual register number.
-      unsigned PhysReg;         // Currently held here.
-      unsigned short LastOpNum; // OpNum on LastUse.
-      bool Dirty;               // Register needs spill.
+      MachineInstr *LastUse;    ///< Last instr to use reg.
+      unsigned VirtReg;         ///< Virtual register number.
+      MCPhysReg PhysReg;        ///< Currently held here.
+      unsigned short LastOpNum; ///< OpNum on LastUse.
+      bool Dirty;               ///< Register needs spill.
 
       explicit LiveReg(unsigned v)
         : LastUse(nullptr), VirtReg(v), PhysReg(0), LastOpNum(0), Dirty(false){}
@@ -83,63 +82,62 @@ namespace {
 
     typedef SparseSet<LiveReg> LiveRegMap;
 
-    // LiveVirtRegs - This map contains entries for each virtual register
-    // that is currently available in a physical register.
+    /// This map contains entries for each virtual register that is currently
+    /// available in a physical register.
     LiveRegMap LiveVirtRegs;
 
     DenseMap<unsigned, SmallVector<MachineInstr *, 4> > LiveDbgValueMap;
 
-    // RegState - Track the state of a physical register.
+    /// Track the state of a physical register.
     enum RegState {
-      // A disabled register is not available for allocation, but an alias may
-      // be in use. A register can only be moved out of the disabled state if
-      // all aliases are disabled.
+      /// A disabled register is not available for allocation, but an alias may
+      /// be in use. A register can only be moved out of the disabled state if
+      /// all aliases are disabled.
       regDisabled,
 
-      // A free register is not currently in use and can be allocated
-      // immediately without checking aliases.
+      /// A free register is not currently in use and can be allocated
+      /// immediately without checking aliases.
       regFree,
 
-      // A reserved register has been assigned explicitly (e.g., setting up a
-      // call parameter), and it remains reserved until it is used.
+      /// A reserved register has been assigned explicitly (e.g., setting up a
+      /// call parameter), and it remains reserved until it is used.
       regReserved
 
-      // A register state may also be a virtual register number, indication that
-      // the physical register is currently allocated to a virtual register. In
-      // that case, LiveVirtRegs contains the inverse mapping.
+      /// A register state may also be a virtual register number, indication
+      /// that the physical register is currently allocated to a virtual
+      /// register. In that case, LiveVirtRegs contains the inverse mapping.
     };
 
-    // PhysRegState - One of the RegState enums, or a virtreg.
+    /// One of the RegState enums, or a virtreg.
     std::vector<unsigned> PhysRegState;
 
     SmallVector<unsigned, 16> VirtDead;
     SmallVector<MachineInstr*, 32> Coalesced;
 
-    // Set of register units.
+    /// Set of register units.
     typedef SparseSet<unsigned> UsedInInstrSet;
 
-    // Set of register units that are used in the current instruction, and so
-    // cannot be allocated.
+    /// Set of register units that are used in the current instruction, and so
+    /// cannot be allocated.
     UsedInInstrSet UsedInInstr;
 
-    // Mark a physreg as used in this instruction.
-    void markRegUsedInInstr(unsigned PhysReg) {
+    /// Mark a physreg as used in this instruction.
+    void markRegUsedInInstr(MCPhysReg PhysReg) {
       for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units)
         UsedInInstr.insert(*Units);
     }
 
-    // Check if a physreg or any of its aliases are used in this instruction.
-    bool isRegUsedInInstr(unsigned PhysReg) const {
+    /// Check if a physreg or any of its aliases are used in this instruction.
+    bool isRegUsedInInstr(MCPhysReg PhysReg) const {
       for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units)
         if (UsedInInstr.count(*Units))
           return true;
       return false;
     }
 
-    // isBulkSpilling - This flag is set when LiveRegMap will be cleared
-    // completely after spilling all live registers. LiveRegMap entries should
-    // not be erased.
-    bool isBulkSpilling;
+    /// This flag is set when LiveRegMap will be cleared completely after
+    /// spilling all live registers. LiveRegMap entries should not be erased.
+    bool isBulkSpilling = false;
 
     enum : unsigned {
       spillClean = 1,
@@ -166,29 +164,29 @@ namespace {
 
   private:
     bool runOnMachineFunction(MachineFunction &Fn) override;
-    void AllocateBasicBlock();
-    void handleThroughOperands(MachineInstr *MI,
+    void allocateBasicBlock(MachineBasicBlock &MBB);
+    void handleThroughOperands(MachineInstr &MI,
                                SmallVectorImpl<unsigned> &VirtDead);
-    int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC);
-    bool isLastUseOfLocalReg(MachineOperand&);
+    int getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass &RC);
+    bool isLastUseOfLocalReg(const MachineOperand &MO) const;
 
-    void addKillFlag(const LiveReg&);
-    void killVirtReg(LiveRegMap::iterator);
+    void addKillFlag(const LiveReg &LRI);
+    void killVirtReg(LiveRegMap::iterator LRI);
     void killVirtReg(unsigned VirtReg);
     void spillVirtReg(MachineBasicBlock::iterator MI, LiveRegMap::iterator);
     void spillVirtReg(MachineBasicBlock::iterator MI, unsigned VirtReg);
 
-    void usePhysReg(MachineOperand&);
-    void definePhysReg(MachineInstr &MI, unsigned PhysReg, RegState NewState);
-    unsigned calcSpillCost(unsigned PhysReg) const;
-    void assignVirtToPhysReg(LiveReg&, unsigned PhysReg);
+    void usePhysReg(MachineOperand &MO);
+    void definePhysReg(MachineInstr &MI, MCPhysReg PhysReg, RegState NewState);
+    unsigned calcSpillCost(MCPhysReg PhysReg) const;
+    void assignVirtToPhysReg(LiveReg&, MCPhysReg PhysReg);
     LiveRegMap::iterator findLiveVirtReg(unsigned VirtReg) {
       return LiveVirtRegs.find(TargetRegisterInfo::virtReg2Index(VirtReg));
     }
     LiveRegMap::const_iterator findLiveVirtReg(unsigned VirtReg) const {
       return LiveVirtRegs.find(TargetRegisterInfo::virtReg2Index(VirtReg));
     }
-    LiveRegMap::iterator assignVirtToPhysReg(unsigned VReg, unsigned PhysReg);
+    LiveRegMap::iterator assignVirtToPhysReg(unsigned VReg, MCPhysReg PhysReg);
     LiveRegMap::iterator allocVirtReg(MachineInstr &MI, LiveRegMap::iterator,
                                       unsigned Hint);
     LiveRegMap::iterator defineVirtReg(MachineInstr &MI, unsigned OpNum,
@@ -196,35 +194,39 @@ namespace {
     LiveRegMap::iterator reloadVirtReg(MachineInstr &MI, unsigned OpNum,
                                        unsigned VirtReg, unsigned Hint);
     void spillAll(MachineBasicBlock::iterator MI);
-    bool setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg);
+    bool setPhysReg(MachineInstr &MI, unsigned OpNum, MCPhysReg PhysReg);
+
+    void dumpState();
   };
-  char RAFast::ID = 0;
+  char RegAllocFast::ID = 0;
 }
 
