LiveInterval.h revision 1cd1d98232c3c3a0bd3810c3bf6c2572ea02f208
1//===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the LiveRange and LiveInterval classes. Given some 11// numbering of each the machine instructions an interval [i, j) is said to be a 12// live interval for register v if there is no instruction with number j' >= j 13// such that v is live at j' and there is no instruction with number i' < i such 14// that v is live at i'. In this implementation intervals can have holes, 15// i.e. an interval might look like [1,20), [50,65), [1000,1001). Each 16// individual range is represented as an instance of LiveRange, and the whole 17// interval is represented as an instance of LiveInterval. 18// 19//===----------------------------------------------------------------------===// 20 21#ifndef LLVM_CODEGEN_LIVEINTERVAL_H 22#define LLVM_CODEGEN_LIVEINTERVAL_H 23 24#include "llvm/ADT/SmallVector.h" 25#include "llvm/Support/Allocator.h" 26#include "llvm/Support/AlignOf.h" 27#include <iosfwd> 28#include <cassert> 29#include <climits> 30 31namespace llvm { 32 class MachineInstr; 33 class MachineRegisterInfo; 34 class TargetRegisterInfo; 35 class raw_ostream; 36 37 /// VNInfo - Value Number Information. 38 /// This class holds information about a machine level values, including 39 /// definition and use points. 40 /// 41 /// Care must be taken in interpreting the def index of the value. The 42 /// following rules apply: 43 /// 44 /// If the isDefAccurate() method returns false then def does not contain the 45 /// index of the defining MachineInstr, or even (necessarily) to a 46 /// MachineInstr at all. In general such a def index is not meaningful 47 /// and should not be used. The exception is that, for values originally 48 /// defined by PHI instructions, after PHI elimination def will contain the 49 /// index of the MBB in which the PHI originally existed. This can be used 50 /// to insert code (spills or copies) which deals with the value, which will 51 /// be live in to the block. 52 53 class VNInfo { 54 private: 55 enum { 56 HAS_PHI_KILL = 1, 57 REDEF_BY_EC = 1 << 1, 58 IS_PHI_DEF = 1 << 2, 59 IS_UNUSED = 1 << 3, 60 IS_DEF_ACCURATE = 1 << 4 61 }; 62 63 unsigned char flags; 64 65 public: 66 /// Holds information about individual kills. 67 struct KillInfo { 68 bool isPHIKill : 1; 69 unsigned killIdx : 31; 70 71 KillInfo(bool isPHIKill, unsigned killIdx) 72 : isPHIKill(isPHIKill), killIdx(killIdx) { 73 74 assert(killIdx != 0 && "Zero kill indices are no longer permitted."); 75 } 76 77 }; 78 79 typedef SmallVector<KillInfo, 4> KillSet; 80 81 /// The ID number of this value. 82 unsigned id; 83 84 /// The index of the defining instruction (if isDefAccurate() returns true). 85 unsigned def; 86 MachineInstr *copy; 87 KillSet kills; 88 89 VNInfo() 90 : flags(IS_UNUSED), id(~1U), def(0), copy(0) {} 91 92 /// VNInfo constructor. 93 /// d is presumed to point to the actual defining instr. If it doesn't 94 /// setIsDefAccurate(false) should be called after construction. 95 VNInfo(unsigned i, unsigned d, MachineInstr *c) 96 : flags(IS_DEF_ACCURATE), id(i), def(d), copy(c) {} 97 98 /// VNInfo construtor, copies values from orig, except for the value number. 99 VNInfo(unsigned i, const VNInfo &orig) 100 : flags(orig.flags), id(i), def(orig.def), copy(orig.copy), 101 kills(orig.kills) {} 102 103 /// Used for copying value number info. 104 unsigned getFlags() const { return flags; } 105 void setFlags(unsigned flags) { this->flags = flags; } 106 107 /// Returns true if one or more kills are PHI nodes. 108 bool hasPHIKill() const { return flags & HAS_PHI_KILL; } 109 void setHasPHIKill(bool hasKill) { 110 if (hasKill) 111 flags |= HAS_PHI_KILL; 112 else 113 flags &= ~HAS_PHI_KILL; 114 } 115 116 /// Returns true if this value is re-defined by an early clobber somewhere 117 /// during the live range. 118 bool hasRedefByEC() const { return flags & REDEF_BY_EC; } 119 void setHasRedefByEC(bool hasRedef) { 120 if (hasRedef) 121 flags |= REDEF_BY_EC; 122 else 123 flags &= ~REDEF_BY_EC; 124 } 125 126 /// Returns true if this value is defined by a PHI instruction (or was, 127 /// PHI instrucions may have been eliminated). 128 bool isPHIDef() const { return flags & IS_PHI_DEF; } 129 void setIsPHIDef(bool phiDef) { 130 if (phiDef) 131 flags |= IS_PHI_DEF; 132 else 133 flags &= ~IS_PHI_DEF; 134 } 135 136 /// Returns true if this value is unused. 