1 //===-- LiveIntervalAnalysis.h - Live Interval Analysis ---------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LiveInterval analysis pass. Given some numbering of
11 // each the machine instructions (in this implemention depth-first order) an
12 // interval [i, j) is said to be a live interval for register v if there is no
13 // instruction with number j' > j such that v is live at j' and there is no
14 // instruction with number i' < i such that v is live at i'. In this
15 // implementation intervals can have holes, i.e. an interval might look like
16 // [1,20), [50,65), [1000,1001).
18 //===----------------------------------------------------------------------===//
20 #ifndef LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
21 #define LLVM_CODEGEN_LIVEINTERVAL_ANALYSIS_H
23 #include "llvm/CodeGen/MachineBasicBlock.h"
24 #include "llvm/CodeGen/MachineFunctionPass.h"
25 #include "llvm/CodeGen/LiveInterval.h"
26 #include "llvm/CodeGen/SlotIndexes.h"
27 #include "llvm/ADT/BitVector.h"
28 #include "llvm/ADT/DenseMap.h"
29 #include "llvm/ADT/SmallPtrSet.h"
30 #include "llvm/ADT/SmallVector.h"
31 #include "llvm/Support/Allocator.h"
39 class MachineLoopInfo;
40 class TargetRegisterInfo;
41 class MachineRegisterInfo;
42 class TargetInstrInfo;
43 class TargetRegisterClass;
46 class LiveIntervals : public MachineFunctionPass {
48 MachineRegisterInfo* mri_;
49 const TargetMachine* tm_;
50 const TargetRegisterInfo* tri_;
51 const TargetInstrInfo* tii_;
54 SlotIndexes* indexes_;
56 /// Special pool allocator for VNInfo's (LiveInterval val#).
58 VNInfo::Allocator VNInfoAllocator;
60 typedef DenseMap<unsigned, LiveInterval*> Reg2IntervalMap;
61 Reg2IntervalMap r2iMap_;
63 /// allocatableRegs_ - A bit vector of allocatable registers.
64 BitVector allocatableRegs_;
66 /// CloneMIs - A list of clones as result of re-materialization.
67 std::vector<MachineInstr*> CloneMIs;
70 static char ID; // Pass identification, replacement for typeid
71 LiveIntervals() : MachineFunctionPass(&ID) {}
73 // Calculate the spill weight to assign to a single instruction.
74 static float getSpillWeight(bool isDef, bool isUse, unsigned loopDepth);
76 // After summing the spill weights of all defs and uses, the final weight
77 // should be normalized, dividing the weight of the interval by its size.
78 // This encourages spilling of intervals that are large and have few uses,
79 // and discourages spilling of small intervals with many uses.
80 void normalizeSpillWeight(LiveInterval &li) {
81 li.weight /= getApproximateInstructionCount(li) + 25;
84 typedef Reg2IntervalMap::iterator iterator;
85 typedef Reg2IntervalMap::const_iterator const_iterator;
86 const_iterator begin() const { return r2iMap_.begin(); }
87 const_iterator end() const { return r2iMap_.end(); }
88 iterator begin() { return r2iMap_.begin(); }
89 iterator end() { return r2iMap_.end(); }
90 unsigned getNumIntervals() const { return (unsigned)r2iMap_.size(); }
92 LiveInterval &getInterval(unsigned reg) {
93 Reg2IntervalMap::iterator I = r2iMap_.find(reg);
94 assert(I != r2iMap_.end() && "Interval does not exist for register");
98 const LiveInterval &getInterval(unsigned reg) const {
99 Reg2IntervalMap::const_iterator I = r2iMap_.find(reg);
100 assert(I != r2iMap_.end() && "Interval does not exist for register");
104 bool hasInterval(unsigned reg) const {
105 return r2iMap_.count(reg);
108 /// getScaledIntervalSize - get the size of an interval in "units,"
109 /// where every function is composed of one thousand units. This
110 /// measure scales properly with empty index slots in the function.
111 double getScaledIntervalSize(LiveInterval& I) {
112 return (1000.0 * I.getSize()) / indexes_->getIndexesLength();
115 /// getFuncInstructionCount - Return the number of instructions in the
116 /// current function.
117 unsigned getFuncInstructionCount() {
118 return indexes_->getFunctionSize();
121 /// getApproximateInstructionCount - computes an estimate of the number
122 /// of instructions in a given LiveInterval.
