LiveInterval.h revision 2254227791ea267426b9ac674fc6d87decb65bc1
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/IntEqClasses.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 class VNInfo { 43 private: 44 enum { 45 HAS_PHI_KILL = 1, 46 REDEF_BY_EC = 1 << 1, 47 IS_PHI_DEF = 1 << 2, 48 IS_UNUSED = 1 << 3 49 }; 50 51 MachineInstr *copy; 52 unsigned char flags; 53 54 public: 55 typedef BumpPtrAllocator Allocator; 56 57 /// The ID number of this value. 58 unsigned id; 59 60 /// The index of the defining instruction (if isDefAccurate() returns true). 61 SlotIndex def; 62 63 /// VNInfo constructor. 64 VNInfo(unsigned i, SlotIndex d, MachineInstr *c) 65 : copy(c), flags(0), id(i), def(d) 66 { } 67 68 /// VNInfo construtor, copies values from orig, except for the value number. 69 VNInfo(unsigned i, const VNInfo &orig) 70 : copy(orig.copy), flags(orig.flags), id(i), def(orig.def) 71 { } 72 73 /// Copy from the parameter into this VNInfo. 74 void copyFrom(VNInfo &src) { 75 flags = src.flags; 76 copy = src.copy; 77 def = src.def; 78 } 79 80 /// Used for copying value number info. 81 unsigned getFlags() const { return flags; } 82 void setFlags(unsigned flags) { this->flags = flags; } 83 84 /// Merge flags from another VNInfo 85 void mergeFlags(const VNInfo *VNI) { 86 flags = (flags | VNI->flags) & ~IS_UNUSED; 87 } 88 89 /// For a register interval, if this VN was definied by a copy instr 90 /// getCopy() returns a pointer to it, otherwise returns 0. 91 /// For a stack interval the behaviour of this method is undefined. 92 MachineInstr* getCopy() const { return copy; } 93 /// For a register interval, set the copy member. 94 /// This method should not be called on stack intervals as it may lead to 95 /// undefined behavior. 96 void setCopy(MachineInstr *c) { copy = c; } 97 98 /// isDefByCopy - Return true when this value was defined by a copy-like 99 /// instruction as determined by MachineInstr::isCopyLike. 100 bool isDefByCopy() const { return copy != 0; } 101 102 /// Returns true if one or more kills are PHI nodes. 103 bool hasPHIKill() const { return flags & HAS_PHI_KILL; } 104 /// Set the PHI kill flag on this value. 105 void setHasPHIKill(bool hasKill) { 106 if (hasKill) 107 flags |= HAS_PHI_KILL; 108 else 109 flags &= ~HAS_PHI_KILL; 110 } 111 112 /// Returns true if this value is re-defined by an early clobber somewhere 113 /// during the live range. 114 bool hasRedefByEC() const { return flags & REDEF_BY_EC; } 115 /// Set the "redef by early clobber" flag on this value. 116 void setHasRedefByEC(bool hasRedef) { 117 if (hasRedef) 118 flags |= REDEF_BY_EC; 119 else 120 flags &= ~REDEF_BY_EC; 121 } 122 123 /// Returns true if this value is defined by a PHI instruction (or was, 124 /// PHI instrucions may have been eliminated). 125 bool isPHIDef() const { return flags & IS_PHI_DEF; } 126 /// Set the "phi def" flag on this value. 127 void setIsPHIDef(bool phiDef) { 128 if (phiDef) 129 flags |= IS_PHI_DEF; 130 else 131 flags &= ~IS_PHI_DEF; 132 } 133 134 /// Returns true if this value is unused. 135 bool isUnused() const { return flags & IS_UNUSED; } 136 /// Set the "is unused" flag on this value. 137 void setIsUnused(bool unused) { 138 if (unused) 139 flags |= IS_UNUSED; 140 else 141 flags &= ~IS_UNUSED; 142 } 143 }; 144 145 /// LiveRange structure - This represents a simple register range in the 146 /// program, with an inclusive start point and an exclusive end point. 147 /// These ranges are rendered as [start,end). 148 struct LiveRange { 149 SlotIndex start; // Start point of the interval (inclusive) 150 SlotIndex end; // End point of the interval (exclusive) 151 VNInfo *valno; // identifier for the value contained in this interval. 152 153 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V) 154 : start(S), end(E), valno(V) { 155 156 assert(S < E && "Cannot create empty or backwards range"); 157 } 158 159 /// contains - Return true if the index is covered by this range. 