137 bool isUnused() const { return flags & IS_UNUSED; } 138 void setIsUnused(bool unused) { 139 if (unused) 140 flags |= IS_UNUSED; 141 else 142 flags &= ~IS_UNUSED; 143 } 144 145 /// Returns true if the def is accurate. 146 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; } 147 void setIsDefAccurate(bool defAccurate) { 148 if (defAccurate) 149 flags |= IS_DEF_ACCURATE; 150 else 151 flags &= ~IS_DEF_ACCURATE; 152 } 153 154 }; 155 156 inline bool operator<(const VNInfo::KillInfo &k1, const VNInfo::KillInfo &k2) { 157 return k1.killIdx < k2.killIdx; 158 } 159 160 inline bool operator<(const VNInfo::KillInfo &k, unsigned idx) { 161 return k.killIdx < idx; 162 } 163 164 inline bool operator<(unsigned idx, const VNInfo::KillInfo &k) { 165 return idx < k.killIdx; 166 } 167 168 /// LiveRange structure - This represents a simple register range in the 169 /// program, with an inclusive start point and an exclusive end point. 170 /// These ranges are rendered as [start,end). 171 struct LiveRange { 172 unsigned start; // Start point of the interval (inclusive) 173 unsigned end; // End point of the interval (exclusive) 174 VNInfo *valno; // identifier for the value contained in this interval. 175 176 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) { 177 assert(S < E && "Cannot create empty or backwards range"); 178 } 179 180 /// contains - Return true if the index is covered by this range. 181 /// 182 bool contains(unsigned I) const { 183 return start <= I && I < end; 184 } 185 186 bool operator<(const LiveRange &LR) const { 187 return start < LR.start || (start == LR.start && end < LR.end); 188 } 189 bool operator==(const LiveRange &LR) const { 190 return start == LR.start && end == LR.end; 191 } 192 193 void dump() const; 194 void print(std::ostream &os) const; 195 void print(std::ostream *os) const { if (os) print(*os); } 196 void print(raw_ostream &os) const; 197 void print(raw_ostream *os) const { if (os) print(*os); } 198 199 private: 200 LiveRange(); // DO NOT IMPLEMENT 201 }; 202 203 std::ostream& operator<<(std::ostream& os, const LiveRange &LR); 204 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR); 205 206 207 inline bool operator<(unsigned V, const LiveRange &LR) { 208 return V < LR.start; 209 } 210 211 inline bool operator<(const LiveRange &LR, unsigned V) { 212 return LR.start < V; 213 } 214 215 /// LiveInterval - This class represents some number of live ranges for a 216 /// register or value. This class also contains a bit of register allocator 217 /// state. 218 class LiveInterval { 219 public: 220 221 typedef SmallVector<LiveRange,4> Ranges; 222 typedef SmallVector<VNInfo*,4> VNInfoList; 223 224 unsigned reg; // the register or stack slot of this interval 225 // if the top bits is set, it represents a stack slot. 226 float weight; // weight of this interval 227 Ranges ranges; // the ranges in which this register is live 228 VNInfoList valnos; // value#'s 229 230 struct InstrSlots { 231 enum { 232 LOAD = 0, 233 USE = 1, 234 DEF = 2, 235 STORE = 3, 236 NUM = 4 237 }; 238 239 static unsigned scale(unsigned slot, unsigned factor) { 240 unsigned index = slot / NUM, 241 offset = slot % NUM; 242 assert(index <= ~0U / (factor * NUM) && 243 "Rescaled interval would overflow"); 244 return index * NUM * factor + offset; 245 } 246 247 }; 248 249 LiveInterval(unsigned Reg, float Weight, bool IsSS = false) 250 : reg(Reg), weight(Weight) { 251 if (IsSS) 252 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1)); 253 } 254 255 typedef Ranges::iterator iterator; 256 iterator begin() { return ranges.begin(); } 257 iterator end() { return ranges.end(); } 258 259 typedef Ranges::const_iterator const_iterator; 260 const_iterator begin() const { return ranges.begin(); } 261 const_iterator end() const { return ranges.end(); } 262 263 typedef VNInfoList::iterator vni_iterator; 264 vni_iterator vni_begin() { return valnos.begin(); } 265 vni_iterator vni_end() { return valnos.end(); } 266 267 typedef VNInfoList::const_iterator const_vni_iterator; 268 const_vni_iterator vni_begin() const { return valnos.begin(); } 269 const_vni_iterator vni_end() const { return valnos.end(); } 270 271 /// advanceTo - Advance the