123 unsigned getApproximateInstructionCount(LiveInterval& I) {
124 double IntervalPercentage = getScaledIntervalSize(I) / 1000.0;
125 return (unsigned)(IntervalPercentage * indexes_->getFunctionSize());
128 /// conflictsWithPhysReg - Returns true if the specified register is used or
129 /// defined during the duration of the specified interval. Copies to and
130 /// from li.reg are allowed. This method is only able to analyze simple
131 /// ranges that stay within a single basic block. Anything else is
132 /// considered a conflict.
133 bool conflictsWithPhysReg(const LiveInterval &li, VirtRegMap &vrm,
136 /// conflictsWithAliasRef - Similar to conflictsWithPhysRegRef except
137 /// it checks for alias uses and defs.
138 bool conflictsWithAliasRef(LiveInterval &li, unsigned Reg,
139 SmallPtrSet<MachineInstr*,32> &JoinedCopies);
142 LiveInterval &getOrCreateInterval(unsigned reg) {
143 Reg2IntervalMap::iterator I = r2iMap_.find(reg);
144 if (I == r2iMap_.end())
145 I = r2iMap_.insert(std::make_pair(reg, createInterval(reg))).first;
149 /// dupInterval - Duplicate a live interval. The caller is responsible for
150 /// managing the allocated memory.
151 LiveInterval *dupInterval(LiveInterval *li);
153 /// addLiveRangeToEndOfBlock - Given a register and an instruction,
154 /// adds a live range from that instruction to the end of its MBB.
155 LiveRange addLiveRangeToEndOfBlock(unsigned reg,
156 MachineInstr* startInst);
160 void removeInterval(unsigned Reg) {
161 DenseMap<unsigned, LiveInterval*>::iterator I = r2iMap_.find(Reg);
166 SlotIndex getZeroIndex() const {
167 return indexes_->getZeroIndex();
170 SlotIndex getInvalidIndex() const {
171 return indexes_->getInvalidIndex();
174 /// isNotInMIMap - returns true if the specified machine instr has been
175 /// removed or was never entered in the map.
176 bool isNotInMIMap(const MachineInstr* Instr) const {
177 return !indexes_->hasIndex(Instr);
180 /// Returns the base index of the given instruction.
181 SlotIndex getInstructionIndex(const MachineInstr *instr) const {
182 return indexes_->getInstructionIndex(instr);
185 /// Returns the instruction associated with the given index.
186 MachineInstr* getInstructionFromIndex(SlotIndex index) const {
187 return indexes_->getInstructionFromIndex(index);
190 /// Return the first index in the given basic block.
191 SlotIndex getMBBStartIdx(const MachineBasicBlock *mbb) const {
192 return indexes_->getMBBStartIdx(mbb);
195 /// Return the last index in the given basic block.
196 SlotIndex getMBBEndIdx(const MachineBasicBlock *mbb) const {
197 return indexes_->getMBBEndIdx(mbb);
200 MachineBasicBlock* getMBBFromIndex(SlotIndex index) const {
201 return indexes_->getMBBFromIndex(index);
204 SlotIndex getMBBTerminatorGap(const MachineBasicBlock *mbb) {
205 return indexes_->getTerminatorGap(mbb);
208 SlotIndex InsertMachineInstrInMaps(MachineInstr *MI) {
209 return indexes_->insertMachineInstrInMaps(MI);
212 void RemoveMachineInstrFromMaps(MachineInstr *MI) {
213 indexes_->removeMachineInstrFromMaps(MI);
216 void ReplaceMachineInstrInMaps(MachineInstr *MI, MachineInstr *NewMI) {
217 indexes_->replaceMachineInstrInMaps(MI, NewMI);
220 bool findLiveInMBBs(SlotIndex Start, SlotIndex End,
221 SmallVectorImpl<MachineBasicBlock*> &MBBs) const {
222 return indexes_->findLiveInMBBs(Start, End, MBBs);
226 indexes_->renumberIndexes();
229 VNInfo::Allocator& getVNInfoAllocator() { return VNInfoAllocator; }
231 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
232 virtual void releaseMemory();
234 /// runOnMachineFunction - pass entry point
235 virtual bool runOnMachineFunction(MachineFunction&);
237 /// print - Implement the dump method.
238 virtual void print(raw_ostream &O, const Module* = 0) const;
240 /// addIntervalsForSpills - Create new intervals for spilled defs / uses of
241 /// the given interval. FIXME: It also returns the weight of the spill slot
242 /// (if any is created) by reference. This is temporary.
