LiveInterval.h revision 5379f412bc6ac6171f3bd73930197bfce88c2faa
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 <iosfwd> 27#include <cassert> 28 29namespace llvm { 30 class MachineInstr; 31 class TargetRegisterInfo; 32 struct LiveInterval; 33 34 /// VNInfo - If the value number definition is undefined (e.g. phi 35 /// merge point), it contains ~0u,x. If the value number is not in use, it 36 /// contains ~1u,x to indicate that the value # is not used. 37 /// def - Instruction # of the definition. 38 /// - or reg # of the definition if it's a stack slot liveinterval. 39 /// copy - Copy iff val# is defined by a copy; zero otherwise. 40 /// hasPHIKill - One or more of the kills are PHI nodes. 41 /// redefByEC - Re-defined by early clobber somewhere during the live range. 42 /// kills - Instruction # of the kills. 43 struct VNInfo { 44 unsigned id; 45 unsigned def; 46 MachineInstr *copy; 47 bool hasPHIKill : 1; 48 bool redefByEC : 1; 49 SmallVector<unsigned, 4> kills; 50 VNInfo() 51 : id(~1U), def(~1U), copy(0), hasPHIKill(false), redefByEC(false) {} 52 VNInfo(unsigned i, unsigned d, MachineInstr *c) 53 : id(i), def(d), copy(c), hasPHIKill(false), redefByEC(false) {} 54 }; 55 56 /// LiveRange structure - This represents a simple register range in the 57 /// program, with an inclusive start point and an exclusive end point. 58 /// These ranges are rendered as [start,end). 59 struct LiveRange { 60 unsigned start; // Start point of the interval (inclusive) 61 unsigned end; // End point of the interval (exclusive) 62 VNInfo *valno; // identifier for the value contained in this interval. 63 64 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) { 65 assert(S < E && "Cannot create empty or backwards range"); 66 } 67 68 /// contains - Return true if the index is covered by this range. 69 /// 70 bool contains(unsigned I) const { 71 return start <= I && I < end; 72 } 73 74 bool operator<(const LiveRange &LR) const { 75 return start < LR.start || (start == LR.start && end < LR.end); 76 } 77 bool operator==(const LiveRange &LR) const { 78 return start == LR.start && end == LR.end; 79 } 80 81 void dump() const; 82 void print(std::ostream &os) const; 83 void print(std::ostream *os) const { if (os) print(*os); } 84 85 private: 86 LiveRange(); // DO NOT IMPLEMENT 87 }; 88 89 std::ostream& operator<<(std::ostream& os, const LiveRange &LR); 90 91 92 inline bool operator<(unsigned V, const LiveRange &LR) { 93 return V < LR.start; 94 } 95 96 inline bool operator<(const LiveRange &LR, unsigned V) { 97 return LR.start < V; 98 } 99 100 /// LiveInterval - This class represents some number of live ranges for a 101 /// register or value. This class also contains a bit of register allocator 102 /// state. 103 struct LiveInterval { 104 typedef SmallVector<LiveRange,4> Ranges; 105 typedef SmallVector<VNInfo*,4> VNInfoList; 106 107 unsigned reg; // the register or stack slot of this interval 108 // if the top bits is set, it represents a stack slot. 109 float weight; // weight of this interval 110 unsigned short preference; // preferred register for this interval 111 Ranges ranges; // the ranges in which this register is live 112 VNInfoList valnos; // value#'s 113 114 public: 115 LiveInterval(unsigned Reg, float Weight, bool IsSS = false) 116 : reg(Reg), weight(Weight), preference(0) { 117 if (IsSS) 118 reg = reg | (1U << (sizeof(unsigned)*8-1)); 119 } 120 121 typedef Ranges::iterator iterator; 122 iterator begin() { return ranges.begin(); } 123 iterator end() { return ranges.end(); } 124 125 typedef Ranges::const_iterator const_iterator; 126 const_iterator begin() const { return ranges.begin(); } 127 const_iterator end() const { return ranges.end(); } 128 129 typedef VNInfoList::iterator vni_iterator; 130 vni_iterator vni_begin() { return valnos.begin(); } 131 vni_iterator vni_end() { return valnos.end(); } 132 133 typedef VNInfoList::const_iterator const_vni_iterator; 134 const_vni_iterator vni_begin() const { return valnos.begin(); } 135 const_vni_iterator vni_end() const { return valnos.end(); } 136 137 /// advanceTo - Advance the specified iterator to point to the LiveRange 138 /// containing the specified position, or end() if the position is past the 139 /// end of the interval. If no LiveRange contains this position, but the 140 /// position is in a hole, this method returns an iterator pointing the the 141 /// LiveRange immediately after the hole. 142 iterator advanceTo(iterator I, unsigned Pos) { 143 if (Pos >= endNumber()) 144 return end(); 145 while (I->end <= Pos) ++I; 146 return I; 147 } 148 149 /// isStackSlot - Return true if this is a stack slot interval. 150 /// 151 bool isStackSlot() const { 152 return reg & (1U << (sizeof(unsigned)*8-1)); 153 } 154 155 /// getStackSlotIndex - Return stack slot index if this is a stack slot 156 /// interval. 157 int getStackSlotIndex() const { 158 assert(isStackSlot() && "Interval is not a stack slot interval!"); 159 return reg & ~(1U << (sizeof(unsigned)*8-1)); 160 } 161 162 bool hasAtLeastOneValue() const { return !valnos.empty(); } 163 164 bool containsOneValue() const { return valnos.size() == 1; } 165 166 unsigned getNumValNums() const { return (unsigned)valnos.size(); } 167 168 /// getValNumInfo - Returns pointer to the specified val#. 169 /// 170 inline VNInfo *getValNumInfo(unsigned ValNo) { 171 return valnos[ValNo]; 172 } 173 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 174 return valnos[ValNo]; 175 } 176 177 /// copyValNumInfo - Copy the value number info for one value number to 178 /// another. 