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81a0382181
When a live interval is being spilled, rather than creating short, non-spillable intervals for every def / use, split the interval at BB boundaries. That is, for every BB where the live interval is defined or used, create a new interval that covers all the defs and uses in the BB. This is designed to eliminate one common problem: multiple reloads of the same value in a single basic block. Note, it does *not* decrease the number of spills since no copies are inserted so the split intervals are *connected* through spill and reloads (or rematerialization). The newly created intervals can be spilled again, in that case, since it does not span multiple basic blocks, it's spilled in the usual manner. However, it can reuse the same stack slot as the previously split interval. This is currently controlled by -split-intervals-at-bb. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44198 91177308-0d34-0410-b5e6-96231b3b80d8
316 lines
12 KiB
C++
316 lines
12 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 was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source 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' abd 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/MachineFunctionPass.h"
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#include "llvm/CodeGen/LiveInterval.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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namespace llvm {
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class LiveVariables;
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class LoopInfo;
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class MRegisterInfo;
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class SSARegMap;
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class TargetInstrInfo;
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class TargetRegisterClass;
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class VirtRegMap;
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typedef std::pair<unsigned, MachineBasicBlock*> IdxMBBPair;
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class LiveIntervals : public MachineFunctionPass {
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MachineFunction* mf_;
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const TargetMachine* tm_;
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const MRegisterInfo* mri_;
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const TargetInstrInfo* tii_;
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LiveVariables* lv_;
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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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/// MBB2IdxMap - The indexes of the first and last instructions in the
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/// specified basic block.
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std::vector<std::pair<unsigned, unsigned> > MBB2IdxMap;
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/// Idx2MBBMap - Sorted list of pairs of index of first instruction
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/// and MBB id.
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std::vector<IdxMBBPair> Idx2MBBMap;
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typedef std::map<MachineInstr*, unsigned> Mi2IndexMap;
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Mi2IndexMap mi2iMap_;
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typedef std::vector<MachineInstr*> Index2MiMap;
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Index2MiMap i2miMap_;
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typedef std::map<unsigned, LiveInterval> Reg2IntervalMap;
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Reg2IntervalMap r2iMap_;
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BitVector allocatableRegs_;
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std::vector<MachineInstr*> ClonedMIs;
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public:
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static char ID; // Pass identification, replacement for typeid
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LiveIntervals() : MachineFunctionPass((intptr_t)&ID) {}
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struct InstrSlots {
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enum {
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LOAD = 0,
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USE = 1,
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DEF = 2,
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STORE = 3,
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NUM = 4
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};
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};
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static unsigned getBaseIndex(unsigned index) {
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return index - (index % InstrSlots::NUM);
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}
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static unsigned getBoundaryIndex(unsigned index) {
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return getBaseIndex(index + InstrSlots::NUM - 1);
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}
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static unsigned getLoadIndex(unsigned index) {
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return getBaseIndex(index) + InstrSlots::LOAD;
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}
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static unsigned getUseIndex(unsigned index) {
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return getBaseIndex(index) + InstrSlots::USE;
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}
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static unsigned getDefIndex(unsigned index) {
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return getBaseIndex(index) + InstrSlots::DEF;
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}
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static unsigned getStoreIndex(unsigned index) {
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return getBaseIndex(index) + InstrSlots::STORE;
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}
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static float getSpillWeight(bool isDef, bool isUse, unsigned loopDepth) {
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return (isDef + isUse) * powf(10.0F, (float)loopDepth);
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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 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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/// getMBBStartIdx - Return the base index of the first instruction in the
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/// specified MachineBasicBlock.
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unsigned getMBBStartIdx(MachineBasicBlock *MBB) const {
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return getMBBStartIdx(MBB->getNumber());
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}
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unsigned getMBBStartIdx(unsigned MBBNo) const {
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assert(MBBNo < MBB2IdxMap.size() && "Invalid MBB number!");
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return MBB2IdxMap[MBBNo].first;
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}
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/// getMBBEndIdx - Return the store index of the last instruction in the
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/// specified MachineBasicBlock.