160 /// 161 bool contains(SlotIndex I) const { 162 return start <= I && I < end; 163 } 164 165 /// containsRange - Return true if the given range, [S, E), is covered by 166 /// this range. 167 bool containsRange(SlotIndex S, SlotIndex E) const { 168 assert((S < E) && "Backwards interval?"); 169 return (start <= S && S < end) && (start < E && E <= end); 170 } 171 172 bool operator<(const LiveRange &LR) const { 173 return start < LR.start || (start == LR.start && end < LR.end); 174 } 175 bool operator==(const LiveRange &LR) const { 176 return start == LR.start && end == LR.end; 177 } 178 179 void dump() const; 180 void print(raw_ostream &os) const; 181 182 private: 183 LiveRange(); // DO NOT IMPLEMENT 184 }; 185 186 template <> struct isPodLike<LiveRange> { static const bool value = true; }; 187 188 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR); 189 190 191 inline bool operator<(SlotIndex V, const LiveRange &LR) { 192 return V < LR.start; 193 } 194 195 inline bool operator<(const LiveRange &LR, SlotIndex V) { 196 return LR.start < V; 197 } 198 199 /// LiveInterval - This class represents some number of live ranges for a 200 /// register or value. This class also contains a bit of register allocator 201 /// state. 202 class LiveInterval { 203 public: 204 205 typedef SmallVector<LiveRange,4> Ranges; 206 typedef SmallVector<VNInfo*,4> VNInfoList; 207 208 const unsigned reg; // the register or stack slot of this interval. 209 float weight; // weight of this interval 210 Ranges ranges; // the ranges in which this register is live 211 VNInfoList valnos; // value#'s 212 213 struct InstrSlots { 214 enum { 215 LOAD = 0, 216 USE = 1, 217 DEF = 2, 218 STORE = 3, 219 NUM = 4 220 }; 221 222 }; 223 224 LiveInterval(unsigned Reg, float Weight) 225 : reg(Reg), weight(Weight) {} 226 227 typedef Ranges::iterator iterator; 228 iterator begin() { return ranges.begin(); } 229 iterator end() { return ranges.end(); } 230 231 typedef Ranges::const_iterator const_iterator; 232 const_iterator begin() const { return ranges.begin(); } 233 const_iterator end() const { return ranges.end(); } 234 235 typedef VNInfoList::iterator vni_iterator; 236 vni_iterator vni_begin() { return valnos.begin(); } 237 vni_iterator vni_end() { return valnos.end(); } 238 239 typedef VNInfoList::const_iterator const_vni_iterator; 240 const_vni_iterator vni_begin() const { return valnos.begin(); } 241 const_vni_iterator vni_end() const { return valnos.end(); } 242 243 /// advanceTo - Advance the specified iterator to point to the LiveRange 244 /// containing the specified position, or end() if the position is past the 245 /// end of the interval. If no LiveRange contains this position, but the 246 /// position is in a hole, this method returns an iterator pointing to the 247 /// LiveRange immediately after the hole. 248 iterator advanceTo(iterator I, SlotIndex Pos) { 249 assert(I != end()); 250 if (Pos >= endIndex()) 251 return end(); 252 while (I->end <= Pos) ++I; 253 return I; 254 } 255 256 /// find - Return an iterator pointing to the first range that ends after 257 /// Pos, or end(). This is the same as advanceTo(begin(), Pos), but faster 258 /// when searching large intervals. 259 /// 260 /// If Pos is contained in a LiveRange, that range is returned. 261 /// If Pos is in a hole, the following LiveRange is returned. 262 /// If Pos is beyond endIndex, end() is returned. 263 iterator find(SlotIndex Pos); 264 265 const_iterator find(SlotIndex Pos) const { 266 return const_cast<LiveInterval*>(this)->find(Pos); 267 } 268 269 void clear() { 270 valnos.clear(); 271 ranges.clear(); 272 } 273 274 bool hasAtLeastOneValue() const { return !valnos.empty(); } 275 276 bool containsOneValue() const { return valnos.size() == 1; } 277 278 unsigned getNumValNums() const { return (unsigned)valnos.size(); } 279 280 /// getValNumInfo - Returns pointer to the specified val#. 