-INITIALIZE_PASS(RAFast, "regallocfast", "Fast Register Allocator", false, false)
+INITIALIZE_PASS(RegAllocFast, "regallocfast", "Fast Register Allocator", false,
+                false)
 
-/// getStackSpaceFor - This allocates space for the specified virtual register
-/// to be held on the stack.
-int RAFast::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
+/// This allocates space for the specified virtual register to be held on the
+/// stack.
+int RegAllocFast::getStackSpaceFor(unsigned VirtReg,
+                                   const TargetRegisterClass &RC) {
   // Find the location Reg would belong...
   int SS = StackSlotForVirtReg[VirtReg];
+  // Already has space allocated?
   if (SS != -1)
-    return SS;          // Already has space allocated?
+    return SS;
 
   // Allocate a new stack object for this spill location...
-  unsigned Size = TRI->getSpillSize(*RC);
-  unsigned Align = TRI->getSpillAlignment(*RC);
-  int FrameIdx = MF->getFrameInfo().CreateSpillStackObject(Size, Align);
+  unsigned Size = TRI->getSpillSize(RC);
+  unsigned Align = TRI->getSpillAlignment(RC);
+  int FrameIdx = MFI->CreateSpillStackObject(Size, Align);
 
   // Assign the slot.
   StackSlotForVirtReg[VirtReg] = FrameIdx;
   return FrameIdx;
 }
 
-/// isLastUseOfLocalReg - Return true if MO is the only remaining reference to
-/// its virtual register, and it is guaranteed to be a block-local register.
-///
-bool RAFast::isLastUseOfLocalReg(MachineOperand &MO) {
+/// Return true if MO is the only remaining reference to its virtual register,
+/// and it is guaranteed to be a block-local register.
+bool RegAllocFast::isLastUseOfLocalReg(const MachineOperand &MO) const {
   // If the register has ever been spilled or reloaded, we conservatively assume
   // it is a global register used in multiple blocks.
   if (StackSlotForVirtReg[MO.getReg()] != -1)
@@ -237,8 +239,8 @@ bool RAFast::isLastUseOfLocalReg(Machine
   return ++I == MRI->reg_nodbg_end();
 }
 
-/// addKillFlag - Set kill flags on last use of a virtual register.
-void RAFast::addKillFlag(const LiveReg &LR) {
+/// Set kill flags on last use of a virtual register.
+void RegAllocFast::addKillFlag(const LiveReg &LR) {
   if (!LR.LastUse) return;
   MachineOperand &MO = LR.LastUse->getOperand(LR.LastOpNum);
   if (MO.isUse() && !LR.LastUse->isRegTiedToDefOperand(LR.LastOpNum)) {
@@ -256,8 +258,8 @@ void RAFast::addKillFlag(const LiveReg &
   }
 }
 
-/// killVirtReg - Mark virtreg as no longer available.
-void RAFast::killVirtReg(LiveRegMap::iterator LRI) {
+/// Mark virtreg as no longer available.
+void RegAllocFast::killVirtReg(LiveRegMap::iterator LRI) {
   addKillFlag(*LRI);
   assert(PhysRegState[LRI->PhysReg] == LRI->VirtReg &&
          "Broken RegState mapping");
@@ -267,8 +269,8 @@ void RAFast::killVirtReg(LiveRegMap::ite
     LiveVirtRegs.erase(LRI);
 }
 
-/// killVirtReg - Mark virtreg as no longer available.
-void RAFast::killVirtReg(unsigned VirtReg) {
+/// Mark virtreg as no longer available.
+void RegAllocFast::killVirtReg(unsigned VirtReg) {
   assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
          "killVirtReg needs a virtual register");
   LiveRegMap::iterator LRI = findLiveVirtReg(VirtReg);
@@ -276,9 +278,10 @@ void RAFast::killVirtReg(unsigned VirtRe
     killVirtReg(LRI);
 }
 
-/// spillVirtReg - This method spills the value specified by VirtReg into the
-/// corresponding stack slot if needed.
-void RAFast::spillVirtReg(MachineBasicBlock::iterator MI, unsigned VirtReg) {
+/// This method spills the value specified by VirtReg into the corresponding
+/// stack slot if needed.
+void RegAllocFast::spillVirtReg(MachineBasicBlock::iterator MI,
+                                unsigned VirtReg) {
   assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
          "Spilling a physical register is illegal!");
   LiveRegMap::iterator LRI = findLiveVirtReg(VirtReg);
@@ -286,9 +289,9 @@ void RAFast::spillVirtReg(MachineBasicBl
   spillVirtReg(MI, LRI);
 }
 
-/// spillVirtReg - Do the actual work of spilling.
-void RAFast::spillVirtReg(MachineBasicBlock::iterator MI,
-                          LiveRegMap::iterator LRI) {
+/// Do the actual work of spilling.
+void RegAllocFast::spillVirtReg(MachineBasicBlock::iterator MI,
+                                LiveRegMap::iterator LRI) {
   LiveReg &LR = *LRI;
   assert(PhysRegState[LR.PhysReg] == LRI->VirtReg && "Broken RegState mapping");
 
@@ -299,10 +302,10 @@ void RAFast::spillVirtReg(MachineBasicBl
     LR.Dirty = false;
     DEBUG(dbgs() << "Spilling " << PrintReg(LRI->VirtReg, TRI)
                  << " in " << PrintReg(LR.PhysReg, TRI));
-    const TargetRegisterClass *RC = MRI->getRegClass(LRI->VirtReg);
+    const TargetRegisterClass &RC = *MRI->getRegClass(LRI->VirtReg);
     int FI = getStackSpaceFor(LRI->VirtReg, RC);
     DEBUG(dbgs() << " to stack slot #" << FI << "\n");
-    TII->storeRegToStackSlot(*MBB, MI, LR.PhysReg, SpillKill, FI, RC, TRI);
+    TII->storeRegToStackSlot(*MBB, MI, LR.PhysReg, SpillKill, FI, &RC, TRI);
     ++NumStores;   // Update statistics
 
