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e5d90416ee
Don't accidentally produce unspillable intervals for deeply nested loops. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97496 91177308-0d34-0410-b5e6-96231b3b80d8
430 lines
18 KiB
C++
430 lines
18 KiB
C++
//===-- LiveIntervalAnalysis.h - Live Interval Analysis ---------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the LiveInterval analysis pass. Given some numbering of
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// each the machine instructions (in this implemention depth-first order) an
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// interval [i, j) is said to be a live interval for register v if there is no
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// instruction with number j' > j such that v is live at j' and there is no
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// instruction with number i' < i such that v is live at i'. In this
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// implementation intervals can have holes, i.e. an interval might look like
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// [1,20), [50,65), [1000,1001).
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
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#define LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/LiveInterval.h"
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#include "llvm/CodeGen/SlotIndexes.h"
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#include "llvm/ADT/BitVector.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Support/Allocator.h"
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#include <cmath>
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#include <iterator>
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namespace llvm {
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class AliasAnalysis;
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class LiveVariables;
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class MachineLoopInfo;
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class TargetRegisterInfo;
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class MachineRegisterInfo;
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class TargetInstrInfo;
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class TargetRegisterClass;
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class VirtRegMap;
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class LiveIntervals : public MachineFunctionPass {
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MachineFunction* mf_;
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MachineRegisterInfo* mri_;
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const TargetMachine* tm_;
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const TargetRegisterInfo* tri_;
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const TargetInstrInfo* tii_;
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AliasAnalysis *aa_;
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LiveVariables* lv_;
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SlotIndexes* indexes_;
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/// Special pool allocator for VNInfo's (LiveInterval val#).
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///
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BumpPtrAllocator VNInfoAllocator;
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typedef DenseMap<unsigned, LiveInterval*> Reg2IntervalMap;
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Reg2IntervalMap r2iMap_;
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/// allocatableRegs_ - A bit vector of allocatable registers.
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BitVector allocatableRegs_;
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/// CloneMIs - A list of clones as result of re-materialization.
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std::vector<MachineInstr*> CloneMIs;
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public:
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static char ID; // Pass identification, replacement for typeid
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LiveIntervals() : MachineFunctionPass(&ID) {}
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// Calculate the spill weight to assign to a single instruction.
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static float getSpillWeight(bool isDef, bool isUse, unsigned loopDepth);
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// After summing the spill weights of all defs and uses, the final weight
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// should be normalized, dividing the weight of the interval by its size.
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// This encourages spilling of intervals that are large and have few uses,
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// and discourages spilling of small intervals with many uses.
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void normalizeSpillWeight(LiveInterval &li) {
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li.weight /= getApproximateInstructionCount(li) + 25;
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}
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typedef Reg2IntervalMap::iterator iterator;
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typedef Reg2IntervalMap::const_iterator const_iterator;
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const_iterator begin() const { return r2iMap_.begin(); }
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const_iterator end() const { return r2iMap_.end(); }
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iterator begin() { return r2iMap_.begin(); }
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iterator end() { return r2iMap_.end(); }
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unsigned getNumIntervals() const { return (unsigned)r2iMap_.size(); }
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LiveInterval &getInterval(unsigned reg) {
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Reg2IntervalMap::iterator I = r2iMap_.find(reg);
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assert(I != r2iMap_.end() && "Interval does not exist for register");
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return *I->second;
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}
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const LiveInterval &getInterval(unsigned reg) const {
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Reg2IntervalMap::const_iterator I = r2iMap_.find(reg);
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assert(I != r2iMap_.end() && "Interval does not exist for register");
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return *I->second;
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}
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bool hasInterval(unsigned reg) const {
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return r2iMap_.count(reg);
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}
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/// getScaledIntervalSize - get the size of an interval in "units,"
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/// where every function is composed of one thousand units. This
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/// measure scales properly with empty index slots in the function.
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double getScaledIntervalSize(LiveInterval& I) {
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return (1000.0 * I.getSize()) / indexes_->getIndexesLength();
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}
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/// getApproximateInstructionCount - computes an estimate of the number
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/// of instructions in a given LiveInterval.
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unsigned getApproximateInstructionCount(LiveInterval& I) {
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double IntervalPercentage = getScaledIntervalSize(I) / 1000.0;
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return (unsigned)(IntervalPercentage * indexes_->getFunctionSize());
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}
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/// conflictsWithPhysReg - Returns true if the specified register is used or
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/// defined during the duration of the specified interval. Copies to and
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/// from li.reg are allowed. This method is only able to analyze simple
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/// ranges that stay within a single basic block. Anything else is
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/// considered a conflict.
