LiveInterval.h revision 15a571436da812c7cecbc3f3423ead2edff50358
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 72 /// The ID number of this value. 73 unsigned id; 74 75 /// The index of the defining instruction (if isDefAccurate() returns true). 76 SlotIndex def; 77 78 /// VNInfo constructor. 79 /// d is presumed to point to the actual defining instr. If it doesn't 80 /// setIsDefAccurate(false) should be called after construction. 81 VNInfo(unsigned i, SlotIndex d, MachineInstr *c) 82 : flags(IS_DEF_ACCURATE), id(i), def(d) { cr.copy = c; } 83 84 /// VNInfo construtor, copies values from orig, except for the value number. 85 VNInfo(unsigned i, const VNInfo &orig) 86 : flags(orig.flags), cr(orig.cr), id(i), def(orig.def) 87 { } 88 89 /// Copy from the parameter into this VNInfo. 90 void copyFrom(VNInfo &src) { 91 flags = src.flags; 92 cr = src.cr; 93 def = src.def; 94 } 95 96 /// Used for copying value number info. 97 unsigned getFlags() const { return flags; } 98 void setFlags(unsigned flags) { this->flags = flags; } 99 100 /// For a register interval, if this VN was definied by a copy instr 101 /// getCopy() returns a pointer to it, otherwise returns 0. 102 /// For a stack interval the behaviour of this method is undefined. 103 MachineInstr* getCopy() const { return cr.copy; } 104 /// For a register interval, set the copy member. 105 /// This method should not be called on stack intervals as it may lead to 106 /// undefined behavior. 107 void setCopy(MachineInstr *c) { cr.copy = c; } 108 109 /// For a stack interval, returns the reg which this stack interval was 110 /// defined from. 111 /// For a register interval the behaviour of this method is undefined. 112 unsigned getReg() const { return cr.reg; } 113 /// For a stack interval, set the defining register. 114 /// This method should not be called on register intervals as it may lead 115 /// to undefined behaviour. 116 void setReg(unsigned reg) { cr.reg = reg; } 117 118 /// Returns true if one or more kills are PHI nodes. 119 bool hasPHIKill() const { return flags & HAS_PHI_KILL; } 120 /// Set the PHI kill flag on this value. 121 void setHasPHIKill(bool hasKill) { 122 if (hasKill) 123 flags |= HAS_PHI_KILL; 124 else 125 flags &= ~HAS_PHI_KILL; 126 } 127 128 /// Returns true if this value is re-defined by an early clobber somewhere 129 /// during the live range. 130 bool hasRedefByEC() const { return flags & REDEF_BY_EC; } 131 /// Set the "redef by early clobber" flag on this value. 132 void setHasRedefByEC(bool hasRedef) { 133 if (hasRedef) 134 flags |= REDEF_BY_EC; 135 else 136 flags &= ~REDEF_BY_EC; 137 } 138 139 /// Returns true if this value is defined by a PHI instruction (or was, 140 /// PHI instrucions may have been eliminated). 141 bool isPHIDef() const { return flags & IS_PHI_DEF; } 142 /// Set the "phi def" flag on this value. 143 void setIsPHIDef(bool phiDef) { 144 if (phiDef) 145 flags |= IS_PHI_DEF; 146 else 147 flags &= ~IS_PHI_DEF; 148 } 149 150 /// Returns true if this value is unused. 151 bool isUnused() const { return flags & IS_UNUSED; } 152 /// Set the "is unused" flag on this value. 153 void setIsUnused(bool unused) { 154 if (unused) 155 flags |= IS_UNUSED; 156 else 157 flags &= ~IS_UNUSED; 158 } 159 160 /// Returns true if the def is accurate. 161 bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; } 162 /// Set the "is def accurate" flag on this value. 163 void setIsDefAccurate(bool defAccurate) { 164 if (defAccurate) 165 flags |= IS_DEF_ACCURATE; 166 else 167 flags &= ~IS_DEF_ACCURATE; 168 } 169 }; 170 171 /// LiveRange structure - This represents a simple register range in the 172 /// program, with an inclusive start point and an exclusive end point. 173 /// These ranges are rendered as [start,end). 174 struct LiveRange { 175 SlotIndex start; // Start point of the interval (inclusive) 176 SlotIndex end; // End point of the interval (exclusive) 177 VNInfo *valno; // identifier for the value contained in this interval. 178 179 LiveRange(SlotIndex S, SlotIndex E, VNInfo *V) 180 : start(S), end(E), valno(V) { 181 182 assert(S < E && "Cannot create empty or backwards range"); 183 } 184 185 /// contains - Return true if the index is covered by this range. 186 /// 187 bool contains(SlotIndex I) const { 188 return start <= I && I < end; 189 } 190 191 /// containsRange - Return true if the given range, [S, E), is covered by 192 /// this range. 