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 31 namespace 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. VNInfo(unsigned i,SlotIndex d,MachineInstr * c)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. VNInfo(unsigned i,const VNInfo & orig)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. copyFrom(VNInfo & src)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. getFlags()81 unsigned getFlags() const { return flags; } setFlags(unsigned flags)82 void setFlags(unsigned flags) { this->flags = flags; } 83 84 /// Merge flags from another VNInfo mergeFlags(const VNInfo * VNI)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. getCopy()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. setCopy(MachineInstr * c)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. isDefByCopy()100 bool isDefByCopy() const { return copy != 0; } 101 102 /// Returns true if one or more kills are PHI nodes. hasPHIKill()103 bool hasPHIKill() const { return flags & HAS_PHI_KILL; } 104 /// Set the PHI kill flag on this value. setHasPHIKill(bool hasKill)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. hasRedefByEC()114 bool hasRedefByEC() const { return flags & REDEF_BY_EC; } 115 /// Set the "redef by early clobber" flag on this value. setHasRedefByEC(bool hasRedef)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). isPHIDef()125 bool isPHIDef() const { return flags & IS_PHI_DEF; } 126 /// Set the "phi def" flag on this value. setIsPHIDef(bool phiDef)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. isUnused()135 bool isUnused() const { return flags & IS_UNUSED; } 136 /// Set the "is unused" flag on this value. setIsUnused(bool unused)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 LiveRangeLiveRange153 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 /// containsLiveRange161 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. containsRangeLiveRange167 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 /// containsValue - Returns true if VNI belongs to this interval. 290 bool containsValue(const VNInfo *VNI) const { 291 return VNI && VNI->id < getNumValNums() && VNI == getValNumInfo(VNI->id); 292 } 293 294 /// getNextValue - Create a new value number and return it. MIIdx specifies 295 /// the instruction that defines the value number. 296 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI, 297 VNInfo::Allocator &VNInfoAllocator) { 298 VNInfo *VNI = 299 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def, CopyMI); 300 valnos.push_back(VNI); 301 return VNI; 302 } 303 304 /// Create a copy of the given value. The new value will be identical except 305 /// for the Value number. 306 VNInfo *createValueCopy(const VNInfo *orig, 307 VNInfo::Allocator &VNInfoAllocator) { 308 VNInfo *VNI = 309 new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig); 310 valnos.push_back(VNI); 311 return VNI; 312 } 313 314 /// RenumberValues - Renumber all values in order of appearance and remove 315 /// unused values. 316 /// Recalculate phi-kill flags in case any phi-def values were removed. 317 void RenumberValues(LiveIntervals &lis); 318 319 /// isOnlyLROfValNo - Return true if the specified live range is the only 320 /// one defined by the its val#. 321 bool isOnlyLROfValNo(const LiveRange *LR) { 322 for (const_iterator I = begin(), E = end(); I != E; ++I) { 323 const LiveRange *Tmp = I; 324 if (Tmp != LR && Tmp->valno == LR->valno) 325 return false; 326 } 327 return true; 328 } 329 330 /// MergeValueNumberInto - This method is called when two value nubmers 331 /// are found to be equivalent. This eliminates V1, replacing all 332 /// LiveRanges with the V1 value number with the V2 value number. This can 333 /// cause merging of V1/V2 values numbers and compaction of the value space. 334 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 335 336 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 337 /// in RHS into this live interval as the specified value number. 338 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 339 /// current interval, it will replace the value numbers of the overlaped 340 /// live ranges with the specified value number. 341 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 342 343 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 344 /// in RHS into this live interval as the specified value number. 345 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 346 /// current interval, but only if the overlapping LiveRanges have the 347 /// specified value number. 