     // If this register is used by DBG_VALUE then insert new DBG_VALUE to
@@ -310,8 +313,7 @@ void RAFast::spillVirtReg(MachineBasicBl
     // value.
     SmallVectorImpl<MachineInstr *> &LRIDbgValues =
       LiveDbgValueMap[LRI->VirtReg];
-    for (unsigned li = 0, le = LRIDbgValues.size(); li != le; ++li) {
-      MachineInstr *DBG = LRIDbgValues[li];
+    for (MachineInstr *DBG : LRIDbgValues) {
       MachineInstr *NewDV = buildDbgValueForSpill(*MBB, MI, *DBG, FI);
       assert(NewDV->getParent() == MBB && "dangling parent pointer");
       (void)NewDV;
@@ -327,32 +329,31 @@ void RAFast::spillVirtReg(MachineBasicBl
   killVirtReg(LRI);
 }
 
-/// spillAll - Spill all dirty virtregs without killing them.
-void RAFast::spillAll(MachineBasicBlock::iterator MI) {
+/// Spill all dirty virtregs without killing them.
+void RegAllocFast::spillAll(MachineBasicBlock::iterator MI) {
   if (LiveVirtRegs.empty()) return;
   isBulkSpilling = true;
   // The LiveRegMap is keyed by an unsigned (the virtreg number), so the order
   // of spilling here is deterministic, if arbitrary.
-  for (LiveRegMap::iterator i = LiveVirtRegs.begin(), e = LiveVirtRegs.end();
-       i != e; ++i)
-    spillVirtReg(MI, i);
+  for (LiveRegMap::iterator I = LiveVirtRegs.begin(), E = LiveVirtRegs.end();
+       I != E; ++I)
+    spillVirtReg(MI, I);
   LiveVirtRegs.clear();
   isBulkSpilling = false;
 }
 
-/// usePhysReg - Handle the direct use of a physical register.
-/// Check that the register is not used by a virtreg.
-/// Kill the physreg, marking it free.
-/// This may add implicit kills to MO->getParent() and invalidate MO.
-void RAFast::usePhysReg(MachineOperand &MO) {
-  unsigned PhysReg = MO.getReg();
-  assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) &&
-         "Bad usePhysReg operand");
-
+/// Handle the direct use of a physical register.  Check that the register is
+/// not used by a virtreg. Kill the physreg, marking it free. This may add
+/// implicit kills to MO->getParent() and invalidate MO.
+void RegAllocFast::usePhysReg(MachineOperand &MO) {
   // Ignore undef uses.
   if (MO.isUndef())
     return;
 
+  unsigned PhysReg = MO.getReg();
+  assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) &&
+         "Bad usePhysReg operand");
+
   markRegUsedInInstr(PhysReg);
   switch (PhysRegState[PhysReg]) {
   case regDisabled:
@@ -371,7 +372,7 @@ void RAFast::usePhysReg(MachineOperand &
 
   // Maybe a superregister is reserved?
   for (MCRegAliasIterator AI(PhysReg, TRI, false); AI.isValid(); ++AI) {
-    unsigned Alias = *AI;
+    MCPhysReg Alias = *AI;
     switch (PhysRegState[Alias]) {
     case regDisabled:
       break;
@@ -409,11 +410,11 @@ void RAFast::usePhysReg(MachineOperand &
   MO.setIsKill();
 }
 
-/// definePhysReg - Mark PhysReg as reserved or free after spilling any
-/// virtregs. This is very similar to defineVirtReg except the physreg is
-/// reserved instead of allocated.
-void RAFast::definePhysReg(MachineInstr &MI, unsigned PhysReg,
-                           RegState NewState) {
+/// Mark PhysReg as reserved or free after spilling any virtregs. This is very
+/// similar to defineVirtReg except the physreg is reserved instead of
+/// allocated.
+void RegAllocFast::definePhysReg(MachineInstr &MI, MCPhysReg PhysReg,
+                                 RegState NewState) {
   markRegUsedInInstr(PhysReg);
   switch (unsigned VirtReg = PhysRegState[PhysReg]) {
   case regDisabled:
@@ -430,7 +431,7 @@ void RAFast::definePhysReg(MachineInstr
   // This is a disabled register, disable all aliases.
   PhysRegState[PhysReg] = NewState;
   for (MCRegAliasIterator AI(PhysReg, TRI, false); AI.isValid(); ++AI) {
-    unsigned Alias = *AI;
+    MCPhysReg Alias = *AI;
     switch (unsigned VirtReg = PhysRegState[Alias]) {
     case regDisabled:
       break;
@@ -448,12 +449,11 @@ void RAFast::definePhysReg(MachineInstr
 }
 
 
-// calcSpillCost - Return the cost of spilling clearing out PhysReg and
-// aliases so it is free for allocation.
-// Returns 0 when PhysReg is free or disabled with all aliases disabled - it
-// can be allocated directly.
-// Returns spillImpossible when PhysReg or an alias can't be spilled.
-unsigned RAFast::calcSpillCost(unsigned PhysReg) const {
+/// \brief Return the cost of spilling clearing out PhysReg and aliases so it is
+/// free for allocation. Returns 0 when PhysReg is free or disabled with all
+/// aliases disabled - it can be allocated directly.
+/// \returns spillImpossible when PhysReg or an alias can't be spilled.
+unsigned RegAllocFast::calcSpillCost(MCPhysReg PhysReg) const {
   if (isRegUsedInInstr(PhysReg)) {
     DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " is already used in instr.\n");
     return spillImpossible;
@@ -478,7 +478,7 @@ unsigned RAFast::calcSpillCost(unsigned
   DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " is disabled.\n");
   unsigned Cost = 0;
   for (MCRegAliasIterator AI(PhysReg, TRI, false); AI.isValid(); ++AI) {
-    unsigned Alias = *AI;
+    MCPhysReg Alias = *AI;
     switch (unsigned VirtReg = PhysRegState[Alias]) {
     case regDisabled:
       break;
@@ -499,11 +499,10 @@ unsigned RAFast::calcSpillCost(unsigned
 }
 
 
-/// assignVirtToPhysReg - This method updates local state so that we know
-/// that PhysReg is the proper container for VirtReg now.  The physical
-/// register must not be used for anything else when this is called.
-///
-void RAFast::assignVirtToPhysReg(LiveReg &LR, unsigned PhysReg) {
+/// \brief This method updates local state so that we know that PhysReg is the
+/// proper container for VirtReg now.  The physical register must not be used
+/// for anything else when this is called.
+void RegAllocFast::assignVirtToPhysReg(LiveReg &LR, MCPhysReg PhysReg) {
   DEBUG(dbgs() << "Assigning " << PrintReg(LR.VirtReg, TRI) << " to "
                << PrintReg(PhysReg, TRI) << "\n");
   PhysRegState[PhysReg] = LR.VirtReg;
@@ -511,32 +510,26 @@ void RAFast::assignVirtToPhysReg(LiveReg
   LR.PhysReg = PhysReg;
 }
 