193 bool containsRange(SlotIndex S, SlotIndex E) const { 194 assert((S < E) && "Backwards interval?"); 195 return (start <= S && S < end) && (start < E && E <= end); 196 } 197 198 bool operator<(const LiveRange &LR) const { 199 return start < LR.start || (start == LR.start && end < LR.end); 200 } 201 bool operator==(const LiveRange &LR) const { 202 return start == LR.start && end == LR.end; 203 } 204 205 void dump() const; 206 void print(raw_ostream &os) const; 207 208 private: 209 LiveRange(); // DO NOT IMPLEMENT 210 }; 211 212 template <> struct isPodLike<LiveRange> { static const bool value = true; }; 213 214 raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR); 215 216 217 inline bool operator<(SlotIndex V, const LiveRange &LR) { 218 return V < LR.start; 219 } 220 221 inline bool operator<(const LiveRange &LR, SlotIndex V) { 222 return LR.start < V; 223 } 224 225 /// LiveInterval - This class represents some number of live ranges for a 226 /// register or value. This class also contains a bit of register allocator 227 /// state. 228 class LiveInterval { 229 public: 230 231 typedef SmallVector<LiveRange,4> Ranges; 232 typedef SmallVector<VNInfo*,4> VNInfoList; 233 234 unsigned reg; // the register or stack slot of this interval 235 // if the top bits is set, it represents a stack slot. 236 float weight; // weight of this interval 237 Ranges ranges; // the ranges in which this register is live 238 VNInfoList valnos; // value#'s 239 240 struct InstrSlots { 241 enum { 242 LOAD = 0, 243 USE = 1, 244 DEF = 2, 245 STORE = 3, 246 NUM = 4 247 }; 248 249 }; 250 251 LiveInterval(unsigned Reg, float Weight, bool IsSS = false) 252 : reg(Reg), weight(Weight) { 253 if (IsSS) 254 reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1)); 255 } 256 257 typedef Ranges::iterator iterator; 258 iterator begin() { return ranges.begin(); } 259 iterator end() { return ranges.end(); } 260 261 typedef Ranges::const_iterator const_iterator; 262 const_iterator begin() const { return ranges.begin(); } 263 const_iterator end() const { return ranges.end(); } 264 265 typedef VNInfoList::iterator vni_iterator; 266 vni_iterator vni_begin() { return valnos.begin(); } 267 vni_iterator vni_end() { return valnos.end(); } 268 269 typedef VNInfoList::const_iterator const_vni_iterator; 270 const_vni_iterator vni_begin() const { return valnos.begin(); } 271 const_vni_iterator vni_end() const { return valnos.end(); } 272 273 /// advanceTo - Advance the specified iterator to point to the LiveRange 274 /// containing the specified position, or end() if the position is past the 275 /// end of the interval. If no LiveRange contains this position, but the 276 /// position is in a hole, this method returns an iterator pointing to the 277 /// LiveRange immediately after the hole. 278 iterator advanceTo(iterator I, SlotIndex Pos) { 279 if (Pos >= endIndex()) 280 return end(); 281 while (I->end <= Pos) ++I; 282 return I; 283 } 284 285 void clear() { 286 valnos.clear(); 287 ranges.clear(); 288 } 289 290 /// isStackSlot - Return true if this is a stack slot interval. 291 /// 292 bool isStackSlot() const { 293 return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1)); 294 } 295 296 /// getStackSlotIndex - Return stack slot index if this is a stack slot 297 /// interval. 298 int getStackSlotIndex() const { 299 assert(isStackSlot() && "Interval is not a stack slot interval!"); 300 return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1)); 301 } 302 303 bool hasAtLeastOneValue() const { return !valnos.empty(); } 304 305 bool containsOneValue() const { return valnos.size() == 1; } 306 307 unsigned getNumValNums() const { return (unsigned)valnos.size(); } 308 309 /// getValNumInfo - Returns pointer to the specified val#. 310 /// 311 inline VNInfo *getValNumInfo(unsigned ValNo) { 312 return valnos[ValNo]; 313 } 314 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 315 return valnos[ValNo]; 316 } 317 318 /// getNextValue - Create a new value number and return it. MIIdx specifies 319 /// the instruction that defines the value number. 320 VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI, 321 bool isDefAccurate, VNInfo::Allocator &VNInfoAllocator) { 322 VNInfo *VNI = VNInfoAllocator.Allocate(); 323 new (VNI) VNInfo((unsigned)valnos.size(), def, CopyMI); 324 VNI->setIsDefAccurate(isDefAccurate); 325 valnos.push_back(VNI); 326 return VNI; 327 } 328 329 /// Create a copy of the given value. The new value will be identical except 330 /// for the Value number. 