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llvm-mirror/include/llvm/CodeGen/LiveIntervalAnalysis.h
Evan Cheng f852810de8 Indentation. 
llvm-svn: 83607
2009-10-09 00:57:38 +00:00

576 lines
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//===-- LiveIntervalAnalysis.h - Live Interval Analysis ---------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the LiveInterval analysis pass. Given some numbering of
// each the machine instructions (in this implemention depth-first order) an
// interval [i, j) is said to be a live interval for register v if there is no
// instruction with number j' > j such that v is live at j' and there is no
// instruction with number i' < i such that v is live at i'. In this
// implementation intervals can have holes, i.e. an interval might look like
// [1,20), [50,65), [1000,1001).
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
#define LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/LiveInterval.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Allocator.h"
#include <cmath>
namespace llvm {
class AliasAnalysis;
class LiveVariables;
class MachineLoopInfo;
class TargetRegisterInfo;
class MachineRegisterInfo;
class TargetInstrInfo;
class TargetRegisterClass;
class VirtRegMap;
typedef std::pair<LiveIndex, MachineBasicBlock*> IdxMBBPair;
inline bool operator<(LiveIndex V, const IdxMBBPair &IM) {
return V < IM.first;
}
inline bool operator<(const IdxMBBPair &IM, LiveIndex V) {
return IM.first < V;
}
struct Idx2MBBCompare {
bool operator()(const IdxMBBPair &LHS, const IdxMBBPair &RHS) const {
return LHS.first < RHS.first;
}
};
class LiveIntervals : public MachineFunctionPass {
MachineFunction* mf_;
MachineRegisterInfo* mri_;
const TargetMachine* tm_;
const TargetRegisterInfo* tri_;
const TargetInstrInfo* tii_;
AliasAnalysis *aa_;
LiveVariables* lv_;
/// Special pool allocator for VNInfo's (LiveInterval val#).
///
BumpPtrAllocator VNInfoAllocator;
/// MBB2IdxMap - The indexes of the first and last instructions in the
/// specified basic block.
std::vector<std::pair<LiveIndex, LiveIndex> > MBB2IdxMap;
/// Idx2MBBMap - Sorted list of pairs of index of first instruction
/// and MBB id.
std::vector<IdxMBBPair> Idx2MBBMap;
/// FunctionSize - The number of instructions present in the function
uint64_t FunctionSize;
typedef DenseMap<const MachineInstr*, LiveIndex> Mi2IndexMap;
Mi2IndexMap mi2iMap_;
typedef std::vector<MachineInstr*> Index2MiMap;
Index2MiMap i2miMap_;
typedef DenseMap<unsigned, LiveInterval*> Reg2IntervalMap;
Reg2IntervalMap r2iMap_;
DenseMap<MachineBasicBlock*, LiveIndex> terminatorGaps;
/// phiJoinCopies - Copy instructions which are PHI joins.
SmallVector<MachineInstr*, 16> phiJoinCopies;
/// allocatableRegs_ - A bit vector of allocatable registers.
BitVector allocatableRegs_;
/// CloneMIs - A list of clones as result of re-materialization.
std::vector<MachineInstr*> CloneMIs;
typedef LiveInterval::InstrSlots InstrSlots;
public:
static char ID; // Pass identification, replacement for typeid
LiveIntervals() : MachineFunctionPass(&ID) {}
LiveIndex getBaseIndex(LiveIndex index) {
return LiveIndex(index, LiveIndex::LOAD);
}
LiveIndex getBoundaryIndex(LiveIndex index) {
return LiveIndex(index,
(LiveIndex::Slot)(LiveIndex::NUM - 1));
}
LiveIndex getLoadIndex(LiveIndex index) {
return LiveIndex(index, LiveIndex::LOAD);
}
LiveIndex getUseIndex(LiveIndex index) {
return LiveIndex(index, LiveIndex::USE);
}
LiveIndex getDefIndex(LiveIndex index) {
return LiveIndex(index, LiveIndex::DEF);
}
LiveIndex getStoreIndex(LiveIndex index) {
return LiveIndex(index, LiveIndex::STORE);
}
LiveIndex getNextSlot(LiveIndex m) const {
return m.nextSlot_();
}
LiveIndex getNextIndex(LiveIndex m) const {
return m.nextIndex_();
}
LiveIndex getPrevSlot(LiveIndex m) const {
return m.prevSlot_();
}
LiveIndex getPrevIndex(LiveIndex m) const {
return m.prevIndex_();
}
static float getSpillWeight(bool isDef, bool isUse, unsigned loopDepth) {
return (isDef + isUse) * powf(10.0F, (float)loopDepth);
}
typedef Reg2IntervalMap::iterator iterator;
typedef Reg2IntervalMap::const_iterator const_iterator;
const_iterator begin() const { return r2iMap_.begin(); }
const_iterator end() const { return r2iMap_.end(); }
iterator begin() { return r2iMap_.begin(); }
iterator end() { return r2iMap_.end(); }
unsigned getNumIntervals() const { return (unsigned)r2iMap_.size(); }
LiveInterval &getInterval(unsigned reg) {
Reg2IntervalMap::iterator I = r2iMap_.find(reg);
assert(I != r2iMap_.end() && "Interval does not exist for register");
return *I->second;
}
const LiveInterval &getInterval(unsigned reg) const {
Reg2IntervalMap::const_iterator I = r2iMap_.find(reg);
assert(I != r2iMap_.end() && "Interval does not exist for register");
return *I->second;
}
bool hasInterval(unsigned reg) const {
return r2iMap_.count(reg);
}
/// getMBBStartIdx - Return the base index of the first instruction in the
/// specified MachineBasicBlock.
