LiveInterval.h revision 24cdd2f82c73de23a183ec6d93498be34dc02de7
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 "llvm/CodeGen/SlotIndexes.h" 28#include <cassert> 29#include <climits> 30 31namespace llvm { 32 class LiveIntervals; 33 class MachineInstr; 34 class MachineRegisterInfo; 35 class TargetRegisterInfo; 36 class raw_ostream; 37 38 /// VNInfo - Value Number Information. 39 /// This class holds information about a machine level values, including 40 /// definition and use points. 41 /// 42 /// Care must be taken in interpreting the def index of the value. The 43 /// following rules apply: 44 /// 45 /// If the isDefAccurate() method returns false then def does not contain the 46 /// index of the defining MachineInstr, or even (necessarily) to a 47 /// MachineInstr at all. In general such a def index is not meaningful 48 /// and should not be used. The exception is that, for values originally 49 /// defined by PHI instructions, after PHI elimination def will contain the 50 /// index of the MBB in which the PHI originally existed. This can be used 51 /// to insert code (spills or copies) which deals with the value, which will 52 /// be live in to the block. 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 union { 65 MachineInstr *copy; 66 unsigned reg; 67 } cr; 68 69 public: 70 typedef SpecificBumpPtrAllocator<VNInfo> Allocator; 71 typedef SmallVector<SlotIndex, 4> KillSet; 72 73 /// The ID number of this value. 74 unsigned id; 75 76 /// The index of the defining instruction (if isDefAccurate() returns true). 77 SlotIndex def; 78 79 KillSet kills; 80 81 /* 82 VNInfo(LiveIntervals &li_) 83 : defflags(IS_UNUSED), id(~1U) { cr.copy = 0; } 84 */ 85 86 /// VNInfo constructor. 87 /// d is presumed to point to the actual defining instr. If it doesn't 88 /// setIsDefAccurate(false) should be called after construction. 89 VNInfo(unsigned i, SlotIndex d, MachineInstr *c) 90 : flags(IS_DEF_ACCURATE), id(i), def(d) { cr.copy = c; } 91 92 /// VNInfo construtor, copies values from orig, except for the value number. 93 VNInfo(unsigned i, const VNInfo &orig) 94 : flags(orig.flags), cr(orig.cr), id(i), def(orig.def), kills(orig.kills) 95 { } 96 97 /// Copy from the parameter into this VNInfo. 98 void copyFrom(VNInfo &src) { 99 flags = src.flags; 100 cr = src.cr; 101 def = src.def; 102 kills = src.kills; 103 } 104 105 /// Used for copying value number info. 106 unsigned getFlags() const { return flags; } 107 void setFlags(unsigned flags) { this->flags = flags; } 108 109 /// For a register interval, if this VN was definied by a copy instr 110 /// getCopy() returns a pointer to it, otherwise returns 0. 111 /// For a stack interval the behaviour of this method is undefined. 112 MachineInstr* getCopy() const { return cr.copy; } 113 /// For a register interval, set the copy member. 114 /// This method should not be called on stack intervals as it may lead to 115 /// undefined behavior. 116 void setCopy(MachineInstr *c) { cr.copy = c; } 117 118 /// For a stack interval, returns the reg which this stack interval was 119 /// defined from. 120 /// For a register interval the behaviour of this method is undefined. 121 unsigned getReg() const { return cr.reg; } 122 /// For a stack interval, set the defining register. 123 /// This method should not be called on register intervals as it may lead 124 /// to undefined behaviour. 125 void setReg(unsigned reg) { cr.reg = reg; } 126 127 /// Returns true if one or more kills are PHI nodes. 128 bool hasPHIKill() const { return flags & HAS_PHI_KILL; } 129 /// Set the PHI kill flag on this value. 130 void setHasPHIKill(bool hasKill) { 131 if (hasKill) 132 flags |= HAS_PHI_KILL; 133 else 134 flags &= ~HAS_PHI_KILL; 135 } 136 137 /// Returns true if this value is re-defined by an early clobber somewhere 138 /// during the live range. 139 bool hasRedefByEC() const { return flags & REDEF_BY_EC; } 140 /// Set the "redef by early clobber" flag on this value. 