281 /// 282 inline VNInfo *getValNumInfo(unsigned ValNo) { 283 return valnos[ValNo]; 284 } 285 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 286 return valnos[ValNo]; 287 } 288 289 /// getNextValue - Create a new value number and return it. MIIdx specifies 290 /// the instruction that defines the value number. 291 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI, 292 VNInfo::Allocator &VNInfoAllocator) { 293 VNInfo *VNI = 294 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def, CopyMI); 295 valnos.push_back(VNI); 296 return VNI; 297 } 298 299 /// Create a copy of the given value. The new value will be identical except 300 /// for the Value number. 301 VNInfo *createValueCopy(const VNInfo *orig, 302 VNInfo::Allocator &VNInfoAllocator) { 303 VNInfo *VNI = 304 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig); 305 valnos.push_back(VNI); 306 return VNI; 307 } 308 309 /// RenumberValues - Renumber all values in order of appearance and remove 310 /// unused values. 311 /// Recalculate phi-kill flags in case any phi-def values were removed. 312 void RenumberValues(LiveIntervals &lis); 313 314 /// isOnlyLROfValNo - Return true if the specified live range is the only 315 /// one defined by the its val#. 316 bool isOnlyLROfValNo(const LiveRange *LR) { 317 for (const_iterator I = begin(), E = end(); I != E; ++I) { 318 const LiveRange *Tmp = I; 319 if (Tmp != LR && Tmp->valno == LR->valno) 320 return false; 321 } 322 return true; 323 } 324 325 /// MergeValueNumberInto - This method is called when two value nubmers 326 /// are found to be equivalent. This eliminates V1, replacing all 327 /// LiveRanges with the V1 value number with the V2 value number. This can 328 /// cause merging of V1/V2 values numbers and compaction of the value space. 329 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 330 331 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 332 /// in RHS into this live interval as the specified value number. 333 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 334 /// current interval, it will replace the value numbers of the overlaped 335 /// live ranges with the specified value number. 336 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 337 338 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 339 /// in RHS into this live interval as the specified value number. 340 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 341 /// current interval, but only if the overlapping LiveRanges have the 342 /// specified value number. 343 void MergeValueInAsValue(const LiveInterval &RHS, 344 const VNInfo *RHSValNo, VNInfo *LHSValNo); 345 346 /// Copy - Copy the specified live interval. This copies all the fields 347 /// except for the register of the interval. 348 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI, 349 VNInfo::Allocator &VNInfoAllocator); 350 351 bool empty() const { return ranges.empty(); } 352 353 /// beginIndex - Return the lowest numbered slot covered by interval. 354 SlotIndex beginIndex() const { 355 assert(!empty() && "Call to beginIndex() on empty interval."); 356 return ranges.front().start; 357 } 358 359 /// endNumber - return the maximum point of the interval of the whole, 360 /// exclusive. 361 SlotIndex endIndex() const { 362 assert(!empty() && "Call to endIndex() on empty interval."); 363 return ranges.back().end; 364 } 365 366 bool expiredAt(SlotIndex index) const { 367 return index >= endIndex(); 368 } 369 370 bool liveAt(SlotIndex index) const { 371 const_iterator r = find(index); 372 return r != end() && r->start <= index; 373 } 374 375 /// killedAt - Return true if a live range ends at index. Note that the kill 376 /// point is not contained in the half-open live range. It is usually the 377 /// getDefIndex() slot following its last use. 378 bool killedAt(SlotIndex index) const { 379 const_iterator r = find(index.getUseIndex()); 380 return r != end() && r->end == index; 381 } 382 383 /// killedInRange - Return true if the interval has kills in [Start,End). 