-RAFast::LiveRegMap::iterator
-RAFast::assignVirtToPhysReg(unsigned VirtReg, unsigned PhysReg) {
+RegAllocFast::LiveRegMap::iterator
+RegAllocFast::assignVirtToPhysReg(unsigned VirtReg, MCPhysReg PhysReg) {
   LiveRegMap::iterator LRI = findLiveVirtReg(VirtReg);
   assert(LRI != LiveVirtRegs.end() && "VirtReg disappeared");
   assignVirtToPhysReg(*LRI, PhysReg);
   return LRI;
 }
 
-/// allocVirtReg - Allocate a physical register for VirtReg.
-RAFast::LiveRegMap::iterator RAFast::allocVirtReg(MachineInstr &MI,
-                                                  LiveRegMap::iterator LRI,
-                                                  unsigned Hint) {
+/// Allocates a physical register for VirtReg.
+RegAllocFast::LiveRegMap::iterator RegAllocFast::allocVirtReg(MachineInstr &MI,
+    LiveRegMap::iterator LRI, unsigned Hint) {
   const unsigned VirtReg = LRI->VirtReg;
 
   assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
          "Can only allocate virtual registers");
 
-  const TargetRegisterClass *RC = MRI->getRegClass(VirtReg);
-
-  // Ignore invalid hints.
-  if (Hint && (!TargetRegisterInfo::isPhysicalRegister(Hint) ||
-               !RC->contains(Hint) || !MRI->isAllocatable(Hint)))
-    Hint = 0;
-
   // Take hint when possible.
-  if (Hint) {
+  const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
+  if (TargetRegisterInfo::isPhysicalRegister(Hint) &&
+      MRI->isAllocatable(Hint) && RC.contains(Hint)) {
     // Ignore the hint if we would have to spill a dirty register.
     unsigned Cost = calcSpillCost(Hint);
     if (Cost < spillDirty) {
@@ -548,11 +541,9 @@ RAFast::LiveRegMap::iterator RAFast::all
     }
   }
 
-  ArrayRef<MCPhysReg> AO = RegClassInfo.getOrder(RC);
-
   // First try to find a completely free register.
-  for (ArrayRef<MCPhysReg>::iterator I = AO.begin(), E = AO.end(); I != E; ++I){
-    unsigned PhysReg = *I;
+  ArrayRef<MCPhysReg> AO = RegClassInfo.getOrder(&RC);
+  for (MCPhysReg PhysReg : AO) {
     if (PhysRegState[PhysReg] == regFree && !isRegUsedInInstr(PhysReg)) {
       assignVirtToPhysReg(*LRI, PhysReg);
       return LRI;
@@ -560,21 +551,22 @@ RAFast::LiveRegMap::iterator RAFast::all
   }
 
   DEBUG(dbgs() << "Allocating " << PrintReg(VirtReg) << " from "
-               << TRI->getRegClassName(RC) << "\n");
+               << TRI->getRegClassName(&RC) << "\n");
 
-  unsigned BestReg = 0, BestCost = spillImpossible;
-  for (ArrayRef<MCPhysReg>::iterator I = AO.begin(), E = AO.end(); I != E; ++I){
-    unsigned Cost = calcSpillCost(*I);
-    DEBUG(dbgs() << "\tRegister: " << PrintReg(*I, TRI) << "\n");
+  unsigned BestReg = 0;
+  unsigned BestCost = spillImpossible;
+  for (MCPhysReg PhysReg : AO) {
+    unsigned Cost = calcSpillCost(PhysReg);
+    DEBUG(dbgs() << "\tRegister: " << PrintReg(PhysReg, TRI) << "\n");
     DEBUG(dbgs() << "\tCost: " << Cost << "\n");
     DEBUG(dbgs() << "\tBestCost: " << BestCost << "\n");
     // Cost is 0 when all aliases are already disabled.
     if (Cost == 0) {
-      assignVirtToPhysReg(*LRI, *I);
+      assignVirtToPhysReg(*LRI, PhysReg);
       return LRI;
     }
     if (Cost < BestCost)
-      BestReg = *I, BestCost = Cost;
+      BestReg = PhysReg, BestCost = Cost;
   }
 
   if (BestReg) {
@@ -593,11 +585,11 @@ RAFast::LiveRegMap::iterator RAFast::all
   return assignVirtToPhysReg(VirtReg, *AO.begin());
 }
 
-/// defineVirtReg - Allocate a register for VirtReg and mark it as dirty.
-RAFast::LiveRegMap::iterator RAFast::defineVirtReg(MachineInstr &MI,
-                                                   unsigned OpNum,
-                                                   unsigned VirtReg,
-                                                   unsigned Hint) {
+/// Allocates a register for VirtReg and mark it as dirty.
+RegAllocFast::LiveRegMap::iterator RegAllocFast::defineVirtReg(MachineInstr &MI,
+                                                               unsigned OpNum,
+                                                               unsigned VirtReg,
+                                                               unsigned Hint) {
   assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
          "Not a virtual register");
   LiveRegMap::iterator LRI;
@@ -627,11 +619,11 @@ RAFast::LiveRegMap::iterator RAFast::def
   return LRI;
 }
 
-/// reloadVirtReg - Make sure VirtReg is available in a physreg and return it.
-RAFast::LiveRegMap::iterator RAFast::reloadVirtReg(MachineInstr &MI,
-                                                   unsigned OpNum,
-                                                   unsigned VirtReg,
-                                                   unsigned Hint) {
+/// Make sure VirtReg is available in a physreg and return it.
+RegAllocFast::LiveRegMap::iterator RegAllocFast::reloadVirtReg(MachineInstr &MI,
+                                                               unsigned OpNum,
+                                                               unsigned VirtReg,
+                                                               unsigned Hint) {
   assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
          "Not a virtual register");
   LiveRegMap::iterator LRI;
@@ -640,11 +632,11 @@ RAFast::LiveRegMap::iterator RAFast::rel
   MachineOperand &MO = MI.getOperand(OpNum);
   if (New) {
     LRI = allocVirtReg(MI, LRI, Hint);
-    const TargetRegisterClass *RC = MRI->getRegClass(VirtReg);
+    const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
     int FrameIndex = getStackSpaceFor(VirtReg, RC);
     DEBUG(dbgs() << "Reloading " << PrintReg(VirtReg, TRI) << " into "
                  << PrintReg(LRI->PhysReg, TRI) << "\n");
-    TII->loadRegFromStackSlot(*MBB, MI, LRI->PhysReg, FrameIndex, RC, TRI);
+    TII->loadRegFromStackSlot(*MBB, MI, LRI->PhysReg, FrameIndex, &RC, TRI);
     ++NumLoads;
   } else if (LRI->Dirty) {
     if (isLastUseOfLocalReg(MO)) {
@@ -678,11 +670,12 @@ RAFast::LiveRegMap::iterator RAFast::rel
   return LRI;
 }
 