specified iterator to point to the LiveRange 272 /// containing the specified position, or end() if the position is past the 273 /// end of the interval. If no LiveRange contains this position, but the 274 /// position is in a hole, this method returns an iterator pointing the the 275 /// LiveRange immediately after the hole. 276 iterator advanceTo(iterator I, unsigned Pos) { 277 if (Pos >= endNumber()) 278 return end(); 279 while (I->end <= Pos) ++I; 280 return I; 281 } 282 283 void clear() { 284 while (!valnos.empty()) { 285 VNInfo *VNI = valnos.back(); 286 valnos.pop_back(); 287 VNI->~VNInfo(); 288 } 289 290 ranges.clear(); 291 } 292 293 /// isStackSlot - Return true if this is a stack slot interval. 294 /// 295 bool isStackSlot() const { 296 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1)); 297 } 298 299 /// getStackSlotIndex - Return stack slot index if this is a stack slot 300 /// interval. 301 int getStackSlotIndex() const { 302 assert(isStackSlot() && "Interval is not a stack slot interval!"); 303 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1)); 304 } 305 306 bool hasAtLeastOneValue() const { return !valnos.empty(); } 307 308 bool containsOneValue() const { return valnos.size() == 1; } 309 310 unsigned getNumValNums() const { return (unsigned)valnos.size(); } 311 312 /// getValNumInfo - Returns pointer to the specified val#. 313 /// 314 inline VNInfo *getValNumInfo(unsigned ValNo) { 315 return valnos[ValNo]; 316 } 317 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 318 return valnos[ValNo]; 319 } 320 321 /// copyValNumInfo - Copy the value number info for one value number to 322 /// another. 323 void copyValNumInfo(VNInfo *DstValNo, const VNInfo *SrcValNo) { 324 DstValNo->def = SrcValNo->def; 325 DstValNo->copy = SrcValNo->copy; 326 DstValNo->setFlags(SrcValNo->getFlags()); 327 DstValNo->kills = SrcValNo->kills; 328 } 329 330 /// getNextValue - Create a new value number and return it. MIIdx specifies 331 /// the instruction that defines the value number. 332 VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI, 333 bool isDefAccurate, BumpPtrAllocator &VNInfoAllocator) { 334 335 assert(MIIdx != ~0u && MIIdx != ~1u && 336 "PHI def / unused flags should now be passed explicitly."); 337 VNInfo *VNI = 338 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo), 339 alignof<VNInfo>())); 340 new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, CopyMI); 341 VNI->setIsDefAccurate(isDefAccurate); 342 valnos.push_back(VNI); 343 return VNI; 344 } 345 346 /// Create a copy of the given value. The new value will be identical except 347 /// for the Value number. 348 VNInfo *createValueCopy(const VNInfo *orig, BumpPtrAllocator &VNInfoAllocator) { 349 350 VNInfo *VNI = 351 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo), 352 alignof<VNInfo>())); 353 354 new (VNI) VNInfo((unsigned)valnos.size(), *orig); 355 valnos.push_back(VNI); 356 return VNI; 357 } 358 359 /// addKill - Add a kill instruction index to the specified value 360 /// number. 361 static void addKill(VNInfo *VNI, unsigned KillIdx, bool phiKill) { 362 VNInfo::KillSet &kills = VNI->kills; 363 VNInfo::KillInfo newKill(phiKill, KillIdx); 364 if (kills.empty()) { 365 kills.push_back(newKill); 366 } else { 367 VNInfo::KillSet::iterator 368 I = std::lower_bound(kills.begin(), kills.end(), newKill); 369 kills.insert(I, newKill); 370 } 371 } 372 373 /// addKills - Add a number of kills into the VNInfo kill vector. If this 374 /// interval is live at a kill point, then the kill is not added. 375 void addKills(VNInfo *VNI, const VNInfo::KillSet &kills) { 376 for (unsigned i = 0, e = static_cast<unsigned>(kills.size()); 377 i != e; ++i) { 378 const VNInfo::KillInfo &Kill = kills[i]; 379 if (!liveBeforeAndAt(Kill.killIdx)) { 380 VNInfo::KillSet::iterator 381 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), Kill); 382 VNI->kills.insert(I, Kill); 383 } 384 } 385 } 386 387 /// removeKill - Remove the specified kill from the list of kills of 388 /// the specified val#. 389 static bool removeKill(VNInfo *VNI, unsigned KillIdx) { 390 VNInfo::KillSet &kills = VNI->kills; 391 VNInfo::KillSet::iterator 392 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 393 if (I != kills.end() && I->killIdx == KillIdx) { 394 kills.erase(I); 395 return true; 396 } 397 return false; 398 } 399 400 /// removeKills - Remove all the kills in specified range 401 /// [Start, End] of the specified val#. 