348 void MergeValueInAsValue(const LiveInterval &RHS, 349 const VNInfo *RHSValNo, VNInfo *LHSValNo); 350 351 /// Copy - Copy the specified live interval. This copies all the fields 352 /// except for the register of the interval. 353 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI, 354 VNInfo::Allocator &VNInfoAllocator); 355 356 bool empty() const { return ranges.empty(); } 357 358 /// beginIndex - Return the lowest numbered slot covered by interval. 359 SlotIndex beginIndex() const { 360 assert(!empty() && "Call to beginIndex() on empty interval."); 361 return ranges.front().start; 362 } 363 364 /// endNumber - return the maximum point of the interval of the whole, 365 /// exclusive. 366 SlotIndex endIndex() const { 367 assert(!empty() && "Call to endIndex() on empty interval."); 368 return ranges.back().end; 369 } 370 371 bool expiredAt(SlotIndex index) const { 372 return index >= endIndex(); 373 } 374 375 bool liveAt(SlotIndex index) const { 376 const_iterator r = find(index); 377 return r != end() && r->start <= index; 378 } 379 380 /// killedAt - Return true if a live range ends at index. Note that the kill 381 /// point is not contained in the half-open live range. It is usually the 382 /// getDefIndex() slot following its last use. 383 bool killedAt(SlotIndex index) const { 384 const_iterator r = find(index.getUseIndex()); 385 return r != end() && r->end == index; 386 } 387 388 /// killedInRange - Return true if the interval has kills in [Start,End). 389 /// Note that the kill point is considered the end of a live range, so it is 390 /// not contained in the live range. If a live range ends at End, it won't 391 /// be counted as a kill by this method. 392 bool killedInRange(SlotIndex Start, SlotIndex End) const; 393 394 /// getLiveRangeContaining - Return the live range that contains the 395 /// specified index, or null if there is none. 396 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const { 397 const_iterator I = FindLiveRangeContaining(Idx); 398 return I == end() ? 0 : &*I; 399 } 400 401 /// getLiveRangeContaining - Return the live range that contains the 402 /// specified index, or null if there is none. 403 LiveRange *getLiveRangeContaining(SlotIndex Idx) { 404 iterator I = FindLiveRangeContaining(Idx); 405 return I == end() ? 0 : &*I; 406 } 407 408 /// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL. 409 VNInfo *getVNInfoAt(SlotIndex Idx) const { 410 const_iterator I = FindLiveRangeContaining(Idx); 411 return I == end() ? 0 : I->valno; 412 } 413 414 /// FindLiveRangeContaining - Return an iterator to the live range that 415 /// contains the specified index, or end() if there is none. 416 iterator FindLiveRangeContaining(SlotIndex Idx) { 417 iterator I = find(Idx); 418 return I != end() && I->start <= Idx ? I : end(); 419 } 420 421 const_iterator FindLiveRangeContaining(SlotIndex Idx) const { 422 const_iterator I = find(Idx); 423 return I != end() && I->start <= Idx ? I : end(); 424 } 425 426 /// findDefinedVNInfo - Find the by the specified 427 /// index (register interval) or defined 428 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const; 429 430 431 /// overlaps - Return true if the intersection of the two live intervals is 432 /// not empty. 433 bool overlaps(const LiveInterval& other) const { 434 if (other.empty()) 435 return false; 436 return overlapsFrom(other, other.begin()); 437 } 438 439 /// overlaps - Return true if the live interval overlaps a range specified 440 /// by [Start, End). 441 bool overlaps(SlotIndex Start, SlotIndex End) const; 442 443 /// overlapsFrom - Return true if the intersection of the two live intervals 444 /// is not empty. The specified iterator is a hint that we can begin 445 /// scanning the Other interval starting at I. 446 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 447 448 /// addRange - Add the specified LiveRange to this interval, merging 449 /// intervals as appropriate. This returns an iterator to the inserted live 450 /// range (which may have grown since it was inserted. 451 void addRange(LiveRange LR) { 452 addRangeFrom(LR, ranges.begin()); 453 } 454 455 /// extendInBlock - If this interval is live before UseIdx in the basic 456 /// block that starts at StartIdx, extend it to be live at UseIdx and return 457 /// the value. If there is no live range before UseIdx, return NULL. 458 VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex UseIdx); 459 460 /// join - Join two live intervals (this, and other) together. This applies 461 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 462 /// the intervals are not joinable, this aborts. 