LiveIndex getMBBStartIdx(MachineBasicBlock *MBB) const {
return getMBBStartIdx(MBB->getNumber());
}
LiveIndex getMBBStartIdx(unsigned MBBNo) const {
assert(MBBNo < MBB2IdxMap.size() && "Invalid MBB number!");
return MBB2IdxMap[MBBNo].first;
}
/// getMBBEndIdx - Return the store index of the last instruction in the
/// specified MachineBasicBlock.
LiveIndex getMBBEndIdx(MachineBasicBlock *MBB) const {
return getMBBEndIdx(MBB->getNumber());
}
LiveIndex getMBBEndIdx(unsigned MBBNo) const {
assert(MBBNo < MBB2IdxMap.size() && "Invalid MBB number!");
return MBB2IdxMap[MBBNo].second;
}
/// getScaledIntervalSize - get the size of an interval in "units,"
/// where every function is composed of one thousand units. This
/// measure scales properly with empty index slots in the function.
double getScaledIntervalSize(LiveInterval& I) {
return (1000.0 / InstrSlots::NUM * I.getSize()) / i2miMap_.size();
}
/// getApproximateInstructionCount - computes an estimate of the number
/// of instructions in a given LiveInterval.
unsigned getApproximateInstructionCount(LiveInterval& I) {
double IntervalPercentage = getScaledIntervalSize(I) / 1000.0;
return (unsigned)(IntervalPercentage * FunctionSize);
}
/// getMBBFromIndex - given an index in any instruction of an
/// MBB return a pointer the MBB
MachineBasicBlock* getMBBFromIndex(LiveIndex index) const {
std::vector<IdxMBBPair>::const_iterator I =
std::lower_bound(Idx2MBBMap.begin(), Idx2MBBMap.end(), index);
// Take the pair containing the index
std::vector<IdxMBBPair>::const_iterator J =
((I != Idx2MBBMap.end() && I->first > index) ||
(I == Idx2MBBMap.end() && Idx2MBBMap.size()>0)) ? (I-1): I;
assert(J != Idx2MBBMap.end() && J->first <= index &&
index <= getMBBEndIdx(J->second) &&
"index does not correspond to an MBB");
return J->second;
}
/// getInstructionIndex - returns the base index of instr
LiveIndex getInstructionIndex(const MachineInstr* instr) const {
Mi2IndexMap::const_iterator it = mi2iMap_.find(instr);
assert(it != mi2iMap_.end() && "Invalid instruction!");
return it->second;
}
/// getInstructionFromIndex - given an index in any slot of an
/// instruction return a pointer the instruction
MachineInstr* getInstructionFromIndex(LiveIndex index) const {
// convert index to vector index
unsigned i = index.getVecIndex();
assert(i < i2miMap_.size() &&
"index does not correspond to an instruction");
return i2miMap_[i];
}
/// hasGapBeforeInstr - Return true if the previous instruction slot,
/// i.e. Index - InstrSlots::NUM, is not occupied.
bool hasGapBeforeInstr(LiveIndex Index) {
Index = getBaseIndex(getPrevIndex(Index));
return getInstructionFromIndex(Index) == 0;
}
/// hasGapAfterInstr - Return true if the successive instruction slot,
/// i.e. Index + InstrSlots::Num, is not occupied.
bool hasGapAfterInstr(LiveIndex Index) {
Index = getBaseIndex(getNextIndex(Index));
return getInstructionFromIndex(Index) == 0;
}
/// findGapBeforeInstr - Find an empty instruction slot before the
/// specified index. If "Furthest" is true, find one that's furthest
/// away from the index (but before any index that's occupied).