402 static void removeKills(VNInfo *VNI, unsigned Start, unsigned End) { 403 VNInfo::KillSet &kills = VNI->kills; 404 405 VNInfo::KillSet::iterator 406 I = std::lower_bound(kills.begin(), kills.end(), Start); 407 VNInfo::KillSet::iterator 408 E = std::upper_bound(kills.begin(), kills.end(), End); 409 kills.erase(I, E); 410 } 411 412 /// isKill - Return true if the specified index is a kill of the 413 /// specified val#. 414 static bool isKill(const VNInfo *VNI, unsigned KillIdx) { 415 const VNInfo::KillSet &kills = VNI->kills; 416 VNInfo::KillSet::const_iterator 417 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 418 return I != kills.end() && I->killIdx == KillIdx; 419 } 420 421 /// isOnlyLROfValNo - Return true if the specified live range is the only 422 /// one defined by the its val#. 423 bool isOnlyLROfValNo(const LiveRange *LR) { 424 for (const_iterator I = begin(), E = end(); I != E; ++I) { 425 const LiveRange *Tmp = I; 426 if (Tmp != LR && Tmp->valno == LR->valno) 427 return false; 428 } 429 return true; 430 } 431 432 /// MergeValueNumberInto - This method is called when two value nubmers 433 /// are found to be equivalent. This eliminates V1, replacing all 434 /// LiveRanges with the V1 value number with the V2 value number. This can 435 /// cause merging of V1/V2 values numbers and compaction of the value space. 436 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 437 438 /// MergeInClobberRanges - For any live ranges that are not defined in the 439 /// current interval, but are defined in the Clobbers interval, mark them 440 /// used with an unknown definition value. Caller must pass in reference to 441 /// VNInfoAllocator since it will create a new val#. 442 void MergeInClobberRanges(const LiveInterval &Clobbers, 443 BumpPtrAllocator &VNInfoAllocator); 444 445 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a 446 /// single LiveRange only. 447 void MergeInClobberRange(unsigned Start, unsigned End, 448 BumpPtrAllocator &VNInfoAllocator); 449 450 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 451 /// in RHS into this live interval as the specified value number. 452 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 453 /// current interval, it will replace the value numbers of the overlaped 454 /// live ranges with the specified value number. 455 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 456 457 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 458 /// in RHS into this live interval as the specified value number. 459 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 460 /// current interval, but only if the overlapping LiveRanges have the 461 /// specified value number. 462 void MergeValueInAsValue(const LiveInterval &RHS, 463 const VNInfo *RHSValNo, VNInfo *LHSValNo); 464 465 /// Copy - Copy the specified live interval. This copies all the fields 466 /// except for the register of the interval. 467 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI, 468 BumpPtrAllocator &VNInfoAllocator); 469 470 bool empty() const { return ranges.empty(); } 471 472 /// beginNumber - Return the lowest numbered slot covered by interval. 473 unsigned beginNumber() const { 474 if (empty()) 475 return 0; 476 return ranges.front().start; 477 } 478 479 /// endNumber - return the maximum point of the interval of the whole, 480 /// exclusive. 481 unsigned endNumber() const { 482 if (empty()) 483 return 0; 484 return ranges.back().end; 485 } 486 487 bool expiredAt(unsigned index) const { 488 return index >= endNumber(); 489 } 490 491 bool liveAt(unsigned index) const; 492 493 // liveBeforeAndAt - Check if the interval is live at the index and the 494 // index just before it. If index is liveAt, check if it starts a new live 495 // range.If it does, then check if the previous live range ends at index-1. 496 bool liveBeforeAndAt(unsigned index) const; 497 498 /// getLiveRangeContaining - Return the live range that contains the 499 /// specified index, or null if there is none. 500 const LiveRange *getLiveRangeContaining(unsigned Idx) const { 501 const_iterator I = FindLiveRangeContaining(Idx); 502 return I == end() ? 