141 void setHasRedefByEC(bool hasRedef) { 142 if (hasRedef) 143 flags |= REDEF_BY_EC; 144 else 145 flags &= ~REDEF_BY_EC; 146 } 147 148 /// Returns true if this value is defined by a PHI instruction (or was, 149 /// PHI instrucions may have been eliminated). 150 bool isPHIDef() const { return flags & IS_PHI_DEF; } 151 /// Set the "phi def" flag on this value. 152 void setIsPHIDef(bool phiDef) { 153 if (phiDef) 154 flags |= IS_PHI_DEF; 155 else 156 flags &= ~IS_PHI_DEF; 157 } 158 159 /// Returns true if this value is unused. 160 bool isUnused() const { return flags & IS_UNUSED; } 161 /// Set the "is unused" flag on this value. 162 void setIsUnused(bool unused) { 163 if (unused) 164 flags |= IS_UNUSED; 165 else 166 flags &= ~IS_UNUSED; 167 } 168 169 /// Returns true if the def is accurate. 170 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; } 171 /// Set the "is def accurate" flag on this value. 172 void setIsDefAccurate(bool defAccurate) { 173 if (defAccurate) 174 flags |= IS_DEF_ACCURATE; 175 else 176 flags &= ~IS_DEF_ACCURATE; 177 } 178 179 /// Returns true if the given index is a kill of this value. 180 bool isKill(SlotIndex k) const { 181 KillSet::const_iterator 182 i = std::lower_bound(kills.begin(), kills.end(), k); 183 return (i != kills.end() && *i == k); 184 } 185 186 /// addKill - Add a kill instruction index to the specified value 187 /// number. 188 void addKill(SlotIndex k) { 189 if (kills.empty()) { 190 kills.push_back(k); 191 } else { 192 KillSet::iterator 193 i = std::lower_bound(kills.begin(), kills.end(), k); 194 kills.insert(i, k); 195 } 196 } 197 198 /// Remove the specified kill index from this value's kills list. 199 /// Returns true if the value was present, otherwise returns false. 200 bool removeKill(SlotIndex k) { 201 KillSet::iterator i = std::lower_bound(kills.begin(), kills.end(), k); 202 if (i != kills.end() && *i == k) { 203 kills.erase(i); 204 return true; 205 } 206 return false; 207 } 208 209 /// Remove all kills in the range [s, e). 210 void removeKills(SlotIndex s, SlotIndex e) { 211 KillSet::iterator 212 si = std::lower_bound(kills.begin(), kills.end(), s), 213 se = std::upper_bound(kills.begin(), kills.end(), e); 214 215 kills.erase(si, se); 216 } 217 218 }; 219 220 /// LiveRange structure - This represents a simple register range in the 221 /// program, with an inclusive start point and an exclusive end point. 222 /// These ranges are rendered as [start,end). 223 struct LiveRange { 224 SlotIndex start; // Start point of the interval (inclusive) 225 SlotIndex end; // End point of the interval (exclusive) 226 VNInfo *valno; // identifier for the value contained in this interval. 227 228 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V) 229 : start(S), end(E), valno(V) { 230 231 assert(S < E && "Cannot create empty or backwards range"); 232 } 233 234 /// contains - Return true if the index is covered by this range. 235 /// 236 bool contains(SlotIndex I) const { 237 return start <= I && I < end; 238 } 239 240 /// containsRange - Return true if the given range, [S, E), is covered by 241 /// this range. 242 bool containsRange(SlotIndex S, SlotIndex E) const { 243 assert((S < E) && "Backwards interval?"); 244 return (start <= S && S < end) && (start < E && E <= end); 245 } 246 247 bool operator<(const LiveRange &LR) const { 248 return start < LR.start || (start == LR.start && end < LR.end); 249 } 250 bool operator==(const LiveRange &LR) const { 251 return start == LR.start && end == LR.end; 252 } 253 254 void dump() const; 255 void print(raw_ostream &os) const; 256 257 private: 258 LiveRange(); // DO NOT IMPLEMENT 259 }; 260 261 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR); 262 263 264 inline bool operator<(SlotIndex V, const LiveRange &LR) { 265 return V < LR.start; 266 } 267 268 inline bool operator<(const LiveRange &LR, SlotIndex V) { 269 return LR.start < V; 270 } 271 272 /// LiveInterval - This class represents some number of live ranges for a 273 /// register or value. This class also contains a bit of register allocator 274 /// state. 