LiveIntervalAnalysis.cpp revision 9a8b490735d216435862a3d52e669357f165550f 
1//===-- LiveIntervals.cpp - Live Interval Analysis ------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the LiveInterval analysis pass which is used
11// by the Linear Scan Register allocator. This pass linearizes the
12// basic blocks of the function in DFS order and uses the
13// LiveVariables pass to conservatively compute live intervals for
14// each virtual and physical register.
15//
16//===----------------------------------------------------------------------===//
17
18#define DEBUG_TYPE "liveintervals"
19#include "LiveIntervals.h"
20#include "llvm/Analysis/LoopInfo.h"
21#include "llvm/CodeGen/LiveVariables.h"
22#include "llvm/CodeGen/MachineFrameInfo.h"
23#include "llvm/CodeGen/MachineInstr.h"
24#include "llvm/CodeGen/Passes.h"
25#include "llvm/CodeGen/SSARegMap.h"
26#include "llvm/Target/MRegisterInfo.h"
27#include "llvm/Target/TargetInstrInfo.h"
28#include "llvm/Target/TargetMachine.h"
29#include "llvm/Support/CFG.h"
30#include "Support/CommandLine.h"
31#include "Support/Debug.h"
32#include "Support/Statistic.h"
33#include "Support/STLExtras.h"
34#include "VirtRegMap.h"
35#include <cmath>
36#include <iostream>
37#include <limits>
38
39using namespace llvm;
40
41namespace {
42    RegisterAnalysis<LiveIntervals> X("liveintervals",
43                                      "Live Interval Analysis");
44
45    Statistic<> numIntervals
46    ("liveintervals", "Number of original intervals");
47
48    Statistic<> numIntervalsAfter
49    ("liveintervals", "Number of intervals after coalescing");
50
51    Statistic<> numJoins
52    ("liveintervals", "Number of interval joins performed");
53
54    Statistic<> numPeep
55    ("liveintervals", "Number of identity moves eliminated after coalescing");
56
57    Statistic<> numFolded
58    ("liveintervals", "Number of loads/stores folded into instructions");
59
60    cl::opt<bool>
61    join("join-liveintervals",
62         cl::desc("Join compatible live intervals"),
63         cl::init(true));
64};
65
66void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const
67{
68    AU.addPreserved<LiveVariables>();
69    AU.addRequired<LiveVariables>();
70    AU.addPreservedID(PHIEliminationID);
71    AU.addRequiredID(PHIEliminationID);
72    AU.addRequiredID(TwoAddressInstructionPassID);
73    AU.addRequired<LoopInfo>();
74    MachineFunctionPass::getAnalysisUsage(AU);
75}
76
77void LiveIntervals::releaseMemory()
78{
79    mbbi2mbbMap_.clear();
80    mi2iMap_.clear();
81    i2miMap_.clear();
82    r2iMap_.clear();
83    r2rMap_.clear();
84    intervals_.clear();
85}
86
87
88/// runOnMachineFunction - Register allocate the whole function
89///
90bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
91    mf_ = &fn;
92    tm_ = &fn.getTarget();
93    mri_ = tm_->getRegisterInfo();
94    lv_ = &getAnalysis<LiveVariables>();
95
96    // number MachineInstrs
97    unsigned miIndex = 0;
98    for (MachineFunction::iterator mbb = mf_->begin(), mbbEnd = mf_->end();
99         mbb != mbbEnd; ++mbb) {
100        const std::pair<MachineBasicBlock*, unsigned>& entry =
101            lv_->getMachineBasicBlockInfo(mbb);
102        bool inserted = mbbi2mbbMap_.insert(std::make_pair(entry.second,
103                                                           entry.first)).second;
104        assert(inserted && "multiple index -> MachineBasicBlock");
105
106        for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
107             mi != miEnd; ++mi) {
108            inserted = mi2iMap_.insert(std::make_pair(mi, miIndex)).second;
109            assert(inserted && "multiple MachineInstr -> index mappings");
110            i2miMap_.push_back(mi);
111            miIndex += InstrSlots::NUM;
112        }
113    }
114
115    computeIntervals();
116
117    numIntervals += intervals_.size();
118
119    // join intervals if requested
120    if (join) joinIntervals();
121
122    numIntervalsAfter += intervals_.size();
123
124    // perform a final pass over the instructions and compute spill
125    // weights, coalesce virtual registers and remove identity moves