LiveIndex findGapBeforeInstr(LiveIndex Index, bool Furthest = false) {
Index = getBaseIndex(getPrevIndex(Index));
if (getInstructionFromIndex(Index))
return LiveIndex(); // No gap!
if (!Furthest)
return Index;
LiveIndex PrevIndex = getBaseIndex(getPrevIndex(Index));
while (getInstructionFromIndex(Index)) {
Index = PrevIndex;
PrevIndex = getBaseIndex(getPrevIndex(Index));
}
return Index;
}
/// InsertMachineInstrInMaps - Insert the specified machine instruction
/// into the instruction index map at the given index.
void InsertMachineInstrInMaps(MachineInstr *MI, LiveIndex Index) {
i2miMap_[Index.getVecIndex()] = MI;
Mi2IndexMap::iterator it = mi2iMap_.find(MI);
assert(it == mi2iMap_.end() && "Already in map!");
mi2iMap_[MI] = Index;
}
/// conflictsWithPhysRegDef - Returns true if the specified register
/// is defined during the duration of the specified interval.
bool conflictsWithPhysRegDef(const LiveInterval &li, VirtRegMap &vrm,
unsigned reg);
/// conflictsWithPhysRegRef - Similar to conflictsWithPhysRegRef except
/// it can check use as well.
bool conflictsWithPhysRegRef(LiveInterval &li, unsigned Reg,
bool CheckUse,
SmallPtrSet<MachineInstr*,32> &JoinedCopies);
/// findLiveInMBBs - Given a live range, if the value of the range
/// is live in any MBB returns true as well as the list of basic blocks
/// in which the value is live.
bool findLiveInMBBs(LiveIndex Start, LiveIndex End,
SmallVectorImpl<MachineBasicBlock*> &MBBs) const;
/// findReachableMBBs - Return a list MBB that can be reached via any
/// branch or fallthroughs. Return true if the list is not empty.
bool findReachableMBBs(LiveIndex Start, LiveIndex End,
SmallVectorImpl<MachineBasicBlock*> &MBBs) const;
// Interval creation
LiveInterval &getOrCreateInterval(unsigned reg) {
Reg2IntervalMap::iterator I = r2iMap_.find(reg);
if (I == r2iMap_.end())
I = r2iMap_.insert(std::make_pair(reg, createInterval(reg))).first;
return *I->second;
}
/// dupInterval - Duplicate a live interval. The caller is responsible for
/// managing the allocated memory.
LiveInterval *dupInterval(LiveInterval *li);
/// addLiveRangeToEndOfBlock - Given a register and an instruction,
/// adds a live range from that instruction to the end of its MBB.
LiveRange addLiveRangeToEndOfBlock(unsigned reg,
MachineInstr* startInst);
// Interval removal
void removeInterval(unsigned Reg) {
DenseMap<unsigned, LiveInterval*>::iterator I = r2iMap_.find(Reg);
delete I->second;
r2iMap_.erase(I);
}
/// isNotInMIMap - returns true if the specified machine instr has been
/// removed or was never entered in the map.
bool isNotInMIMap(MachineInstr* instr) const {
return !mi2iMap_.count(instr);
}
/// RemoveMachineInstrFromMaps - This marks the specified machine instr as
/// deleted.
void RemoveMachineInstrFromMaps(MachineInstr *MI) {
// remove index -> MachineInstr and
// MachineInstr -> index mappings
Mi2IndexMap::iterator mi2i = mi2iMap_.find(MI);
if (mi2i != mi2iMap_.end()) {
i2miMap_[mi2i->second.index/InstrSlots::NUM] = 0;
mi2iMap_.erase(mi2i);
}
}
/// ReplaceMachineInstrInMaps - Replacing a machine instr with a new one in
/// maps used by register allocator.
void ReplaceMachineInstrInMaps(MachineInstr *MI, MachineInstr *NewMI) {
Mi2IndexMap::iterator mi2i = mi2iMap_.find(MI);
if (mi2i == mi2iMap_.end())
return;
i2miMap_[mi2i->second.index/InstrSlots::NUM] = NewMI;
Mi2IndexMap::iterator it = mi2iMap_.find(MI);
assert(it != mi2iMap_.end() && "Invalid instruction!");
LiveIndex Index = it->second;
mi2iMap_.erase(it);
mi2iMap_[NewMI] = Index;
}
BumpPtrAllocator& getVNInfoAllocator() { return VNInfoAllocator; }
/// getVNInfoSourceReg - Helper function that parses the specified VNInfo
/// copy field and returns the source register that defines it.