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bool conflictsWithPhysReg(const LiveInterval &li, VirtRegMap &vrm,
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unsigned reg);
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/// conflictsWithPhysRegRef - Similar to conflictsWithPhysRegRef except
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/// it can check use as well.
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bool conflictsWithPhysRegRef(LiveInterval &li, unsigned Reg,
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bool CheckUse,
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SmallPtrSet<MachineInstr*,32> &JoinedCopies);
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// Interval creation
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LiveInterval &getOrCreateInterval(unsigned reg) {
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Reg2IntervalMap::iterator I = r2iMap_.find(reg);
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if (I == r2iMap_.end())
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I = r2iMap_.insert(std::make_pair(reg, createInterval(reg))).first;
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return *I->second;
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}
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/// dupInterval - Duplicate a live interval. The caller is responsible for
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/// managing the allocated memory.
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LiveInterval *dupInterval(LiveInterval *li);
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/// addLiveRangeToEndOfBlock - Given a register and an instruction,
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/// adds a live range from that instruction to the end of its MBB.
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LiveRange addLiveRangeToEndOfBlock(unsigned reg,
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MachineInstr* startInst);
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// Interval removal
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void removeInterval(unsigned Reg) {
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DenseMap<unsigned, LiveInterval*>::iterator I = r2iMap_.find(Reg);
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delete I->second;
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r2iMap_.erase(I);
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}
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SlotIndex getZeroIndex() const {
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return indexes_->getZeroIndex();
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}
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SlotIndex getInvalidIndex() const {
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return indexes_->getInvalidIndex();
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}
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/// isNotInMIMap - returns true if the specified machine instr has been
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/// removed or was never entered in the map.
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bool isNotInMIMap(const MachineInstr* Instr) const {
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return !indexes_->hasIndex(Instr);
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}
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/// Returns the base index of the given instruction.
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SlotIndex getInstructionIndex(const MachineInstr *instr) const {
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return indexes_->getInstructionIndex(instr);
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}
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/// Returns the instruction associated with the given index.
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MachineInstr* getInstructionFromIndex(SlotIndex index) const {
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return indexes_->getInstructionFromIndex(index);
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}
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/// Return the first index in the given basic block.
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SlotIndex getMBBStartIdx(const MachineBasicBlock *mbb) const {
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return indexes_->getMBBStartIdx(mbb);
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}
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/// Return the last index in the given basic block.
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SlotIndex getMBBEndIdx(const MachineBasicBlock *mbb) const {
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return indexes_->getMBBEndIdx(mbb);
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}
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MachineBasicBlock* getMBBFromIndex(SlotIndex index) const {
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return indexes_->getMBBFromIndex(index);
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}
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SlotIndex getMBBTerminatorGap(const MachineBasicBlock *mbb) {
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return indexes_->getTerminatorGap(mbb);
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}
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SlotIndex InsertMachineInstrInMaps(MachineInstr *MI) {
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return indexes_->insertMachineInstrInMaps(MI);
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}
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void RemoveMachineInstrFromMaps(MachineInstr *MI) {
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indexes_->removeMachineInstrFromMaps(MI);
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}
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void ReplaceMachineInstrInMaps(MachineInstr *MI, MachineInstr *NewMI) {
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indexes_->replaceMachineInstrInMaps(MI, NewMI);
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}
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bool findLiveInMBBs(SlotIndex Start, SlotIndex End,
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SmallVectorImpl<MachineBasicBlock*> &MBBs) const {
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return indexes_->findLiveInMBBs(Start, End, MBBs);
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}
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void renumber() {
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indexes_->renumberIndexes();
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}
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BumpPtrAllocator& getVNInfoAllocator() { return VNInfoAllocator; }
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/// getVNInfoSourceReg - Helper function that parses the specified VNInfo
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/// copy field and returns the source register that defines it.
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unsigned getVNInfoSourceReg(const VNInfo *VNI) const;
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virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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virtual void releaseMemory();
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/// runOnMachineFunction - pass entry point
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virtual bool runOnMachineFunction(MachineFunction&);
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/// print - Implement the dump method.
