LiveInterval.h revision 549f27d3070195d6647b796841a5291b4549e8e0
1//===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source 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/Streams.h" 26#include <iosfwd> 27#include <vector> 28#include <cassert> 29 30namespace llvm { 31 class MachineInstr; 32 class MRegisterInfo; 33 34 /// LiveRange structure - This represents a simple register range in the 35 /// program, with an inclusive start point and an exclusive end point. 36 /// These ranges are rendered as [start,end). 37 struct LiveRange { 38 unsigned start; // Start point of the interval (inclusive) 39 unsigned end; // End point of the interval (exclusive) 40 unsigned ValId; // identifier for the value contained in this interval. 41 42 LiveRange(unsigned S, unsigned E, unsigned V) : start(S), end(E), ValId(V) { 43 assert(S < E && "Cannot create empty or backwards range"); 44 } 45 46 /// contains - Return true if the index is covered by this range. 47 /// 48 bool contains(unsigned I) const { 49 return start <= I && I < end; 50 } 51 52 bool operator<(const LiveRange &LR) const { 53 return start < LR.start || (start == LR.start && end < LR.end); 54 } 55 bool operator==(const LiveRange &LR) const { 56 return start == LR.start && end == LR.end; 57 } 58 59 void dump() const; 60 void print(std::ostream &os) const; 61 void print(std::ostream *os) const { if (os) print(*os); } 62 63 private: 64 LiveRange(); // DO NOT IMPLEMENT 65 }; 66 67 std::ostream& operator<<(std::ostream& os, const LiveRange &LR); 68 69 70 inline bool operator<(unsigned V, const LiveRange &LR) { 71 return V < LR.start; 72 } 73 74 inline bool operator<(const LiveRange &LR, unsigned V) { 75 return LR.start < V; 76 } 77 78 /// LiveInterval - This class represents some number of live ranges for a 79 /// register or value. This class also contains a bit of register allocator 80 /// state. 81 struct LiveInterval { 82 typedef SmallVector<LiveRange,4> Ranges; 83 unsigned reg; // the register of this interval 84 unsigned preference; // preferred register to allocate for this interval 85 float weight; // weight of this interval 86 Ranges ranges; // the ranges in which this register is live 87 88 /// ValueNumberInfo - If the value number definition is undefined (e.g. phi 89 /// merge point), it contains ~0u,x. If the value number is not in use, it 90 /// contains ~1u,x to indicate that the value # is not used. 91 struct VNInfo { 92 unsigned def; // instruction # of the definition 93 unsigned reg; // src reg: non-zero iff val# is defined by a copy 94 SmallVector<unsigned, 4> kills; // instruction #s of the kills 95 VNInfo() : def(~1U), reg(0) {}; 96 VNInfo(unsigned d, unsigned r) : def(d), reg(r) {}; 97 }; 98 private: 99 SmallVector<VNInfo, 4> ValueNumberInfo; 100 public: 101 102 LiveInterval(unsigned Reg, float Weight) 103 : reg(Reg), preference(0), weight(Weight) { 104 } 105 106 typedef Ranges::iterator iterator; 107 iterator begin() { return ranges.begin(); } 108 iterator end() { return ranges.end(); } 109 110 typedef Ranges::const_iterator const_iterator; 111 const_iterator begin() const { return ranges.begin(); } 112 const_iterator end() const { return ranges.end(); } 113 114 115 /// advanceTo - Advance the specified iterator to point to the LiveRange 116 /// containing the specified position, or end() if the position is past the 117 /// end of the interval. If no LiveRange contains this position, but the 118 /// position is in a hole, this method returns an iterator pointing the the 119 /// LiveRange immediately after the hole. 120 iterator advanceTo(iterator I, unsigned Pos) { 121 if (Pos >= endNumber()) 122 return end(); 123 while (I->end <= Pos) ++I; 124 return I; 125 } 126 127 void swap(LiveInterval& other) { 128 std::swap(reg, other.reg); 129 std::swap(weight, other.weight); 130 std::swap(ranges, other.ranges); 131 std::swap(ValueNumberInfo, other.ValueNumberInfo); 132 } 133 134 bool containsOneValue() const { return ValueNumberInfo.size() == 1; } 135 136 unsigned getNumValNums() const { return ValueNumberInfo.size(); } 137 138 /// getNextValue - Create a new value number and return it. MIIdx specifies 139 /// the instruction that defines the value number. 