275 class LiveInterval { 276 public: 277 278 typedef SmallVector<LiveRange,4> Ranges; 279 typedef SmallVector<VNInfo*,4> VNInfoList; 280 281 unsigned reg; // the register or stack slot of this interval 282 // if the top bits is set, it represents a stack slot. 283 float weight; // weight of this interval 284 Ranges ranges; // the ranges in which this register is live 285 VNInfoList valnos; // value#'s 286 287 struct InstrSlots { 288 enum { 289 LOAD = 0, 290 USE = 1, 291 DEF = 2, 292 STORE = 3, 293 NUM = 4 294 }; 295 296 }; 297 298 LiveInterval(unsigned Reg, float Weight, bool IsSS = false) 299 : reg(Reg), weight(Weight) { 300 if (IsSS) 301 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1)); 302 } 303 304 typedef Ranges::iterator iterator; 305 iterator begin() { return ranges.begin(); } 306 iterator end() { return ranges.end(); } 307 308 typedef Ranges::const_iterator const_iterator; 309 const_iterator begin() const { return ranges.begin(); } 310 const_iterator end() const { return ranges.end(); } 311 312 typedef VNInfoList::iterator vni_iterator; 313 vni_iterator vni_begin() { return valnos.begin(); } 314 vni_iterator vni_end() { return valnos.end(); } 315 316 typedef VNInfoList::const_iterator const_vni_iterator; 317 const_vni_iterator vni_begin() const { return valnos.begin(); } 318 const_vni_iterator vni_end() const { return valnos.end(); } 319 320 /// advanceTo - Advance the specified iterator to point to the LiveRange 321 /// containing the specified position, or end() if the position is past the 322 /// end of the interval. If no LiveRange contains this position, but the 323 /// position is in a hole, this method returns an iterator pointing to the 324 /// LiveRange immediately after the hole. 325 iterator advanceTo(iterator I, SlotIndex Pos) { 326 if (Pos >= endIndex()) 327 return end(); 328 while (I->end <= Pos) ++I; 329 return I; 330 } 331 332 void clear() { 333 valnos.clear(); 334 ranges.clear(); 335 } 336 337 /// isStackSlot - Return true if this is a stack slot interval. 338 /// 339 bool isStackSlot() const { 340 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1)); 341 } 342 343 /// getStackSlotIndex - Return stack slot index if this is a stack slot 344 /// interval. 345 int getStackSlotIndex() const { 346 assert(isStackSlot() && "Interval is not a stack slot interval!"); 347 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1)); 348 } 349 350 bool hasAtLeastOneValue() const { return !valnos.empty(); } 351 352 bool containsOneValue() const { return valnos.size() == 1; } 353 354 unsigned getNumValNums() const { return (unsigned)valnos.size(); } 355 356 /// getValNumInfo - Returns pointer to the specified val#. 357 /// 358 inline VNInfo *getValNumInfo(unsigned ValNo) { 359 return valnos[ValNo]; 360 } 361 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 362 return valnos[ValNo]; 363 } 364 365 /// getNextValue - Create a new value number and return it. MIIdx specifies 366 /// the instruction that defines the value number. 367 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI, 368 bool isDefAccurate, VNInfo::Allocator &VNInfoAllocator) { 369 VNInfo *VNI = VNInfoAllocator.Allocate(); 370 new (VNI) VNInfo((unsigned)valnos.size(), def, CopyMI); 371 VNI->setIsDefAccurate(isDefAccurate); 372 valnos.push_back(VNI); 373 return VNI; 374 } 375 376 /// Create a copy of the given value. The new value will be identical except 377 /// for the Value number. 378 VNInfo *createValueCopy(const VNInfo *orig, 379 VNInfo::Allocator &VNInfoAllocator) { 380 VNInfo *VNI = VNInfoAllocator.Allocate(); 381 new (VNI) VNInfo((unsigned)valnos.size(), *orig); 382 valnos.push_back(VNI); 383 return VNI; 384 } 385 386 /// addKills - Add a number of kills into the VNInfo kill vector. If this 387 /// interval is live at a kill point, then the kill is not added. 