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virtual void print(raw_ostream &O, const Module* = 0) const;
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/// addIntervalsForSpills - Create new intervals for spilled defs / uses of
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/// the given interval. FIXME: It also returns the weight of the spill slot
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/// (if any is created) by reference. This is temporary.
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std::vector<LiveInterval*>
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addIntervalsForSpills(const LiveInterval& i,
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SmallVectorImpl<LiveInterval*> &SpillIs,
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const MachineLoopInfo *loopInfo, VirtRegMap& vrm);
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/// addIntervalsForSpillsFast - Quickly create new intervals for spilled
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/// defs / uses without remat or splitting.
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std::vector<LiveInterval*>
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addIntervalsForSpillsFast(const LiveInterval &li,
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const MachineLoopInfo *loopInfo, VirtRegMap &vrm);
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/// spillPhysRegAroundRegDefsUses - Spill the specified physical register
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/// around all defs and uses of the specified interval. Return true if it
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/// was able to cut its interval.
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bool spillPhysRegAroundRegDefsUses(const LiveInterval &li,
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unsigned PhysReg, VirtRegMap &vrm);
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/// isReMaterializable - Returns true if every definition of MI of every
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/// val# of the specified interval is re-materializable. Also returns true
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/// by reference if all of the defs are load instructions.
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bool isReMaterializable(const LiveInterval &li,
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SmallVectorImpl<LiveInterval*> &SpillIs,
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bool &isLoad);
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/// isReMaterializable - Returns true if the definition MI of the specified
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/// val# of the specified interval is re-materializable.
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bool isReMaterializable(const LiveInterval &li, const VNInfo *ValNo,
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MachineInstr *MI);
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/// getRepresentativeReg - Find the largest super register of the specified
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/// physical register.
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unsigned getRepresentativeReg(unsigned Reg) const;
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/// getNumConflictsWithPhysReg - Return the number of uses and defs of the
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/// specified interval that conflicts with the specified physical register.
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unsigned getNumConflictsWithPhysReg(const LiveInterval &li,
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unsigned PhysReg) const;
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/// processImplicitDefs - Process IMPLICIT_DEF instructions. Add isUndef
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/// marker to implicit_def defs and their uses.
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void processImplicitDefs();
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/// intervalIsInOneMBB - Returns true if the specified interval is entirely
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/// within a single basic block.
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bool intervalIsInOneMBB(const LiveInterval &li) const;
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private:
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/// computeIntervals - Compute live intervals.
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void computeIntervals();
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/// handleRegisterDef - update intervals for a register def
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/// (calls handlePhysicalRegisterDef and
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/// handleVirtualRegisterDef)
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void handleRegisterDef(MachineBasicBlock *MBB,
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MachineBasicBlock::iterator MI,
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SlotIndex MIIdx,
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MachineOperand& MO, unsigned MOIdx);
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/// handleVirtualRegisterDef - update intervals for a virtual
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/// register def
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void handleVirtualRegisterDef(MachineBasicBlock *MBB,
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MachineBasicBlock::iterator MI,
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SlotIndex MIIdx, MachineOperand& MO,
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unsigned MOIdx,
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LiveInterval& interval);
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/// handlePhysicalRegisterDef - update intervals for a physical register
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/// def.
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void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
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MachineBasicBlock::iterator mi,
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SlotIndex MIIdx, MachineOperand& MO,
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LiveInterval &interval,
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MachineInstr *CopyMI);
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/// handleLiveInRegister - Create interval for a livein register.
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void handleLiveInRegister(MachineBasicBlock* mbb,
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SlotIndex MIIdx,
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LiveInterval &interval, bool isAlias = false);
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/// getReMatImplicitUse - If the remat definition MI has one (for now, we
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/// only allow one) virtual register operand, then its uses are implicitly
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/// using the register. Returns the virtual register.
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unsigned getReMatImplicitUse(const LiveInterval &li,
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MachineInstr *MI) const;
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/// isValNoAvailableAt - Return true if the val# of the specified interval
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/// which reaches the given instruction also reaches the specified use
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/// index.
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bool isValNoAvailableAt(const LiveInterval &li, MachineInstr *MI,
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SlotIndex UseIdx) const;
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/// isReMaterializable - Returns true if the definition MI of the specified
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/// val# of the specified interval is re-materializable. Also returns true
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/// by reference if the def is a load.