140 unsigned getNextValue(unsigned MIIdx, unsigned SrcReg) { 141 ValueNumberInfo.push_back(VNInfo(MIIdx, SrcReg)); 142 return ValueNumberInfo.size()-1; 143 } 144 145 /// getDefForValNum - Return the machine instruction index that defines the 146 /// specified value number. 147 unsigned getDefForValNum(unsigned ValNo) const { 148 assert(ValNo < ValueNumberInfo.size()); 149 return ValueNumberInfo[ValNo].def; 150 } 151 152 /// getSrcRegForValNum - If the machine instruction that defines the 153 /// specified value number is a copy, returns the source register. Otherwise, 154 /// returns zero. 155 unsigned getSrcRegForValNum(unsigned ValNo) const { 156 assert(ValNo < ValueNumberInfo.size()); 157 return ValueNumberInfo[ValNo].reg; 158 } 159 160 /// setDefForValNum - Set the machine instruction index that defines the 161 /// specified value number. 162 void setDefForValNum(unsigned ValNo, unsigned NewDef) { 163 assert(ValNo < ValueNumberInfo.size()); 164 ValueNumberInfo[ValNo].def = NewDef; 165 } 166 167 /// setSrcRegForValNum - Set the source register of the specified value 168 /// number. 169 void setSrcRegForValNum(unsigned ValNo, unsigned NewReg) { 170 assert(ValNo < ValueNumberInfo.size()); 171 ValueNumberInfo[ValNo].reg = NewReg; 172 } 173 174 /// getKillsForValNum - Return the kill instruction indexes of the specified 175 /// value number. 176 const SmallVector<unsigned, 4> &getKillsForValNum(unsigned ValNo) const { 177 assert(ValNo < ValueNumberInfo.size()); 178 return ValueNumberInfo[ValNo].kills; 179 } 180 181 /// addKillForValNum - Add a kill instruction index to the specified value 182 /// number. 183 void addKillForValNum(unsigned ValNo, unsigned KillIdx) { 184 assert(ValNo < ValueNumberInfo.size()); 185 SmallVector<unsigned, 4> &kills = ValueNumberInfo[ValNo].kills; 186 if (kills.empty()) { 187 kills.push_back(KillIdx); 188 } else { 189 SmallVector<unsigned, 4>::iterator 190 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 191 kills.insert(I, KillIdx); 192 } 193 } 194 195 /// addKills - Add a number of kills into the VNInfo kill vector. If this 196 /// interval is live at a kill point, then the kill is not added. 197 void addKills(VNInfo &VNI, const SmallVector<unsigned, 4> &kills) { 198 for (unsigned i = 0, e = kills.size(); i != e; ++i) { 199 unsigned KillIdx = kills[i]; 200 if (!liveAt(KillIdx)) { 201 SmallVector<unsigned, 4>::iterator 202 I = std::lower_bound(VNI.kills.begin(), VNI.kills.end(), KillIdx); 203 VNI.kills.insert(I, KillIdx); 204 } 205 } 206 } 207 208 /// addKillsForValNum - Add a number of kills into the kills vector of 209 /// the specified value number. 210 void addKillsForValNum(unsigned ValNo, 211 const SmallVector<unsigned, 4> &kills) { 212 addKills(ValueNumberInfo[ValNo], kills); 213 } 214 215 /// isKillForValNum - Returns true if KillIdx is a kill of the specified 216 /// val#. 217 bool isKillForValNum(unsigned ValNo, unsigned KillIdx) const { 218 assert(ValNo < ValueNumberInfo.size()); 219 const SmallVector<unsigned, 4> &kills = ValueNumberInfo[ValNo].kills; 220 SmallVector<unsigned, 4>::const_iterator 221 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 222 if (I == kills.end()) 223 return false; 224 return *I == KillIdx; 225 } 226 227 /// removeKill - Remove the specified kill from the list of kills of 228 /// the specified val#. 