126    const LoopInfo& loopInfo = getAnalysis<LoopInfo>();
127    const TargetInstrInfo& tii = tm_->getInstrInfo();
128
129    for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
130         mbbi != mbbe; ++mbbi) {
131        MachineBasicBlock* mbb = mbbi;
132        unsigned loopDepth = loopInfo.getLoopDepth(mbb->getBasicBlock());
133
134        for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
135             mii != mie; ) {
136            for (unsigned i = 0; i < mii->getNumOperands(); ++i) {
137                const MachineOperand& mop = mii->getOperand(i);
138                if (mop.isRegister() && mop.getReg()) {
139                    // replace register with representative register
140                    unsigned reg = rep(mop.getReg());
141                    mii->SetMachineOperandReg(i, reg);
142
143                    if (MRegisterInfo::isVirtualRegister(reg)) {
144                        Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
145                        assert(r2iit != r2iMap_.end());
146                        r2iit->second->weight += pow(10.0F, loopDepth);
147                    }
148                }
149            }
150
151            // if the move is now an identity move delete it
152            unsigned srcReg, dstReg;
153            if (tii.isMoveInstr(*mii, srcReg, dstReg) && srcReg == dstReg) {
154                // remove from def list
155                Interval& interval = getOrCreateInterval(dstReg);
156                unsigned defIndex = getInstructionIndex(mii);
157                Interval::Defs::iterator d = std::lower_bound(
158                    interval.defs.begin(), interval.defs.end(), defIndex);
159                assert(*d == defIndex && "Def index not found in def list!");
160                interval.defs.erase(d);
161                // remove index -> MachineInstr and
162                // MachineInstr -> index mappings
163                Mi2IndexMap::iterator mi2i = mi2iMap_.find(mii);
164                if (mi2i != mi2iMap_.end()) {
165                    i2miMap_[mi2i->second/InstrSlots::NUM] = 0;
166                    mi2iMap_.erase(mi2i);
167                }
168                mii = mbbi->erase(mii);
169                ++numPeep;
170            }
171            else
172                ++mii;
173        }
174    }
175
176    intervals_.sort(StartPointComp());
177    DEBUG(std::cerr << "********** INTERVALS **********\n");
178    DEBUG(std::copy(intervals_.begin(), intervals_.end(),
179                    std::ostream_iterator<Interval>(std::cerr, "\n")));
180    DEBUG(std::cerr << "********** MACHINEINSTRS **********\n");
181    DEBUG(
182        for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
183             mbbi != mbbe; ++mbbi) {
184            std::cerr << mbbi->getBasicBlock()->getName() << ":\n";
185            for (MachineBasicBlock::iterator mii = mbbi->begin(),
186                     mie = mbbi->end(); mii != mie; ++mii) {
187                std::cerr << getInstructionIndex(mii) << '\t';
188                mii->print(std::cerr, *tm_);
189            }
190        });
191
192    return true;
193}
194
195void LiveIntervals::updateSpilledInterval(Interval& li,
196                                          VirtRegMap& vrm,
197                                          int slot)
198{
199    assert(li.weight != std::numeric_limits<float>::infinity() &&
200           "attempt to spill already spilled interval!");
201    Interval::Ranges oldRanges;
202    swap(oldRanges, li.ranges);
203
204    DEBUG(std::cerr << "\t\t\t\tupdating interval: " << li);
205
206    for (Interval::Ranges::iterator i = oldRanges.begin(), e = oldRanges.end();
207         i != e; ++i) {
208        unsigned index = getBaseIndex(i->first);
209        unsigned end = getBaseIndex(i->second-1) + InstrSlots::NUM;
210        for (; index < end; index += InstrSlots::NUM) {
211            // skip deleted instructions
212            while (!getInstructionFromIndex(index)) index += InstrSlots::NUM;
213            MachineBasicBlock::iterator mi = getInstructionFromIndex(index);