-// setPhysReg - Change operand OpNum in MI the refer the PhysReg, considering
-// subregs. This may invalidate any operand pointers.
-// Return true if the operand kills its register.
-bool RAFast::setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg) {
-  MachineOperand &MO = MI->getOperand(OpNum);
+/// Changes operand OpNum in MI the refer the PhysReg, considering subregs. This
+/// may invalidate any operand pointers.  Return true if the operand kills its
+/// register.
+bool RegAllocFast::setPhysReg(MachineInstr &MI, unsigned OpNum,
+                              MCPhysReg PhysReg) {
+  MachineOperand &MO = MI.getOperand(OpNum);
   bool Dead = MO.isDead();
   if (!MO.getSubReg()) {
     MO.setReg(PhysReg);
@@ -696,32 +689,31 @@ bool RAFast::setPhysReg(MachineInstr *MI
   // A kill flag implies killing the full register. Add corresponding super
   // register kill.
   if (MO.isKill()) {
-    MI->addRegisterKilled(PhysReg, TRI, true);
+    MI.addRegisterKilled(PhysReg, TRI, true);
     return true;
   }
 
   // A <def,read-undef> of a sub-register requires an implicit def of the full
   // register.
   if (MO.isDef() && MO.isUndef())
-    MI->addRegisterDefined(PhysReg, TRI);
+    MI.addRegisterDefined(PhysReg, TRI);
 
   return Dead;
 }
 
-// Handle special instruction operand like early clobbers and tied ops when
+// Handles special instruction operand like early clobbers and tied ops when
 // there are additional physreg defines.
-void RAFast::handleThroughOperands(MachineInstr *MI,
-                                   SmallVectorImpl<unsigned> &VirtDead) {
+void RegAllocFast::handleThroughOperands(MachineInstr &MI,
+                                         SmallVectorImpl<unsigned> &VirtDead) {
   DEBUG(dbgs() << "Scanning for through registers:");
   SmallSet<unsigned, 8> ThroughRegs;
-  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI->getOperand(i);
+  for (const MachineOperand &MO : MI.operands()) {
     if (!MO.isReg()) continue;
     unsigned Reg = MO.getReg();
     if (!TargetRegisterInfo::isVirtualRegister(Reg))
       continue;
-    if (MO.isEarlyClobber() || MI->isRegTiedToDefOperand(i) ||
-        (MO.getSubReg() && MI->readsVirtualRegister(Reg))) {
+    if (MO.isEarlyClobber() || (MO.isUse() && MO.isTied()) ||
+        (MO.getSubReg() && MI.readsVirtualRegister(Reg))) {
       if (ThroughRegs.insert(Reg).second)
         DEBUG(dbgs() << ' ' << PrintReg(Reg));
     }
@@ -730,63 +722,61 @@ void RAFast::handleThroughOperands(Machi
   // If any physreg defines collide with preallocated through registers,
   // we must spill and reallocate.
   DEBUG(dbgs() << "\nChecking for physdef collisions.\n");
-  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI->getOperand(i);
+  for (const MachineOperand &MO : MI.operands()) {
     if (!MO.isReg() || !MO.isDef()) continue;
     unsigned Reg = MO.getReg();
     if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
     markRegUsedInInstr(Reg);
     for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) {
       if (ThroughRegs.count(PhysRegState[*AI]))
-        definePhysReg(*MI, *AI, regFree);
+        definePhysReg(MI, *AI, regFree);
     }
   }
 
   SmallVector<unsigned, 8> PartialDefs;
   DEBUG(dbgs() << "Allocating tied uses.\n");
-  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI->getOperand(i);
+  for (unsigned I = 0, E = MI.getNumOperands(); I != E; ++I) {
+    const MachineOperand &MO = MI.getOperand(I);
     if (!MO.isReg()) continue;
     unsigned Reg = MO.getReg();
     if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
     if (MO.isUse()) {
-      unsigned DefIdx = 0;
-      if (!MI->isRegTiedToDefOperand(i, &DefIdx)) continue;
-      DEBUG(dbgs() << "Operand " << i << "("<< MO << ") is tied to operand "
+      if (!MO.isTied()) continue;
+      unsigned DefIdx = MI.findTiedOperandIdx(I);
+      DEBUG(dbgs() << "Operand " << I << "("<< MO << ") is tied to operand "
         << DefIdx << ".\n");
-      LiveRegMap::iterator LRI = reloadVirtReg(*MI, i, Reg, 0);
-      unsigned PhysReg = LRI->PhysReg;
-      setPhysReg(MI, i, PhysReg);
+      LiveRegMap::iterator LRI = reloadVirtReg(MI, I, Reg, 0);
+      MCPhysReg PhysReg = LRI->PhysReg;
+      setPhysReg(MI, I, PhysReg);
       // Note: we don't update the def operand yet. That would cause the normal
       // def-scan to attempt spilling.
-    } else if (MO.getSubReg() && MI->readsVirtualRegister(Reg)) {
+    } else if (MO.getSubReg() && MI.readsVirtualRegister(Reg)) {
       DEBUG(dbgs() << "Partial redefine: " << MO << "\n");
       // Reload the register, but don't assign to the operand just yet.
       // That would confuse the later phys-def processing pass.
-      LiveRegMap::iterator LRI = reloadVirtReg(*MI, i, Reg, 0);
+      LiveRegMap::iterator LRI = reloadVirtReg(MI, I, Reg, 0);
       PartialDefs.push_back(LRI->PhysReg);
     }
   }
 
   DEBUG(dbgs() << "Allocating early clobbers.\n");
-  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI->getOperand(i);
+  for (unsigned I = 0, E = MI.getNumOperands(); I != E; ++I) {
+    const MachineOperand &MO = MI.getOperand(I);
     if (!MO.isReg()) continue;
     unsigned Reg = MO.getReg();
     if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
     if (!MO.isEarlyClobber())
       continue;
     // Note: defineVirtReg may invalidate MO.
-    LiveRegMap::iterator LRI = defineVirtReg(*MI, i, Reg, 0);
-    unsigned PhysReg = LRI->PhysReg;
-    if (setPhysReg(MI, i, PhysReg))
+    LiveRegMap::iterator LRI = defineVirtReg(MI, I, Reg, 0);
+    MCPhysReg PhysReg = LRI->PhysReg;
+    if (setPhysReg(MI, I, PhysReg))
       VirtDead.push_back(Reg);
   }
 