243 std::vector<LiveInterval*>
244 addIntervalsForSpills(const LiveInterval& i,
245 SmallVectorImpl<LiveInterval*> &SpillIs,
246 const MachineLoopInfo *loopInfo, VirtRegMap& vrm);
248 /// spillPhysRegAroundRegDefsUses - Spill the specified physical register
249 /// around all defs and uses of the specified interval. Return true if it
250 /// was able to cut its interval.
251 bool spillPhysRegAroundRegDefsUses(const LiveInterval &li,
252 unsigned PhysReg, VirtRegMap &vrm);
254 /// isReMaterializable - Returns true if every definition of MI of every
255 /// val# of the specified interval is re-materializable. Also returns true
256 /// by reference if all of the defs are load instructions.
257 bool isReMaterializable(const LiveInterval &li,
258 SmallVectorImpl<LiveInterval*> &SpillIs,
261 /// isReMaterializable - Returns true if the definition MI of the specified
262 /// val# of the specified interval is re-materializable.
263 bool isReMaterializable(const LiveInterval &li, const VNInfo *ValNo,
266 /// getRepresentativeReg - Find the largest super register of the specified
267 /// physical register.
268 unsigned getRepresentativeReg(unsigned Reg) const;
270 /// getNumConflictsWithPhysReg - Return the number of uses and defs of the
271 /// specified interval that conflicts with the specified physical register.
272 unsigned getNumConflictsWithPhysReg(const LiveInterval &li,
273 unsigned PhysReg) const;
275 /// processImplicitDefs - Process IMPLICIT_DEF instructions. Add isUndef
276 /// marker to implicit_def defs and their uses.
277 void processImplicitDefs();
279 /// intervalIsInOneMBB - Returns true if the specified interval is entirely
280 /// within a single basic block.
281 bool intervalIsInOneMBB(const LiveInterval &li) const;
284 /// computeIntervals - Compute live intervals.
285 void computeIntervals();
287 /// handleRegisterDef - update intervals for a register def
288 /// (calls handlePhysicalRegisterDef and
289 /// handleVirtualRegisterDef)
290 void handleRegisterDef(MachineBasicBlock *MBB,
291 MachineBasicBlock::iterator MI,
293 MachineOperand& MO, unsigned MOIdx);
295 /// isPartialRedef - Return true if the specified def at the specific index
296 /// is partially re-defining the specified live interval. A common case of
297 /// this is a definition of the sub-register.
298 bool isPartialRedef(SlotIndex MIIdx, MachineOperand &MO,
299 LiveInterval &interval);
301 /// handleVirtualRegisterDef - update intervals for a virtual
303 void handleVirtualRegisterDef(MachineBasicBlock *MBB,
304 MachineBasicBlock::iterator MI,
305 SlotIndex MIIdx, MachineOperand& MO,
307 LiveInterval& interval);
309 /// handlePhysicalRegisterDef - update intervals for a physical register
311 void handlePhysicalRegisterDef(MachineBasicBlock* mbb,
312 MachineBasicBlock::iterator mi,
313 SlotIndex MIIdx, MachineOperand& MO,
314 LiveInterval &interval,
315 MachineInstr *CopyMI);
317 /// handleLiveInRegister - Create interval for a livein register.
318 void handleLiveInRegister(MachineBasicBlock* mbb,
320 LiveInterval &interval, bool isAlias = false);
322 /// getReMatImplicitUse - If the remat definition MI has one (for now, we
323 /// only allow one) virtual register operand, then its uses are implicitly
324 /// using the register. Returns the virtual register.
325 unsigned getReMatImplicitUse(const LiveInterval &li,
326 MachineInstr *MI) const;
328 /// isValNoAvailableAt - Return true if the val# of the specified interval
329 /// which reaches the given instruction also reaches the specified use
331 bool isValNoAvailableAt(const LiveInterval &li, MachineInstr *MI,
332 SlotIndex UseIdx) const;
334 /// isReMaterializable - Returns true if the definition MI of the specified
335 /// val# of the specified interval is re-materializable. Also returns true
336 /// by reference if the def is a load.