214
215        for_operand:
216            for (unsigned i = 0; i < mi->getNumOperands(); ++i) {
217                MachineOperand& mop = mi->getOperand(i);
218                if (mop.isRegister() && mop.getReg() == li.reg) {
219                    if (MachineInstr* fmi =
220                        mri_->foldMemoryOperand(mi, i, slot)) {
221                        lv_->instructionChanged(mi, fmi);
222                        vrm.virtFolded(li.reg, mi, fmi);
223                        mi2iMap_.erase(mi);
224                        i2miMap_[index/InstrSlots::NUM] = fmi;
225                        mi2iMap_[fmi] = index;
226                        MachineBasicBlock& mbb = *mi->getParent();
227                        mi = mbb.insert(mbb.erase(mi), fmi);
228                        ++numFolded;
229                        goto for_operand;
230                    }
231                    else {
232                        // This is tricky. We need to add information in
233                        // the interval about the spill code so we have to
234                        // use our extra load/store slots.
235                        //
236                        // If we have a use we are going to have a load so
237                        // we start the interval from the load slot
238                        // onwards. Otherwise we start from the def slot.
239                        unsigned start = (mop.isUse() ?
240                                          getLoadIndex(index) :
241                                          getDefIndex(index));
242                        // If we have a def we are going to have a store
243                        // right after it so we end the interval after the
244                        // use of the next instruction. Otherwise we end
245                        // after the use of this instruction.
246                        unsigned end = 1 + (mop.isDef() ?
247                                            getUseIndex(index+InstrSlots::NUM) :
248                                            getUseIndex(index));
249                        li.addRange(start, end);
250                    }
251                }
252            }
253        }
254    }
255    // the new spill weight is now infinity as it cannot be spilled again
256    li.weight = std::numeric_limits<float>::infinity();
257    DEBUG(std::cerr << '\n');
258    DEBUG(std::cerr << "\t\t\t\tupdated interval: " << li << '\n');
259}
260
261void LiveIntervals::printRegName(unsigned reg) const
262{
263    if (MRegisterInfo::isPhysicalRegister(reg))
264        std::cerr << mri_->getName(reg);
265    else
266        std::cerr << "%reg" << reg;
267}
268
269void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock* mbb,
270                                             MachineBasicBlock::iterator mi,
271                                             Interval& interval)
272{
273    DEBUG(std::cerr << "\t\tregister: "; printRegName(interval.reg));
274    LiveVariables::VarInfo& vi = lv_->getVarInfo(interval.reg);
275
276    // iterate over all of the blocks that the variable is completely
277    // live in, adding them to the live interval. obviously we only
278    // need to do this once.
279    if (interval.empty()) {
280        for (unsigned i = 0, e = vi.AliveBlocks.size(); i != e; ++i) {
281            if (vi.AliveBlocks[i]) {
282                MachineBasicBlock* mbb = lv_->getIndexMachineBasicBlock(i);
283                if (!mbb->empty()) {
284                    interval.addRange(
285                        getInstructionIndex(&mbb->front()),
286                        getInstructionIndex(&mbb->back()) + InstrSlots::NUM);
287                }
288            }
289        }
290    }
291
292    unsigned baseIndex = getInstructionIndex(mi);
293    interval.defs.push_back(baseIndex);
294
295    bool killedInDefiningBasicBlock = false;
296    for (int i = 0, e = vi.Kills.size(); i != e; ++i) {
297        MachineBasicBlock* killerBlock = vi.Kills[i].first;
298        MachineInstr* killerInstr = vi.Kills[i].second;
299        unsigned start = (mbb == killerBlock ?