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unsigned getMBBEndIdx(MachineBasicBlock *MBB) const {
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return getMBBEndIdx(MBB->getNumber());
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}
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unsigned getMBBEndIdx(unsigned MBBNo) const {
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assert(MBBNo < MBB2IdxMap.size() && "Invalid MBB number!");
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return MBB2IdxMap[MBBNo].second;
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}
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/// getInstructionIndex - returns the base index of instr
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unsigned getInstructionIndex(MachineInstr* instr) const {
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Mi2IndexMap::const_iterator it = mi2iMap_.find(instr);
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assert(it != mi2iMap_.end() && "Invalid instruction!");
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return it->second;
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}
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/// getInstructionFromIndex - given an index in any slot of an
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/// instruction return a pointer the instruction
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MachineInstr* getInstructionFromIndex(unsigned index) const {
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index /= InstrSlots::NUM; // convert index to vector index
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assert(index < i2miMap_.size() &&
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"index does not correspond to an instruction");
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return i2miMap_[index];
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}
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/// conflictsWithPhysRegDef - Returns true if the specified register
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/// is defined during the duration of the specified interval.
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bool conflictsWithPhysRegDef(const LiveInterval &li, VirtRegMap &vrm,
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unsigned reg);
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/// findLiveInMBBs - Given a live range, if the value of the range
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/// is live in any MBB returns true as well as the list of basic blocks
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/// where the value is live in.
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bool findLiveInMBBs(const LiveRange &LR,
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SmallVectorImpl<MachineBasicBlock*> &MBBs) const;
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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(I, std::make_pair(reg, createInterval(reg)));
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return I->second;
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}
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// Interval removal
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void removeInterval(unsigned Reg) {
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r2iMap_.erase(Reg);
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}
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/// isRemoved - returns true if the specified machine instr has been
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/// removed.
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bool isRemoved(MachineInstr* instr) const {
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return !mi2iMap_.count(instr);
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}
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/// RemoveMachineInstrFromMaps - This marks the specified machine instr as
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/// deleted.
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void RemoveMachineInstrFromMaps(MachineInstr *MI) {
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// remove index -> MachineInstr and
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// MachineInstr -> index mappings
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Mi2IndexMap::iterator mi2i = mi2iMap_.find(MI);
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if (mi2i != mi2iMap_.end()) {
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i2miMap_[mi2i->second/InstrSlots::NUM] = 0;
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mi2iMap_.erase(mi2i);
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}
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}
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BumpPtrAllocator& getVNInfoAllocator() { return VNInfoAllocator; }
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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(std::ostream &O, const Module* = 0) const;
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void print(std::ostream *O, const Module* M = 0) const {
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if (O) print(*O, M);
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}
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/// addIntervalsForSpills - Create new intervals for spilled defs / uses of
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/// the given interval.
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std::vector<LiveInterval*>
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addIntervalsForSpills(const LiveInterval& i,
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const LoopInfo *loopInfo, VirtRegMap& vrm);
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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, unsigned MIIdx,
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unsigned reg);
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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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unsigned MIIdx,
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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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unsigned MIIdx,
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LiveInterval &interval,
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unsigned SrcReg);
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/// handleLiveInRegister - Create interval for a livein register.
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void handleLiveInRegister(MachineBasicBlock* mbb,
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unsigned MIIdx,
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LiveInterval &interval, bool isAlias = false);
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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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/// 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, unsigned index, unsigned i,
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bool isSS, int slot, unsigned reg);
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bool anyKillInMBBAfterIdx(const LiveInterval &li,
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MachineBasicBlock *MBB, unsigned Idx,
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const VNInfo *VNI = NULL) const;
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bool intervalIsInOneMBB(const LiveInterval &li) const;
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/// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper functions
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/// for addIntervalsForSpills to rewrite uses / defs for the given live range.
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void rewriteInstructionForSpills(const LiveInterval &li, bool TrySplit,
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unsigned id, unsigned index, unsigned end, MachineInstr *MI,
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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, SSARegMap *RegMap, const TargetRegisterClass* rc,
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SmallVector<int, 4> &ReMatIds,
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unsigned &NewVReg, bool &HasDef, bool &HasUse, const LoopInfo *loopInfo,
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std::vector<unsigned> &NewVRegs,
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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, SSARegMap *RegMap, const TargetRegisterClass* rc,
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SmallVector<int, 4> &ReMatIds, const LoopInfo *loopInfo,
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BitVector &SpillMBBs,
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std::vector<std::pair<int, unsigned> > &SpillIdxes,
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std::vector<unsigned> &NewVRegs,
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std::vector<LiveInterval*> &NewLIs);
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static LiveInterval createInterval(unsigned Reg);
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void printRegName(unsigned reg) const;
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};
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} // End llvm namespace
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#endif
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