388 void addKills(VNInfo *VNI, const VNInfo::KillSet &kills) { 389 for (unsigned i = 0, e = static_cast<unsigned>(kills.size()); 390 i != e; ++i) { 391 if (!liveBeforeAndAt(kills[i])) { 392 VNI->addKill(kills[i]); 393 } 394 } 395 } 396 397 /// isOnlyLROfValNo - Return true if the specified live range is the only 398 /// one defined by the its val#. 399 bool isOnlyLROfValNo(const LiveRange *LR) { 400 for (const_iterator I = begin(), E = end(); I != E; ++I) { 401 const LiveRange *Tmp = I; 402 if (Tmp != LR && Tmp->valno == LR->valno) 403 return false; 404 } 405 return true; 406 } 407 408 /// MergeValueNumberInto - This method is called when two value nubmers 409 /// are found to be equivalent. This eliminates V1, replacing all 410 /// LiveRanges with the V1 value number with the V2 value number. This can 411 /// cause merging of V1/V2 values numbers and compaction of the value space. 412 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 413 414 /// MergeInClobberRanges - For any live ranges that are not defined in the 415 /// current interval, but are defined in the Clobbers interval, mark them 416 /// used with an unknown definition value. Caller must pass in reference to 417 /// VNInfoAllocator since it will create a new val#. 418 void MergeInClobberRanges(LiveIntervals &li_, 419 const LiveInterval &Clobbers, 420 VNInfo::Allocator &VNInfoAllocator); 421 422 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a 423 /// single LiveRange only. 424 void MergeInClobberRange(LiveIntervals &li_, 425 SlotIndex Start, 426 SlotIndex End, 427 VNInfo::Allocator &VNInfoAllocator); 428 429 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 430 /// in RHS into this live interval as the specified value number. 431 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 432 /// current interval, it will replace the value numbers of the overlaped 433 /// live ranges with the specified value number. 434 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 435 436 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 437 /// in RHS into this live interval as the specified value number. 438 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 439 /// current interval, but only if the overlapping LiveRanges have the 440 /// specified value number. 441 void MergeValueInAsValue(const LiveInterval &RHS, 442 const VNInfo *RHSValNo, VNInfo *LHSValNo); 443 444 /// Copy - Copy the specified live interval. This copies all the fields 445 /// except for the register of the interval. 446 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI, 447 VNInfo::Allocator &VNInfoAllocator); 448 449 bool empty() const { return ranges.empty(); } 450 451 /// beginIndex - Return the lowest numbered slot covered by interval. 452 SlotIndex beginIndex() const { 453 assert(!empty() && "Call to beginIndex() on empty interval."); 454 return ranges.front().start; 455 } 456 457 /// endNumber - return the maximum point of the interval of the whole, 458 /// exclusive. 459 SlotIndex endIndex() const { 460 assert(!empty() && "Call to endIndex() on empty interval."); 461 return ranges.back().end; 462 } 463 464 bool expiredAt(SlotIndex index) const { 465 return index >= endIndex(); 466 } 467 468 bool liveAt(SlotIndex index) const; 469 470 // liveBeforeAndAt - Check if the interval is live at the index and the 471 // index just before it. If index is liveAt, check if it starts a new live 472 // range.If it does, then check if the previous live range ends at index-1. 473 bool liveBeforeAndAt(SlotIndex index) const; 474 475 /// getLiveRangeContaining - Return the live range that contains the 476 /// specified index, or null if there is none. 477 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const { 478 const_iterator I = FindLiveRangeContaining(Idx); 479 return I == end() ? 0 : &*I; 480 } 481 482 /// getLiveRangeContaining - Return the live range that contains the 483 /// specified index, or null if there is none. 484 LiveRange *getLiveRangeContaining(SlotIndex Idx) { 485 iterator I = FindLiveRangeContaining(Idx); 486 return I == end() ? 