300                          getDefIndex(baseIndex) :
301                          getInstructionIndex(&killerBlock->front()));
302        unsigned end = (killerInstr == mi ?
303                         // dead
304                        start + 1 :
305                        // killed
306                        getUseIndex(getInstructionIndex(killerInstr))+1);
307        // we do not want to add invalid ranges. these can happen when
308        // a variable has its latest use and is redefined later on in
309        // the same basic block (common with variables introduced by
310        // PHI elimination)
311        if (start < end) {
312            killedInDefiningBasicBlock |= mbb == killerBlock;
313            interval.addRange(start, end);
314        }
315    }
316
317    if (!killedInDefiningBasicBlock) {
318        unsigned end = getInstructionIndex(&mbb->back()) + InstrSlots::NUM;
319        interval.addRange(getDefIndex(baseIndex), end);
320    }
321    DEBUG(std::cerr << '\n');
322}
323
324void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock* mbb,
325                                              MachineBasicBlock::iterator mi,
326                                              Interval& interval)
327{
328    DEBUG(std::cerr << "\t\tregister: "; printRegName(interval.reg));
329    typedef LiveVariables::killed_iterator KillIter;
330
331    MachineBasicBlock::iterator e = mbb->end();
332    unsigned baseIndex = getInstructionIndex(mi);
333    interval.defs.push_back(baseIndex);
334    unsigned start = getDefIndex(baseIndex);
335    unsigned end = start;
336
337    // a variable can be dead by the instruction defining it
338    for (KillIter ki = lv_->dead_begin(mi), ke = lv_->dead_end(mi);
339         ki != ke; ++ki) {
340        if (interval.reg == ki->second) {
341            DEBUG(std::cerr << " dead");
342            end = getDefIndex(start) + 1;
343            goto exit;
344        }
345    }
346
347    // a variable can only be killed by subsequent instructions
348    do {
349        ++mi;
350        baseIndex += InstrSlots::NUM;
351        for (KillIter ki = lv_->killed_begin(mi), ke = lv_->killed_end(mi);
352             ki != ke; ++ki) {
353            if (interval.reg == ki->second) {
354                DEBUG(std::cerr << " killed");
355                end = getUseIndex(baseIndex) + 1;
356                goto exit;
357            }
358        }
359    } while (mi != e);
360
361exit:
362    assert(start < end && "did not find end of interval?");
363    interval.addRange(start, end);
364    DEBUG(std::cerr << '\n');
365}
366
367void LiveIntervals::handleRegisterDef(MachineBasicBlock* mbb,
368                                      MachineBasicBlock::iterator mi,
369                                      unsigned reg)
370{
371    if (MRegisterInfo::isPhysicalRegister(reg)) {
372        if (lv_->getAllocatablePhysicalRegisters()[reg]) {
373            handlePhysicalRegisterDef(mbb, mi, getOrCreateInterval(reg));
374            for (const unsigned* as = mri_->getAliasSet(reg); *as; ++as)
375                handlePhysicalRegisterDef(mbb, mi, getOrCreateInterval(*as));
376        }
377    }
378    else
379        handleVirtualRegisterDef(mbb, mi, getOrCreateInterval(reg));
380}
381
382unsigned LiveIntervals::getInstructionIndex(MachineInstr* instr) const
383{
384    Mi2IndexMap::const_iterator it = mi2iMap_.find(instr);
385    return (it == mi2iMap_.end() ?