   // Restore UsedInInstr to a state usable for allocating normal virtual uses.
   UsedInInstr.clear();
-  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI->getOperand(i);
+  for (const MachineOperand &MO : MI.operands()) {
     if (!MO.isReg() || (MO.isDef() && !MO.isEarlyClobber())) continue;
     unsigned Reg = MO.getReg();
     if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
@@ -796,20 +786,56 @@ void RAFast::handleThroughOperands(Machi
   }
 
   // Also mark PartialDefs as used to avoid reallocation.
-  for (unsigned i = 0, e = PartialDefs.size(); i != e; ++i)
-    markRegUsedInInstr(PartialDefs[i]);
+  for (unsigned PartialDef : PartialDefs)
+    markRegUsedInInstr(PartialDef);
 }
 
-void RAFast::AllocateBasicBlock() {
-  DEBUG(dbgs() << "\nAllocating " << *MBB);
+#ifndef NDEBUG
+void RegAllocFast::dumpState() {
+  for (unsigned Reg = 1, E = TRI->getNumRegs(); Reg != E; ++Reg) {
+    if (PhysRegState[Reg] == regDisabled) continue;
+    dbgs() << " " << TRI->getName(Reg);
+    switch(PhysRegState[Reg]) {
+    case regFree:
+      break;
+    case regReserved:
+      dbgs() << "*";
+      break;
+    default: {
+      dbgs() << '=' << PrintReg(PhysRegState[Reg]);
+      LiveRegMap::iterator I = findLiveVirtReg(PhysRegState[Reg]);
+      assert(I != LiveVirtRegs.end() && "Missing VirtReg entry");
+      if (I->Dirty)
+        dbgs() << "*";
+      assert(I->PhysReg == Reg && "Bad inverse map");
+      break;
+    }
+    }
+  }
+  dbgs() << '\n';
+  // Check that LiveVirtRegs is the inverse.
+  for (LiveRegMap::iterator i = LiveVirtRegs.begin(),
+       e = LiveVirtRegs.end(); i != e; ++i) {
+    assert(TargetRegisterInfo::isVirtualRegister(i->VirtReg) &&
+           "Bad map key");
+    assert(TargetRegisterInfo::isPhysicalRegister(i->PhysReg) &&
+           "Bad map value");
+    assert(PhysRegState[i->PhysReg] == i->VirtReg && "Bad inverse map");
+  }
+}
+#endif
+
+void RegAllocFast::allocateBasicBlock(MachineBasicBlock &MBB) {
+  this->MBB = &MBB;
+  DEBUG(dbgs() << "\nAllocating " << MBB);
 
   PhysRegState.assign(TRI->getNumRegs(), regDisabled);
   assert(LiveVirtRegs.empty() && "Mapping not cleared from last block?");
 
-  MachineBasicBlock::iterator MII = MBB->begin();
+  MachineBasicBlock::iterator MII = MBB.begin();
 
   // Add live-in registers as live.
-  for (const auto &LI : MBB->liveins())
+  for (const MachineBasicBlock::RegisterMaskPair LI : MBB.liveins())
     if (MRI->isAllocatable(LI.PhysReg))
       definePhysReg(*MII, LI.PhysReg, regReserved);
 
@@ -817,56 +843,27 @@ void RAFast::AllocateBasicBlock() {
   Coalesced.clear();
 
   // Otherwise, sequentially allocate each instruction in the MBB.
-  while (MII != MBB->end()) {
-    MachineInstr *MI = &*MII++;
-    const MCInstrDesc &MCID = MI->getDesc();
-    DEBUG({
-        dbgs() << "\n>> " << *MI << "Regs:";
-        for (unsigned Reg = 1, E = TRI->getNumRegs(); Reg != E; ++Reg) {
-          if (PhysRegState[Reg] == regDisabled) continue;
-          dbgs() << " " << TRI->getName(Reg);
-          switch(PhysRegState[Reg]) {
-          case regFree:
-            break;
-          case regReserved:
-            dbgs() << "*";
-            break;
-          default: {
-            dbgs() << '=' << PrintReg(PhysRegState[Reg]);
-            LiveRegMap::iterator I = findLiveVirtReg(PhysRegState[Reg]);
-            assert(I != LiveVirtRegs.end() && "Missing VirtReg entry");
-            if (I->Dirty)
-              dbgs() << "*";
-            assert(I->PhysReg == Reg && "Bad inverse map");
-            break;
-          }
-          }
-        }
-        dbgs() << '\n';
-        // Check that LiveVirtRegs is the inverse.
-        for (LiveRegMap::iterator i = LiveVirtRegs.begin(),
-             e = LiveVirtRegs.end(); i != e; ++i) {
-           assert(TargetRegisterInfo::isVirtualRegister(i->VirtReg) &&
-                  "Bad map key");
-           assert(TargetRegisterInfo::isPhysicalRegister(i->PhysReg) &&
-                  "Bad map value");
-           assert(PhysRegState[i->PhysReg] == i->VirtReg && "Bad inverse map");
-        }
-      });
+  for (MachineInstr &MI : MBB) {
+    const MCInstrDesc &MCID = MI.getDesc();
+    DEBUG(
+      dbgs() << "\n>> " << MI << "Regs:";
+      dumpState()
+    );
 