0 : &*I; 503 } 504 505 /// getLiveRangeContaining - Return the live range that contains the 506 /// specified index, or null if there is none. 507 LiveRange *getLiveRangeContaining(unsigned Idx) { 508 iterator I = FindLiveRangeContaining(Idx); 509 return I == end() ? 0 : &*I; 510 } 511 512 /// FindLiveRangeContaining - Return an iterator to the live range that 513 /// contains the specified index, or end() if there is none. 514 const_iterator FindLiveRangeContaining(unsigned Idx) const; 515 516 /// FindLiveRangeContaining - Return an iterator to the live range that 517 /// contains the specified index, or end() if there is none. 518 iterator FindLiveRangeContaining(unsigned Idx); 519 520 /// findDefinedVNInfo - Find the VNInfo that's defined at the specified 521 /// index (register interval) or defined by the specified register (stack 522 /// inteval). 523 VNInfo *findDefinedVNInfo(unsigned DefIdxOrReg) const; 524 525 /// overlaps - Return true if the intersection of the two live intervals is 526 /// not empty. 527 bool overlaps(const LiveInterval& other) const { 528 return overlapsFrom(other, other.begin()); 529 } 530 531 /// overlaps - Return true if the live interval overlaps a range specified 532 /// by [Start, End). 533 bool overlaps(unsigned Start, unsigned End) const; 534 535 /// overlapsFrom - Return true if the intersection of the two live intervals 536 /// is not empty. The specified iterator is a hint that we can begin 537 /// scanning the Other interval starting at I. 538 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 539 540 /// addRange - Add the specified LiveRange to this interval, merging 541 /// intervals as appropriate. This returns an iterator to the inserted live 542 /// range (which may have grown since it was inserted. 543 void addRange(LiveRange LR) { 544 addRangeFrom(LR, ranges.begin()); 545 } 546 547 /// join - Join two live intervals (this, and other) together. This applies 548 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 549 /// the intervals are not joinable, this aborts. 550 void join(LiveInterval &Other, const int *ValNoAssignments, 551 const int *RHSValNoAssignments, 552 SmallVector<VNInfo*, 16> &NewVNInfo, 553 MachineRegisterInfo *MRI); 554 555 /// isInOneLiveRange - Return true if the range specified is entirely in the 556 /// a single LiveRange of the live interval. 557 bool isInOneLiveRange(unsigned Start, unsigned End); 558 559 /// removeRange - Remove the specified range from this interval. Note that 560 /// the range must be a single LiveRange in its entirety. 561 void removeRange(unsigned Start, unsigned End, bool RemoveDeadValNo = false); 562 563 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 564 removeRange(LR.start, LR.end, RemoveDeadValNo); 565 } 566 567 /// removeValNo - Remove all the ranges defined by the specified value#. 568 /// Also remove the value# from value# list. 569 void removeValNo(VNInfo *ValNo); 570 571 /// scaleNumbering - Renumber VNI and ranges to provide gaps for new 572 /// instructions. 573 void scaleNumbering(unsigned factor); 574 575 /// getSize - Returns the sum of sizes of all the LiveRange's. 576 /// 577 unsigned getSize() const; 578 579 /// ComputeJoinedWeight - Set the weight of a live interval after 580 /// Other has been merged into it. 581 void ComputeJoinedWeight(const LiveInterval &Other); 582 583 bool operator<(const LiveInterval& other) const { 584 return beginNumber() < other.beginNumber(); 585 } 586 587 void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const; 588 void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const { 589 if (OS) print(*OS, TRI); 590 } 591 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const; 592 void print(raw_ostream *OS, const TargetRegisterInfo *TRI = 0) const { 593 if (OS) print(*OS, TRI); 594 } 595 void dump() const; 596 597 private: 598 599 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 600 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd); 601 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr); 602 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 603 604 }; 605 606 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) { 607 LI.print(OS); 608 return OS; 609 } 610 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) { 611 LI.print(OS); 612 return OS; 613 } 614} 615 616#endif 617