386            std::numeric_limits<unsigned>::max() :
387            it->second);
388}
389
390MachineInstr* LiveIntervals::getInstructionFromIndex(unsigned index) const
391{
392    index /= InstrSlots::NUM; // convert index to vector index
393    assert(index < i2miMap_.size() &&
394           "index does not correspond to an instruction");
395    return i2miMap_[index];
396}
397
398/// computeIntervals - computes the live intervals for virtual
399/// registers. for some ordering of the machine instructions [1,N] a
400/// live interval is an interval [i, j) where 1 <= i <= j < N for
401/// which a variable is live
402void LiveIntervals::computeIntervals()
403{
404    DEBUG(std::cerr << "********** COMPUTING LIVE INTERVALS **********\n");
405    DEBUG(std::cerr << "********** Function: "
406          << mf_->getFunction()->getName() << '\n');
407
408    for (MbbIndex2MbbMap::iterator
409             it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
410         it != itEnd; ++it) {
411        MachineBasicBlock* mbb = it->second;
412        DEBUG(std::cerr << mbb->getBasicBlock()->getName() << ":\n");
413
414        for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
415             mi != miEnd; ++mi) {
416            const TargetInstrDescriptor& tid =
417                tm_->getInstrInfo().get(mi->getOpcode());
418            DEBUG(std::cerr << getInstructionIndex(mi) << "\t";
419                  mi->print(std::cerr, *tm_));
420
421            // handle implicit defs
422            for (const unsigned* id = tid.ImplicitDefs; *id; ++id)
423                handleRegisterDef(mbb, mi, *id);
424
425            // handle explicit defs
426            for (int i = mi->getNumOperands() - 1; i >= 0; --i) {
427                MachineOperand& mop = mi->getOperand(i);
428                // handle register defs - build intervals
429                if (mop.isRegister() && mop.getReg() && mop.isDef())
430                    handleRegisterDef(mbb, mi, mop.getReg());
431            }
432        }
433    }
434}
435
436unsigned LiveIntervals::rep(unsigned reg)
437{
438    Reg2RegMap::iterator it = r2rMap_.find(reg);
439    if (it != r2rMap_.end())
440        return it->second = rep(it->second);
441    return reg;
442}
443
444void LiveIntervals::joinIntervals()
445{
446    DEBUG(std::cerr << "********** JOINING INTERVALS ***********\n");
447
448    const TargetInstrInfo& tii = tm_->getInstrInfo();
449
450    for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
451         mbbi != mbbe; ++mbbi) {
452        MachineBasicBlock* mbb = mbbi;
453        DEBUG(std::cerr << mbb->getBasicBlock()->getName() << ":\n");
454
455        for (MachineBasicBlock::iterator mi = mbb->begin(), mie = mbb->end();
456             mi != mie; ++mi) {
457            const TargetInstrDescriptor& tid =
458                tm_->getInstrInfo().get(mi->getOpcode());
459            DEBUG(std::cerr << getInstructionIndex(mi) << '\t';
460                  mi->print(std::cerr, *tm_););
461
462            // we only join virtual registers with allocatable
463            // physical registers since we do not have liveness information
464            // on not allocatable physical registers
465            unsigned regA, regB;
466            if (tii.isMoveInstr(*mi, regA, regB) &&
467                (MRegisterInfo::isVirtualRegister(regA) ||
468                 lv_->getAllocatablePhysicalRegisters()[regA]) &&
469                (MRegisterInfo::isVirtualRegister(regB) ||
470                 lv_->getAllocatablePhysicalRegisters()[regB])) {
471
472                // get representative registers
473                regA = rep(regA);
474                regB = rep(regB);
475
476                // if they are already joined we continue
477                if (regA == regB)
478                    continue;
479
480                Reg2IntervalMap::iterator r2iA = r2iMap_.find(regA);
481                assert(r2iA != r2iMap_.end());
482                Reg2IntervalMap::iterator r2iB = r2iMap_.find(regB);
483                assert(r2iB != r2iMap_.end());
484
485                Intervals::iterator intA = r2iA->second;
486                Intervals::iterator intB = r2iB->second;
487
488                // both A and B are virtual registers
489                if (MRegisterInfo::isVirtualRegister(intA->reg) &&