0 : &*I; 487 } 488 489 /// FindLiveRangeContaining - Return an iterator to the live range that 490 /// contains the specified index, or end() if there is none. 491 const_iterator FindLiveRangeContaining(SlotIndex Idx) const; 492 493 /// FindLiveRangeContaining - Return an iterator to the live range that 494 /// contains the specified index, or end() if there is none. 495 iterator FindLiveRangeContaining(SlotIndex Idx); 496 497 /// findDefinedVNInfo - Find the by the specified 498 /// index (register interval) or defined 499 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const; 500 501 /// findDefinedVNInfo - Find the VNInfo that's defined by the specified 502 /// register (stack inteval only). 503 VNInfo *findDefinedVNInfoForStackInt(unsigned Reg) const; 504 505 506 /// overlaps - Return true if the intersection of the two live intervals is 507 /// not empty. 508 bool overlaps(const LiveInterval& other) const { 509 return overlapsFrom(other, other.begin()); 510 } 511 512 /// overlaps - Return true if the live interval overlaps a range specified 513 /// by [Start, End). 514 bool overlaps(SlotIndex Start, SlotIndex End) const; 515 516 /// overlapsFrom - Return true if the intersection of the two live intervals 517 /// is not empty. The specified iterator is a hint that we can begin 518 /// scanning the Other interval starting at I. 519 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 520 521 /// addRange - Add the specified LiveRange to this interval, merging 522 /// intervals as appropriate. This returns an iterator to the inserted live 523 /// range (which may have grown since it was inserted. 524 void addRange(LiveRange LR) { 525 addRangeFrom(LR, ranges.begin()); 526 } 527 528 /// join - Join two live intervals (this, and other) together. This applies 529 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 530 /// the intervals are not joinable, this aborts. 531 void join(LiveInterval &Other, 532 const int *ValNoAssignments, 533 const int *RHSValNoAssignments, 534 SmallVector<VNInfo*, 16> &NewVNInfo, 535 MachineRegisterInfo *MRI); 536 537 /// isInOneLiveRange - Return true if the range specified is entirely in the 538 /// a single LiveRange of the live interval. 539 bool isInOneLiveRange(SlotIndex Start, SlotIndex End); 540 541 /// removeRange - Remove the specified range from this interval. Note that 542 /// the range must be a single LiveRange in its entirety. 543 void removeRange(SlotIndex Start, SlotIndex End, 544 bool RemoveDeadValNo = false); 545 546 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 547 removeRange(LR.start, LR.end, RemoveDeadValNo); 548 } 549 550 /// removeValNo - Remove all the ranges defined by the specified value#. 551 /// Also remove the value# from value# list. 552 void removeValNo(VNInfo *ValNo); 553 554 /// getSize - Returns the sum of sizes of all the LiveRange's. 555 /// 556 unsigned getSize() const; 557 558 /// isSpillable - Can this interval be spilled? 559 bool isSpillable() const { 560 return weight != HUGE_VALF; 561 } 562 563 /// markNotSpillable - Mark interval as not spillable 564 void markNotSpillable() { 565 weight = HUGE_VALF; 566 } 567 568 /// ComputeJoinedWeight - Set the weight of a live interval after 569 /// Other has been merged into it. 570 void ComputeJoinedWeight(const LiveInterval &Other); 571 572 bool operator<(const LiveInterval& other) const { 573 const SlotIndex &thisIndex = beginIndex(); 574 const SlotIndex &otherIndex = other.beginIndex(); 575 return (thisIndex < otherIndex || 576 (thisIndex == otherIndex && reg < other.reg)); 577 } 578 579 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const; 580 void dump() const; 581 582 private: 583 584 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 585 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd); 586 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr); 587 588 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 589 590 }; 591 592 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) { 593 LI.print(OS); 594 return OS; 595 } 596} 597 598#endif 599