unsigned getVNInfoSourceReg(const VNInfo *VNI) const;
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual void releaseMemory();
/// runOnMachineFunction - pass entry point
virtual bool runOnMachineFunction(MachineFunction&);
/// print - Implement the dump method.
virtual void print(raw_ostream &O, const Module* = 0) const;
/// addIntervalsForSpills - Create new intervals for spilled defs / uses of
/// the given interval. FIXME: It also returns the weight of the spill slot
/// (if any is created) by reference. This is temporary.
std::vector<LiveInterval*>
addIntervalsForSpills(const LiveInterval& i,
SmallVectorImpl<LiveInterval*> &SpillIs,
const MachineLoopInfo *loopInfo, VirtRegMap& vrm);
/// addIntervalsForSpillsFast - Quickly create new intervals for spilled
/// defs / uses without remat or splitting.
std::vector<LiveInterval*>
addIntervalsForSpillsFast(const LiveInterval &li,
const MachineLoopInfo *loopInfo, VirtRegMap &vrm);
/// spillPhysRegAroundRegDefsUses - Spill the specified physical register
/// around all defs and uses of the specified interval. Return true if it
/// was able to cut its interval.
bool spillPhysRegAroundRegDefsUses(const LiveInterval &li,
unsigned PhysReg, VirtRegMap &vrm);
/// isReMaterializable - Returns true if every definition of MI of every
/// val# of the specified interval is re-materializable. Also returns true
/// by reference if all of the defs are load instructions.
bool isReMaterializable(const LiveInterval &li,
SmallVectorImpl<LiveInterval*> &SpillIs,
bool &isLoad);
/// isReMaterializable - Returns true if the definition MI of the specified
/// val# of the specified interval is re-materializable.
bool isReMaterializable(const LiveInterval &li, const VNInfo *ValNo,
MachineInstr *MI);
/// getRepresentativeReg - Find the largest super register of the specified
/// physical register.
unsigned getRepresentativeReg(unsigned Reg) const;
/// getNumConflictsWithPhysReg - Return the number of uses and defs of the
/// specified interval that conflicts with the specified physical register.
unsigned getNumConflictsWithPhysReg(const LiveInterval &li,
unsigned PhysReg) const;
/// processImplicitDefs - Process IMPLICIT_DEF instructions. Add isUndef
/// marker to implicit_def defs and their uses.
void processImplicitDefs();
/// computeNumbering - Compute the index numbering.
void computeNumbering();
/// scaleNumbering - Rescale interval numbers to introduce gaps for new
/// instructions
void scaleNumbering(int factor);
/// intervalIsInOneMBB - Returns true if the specified interval is entirely
/// within a single basic block.
bool intervalIsInOneMBB(const LiveInterval &li) const;
private:
/// computeIntervals - Compute live intervals.
void computeIntervals();
bool isProfitableToCoalesce(LiveInterval &DstInt, LiveInterval &SrcInt,
SmallVector<MachineInstr*,16> &IdentCopies,
SmallVector<MachineInstr*,16> &OtherCopies);
void performEarlyCoalescing();
/// handleRegisterDef - update intervals for a register def
/// (calls handlePhysicalRegisterDef and
/// handleVirtualRegisterDef)
void handleRegisterDef(MachineBasicBlock *MBB,
MachineBasicBlock::iterator MI,
LiveIndex MIIdx,
MachineOperand& MO, unsigned MOIdx);
/// handleVirtualRegisterDef - update intervals for a virtual
/// register def
void handleVirtualRegisterDef(MachineBasicBlock *MBB,
MachineBasicBlock::iterator MI,
LiveIndex MIIdx, MachineOperand& MO,
unsigned MOIdx,
LiveInterval& interval);
/// handlePhysicalRegisterDef - update intervals for a physical register
/// def.
void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
MachineBasicBlock::iterator mi,
LiveIndex MIIdx, MachineOperand& MO,
LiveInterval &interval,
MachineInstr *CopyMI);
/// handleLiveInRegister - Create interval for a livein register.
void handleLiveInRegister(MachineBasicBlock* mbb,
LiveIndex MIIdx,
LiveInterval &interval, bool isAlias = false);
/// getReMatImplicitUse - If the remat definition MI has one (for now, we
/// only allow one) virtual register operand, then its uses are implicitly
/// using the register. Returns the virtual register.
unsigned getReMatImplicitUse(const LiveInterval &li,
MachineInstr *MI) const;
/// isValNoAvailableAt - Return true if the val# of the specified interval
/// which reaches the given instruction also reaches the specified use
/// index.