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bool isReMaterializable(const LiveInterval &li, const VNInfo *ValNo,
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MachineInstr *MI,
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SmallVectorImpl<LiveInterval*> &SpillIs,
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bool &isLoad);
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/// tryFoldMemoryOperand - Attempts to fold either a spill / restore from
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/// slot / to reg or any rematerialized load into ith operand of specified
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/// MI. If it is successul, MI is updated with the newly created MI and
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/// returns true.
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bool tryFoldMemoryOperand(MachineInstr* &MI, VirtRegMap &vrm,
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MachineInstr *DefMI, SlotIndex InstrIdx,
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SmallVector<unsigned, 2> &Ops,
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bool isSS, int FrameIndex, unsigned Reg);
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/// canFoldMemoryOperand - Return true if the specified load / store
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/// folding is possible.
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bool canFoldMemoryOperand(MachineInstr *MI,
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SmallVector<unsigned, 2> &Ops,
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bool ReMatLoadSS) const;
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/// anyKillInMBBAfterIdx - Returns true if there is a kill of the specified
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/// VNInfo that's after the specified index but is within the basic block.
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bool anyKillInMBBAfterIdx(const LiveInterval &li, const VNInfo *VNI,
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MachineBasicBlock *MBB,
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SlotIndex Idx) const;
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/// hasAllocatableSuperReg - Return true if the specified physical register
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/// has any super register that's allocatable.
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bool hasAllocatableSuperReg(unsigned Reg) const;
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/// SRInfo - Spill / restore info.
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struct SRInfo {
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SlotIndex index;
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unsigned vreg;
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bool canFold;
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SRInfo(SlotIndex i, unsigned vr, bool f)
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: index(i), vreg(vr), canFold(f) {}
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};
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bool alsoFoldARestore(int Id, SlotIndex index, unsigned vr,
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BitVector &RestoreMBBs,
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DenseMap<unsigned,std::vector<SRInfo> >&RestoreIdxes);
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void eraseRestoreInfo(int Id, SlotIndex index, unsigned vr,
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BitVector &RestoreMBBs,
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DenseMap<unsigned,std::vector<SRInfo> >&RestoreIdxes);
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/// handleSpilledImpDefs - Remove IMPLICIT_DEF instructions which are being
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/// spilled and create empty intervals for their uses.
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void handleSpilledImpDefs(const LiveInterval &li, VirtRegMap &vrm,
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const TargetRegisterClass* rc,
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std::vector<LiveInterval*> &NewLIs);
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/// rewriteImplicitOps - Rewrite implicit use operands of MI (i.e. uses of
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/// interval on to-be re-materialized operands of MI) with new register.
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void rewriteImplicitOps(const LiveInterval &li,
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MachineInstr *MI, unsigned NewVReg, VirtRegMap &vrm);
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/// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper
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/// functions for addIntervalsForSpills to rewrite uses / defs for the given
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/// live range.
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bool rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
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bool TrySplit, SlotIndex index, SlotIndex end,
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MachineInstr *MI, MachineInstr *OrigDefMI, MachineInstr *DefMI,
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unsigned Slot, int LdSlot,
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bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
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VirtRegMap &vrm, const TargetRegisterClass* rc,
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SmallVector<int, 4> &ReMatIds, const MachineLoopInfo *loopInfo,
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unsigned &NewVReg, unsigned ImpUse, bool &HasDef, bool &HasUse,
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DenseMap<unsigned,unsigned> &MBBVRegsMap,
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std::vector<LiveInterval*> &NewLIs);
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void rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
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LiveInterval::Ranges::const_iterator &I,
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MachineInstr *OrigDefMI, MachineInstr *DefMI, unsigned Slot, int LdSlot,
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bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
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VirtRegMap &vrm, const TargetRegisterClass* rc,
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SmallVector<int, 4> &ReMatIds, const MachineLoopInfo *loopInfo,
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BitVector &SpillMBBs,
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DenseMap<unsigned,std::vector<SRInfo> > &SpillIdxes,
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BitVector &RestoreMBBs,
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DenseMap<unsigned,std::vector<SRInfo> > &RestoreIdxes,
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DenseMap<unsigned,unsigned> &MBBVRegsMap,
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std::vector<LiveInterval*> &NewLIs);
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// Normalize the spill weight of all the intervals in NewLIs.
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void normalizeSpillWeights(std::vector<LiveInterval*> &NewLIs);
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static LiveInterval* createInterval(unsigned Reg);
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void printInstrs(raw_ostream &O) const;
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void dumpInstrs() const;
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};
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} // End llvm namespace
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#endif
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