490                    MRegisterInfo::isVirtualRegister(intB->reg)) {
491
492                    const TargetRegisterClass *rcA, *rcB;
493                    rcA = mf_->getSSARegMap()->getRegClass(intA->reg);
494                    rcB = mf_->getSSARegMap()->getRegClass(intB->reg);
495                    assert(rcA == rcB && "registers must be of the same class");
496
497                    // if their intervals do not overlap we join them
498                    if (!intB->overlaps(*intA)) {
499                        intA->join(*intB);
500                        r2iB->second = r2iA->second;
501                        r2rMap_.insert(std::make_pair(intB->reg, intA->reg));
502                        intervals_.erase(intB);
503                    }
504                }
505                else if (MRegisterInfo::isPhysicalRegister(intA->reg) ^
506                         MRegisterInfo::isPhysicalRegister(intB->reg)) {
507                    if (MRegisterInfo::isPhysicalRegister(intB->reg)) {
508                        std::swap(regA, regB);
509                        std::swap(intA, intB);
510                        std::swap(r2iA, r2iB);
511                    }
512
513                    assert(MRegisterInfo::isPhysicalRegister(intA->reg) &&
514                           MRegisterInfo::isVirtualRegister(intB->reg) &&
515                           "A must be physical and B must be virtual");
516
517                    if (!intA->overlaps(*intB) &&
518                        !overlapsAliases(*intA, *intB)) {
519                        intA->join(*intB);
520                        r2iB->second = r2iA->second;
521                        r2rMap_.insert(std::make_pair(intB->reg, intA->reg));
522                        intervals_.erase(intB);
523                    }
524                }
525            }
526        }
527    }
528}
529
530bool LiveIntervals::overlapsAliases(const Interval& lhs,
531                                    const Interval& rhs) const
532{
533    assert(MRegisterInfo::isPhysicalRegister(lhs.reg) &&
534           "first interval must describe a physical register");
535
536    for (const unsigned* as = mri_->getAliasSet(lhs.reg); *as; ++as) {
537        Reg2IntervalMap::const_iterator r2i = r2iMap_.find(*as);
538        assert(r2i != r2iMap_.end() && "alias does not have interval?");
539        if (rhs.overlaps(*r2i->second))
540            return true;
541    }
542
543    return false;
544}
545
546LiveIntervals::Interval& LiveIntervals::getOrCreateInterval(unsigned reg)
547{
548    Reg2IntervalMap::iterator r2iit = r2iMap_.lower_bound(reg);
549    if (r2iit == r2iMap_.end() || r2iit->first != reg) {
550        intervals_.push_back(Interval(reg));
551        r2iit = r2iMap_.insert(r2iit, std::make_pair(reg, --intervals_.end()));
552    }
553
554    return *r2iit->second;
555}
556
557LiveIntervals::Interval::Interval(unsigned r)
558    : reg(r),
559      weight((MRegisterInfo::isPhysicalRegister(r) ?
560              std::numeric_limits<float>::infinity() : 0.0F))
561{
562
563}
564
565bool LiveIntervals::Interval::spilled() const
566{
567    return (weight == std::numeric_limits<float>::infinity() &&
568            MRegisterInfo::isVirtualRegister(reg));
569}
570
571// An example for liveAt():
572//
573// this = [1,4), liveAt(0) will return false. The instruction defining
574// this spans slots [0,3]. The interval belongs to an spilled
575// definition of the variable it represents. This is because slot 1 is
576// used (def slot) and spans up to slot 3 (store slot).
577//
578bool LiveIntervals::Interval::liveAt(unsigned index) const
579{
580    Range dummy(index, index+1);
581    Ranges::const_iterator r = std::upper_bound(ranges.begin(),
582                                                ranges.end(),
583                                                dummy);
584    if (r == ranges.begin())
585        return false;
586
587    --r;
588    return index >= r->first && index < r->second;
589}
590
591// An example for overlaps():
592//
593// 0: A = ...
594// 4: B = ...
595// 8: C = A + B ;; last use of A
596//
597// The live intervals should look like:
598//
599// A = [3, 11)
600// B = [7, x)
601// C = [11, y)
602//
603// A->overlaps(C) should return false since we want to be able to join
604// A and C.