229 static bool removeKill(VNInfo &VNI, unsigned KillIdx) { 230 SmallVector<unsigned, 4> &kills = VNI.kills; 231 SmallVector<unsigned, 4>::iterator 232 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 233 if (I != kills.end() && *I == KillIdx) { 234 kills.erase(I); 235 return true; 236 } 237 return false; 238 } 239 240 /// removeKillForValNum - Remove the specified kill from the list of kills 241 /// of the specified val#. 242 bool removeKillForValNum(unsigned ValNo, unsigned KillIdx) { 243 assert(ValNo < ValueNumberInfo.size()); 244 return removeKill(ValueNumberInfo[ValNo], KillIdx); 245 } 246 247 /// removeKillForValNum - Remove all the kills in specified range 248 /// [Start, End] of the specified val#. 249 void removeKillForValNum(unsigned ValNo, unsigned Start, unsigned End) { 250 assert(ValNo < ValueNumberInfo.size()); 251 SmallVector<unsigned, 4> &kills = ValueNumberInfo[ValNo].kills; 252 SmallVector<unsigned, 4>::iterator 253 I = std::lower_bound(kills.begin(), kills.end(), Start); 254 SmallVector<unsigned, 4>::iterator 255 E = std::upper_bound(kills.begin(), kills.end(), End); 256 kills.erase(I, E); 257 } 258 259 /// replaceKill - Replace a kill index of the specified value# with a new 260 /// kill. Returns true if OldKill was indeed a kill point. 261 static bool replaceKill(VNInfo &VNI, unsigned OldKill, unsigned NewKill) { 262 SmallVector<unsigned, 4> &kills = VNI.kills; 263 SmallVector<unsigned, 4>::iterator 264 I = std::lower_bound(kills.begin(), kills.end(), OldKill); 265 if (I != kills.end() && *I == OldKill) { 266 *I = NewKill; 267 return true; 268 } 269 return false; 270 } 271 272 /// replaceKillForValNum - Replace a kill index of the specified value# with 273 /// a new kill. Returns true if OldKill was indeed a kill point. 274 bool replaceKillForValNum(unsigned ValNo, unsigned OldKill, 275 unsigned NewKill) { 276 assert(ValNo < ValueNumberInfo.size()); 277 return replaceKill(ValueNumberInfo[ValNo], OldKill, NewKill); 278 } 279 280 /// getValNumInfo - Returns a copy of the specified val#. 281 /// 282 VNInfo getValNumInfo(unsigned ValNo) const { 283 assert(ValNo < ValueNumberInfo.size()); 284 return ValueNumberInfo[ValNo]; 285 } 286 287 /// setValNumInfo - Change the value number info for the specified 288 /// value number. 289 void setValNumInfo(unsigned ValNo, const VNInfo &I) { 290 ValueNumberInfo[ValNo] = I; 291 } 292 293 /// copyValNumInfo - Copy the value number info for one value number to 294 /// another. 295 void copyValNumInfo(unsigned DstValNo, unsigned SrcValNo) { 296 ValueNumberInfo[DstValNo] = ValueNumberInfo[SrcValNo]; 297 } 298 void copyValNumInfo(unsigned DstValNo, const LiveInterval &SrcLI, 299 unsigned SrcValNo) { 300 ValueNumberInfo[DstValNo] = SrcLI.ValueNumberInfo[SrcValNo]; 301 } 302 303 /// MergeValueNumberInto - This method is called when two value nubmers 304 /// are found to be equivalent. This eliminates V1, replacing all 305 /// LiveRanges with the V1 value number with the V2 value number. This can 306 /// cause merging of V1/V2 values numbers and compaction of the value space. 307 void MergeValueNumberInto(unsigned V1, unsigned V2); 308 309 /// MergeInClobberRanges - For any live ranges that are not defined in the 310 /// current interval, but are defined in the Clobbers interval, mark them 311 /// used with an unknown definition value. 312 void MergeInClobberRanges(const LiveInterval &Clobbers); 313 314 315 /// MergeRangesInAsValue - Merge all of the intervals in RHS into this live 316 /// interval as the specified value number. The LiveRanges in RHS are 317 /// allowed to overlap with LiveRanges in the current interval, but only if 318 /// the overlapping LiveRanges have the specified value number. 319 void MergeRangesInAsValue(const LiveInterval &RHS, unsigned LHSValNo); 320 321 bool empty() const { return ranges.empty(); } 322 323 /// beginNumber - Return the lowest numbered slot covered by interval. 