331 VNInfo *createValueCopy(const VNInfo *orig, 332 VNInfo::Allocator &VNInfoAllocator) { 333 VNInfo *VNI = VNInfoAllocator.Allocate(); 334 new (VNI) VNInfo((unsigned)valnos.size(), *orig); 335 valnos.push_back(VNI); 336 return VNI; 337 } 338 339 /// isOnlyLROfValNo - Return true if the specified live range is the only 340 /// one defined by the its val#. 341 bool isOnlyLROfValNo(const LiveRange *LR) { 342 for (const_iterator I = begin(), E = end(); I != E; ++I) { 343 const LiveRange *Tmp = I; 344 if (Tmp != LR && Tmp->valno == LR->valno) 345 return false; 346 } 347 return true; 348 } 349 350 /// MergeValueNumberInto - This method is called when two value nubmers 351 /// are found to be equivalent. This eliminates V1, replacing all 352 /// LiveRanges with the V1 value number with the V2 value number. This can 353 /// cause merging of V1/V2 values numbers and compaction of the value space. 354 VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 355 356 /// MergeInClobberRanges - For any live ranges that are not defined in the 357 /// current interval, but are defined in the Clobbers interval, mark them 358 /// used with an unknown definition value. Caller must pass in reference to 359 /// VNInfoAllocator since it will create a new val#. 360 void MergeInClobberRanges(LiveIntervals &li_, 361 const LiveInterval &Clobbers, 362 VNInfo::Allocator &VNInfoAllocator); 363 364 /// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a 365 /// single LiveRange only. 366 void MergeInClobberRange(LiveIntervals &li_, 367 SlotIndex Start, 368 SlotIndex End, 369 VNInfo::Allocator &VNInfoAllocator); 370 371 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 372 /// in RHS into this live interval as the specified value number. 373 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 374 /// current interval, it will replace the value numbers of the overlaped 375 /// live ranges with the specified value number. 376 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 377 378 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 379 /// in RHS into this live interval as the specified value number. 380 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 381 /// current interval, but only if the overlapping LiveRanges have the 382 /// specified value number. 383 void MergeValueInAsValue(const LiveInterval &RHS, 384 const VNInfo *RHSValNo, VNInfo *LHSValNo); 385 386 /// Copy - Copy the specified live interval. This copies all the fields 387 /// except for the register of the interval. 388 void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI, 389 VNInfo::Allocator &VNInfoAllocator); 390 391 bool empty() const { return ranges.empty(); } 392 393 /// beginIndex - Return the lowest numbered slot covered by interval. 394 SlotIndex beginIndex() const { 395 assert(!empty() && "Call to beginIndex() on empty interval."); 396 return ranges.front().start; 397 } 398 399 /// endNumber - return the maximum point of the interval of the whole, 400 /// exclusive. 401 SlotIndex endIndex() const { 402 assert(!empty() && "Call to endIndex() on empty interval."); 403 return ranges.back().end; 404 } 405 406 bool expiredAt(SlotIndex index) const { 407 return index >= endIndex(); 408 } 409 410 bool liveAt(SlotIndex index) const; 411 412 // liveBeforeAndAt - Check if the interval is live at the index and the 413 // index just before it. If index is liveAt, check if it starts a new live 414 // range.If it does, then check if the previous live range ends at index-1. 415 bool liveBeforeAndAt(SlotIndex index) const; 416 417 /// killedAt - Return true if a live range ends at index. Note that the kill 418 /// point is not contained in the half-open live range. It is usually the 419 /// getDefIndex() slot following its last use. 420 bool killedAt(SlotIndex index) const; 421 422 /// killedInRange - Return true if the interval has kills in [Start,End). 423 /// Note that the kill point is considered the end of a live range, so it is 424 /// not contained in the live range. If a live range ends at End, it won't 425 /// be counted as a kill by this method. 426 bool killedInRange(SlotIndex Start, SlotIndex End) const; 427 428 /// getLiveRangeContaining - Return the live range that contains the 429 /// specified index, or null if there is none. 430 const LiveRange *getLiveRangeContaining(SlotIndex Idx) const { 431 const_iterator I = FindLiveRangeContaining(Idx); 432 return I == end() ? 