384 /// Note that the kill point is considered the end of a live range, so it is 385 /// not contained in the live range. If a live range ends at End, it won't 386 /// be counted as a kill by this method. 387 bool killedInRange(SlotIndex Start, SlotIndex End) const; 388 389 /// getLiveRangeContaining - Return the live range that contains the 390 /// specified index, or null if there is none. 391 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const { 392 const_iterator I = FindLiveRangeContaining(Idx); 393 return I == end() ? 0 : &*I; 394 } 395 396 /// getLiveRangeContaining - Return the live range that contains the 397 /// specified index, or null if there is none. 398 LiveRange *getLiveRangeContaining(SlotIndex Idx) { 399 iterator I = FindLiveRangeContaining(Idx); 400 return I == end() ? 0 : &*I; 401 } 402 403 /// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL. 404 VNInfo *getVNInfoAt(SlotIndex Idx) const { 405 const_iterator I = FindLiveRangeContaining(Idx); 406 return I == end() ? 0 : I->valno; 407 } 408 409 /// FindLiveRangeContaining - Return an iterator to the live range that 410 /// contains the specified index, or end() if there is none. 411 iterator FindLiveRangeContaining(SlotIndex Idx) { 412 iterator I = find(Idx); 413 return I != end() && I->start <= Idx ? I : end(); 414 } 415 416 const_iterator FindLiveRangeContaining(SlotIndex Idx) const { 417 const_iterator I = find(Idx); 418 return I != end() && I->start <= Idx ? I : end(); 419 } 420 421 /// findDefinedVNInfo - Find the by the specified 422 /// index (register interval) or defined 423 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const; 424 425 426 /// overlaps - Return true if the intersection of the two live intervals is 427 /// not empty. 428 bool overlaps(const LiveInterval& other) const { 429 if (other.empty()) 430 return false; 431 return overlapsFrom(other, other.begin()); 432 } 433 434 /// overlaps - Return true if the live interval overlaps a range specified 435 /// by [Start, End). 436 bool overlaps(SlotIndex Start, SlotIndex End) const; 437 438 /// overlapsFrom - Return true if the intersection of the two live intervals 439 /// is not empty. The specified iterator is a hint that we can begin 440 /// scanning the Other interval starting at I. 441 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 442 443 /// addRange - Add the specified LiveRange to this interval, merging 444 /// intervals as appropriate. This returns an iterator to the inserted live 445 /// range (which may have grown since it was inserted. 446 void addRange(LiveRange LR) { 447 addRangeFrom(LR, ranges.begin()); 448 } 449 450 /// extendInBlock - If this interval is live before UseIdx in the basic 451 /// block that starts at StartIdx, extend it to be live at UseIdx and return 452 /// the value. If there is no live range before UseIdx, return NULL. 453 VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex UseIdx); 454 455 /// join - Join two live intervals (this, and other) together. This applies 456 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 457 /// the intervals are not joinable, this aborts. 458 void join(LiveInterval &Other, 459 const int *ValNoAssignments, 460 const int *RHSValNoAssignments, 461 SmallVector<VNInfo*, 16> &NewVNInfo, 462 MachineRegisterInfo *MRI); 463 464 /// isInOneLiveRange - Return true if the range specified is entirely in the 465 /// a single LiveRange of the live interval. 