324 unsigned beginNumber() const { 325 assert(!empty() && "empty interval for register"); 326 return ranges.front().start; 327 } 328 329 /// endNumber - return the maximum point of the interval of the whole, 330 /// exclusive. 331 unsigned endNumber() const { 332 assert(!empty() && "empty interval for register"); 333 return ranges.back().end; 334 } 335 336 bool expiredAt(unsigned index) const { 337 return index >= endNumber(); 338 } 339 340 bool liveAt(unsigned index) const; 341 342 /// getLiveRangeContaining - Return the live range that contains the 343 /// specified index, or null if there is none. 344 const LiveRange *getLiveRangeContaining(unsigned Idx) const { 345 const_iterator I = FindLiveRangeContaining(Idx); 346 return I == end() ? 0 : &*I; 347 } 348 349 /// FindLiveRangeContaining - Return an iterator to the live range that 350 /// contains the specified index, or end() if there is none. 351 const_iterator FindLiveRangeContaining(unsigned Idx) const; 352 353 /// FindLiveRangeContaining - Return an iterator to the live range that 354 /// contains the specified index, or end() if there is none. 355 iterator FindLiveRangeContaining(unsigned Idx); 356 357 /// getOverlapingRanges - Given another live interval which is defined as a 358 /// copy from this one, return a list of all of the live ranges where the 359 /// two overlap and have different value numbers. 360 void getOverlapingRanges(const LiveInterval &Other, unsigned CopyIdx, 361 std::vector<LiveRange*> &Ranges); 362 363 /// overlaps - Return true if the intersection of the two live intervals is 364 /// not empty. 365 bool overlaps(const LiveInterval& other) const { 366 return overlapsFrom(other, other.begin()); 367 } 368 369 /// overlapsFrom - Return true if the intersection of the two live intervals 370 /// is not empty. The specified iterator is a hint that we can begin 371 /// scanning the Other interval starting at I. 372 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 373 374 /// addRange - Add the specified LiveRange to this interval, merging 375 /// intervals as appropriate. This returns an iterator to the inserted live 376 /// range (which may have grown since it was inserted. 377 void addRange(LiveRange LR) { 378 addRangeFrom(LR, ranges.begin()); 379 } 380 381 /// join - Join two live intervals (this, and other) together. This applies 382 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 383 /// the intervals are not joinable, this aborts. 384 void join(LiveInterval &Other, int *ValNoAssignments, 385 int *RHSValNoAssignments, 386 SmallVector<VNInfo,16> &NewValueNumberInfo); 387 388 /// removeRange - Remove the specified range from this interval. Note that 389 /// the range must already be in this interval in its entirety. 390 void removeRange(unsigned Start, unsigned End); 391 392 void removeRange(LiveRange LR) { 393 removeRange(LR.start, LR.end); 394 } 395 396 /// getSize - Returns the sum of sizes of all the LiveRange's. 397 /// 398 unsigned getSize() const; 399 400 bool operator<(const LiveInterval& other) const { 401 return beginNumber() < other.beginNumber(); 402 } 403 404 void print(std::ostream &OS, const MRegisterInfo *MRI = 0) const; 405 void print(std::ostream *OS, const MRegisterInfo *MRI = 0) const { 406 if (OS) print(*OS, MRI); 407 } 408 void dump() const; 409 410 private: 411 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 412 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd); 413 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr); 414 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 415 }; 416 417 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) { 418 LI.print(OS); 419 return OS; 420 } 421} 422 423#endif 424