bool isValNoAvailableAt(const LiveInterval &li, MachineInstr *MI,
LiveIndex UseIdx) const;
/// isReMaterializable - Returns true if the definition MI of the specified
/// val# of the specified interval is re-materializable. Also returns true
/// by reference if the def is a load.
bool isReMaterializable(const LiveInterval &li, const VNInfo *ValNo,
MachineInstr *MI,
SmallVectorImpl<LiveInterval*> &SpillIs,
bool &isLoad);
/// tryFoldMemoryOperand - Attempts to fold either a spill / restore from
/// slot / to reg or any rematerialized load into ith operand of specified
/// MI. If it is successul, MI is updated with the newly created MI and
/// returns true.
bool tryFoldMemoryOperand(MachineInstr* &MI, VirtRegMap &vrm,
MachineInstr *DefMI, LiveIndex InstrIdx,
SmallVector<unsigned, 2> &Ops,
bool isSS, int FrameIndex, unsigned Reg);
/// canFoldMemoryOperand - Return true if the specified load / store
/// folding is possible.
bool canFoldMemoryOperand(MachineInstr *MI,
SmallVector<unsigned, 2> &Ops,
bool ReMatLoadSS) const;
/// anyKillInMBBAfterIdx - Returns true if there is a kill of the specified
/// VNInfo that's after the specified index but is within the basic block.
bool anyKillInMBBAfterIdx(const LiveInterval &li, const VNInfo *VNI,
MachineBasicBlock *MBB,
LiveIndex Idx) const;
/// hasAllocatableSuperReg - Return true if the specified physical register
/// has any super register that's allocatable.
bool hasAllocatableSuperReg(unsigned Reg) const;
/// SRInfo - Spill / restore info.
struct SRInfo {
LiveIndex index;
unsigned vreg;
bool canFold;
SRInfo(LiveIndex i, unsigned vr, bool f)
: index(i), vreg(vr), canFold(f) {}
};
bool alsoFoldARestore(int Id, LiveIndex index, unsigned vr,
BitVector &RestoreMBBs,
DenseMap<unsigned,std::vector<SRInfo> >&RestoreIdxes);
void eraseRestoreInfo(int Id, LiveIndex index, unsigned vr,
BitVector &RestoreMBBs,
DenseMap<unsigned,std::vector<SRInfo> >&RestoreIdxes);
/// handleSpilledImpDefs - Remove IMPLICIT_DEF instructions which are being
/// spilled and create empty intervals for their uses.
void handleSpilledImpDefs(const LiveInterval &li, VirtRegMap &vrm,
const TargetRegisterClass* rc,
std::vector<LiveInterval*> &NewLIs);
/// rewriteImplicitOps - Rewrite implicit use operands of MI (i.e. uses of
/// interval on to-be re-materialized operands of MI) with new register.
void rewriteImplicitOps(const LiveInterval &li,
MachineInstr *MI, unsigned NewVReg, VirtRegMap &vrm);
/// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper
/// functions for addIntervalsForSpills to rewrite uses / defs for the given
/// live range.
bool rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
bool TrySplit, LiveIndex index, LiveIndex end,
MachineInstr *MI, MachineInstr *OrigDefMI, MachineInstr *DefMI,
unsigned Slot, int LdSlot,
bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
VirtRegMap &vrm, const TargetRegisterClass* rc,
SmallVector<int, 4> &ReMatIds, const MachineLoopInfo *loopInfo,
unsigned &NewVReg, unsigned ImpUse, bool &HasDef, bool &HasUse,
DenseMap<unsigned,unsigned> &MBBVRegsMap,
std::vector<LiveInterval*> &NewLIs);
void rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
LiveInterval::Ranges::const_iterator &I,
MachineInstr *OrigDefMI, MachineInstr *DefMI, unsigned Slot, int LdSlot,
bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
VirtRegMap &vrm, const TargetRegisterClass* rc,
SmallVector<int, 4> &ReMatIds, const MachineLoopInfo *loopInfo,
BitVector &SpillMBBs,
DenseMap<unsigned,std::vector<SRInfo> > &SpillIdxes,
BitVector &RestoreMBBs,
DenseMap<unsigned,std::vector<SRInfo> > &RestoreIdxes,
DenseMap<unsigned,unsigned> &MBBVRegsMap,
std::vector<LiveInterval*> &NewLIs);
static LiveInterval* createInterval(unsigned Reg);
void printInstrs(raw_ostream &O) const;
void dumpInstrs() const;
};
} // End llvm namespace
#endif
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