466 bool isInOneLiveRange(SlotIndex Start, SlotIndex End) const { 467 const_iterator r = find(Start); 468 return r != end() && r->containsRange(Start, End); 469 } 470 471 /// removeRange - Remove the specified range from this interval. Note that 472 /// the range must be a single LiveRange in its entirety. 473 void removeRange(SlotIndex Start, SlotIndex End, 474 bool RemoveDeadValNo = false); 475 476 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 477 removeRange(LR.start, LR.end, RemoveDeadValNo); 478 } 479 480 /// removeValNo - Remove all the ranges defined by the specified value#. 481 /// Also remove the value# from value# list. 482 void removeValNo(VNInfo *ValNo); 483 484 /// getSize - Returns the sum of sizes of all the LiveRange's. 485 /// 486 unsigned getSize() const; 487 488 /// Returns true if the live interval is zero length, i.e. no live ranges 489 /// span instructions. It doesn't pay to spill such an interval. 490 bool isZeroLength() const { 491 for (const_iterator i = begin(), e = end(); i != e; ++i) 492 if (i->end.getPrevIndex() > i->start) 493 return false; 494 return true; 495 } 496 497 /// isSpillable - Can this interval be spilled? 498 bool isSpillable() const { 499 return weight != HUGE_VALF; 500 } 501 502 /// markNotSpillable - Mark interval as not spillable 503 void markNotSpillable() { 504 weight = HUGE_VALF; 505 } 506 507 /// ComputeJoinedWeight - Set the weight of a live interval after 508 /// Other has been merged into it. 509 void ComputeJoinedWeight(const LiveInterval &Other); 510 511 bool operator<(const LiveInterval& other) const { 512 const SlotIndex &thisIndex = beginIndex(); 513 const SlotIndex &otherIndex = other.beginIndex(); 514 return (thisIndex < otherIndex || 515 (thisIndex == otherIndex && reg < other.reg)); 516 } 517 518 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const; 519 void dump() const; 520 521 private: 522 523 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 524 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd); 525 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr); 526 void markValNoForDeletion(VNInfo *V); 527 528 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 529 530 }; 531 532 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) { 533 LI.print(OS); 534 return OS; 535 } 536 537 /// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a 538 /// LiveInterval into equivalence clases of connected components. A 539 /// LiveInterval that has multiple connected components can be broken into 540 /// multiple LiveIntervals. 541 /// 542 /// Given a LiveInterval that may have multiple connected components, run: 543 /// 544 /// unsigned numComps = ConEQ.Classify(LI); 545 /// if (numComps > 1) { 546 /// // allocate numComps-1 new LiveIntervals into LIS[1..] 547 /// ConEQ.Distribute(LIS); 548 /// } 549 550 class ConnectedVNInfoEqClasses { 551 LiveIntervals &LIS; 552 IntEqClasses EqClass; 553 554 // Note that values a and b are connected. 555 void Connect(unsigned a, unsigned b); 556 557 unsigned Renumber(); 558 559 public: 560 explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : LIS(lis) {} 561 562 /// Classify - Classify the values in LI into connected components. 563 /// Return the number of connected components. 564 unsigned Classify(const LiveInterval *LI); 565 566 /// getEqClass - Classify creates equivalence classes numbered 0..N. Return 567 /// the equivalence class assigned the VNI. 568 unsigned getEqClass(const VNInfo *VNI) const { return EqClass[VNI->id]; } 569 570 /// Distribute - Distribute values in LIV[0] into a separate LiveInterval 571 /// for each connected component. LIV must have a LiveInterval for each 572 /// connected component. The LiveIntervals in Liv[1..] must be empty. 573 /// Instructions using LIV[0] are rewritten. 574 void Distribute(LiveInterval *LIV[], MachineRegisterInfo &MRI); 575 576 }; 577 578} 579#endif 580