     // Debug values are not allowed to change codegen in any way.
-    if (MI->isDebugValue()) {
+    if (MI.isDebugValue()) {
       bool ScanDbgValue = true;
+      MachineInstr *DebugMI = &MI;
       while (ScanDbgValue) {
         ScanDbgValue = false;
-        for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-          MachineOperand &MO = MI->getOperand(i);
+        for (unsigned I = 0, E = DebugMI->getNumOperands(); I != E; ++I) {
+          MachineOperand &MO = DebugMI->getOperand(I);
           if (!MO.isReg()) continue;
           unsigned Reg = MO.getReg();
           if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
           LiveRegMap::iterator LRI = findLiveVirtReg(Reg);
           if (LRI != LiveVirtRegs.end())
-            setPhysReg(MI, i, LRI->PhysReg);
+            setPhysReg(*DebugMI, I, LRI->PhysReg);
           else {
             int SS = StackSlotForVirtReg[Reg];
             if (SS == -1) {
@@ -876,18 +873,18 @@ void RAFast::AllocateBasicBlock() {
             }
             else {
               // Modify DBG_VALUE now that the value is in a spill slot.
-              bool IsIndirect = MI->isIndirectDebugValue();
+              bool IsIndirect = DebugMI->isIndirectDebugValue();
               if (IsIndirect)
-                assert(MI->getOperand(1).getImm() == 0 &&
+                assert(DebugMI->getOperand(1).getImm() == 0 &&
                        "DBG_VALUE with nonzero offset");
-              const MDNode *Var = MI->getDebugVariable();
-              const MDNode *Expr = MI->getDebugExpression();
-              DebugLoc DL = MI->getDebugLoc();
-              MachineBasicBlock *MBB = MI->getParent();
+              const MDNode *Var = DebugMI->getDebugVariable();
+              const MDNode *Expr = DebugMI->getDebugExpression();
+              DebugLoc DL = DebugMI->getDebugLoc();
+              MachineBasicBlock *MBB = DebugMI->getParent();
               assert(
                   cast<DILocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
                   "Expected inlined-at fields to agree");
-              MachineInstr *NewDV = BuildMI(*MBB, MBB->erase(MI), DL,
+              MachineInstr *NewDV = BuildMI(*MBB, MBB->erase(DebugMI), DL,
                                             TII->get(TargetOpcode::DBG_VALUE))
                                         .addFrameIndex(SS)
                                         .addImm(0U)
@@ -896,12 +893,12 @@ void RAFast::AllocateBasicBlock() {
               DEBUG(dbgs() << "Modifying debug info due to spill:"
                            << "\t" << *NewDV);
               // Scan NewDV operands from the beginning.
-              MI = NewDV;
+              DebugMI = NewDV;
               ScanDbgValue = true;
               break;
             }
           }
-          LiveDbgValueMap[Reg].push_back(MI);
+          LiveDbgValueMap[Reg].push_back(DebugMI);
         }
       }
       // Next instruction.
@@ -909,12 +906,15 @@ void RAFast::AllocateBasicBlock() {
     }
 
     // If this is a copy, we may be able to coalesce.
-    unsigned CopySrc = 0, CopyDst = 0, CopySrcSub = 0, CopyDstSub = 0;
-    if (MI->isCopy()) {
-      CopyDst = MI->getOperand(0).getReg();
-      CopySrc = MI->getOperand(1).getReg();
-      CopyDstSub = MI->getOperand(0).getSubReg();
-      CopySrcSub = MI->getOperand(1).getSubReg();
+    unsigned CopySrcReg = 0;
+    unsigned CopyDstReg = 0;
+    unsigned CopySrcSub = 0;
+    unsigned CopyDstSub = 0;
+    if (MI.isCopy()) {
+      CopyDstReg = MI.getOperand(0).getReg();
+      CopySrcReg = MI.getOperand(1).getReg();
+      CopyDstSub = MI.getOperand(0).getSubReg();
+      CopySrcSub = MI.getOperand(1).getSubReg();
     }
 
     // Track registers used by instruction.
@@ -928,8 +928,8 @@ void RAFast::AllocateBasicBlock() {
     bool hasEarlyClobbers = false;
     bool hasPartialRedefs = false;
     bool hasPhysDefs = false;
-    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = MI->getOperand(i);
+    for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+      MachineOperand &MO = MI.getOperand(i);
       // Make sure MRI knows about registers clobbered by regmasks.
       if (MO.isRegMask()) {
         MRI->addPhysRegsUsedFromRegMask(MO.getRegMask());
@@ -946,7 +946,7 @@ void RAFast::AllocateBasicBlock() {
         } else {
           if (MO.isEarlyClobber())
             hasEarlyClobbers = true;
-          if (MO.getSubReg() && MI->readsVirtualRegister(Reg))
+          if (MO.getSubReg() && MI.readsVirtualRegister(Reg))
             hasPartialRedefs = true;
         }
         continue;
@@ -955,7 +955,7 @@ void RAFast::AllocateBasicBlock() {
       if (MO.isUse()) {
         usePhysReg(MO);
       } else if (MO.isEarlyClobber()) {
-        definePhysReg(*MI, Reg,
+        definePhysReg(MI, Reg,
                       (MO.isImplicit() || MO.isDead()) ? regFree : regReserved);
         hasEarlyClobbers = true;
       } else
@@ -971,11 +971,11 @@ void RAFast::AllocateBasicBlock() {
     // sure the same register is allocated to uses and defs.
     // We didn't detect inline asm tied operands above, so just make this extra
     // pass for all inline asm.
-    if (MI->isInlineAsm() || hasEarlyClobbers || hasPartialRedefs ||
+    if (MI.isInlineAsm() || hasEarlyClobbers || hasPartialRedefs ||
         (hasTiedOps && (hasPhysDefs || MCID.getNumDefs() > 1))) {
       handleThroughOperands(MI, VirtDead);
       // Don't attempt coalescing when we have funny stuff going on.
-      CopyDst = 0;
+      CopyDstReg = 0;
       // Pretend we have early clobbers so the use operands get marked below.
       // This is not necessary for the common case of a single tied use.
       hasEarlyClobbers = true;
@@ -983,16 +983,16 @@ void RAFast::AllocateBasicBlock() {
 
     // Second scan.
     // Allocate virtreg uses.
-    for (unsigned i = 0; i != VirtOpEnd; ++i) {
-      MachineOperand &MO = MI->getOperand(i);
+    for (unsigned I = 0; I != VirtOpEnd; ++I) {
+      const MachineOperand &MO = MI.getOperand(I);
       if (!MO.isReg()) continue;
       unsigned Reg = MO.getReg();
       if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
       if (MO.isUse()) {
-        LiveRegMap::iterator LRI = reloadVirtReg(*MI, i, Reg, CopyDst);
-        unsigned PhysReg = LRI->PhysReg;
-        CopySrc = (CopySrc == Reg || CopySrc == PhysReg) ? PhysReg : 0;
-        if (setPhysReg(MI, i, PhysReg))
+        LiveRegMap::iterator LRI = reloadVirtReg(MI, I, Reg, CopyDstReg);
+        MCPhysReg PhysReg = LRI->PhysReg;
+        CopySrcReg = (CopySrcReg == Reg || CopySrcReg == PhysReg) ? PhysReg : 0;
+        if (setPhysReg(MI, I, PhysReg))
           killVirtReg(LRI);
       }
     }
@@ -1001,19 +1001,18 @@ void RAFast::AllocateBasicBlock() {
     // this point.
     UsedInInstr.clear();
     if (hasEarlyClobbers) {
-      for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-        MachineOperand &MO = MI->getOperand(i);
+      for (const MachineOperand &MO : MI.operands()) {
         if (!MO.isReg()) continue;
         unsigned Reg = MO.getReg();
         if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
         // Look for physreg defs and tied uses.
-        if (!MO.isDef() && !MI->isRegTiedToDefOperand(i)) continue;
+        if (!MO.isDef() && !MO.isTied()) continue;
         markRegUsedInInstr(Reg);
       }
     }
 