0 : &*I; 433 } 434 435 /// getLiveRangeContaining - Return the live range that contains the 436 /// specified index, or null if there is none. 437 LiveRange *getLiveRangeContaining(SlotIndex Idx) { 438 iterator I = FindLiveRangeContaining(Idx); 439 return I == end() ? 0 : &*I; 440 } 441 442 /// FindLiveRangeContaining - Return an iterator to the live range that 443 /// contains the specified index, or end() if there is none. 444 const_iterator FindLiveRangeContaining(SlotIndex Idx) const; 445 446 /// FindLiveRangeContaining - Return an iterator to the live range that 447 /// contains the specified index, or end() if there is none. 448 iterator FindLiveRangeContaining(SlotIndex Idx); 449 450 /// findDefinedVNInfo - Find the by the specified 451 /// index (register interval) or defined 452 VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const; 453 454 /// findDefinedVNInfo - Find the VNInfo that's defined by the specified 455 /// register (stack inteval only). 456 VNInfo *findDefinedVNInfoForStackInt(unsigned Reg) const; 457 458 459 /// overlaps - Return true if the intersection of the two live intervals is 460 /// not empty. 461 bool overlaps(const LiveInterval& other) const { 462 return overlapsFrom(other, other.begin()); 463 } 464 465 /// overlaps - Return true if the live interval overlaps a range specified 466 /// by [Start, End). 467 bool overlaps(SlotIndex Start, SlotIndex End) const; 468 469 /// overlapsFrom - Return true if the intersection of the two live intervals 470 /// is not empty. The specified iterator is a hint that we can begin 471 /// scanning the Other interval starting at I. 472 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 473 474 /// addRange - Add the specified LiveRange to this interval, merging 475 /// intervals as appropriate. This returns an iterator to the inserted live 476 /// range (which may have grown since it was inserted. 477 void addRange(LiveRange LR) { 478 addRangeFrom(LR, ranges.begin()); 479 } 480 481 /// join - Join two live intervals (this, and other) together. This applies 482 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 483 /// the intervals are not joinable, this aborts. 484 void join(LiveInterval &Other, 485 const int *ValNoAssignments, 486 const int *RHSValNoAssignments, 487 SmallVector<VNInfo*, 16> &NewVNInfo, 488 MachineRegisterInfo *MRI); 489 490 /// isInOneLiveRange - Return true if the range specified is entirely in the 491 /// a single LiveRange of the live interval. 492 bool isInOneLiveRange(SlotIndex Start, SlotIndex End); 493 494 /// removeRange - Remove the specified range from this interval. Note that 495 /// the range must be a single LiveRange in its entirety. 496 void removeRange(SlotIndex Start, SlotIndex End, 497 bool RemoveDeadValNo = false); 498 499 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 500 removeRange(LR.start, LR.end, RemoveDeadValNo); 501 } 502 503 /// removeValNo - Remove all the ranges defined by the specified value#. 504 /// Also remove the value# from value# list. 505 void removeValNo(VNInfo *ValNo); 506 507 /// getSize - Returns the sum of sizes of all the LiveRange's. 508 /// 509 unsigned getSize() const; 510 511 /// isSpillable - Can this interval be spilled? 512 bool isSpillable() const { 513 return weight != HUGE_VALF; 514 } 515 516 /// markNotSpillable - Mark interval as not spillable 517 void markNotSpillable() { 518 weight = HUGE_VALF; 519 } 520 521 /// ComputeJoinedWeight - Set the weight of a live interval after 522 /// Other has been merged into it. 523 void ComputeJoinedWeight(const LiveInterval &Other); 524 525 bool operator<(const LiveInterval& other) const { 526 const SlotIndex &thisIndex = beginIndex(); 527 const SlotIndex &otherIndex = other.beginIndex(); 528 return (thisIndex < otherIndex || 529 (thisIndex == otherIndex && reg < other.reg)); 530 } 531 532 void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const; 533 void dump() const; 534 535 private: 536 537 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 538 void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd); 539 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr); 540 541 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 542 543 }; 544 545 inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) { 546 LI.print(OS); 547 return OS; 548 } 549} 550 551#endif 552