605bool LiveIntervals::Interval::overlaps(const Interval& other) const
606{
607    Ranges::const_iterator i = ranges.begin();
608    Ranges::const_iterator ie = ranges.end();
609    Ranges::const_iterator j = other.ranges.begin();
610    Ranges::const_iterator je = other.ranges.end();
611    if (i->first < j->first) {
612        i = std::upper_bound(i, ie, *j);
613        if (i != ranges.begin()) --i;
614    }
615    else if (j->first < i->first) {
616        j = std::upper_bound(j, je, *i);
617        if (j != other.ranges.begin()) --j;
618    }
619
620    while (i != ie && j != je) {
621        if (i->first == j->first) {
622            return true;
623        }
624        else {
625            if (i->first > j->first) {
626                swap(i, j);
627                swap(ie, je);
628            }
629            assert(i->first < j->first);
630
631            if (i->second > j->first) {
632                return true;
633            }
634            else {
635                ++i;
636            }
637        }
638    }
639
640    return false;
641}
642
643void LiveIntervals::Interval::addRange(unsigned start, unsigned end)
644{
645    assert(start < end && "Invalid range to add!");
646    DEBUG(std::cerr << " +[" << start << ',' << end << ")");
647    //assert(start < end && "invalid range?");
648    Range range = std::make_pair(start, end);
649    Ranges::iterator it =
650        ranges.insert(std::upper_bound(ranges.begin(), ranges.end(), range),
651                      range);
652
653    it = mergeRangesForward(it);
654    it = mergeRangesBackward(it);
655}
656
657void LiveIntervals::Interval::join(const LiveIntervals::Interval& other)
658{
659    DEBUG(std::cerr << "\t\tjoining " << *this << " with " << other << '\n');
660    Ranges::iterator cur = ranges.begin();
661
662    for (Ranges::const_iterator i = other.ranges.begin(),
663             e = other.ranges.end(); i != e; ++i) {
664        cur = ranges.insert(std::upper_bound(cur, ranges.end(), *i), *i);
665        cur = mergeRangesForward(cur);
666        cur = mergeRangesBackward(cur);
667    }
668    weight += other.weight;
669    Defs u;
670    std::set_union(defs.begin(), defs.end(),
671                   other.defs.begin(), other.defs.end(),
672                   std::back_inserter(u));
673    defs = u;
674    ++numJoins;
675}
676
677LiveIntervals::Interval::Ranges::iterator
678LiveIntervals::Interval::mergeRangesForward(Ranges::iterator it)
679{
680    Ranges::iterator n;
681    while ((n = next(it)) != ranges.end()) {
682        if (n->first > it->second)
683            break;
684        it->second = std::max(it->second, n->second);
685        n = ranges.erase(n);
686    }
687    return it;
688}
689
690LiveIntervals::Interval::Ranges::iterator
691LiveIntervals::Interval::mergeRangesBackward(Ranges::iterator it)
692{
693    while (it != ranges.begin()) {
694        Ranges::iterator p = prior(it);
695        if (it->first > p->second)
696            break;
697
698        it->first = std::min(it->first, p->first);
699        it->second = std::max(it->second, p->second);
700        it = ranges.erase(p);
701    }
702
703    return it;
704}
705
706std::ostream& llvm::operator<<(std::ostream& os,
707                               const LiveIntervals::Interval& li)
708{
709    os << "%reg" << li.reg << ',' << li.weight;
710    if (li.empty())
711        return os << "EMPTY";
712
713    os << " {" << li.defs.front();
714    for (LiveIntervals::Interval::Defs::const_iterator
715             i = next(li.defs.begin()), e = li.defs.end(); i != e; ++i)
716        os << ", " << *i;
717    os << "}";
718
719    os << " = ";
720    for (LiveIntervals::Interval::Ranges::const_iterator
721             i = li.ranges.begin(), e = li.ranges.end(); i != e; ++i) {
722        os << "[" << i->first << "," << i->second << ")";
723    }
724    return os;
725}
726