-    unsigned DefOpEnd = MI->getNumOperands();
-    if (MI->isCall()) {
+    unsigned DefOpEnd = MI.getNumOperands();
+    if (MI.isCall()) {
       // Spill all virtregs before a call. This serves one purpose: If an
       // exception is thrown, the landing pad is going to expect to find
       // registers in their spill slots.
@@ -1027,80 +1026,78 @@ void RAFast::AllocateBasicBlock() {
 
     // Third scan.
     // Allocate defs and collect dead defs.
-    for (unsigned i = 0; i != DefOpEnd; ++i) {
-      MachineOperand &MO = MI->getOperand(i);
+    for (unsigned I = 0; I != DefOpEnd; ++I) {
+      const MachineOperand &MO = MI.getOperand(I);
       if (!MO.isReg() || !MO.isDef() || !MO.getReg() || MO.isEarlyClobber())
         continue;
       unsigned Reg = MO.getReg();
 
       if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
         if (!MRI->isAllocatable(Reg)) continue;
-        definePhysReg(*MI, Reg, MO.isDead() ? regFree : regReserved);
+        definePhysReg(MI, Reg, MO.isDead() ? regFree : regReserved);
         continue;
       }
-      LiveRegMap::iterator LRI = defineVirtReg(*MI, i, Reg, CopySrc);
-      unsigned PhysReg = LRI->PhysReg;
-      if (setPhysReg(MI, i, PhysReg)) {
+      LiveRegMap::iterator LRI = defineVirtReg(MI, I, Reg, CopySrcReg);
+      MCPhysReg PhysReg = LRI->PhysReg;
+      if (setPhysReg(MI, I, PhysReg)) {
         VirtDead.push_back(Reg);
-        CopyDst = 0; // cancel coalescing;
+        CopyDstReg = 0; // cancel coalescing;
       } else
-        CopyDst = (CopyDst == Reg || CopyDst == PhysReg) ? PhysReg : 0;
+        CopyDstReg = (CopyDstReg == Reg || CopyDstReg == PhysReg) ? PhysReg : 0;
     }
 
     // Kill dead defs after the scan to ensure that multiple defs of the same
     // register are allocated identically. We didn't need to do this for uses
     // because we are crerating our own kill flags, and they are always at the
     // last use.
-    for (unsigned i = 0, e = VirtDead.size(); i != e; ++i)
-      killVirtReg(VirtDead[i]);
+    for (unsigned VirtReg : VirtDead)
+      killVirtReg(VirtReg);
     VirtDead.clear();
 
-    if (CopyDst && CopyDst == CopySrc && CopyDstSub == CopySrcSub) {
-      DEBUG(dbgs() << "-- coalescing: " << *MI);
-      Coalesced.push_back(MI);
+    if (CopyDstReg && CopyDstReg == CopySrcReg && CopyDstSub == CopySrcSub) {
+      DEBUG(dbgs() << "-- coalescing: " << MI);
+      Coalesced.push_back(&MI);
     } else {
-      DEBUG(dbgs() << "<< " << *MI);
+      DEBUG(dbgs() << "<< " << MI);
     }
   }
 
   // Spill all physical registers holding virtual registers now.
   DEBUG(dbgs() << "Spilling live registers at end of block.\n");
-  spillAll(MBB->getFirstTerminator());
+  spillAll(MBB.getFirstTerminator());
 
   // Erase all the coalesced copies. We are delaying it until now because
   // LiveVirtRegs might refer to the instrs.
-  for (unsigned i = 0, e = Coalesced.size(); i != e; ++i)
-    MBB->erase(Coalesced[i]);
+  for (MachineInstr *MI : Coalesced)
+    MBB.erase(MI);
   NumCopies += Coalesced.size();
 
-  DEBUG(MBB->dump());
+  DEBUG(MBB.dump());
 }
 
-/// runOnMachineFunction - Register allocate the whole function
-///
-bool RAFast::runOnMachineFunction(MachineFunction &Fn) {
+/// Allocates registers for a function.
+bool RegAllocFast::runOnMachineFunction(MachineFunction &MF) {
   DEBUG(dbgs() << "********** FAST REGISTER ALLOCATION **********\n"
-               << "********** Function: " << Fn.getName() << '\n');
-  MF = &Fn;
-  MRI = &MF->getRegInfo();
-  TRI = MF->getSubtarget().getRegisterInfo();
-  TII = MF->getSubtarget().getInstrInfo();
-  MRI->freezeReservedRegs(Fn);
-  RegClassInfo.runOnMachineFunction(Fn);
+               << "********** Function: " << MF.getName() << '\n');
+  MRI = &MF.getRegInfo();
+  const TargetSubtargetInfo &STI = MF.getSubtarget();
+  TRI = STI.getRegisterInfo();
+  TII = STI.getInstrInfo();
+  MFI = &MF.getFrameInfo();
+  MRI->freezeReservedRegs(MF);
+  RegClassInfo.runOnMachineFunction(MF);
   UsedInInstr.clear();
   UsedInInstr.setUniverse(TRI->getNumRegUnits());
 
   // initialize the virtual->physical register map to have a 'null'
   // mapping for all virtual registers
-  StackSlotForVirtReg.resize(MRI->getNumVirtRegs());
-  LiveVirtRegs.setUniverse(MRI->getNumVirtRegs());
+  unsigned NumVirtRegs = MRI->getNumVirtRegs();
+  StackSlotForVirtReg.resize(NumVirtRegs);
+  LiveVirtRegs.setUniverse(NumVirtRegs);
 
   // Loop over all of the basic blocks, eliminating virtual register references
-  for (MachineFunction::iterator MBBi = Fn.begin(), MBBe = Fn.end();
-       MBBi != MBBe; ++MBBi) {
-    MBB = &*MBBi;
-    AllocateBasicBlock();
-  }
+  for (MachineBasicBlock &MBB : MF)
+    allocateBasicBlock(MBB);
 
   // All machine operands and other references to virtual registers have been
   // replaced. Remove the virtual registers.
@@ -1112,5 +1109,5 @@ bool RAFast::runOnMachineFunction(Machin
 }
 
 FunctionPass *llvm::createFastRegisterAllocator() {
-  return new RAFast();
+  return new RegAllocFast();
 }




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