463 void join(LiveInterval &Other, 464 const int *ValNoAssignments, 465 const int *RHSValNoAssignments, 466 SmallVector<VNInfo*, 16> &NewVNInfo, 467 MachineRegisterInfo *MRI); 468 469 /// isInOneLiveRange - Return true if the range specified is entirely in the 470 /// a single LiveRange of the live interval. 471 bool isInOneLiveRange(SlotIndex Start, SlotIndex End) const { 472 const_iterator r = find(Start); 473 return r != end() && r->containsRange(Start, End); 474 } 475 476 /// removeRange - Remove the specified range from this interval. Note that 477 /// the range must be a single LiveRange in its entirety. 478 void removeRange(SlotIndex Start, SlotIndex End, 479 bool RemoveDeadValNo = false); 480 481 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 482 removeRange(LR.start, LR.end, RemoveDeadValNo); 483 } 484 485 /// removeValNo - Remove all the ranges defined by the specified value#. 486 /// Also remove the value# from value# list. 487 void removeValNo(VNInfo *ValNo); 488 489 /// getSize - Returns the sum of sizes of all the LiveRange's. 490 /// 491 unsigned getSize() const; 492 493 /// Returns true if the live interval is zero length, i.e. no live ranges 494 /// span instructions. It doesn't pay to spill such an interval. 495 bool isZeroLength(SlotIndexes *Indexes) const { 496 for (const_iterator i = begin(), e = end(); i != e; ++i) 497 if (Indexes->getNextNonNullIndex(i->start).getBaseIndex() < 498 i->end.getBaseIndex()) 499 return false; 500 return true; 501 } 502 503 /// isSpillable - Can this interval be spilled? 504 bool isSpillable() const { 505 return weight != HUGE_VALF; 506 } 507 508 /// markNotSpillable - Mark interval as not spillable 509 void markNotSpillable() { 510 weight = HUGE_VALF; 511 } 512 513 /// ComputeJoinedWeight - Set the weight of a live interval after 514 /// Other has been merged into it. 515 void ComputeJoinedWeight(const LiveInterval &Other); 516 517 bool operator<(const LiveInterval& other) const { 518 const SlotIndex &thisIndex = beginIndex(); 519 const SlotIndex &otherIndex = other.beginIndex(); 520 return (thisIndex < otherIndex || 521 (thisIndex == otherIndex && reg < other.reg)); 522 } 523 524 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const; 525 void dump() const; 526 527 private: 528 529 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 530 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd); 531 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr); 532 void markValNoForDeletion(VNInfo *V); 533 534 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 535 536 }; 537 538 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) { 539 LI.print(OS); 540 return OS; 541 } 542 543 /// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a 544 /// LiveInterval into equivalence clases of connected components. A 545 /// LiveInterval that has multiple connected components can be broken into 546 /// multiple LiveIntervals. 547 /// 548 /// Given a LiveInterval that may have multiple connected components, run: 549 /// 550 /// unsigned numComps = ConEQ.Classify(LI); 551 /// if (numComps > 1) { 552 /// // allocate numComps-1 new LiveIntervals into LIS[1..] 553 /// ConEQ.Distribute(LIS); 554 /// } 555 556 class ConnectedVNInfoEqClasses { 557 LiveIntervals &LIS; 558 IntEqClasses EqClass; 559 560 // Note that values a and b are connected. 561 void Connect(unsigned a, unsigned b); 562 563 unsigned Renumber(); 564 565 public: 566 explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : LIS(lis) {} 567 568 /// Classify - Classify the values in LI into connected components. 569 /// Return the number of connected components. 570 unsigned Classify(const LiveInterval *LI); 571 572 /// getEqClass - Classify creates equivalence classes numbered 0..N. Return 573 /// the equivalence class assigned the VNI. 574 unsigned getEqClass(const VNInfo *VNI) const { return EqClass[VNI->id]; } 575 576 /// Distribute - Distribute values in LIV[0] into a separate LiveInterval 577 /// for each connected component. LIV must have a LiveInterval for each 578 /// connected component. The LiveIntervals in Liv[1..] must be empty. 579 /// Instructions using LIV[0] are rewritten. 580 void Distribute(LiveInterval *LIV[], MachineRegisterInfo &MRI); 581 582 }; 583 584 } 585 #endif 586