337 bool isReMaterializable(const LiveInterval &li, const VNInfo *ValNo,
339 SmallVectorImpl<LiveInterval*> &SpillIs,
342 /// tryFoldMemoryOperand - Attempts to fold either a spill / restore from
343 /// slot / to reg or any rematerialized load into ith operand of specified
344 /// MI. If it is successul, MI is updated with the newly created MI and
346 bool tryFoldMemoryOperand(MachineInstr* &MI, VirtRegMap &vrm,
347 MachineInstr *DefMI, SlotIndex InstrIdx,
348 SmallVector<unsigned, 2> &Ops,
349 bool isSS, int FrameIndex, unsigned Reg);
351 /// canFoldMemoryOperand - Return true if the specified load / store
352 /// folding is possible.
353 bool canFoldMemoryOperand(MachineInstr *MI,
354 SmallVector<unsigned, 2> &Ops,
355 bool ReMatLoadSS) const;
357 /// anyKillInMBBAfterIdx - Returns true if there is a kill of the specified
358 /// VNInfo that's after the specified index but is within the basic block.
359 bool anyKillInMBBAfterIdx(const LiveInterval &li, const VNInfo *VNI,
360 MachineBasicBlock *MBB,
361 SlotIndex Idx) const;
363 /// hasAllocatableSuperReg - Return true if the specified physical register
364 /// has any super register that's allocatable.
365 bool hasAllocatableSuperReg(unsigned Reg) const;
367 /// SRInfo - Spill / restore info.
372 SRInfo(SlotIndex i, unsigned vr, bool f)
373 : index(i), vreg(vr), canFold(f) {}
376 bool alsoFoldARestore(int Id, SlotIndex index, unsigned vr,
377 BitVector &RestoreMBBs,
378 DenseMap<unsigned,std::vector<SRInfo> >&RestoreIdxes);
379 void eraseRestoreInfo(int Id, SlotIndex index, unsigned vr,
380 BitVector &RestoreMBBs,
381 DenseMap<unsigned,std::vector<SRInfo> >&RestoreIdxes);
383 /// handleSpilledImpDefs - Remove IMPLICIT_DEF instructions which are being
384 /// spilled and create empty intervals for their uses.
385 void handleSpilledImpDefs(const LiveInterval &li, VirtRegMap &vrm,
386 const TargetRegisterClass* rc,
387 std::vector<LiveInterval*> &NewLIs);
389 /// rewriteImplicitOps - Rewrite implicit use operands of MI (i.e. uses of
390 /// interval on to-be re-materialized operands of MI) with new register.
391 void rewriteImplicitOps(const LiveInterval &li,
392 MachineInstr *MI, unsigned NewVReg, VirtRegMap &vrm);
394 /// rewriteInstructionForSpills, rewriteInstructionsForSpills - Helper
395 /// functions for addIntervalsForSpills to rewrite uses / defs for the given
397 bool rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
398 bool TrySplit, SlotIndex index, SlotIndex end,
399 MachineInstr *MI, MachineInstr *OrigDefMI, MachineInstr *DefMI,
400 unsigned Slot, int LdSlot,
401 bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
402 VirtRegMap &vrm, const TargetRegisterClass* rc,
403 SmallVector<int, 4> &ReMatIds, const MachineLoopInfo *loopInfo,
404 unsigned &NewVReg, unsigned ImpUse, bool &HasDef, bool &HasUse,
405 DenseMap<unsigned,unsigned> &MBBVRegsMap,
406 std::vector<LiveInterval*> &NewLIs);
407 void rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
408 LiveInterval::Ranges::const_iterator &I,
409 MachineInstr *OrigDefMI, MachineInstr *DefMI, unsigned Slot, int LdSlot,
410 bool isLoad, bool isLoadSS, bool DefIsReMat, bool CanDelete,
411 VirtRegMap &vrm, const TargetRegisterClass* rc,
412 SmallVector<int, 4> &ReMatIds, const MachineLoopInfo *loopInfo,
413 BitVector &SpillMBBs,
414 DenseMap<unsigned,std::vector<SRInfo> > &SpillIdxes,
415 BitVector &RestoreMBBs,
416 DenseMap<unsigned,std::vector<SRInfo> > &RestoreIdxes,
417 DenseMap<unsigned,unsigned> &MBBVRegsMap,
418 std::vector<LiveInterval*> &NewLIs);
420 // Normalize the spill weight of all the intervals in NewLIs.
421 void normalizeSpillWeights(std::vector<LiveInterval*> &NewLIs);
423 static LiveInterval* createInterval(unsigned Reg);
425 void printInstrs(raw_ostream &O) const;
426 void dumpInstrs() const;
428 } // End llvm namespace