179 void copyValNumInfo(VNInfo *DstValNo, const VNInfo *SrcValNo) { 180 DstValNo->def = SrcValNo->def; 181 DstValNo->copy = SrcValNo->copy; 182 DstValNo->hasPHIKill = SrcValNo->hasPHIKill; 183 DstValNo->redefByEC = SrcValNo->redefByEC; 184 DstValNo->kills = SrcValNo->kills; 185 } 186 187 /// getNextValue - Create a new value number and return it. MIIdx specifies 188 /// the instruction that defines the value number. 189 VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI, 190 BumpPtrAllocator &VNInfoAllocator) { 191#ifdef __GNUC__ 192 unsigned Alignment = (unsigned)__alignof__(VNInfo); 193#else 194 // FIXME: ugly. 195 unsigned Alignment = 8; 196#endif 197 VNInfo *VNI = 198 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo), 199 Alignment)); 200 new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, CopyMI); 201 valnos.push_back(VNI); 202 return VNI; 203 } 204 205 /// addKill - Add a kill instruction index to the specified value 206 /// number. 207 static void addKill(VNInfo *VNI, unsigned KillIdx) { 208 SmallVector<unsigned, 4> &kills = VNI->kills; 209 if (kills.empty()) { 210 kills.push_back(KillIdx); 211 } else { 212 SmallVector<unsigned, 4>::iterator 213 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 214 kills.insert(I, KillIdx); 215 } 216 } 217 218 /// addKills - Add a number of kills into the VNInfo kill vector. If this 219 /// interval is live at a kill point, then the kill is not added. 220 void addKills(VNInfo *VNI, const SmallVector<unsigned, 4> &kills) { 221 for (unsigned i = 0, e = static_cast<unsigned>(kills.size()); 222 i != e; ++i) { 223 unsigned KillIdx = kills[i]; 224 if (!liveBeforeAndAt(KillIdx)) { 225 SmallVector<unsigned, 4>::iterator 226 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), KillIdx); 227 VNI->kills.insert(I, KillIdx); 228 } 229 } 230 } 231 232 /// removeKill - Remove the specified kill from the list of kills of 233 /// the specified val#. 234 static bool removeKill(VNInfo *VNI, unsigned KillIdx) { 235 SmallVector<unsigned, 4> &kills = VNI->kills; 236 SmallVector<unsigned, 4>::iterator 237 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 238 if (I != kills.end() && *I == KillIdx) { 239 kills.erase(I); 240 return true; 241 } 242 return false; 243 } 244 245 /// removeKills - Remove all the kills in specified range 246 /// [Start, End] of the specified val#. 247 void removeKills(VNInfo *VNI, unsigned Start, unsigned End) { 248 SmallVector<unsigned, 4> &kills = VNI->kills; 249 SmallVector<unsigned, 4>::iterator 250 I = std::lower_bound(kills.begin(), kills.end(), Start); 251 SmallVector<unsigned, 4>::iterator 252 E = std::upper_bound(kills.begin(), kills.end(), End); 253 kills.erase(I, E); 254 } 255 256 /// isKill - Return true if the specified index is a kill of the 257 /// specified val#. 258 bool isKill(const VNInfo *VNI, unsigned KillIdx) const { 259 const SmallVector<unsigned, 4> &kills = VNI->kills; 260 SmallVector<unsigned, 4>::const_iterator 261 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 262 return I != kills.end() && *I == KillIdx; 263 } 264 265 /// MergeValueNumberInto - This method is called when two value nubmers 266 /// are found to be equivalent. This eliminates V1, replacing all 267 /// LiveRanges with the V1 value number with the V2 value number. This can 268 /// cause merging of V1/V2 values numbers and compaction of the value space. 269 void MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 270 271 /// MergeInClobberRanges - For any live ranges that are not defined in the 272 /// current interval, but are defined in the Clobbers interval, mark them 273 /// used with an unknown definition value. Caller must pass in reference to 274 /// VNInfoAllocator since it will create a new val#. 275 void MergeInClobberRanges(const LiveInterval &Clobbers, 276 BumpPtrAllocator &VNInfoAllocator); 277 278 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 279 /// in RHS into this live interval as the specified value number. 280 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 281 /// current interval, it will replace the value numbers of the overlaped 282 /// live ranges with the specified value number. 283 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 284 285 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 286 /// in RHS into this live interval as the specified value number. 287 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 288 /// current interval, but only if the overlapping LiveRanges have the 289 /// specified value number. 290 void MergeValueInAsValue(const LiveInterval &RHS, 291 const VNInfo *RHSValNo, VNInfo *LHSValNo); 292 293 /// Copy - Copy the specified live interval. This copies all the fields 294 /// except for the register of the interval. 295 void Copy(const LiveInterval &RHS, BumpPtrAllocator &VNInfoAllocator); 296 297 bool empty() const { return ranges.empty(); } 298 299 /// beginNumber - Return the lowest numbered slot covered by interval. 300 unsigned beginNumber() const { 301 if (empty()) 302 return 0; 303 return ranges.front().start; 304 } 305 306 /// endNumber - return the maximum point of the interval of the whole, 307 /// exclusive. 308 unsigned endNumber() const { 309 if (empty()) 310 return 0; 311 return ranges.back().end; 312 } 313 314 bool expiredAt(unsigned index) const { 315 return index >= endNumber(); 316 } 317 318 bool liveAt(unsigned index) const; 319 320 // liveBeforeAndAt - Check if the interval is live at the index and the 321 // index just before it. If index is liveAt, check if it starts a new live 322 // range.If it does, then check if the previous live range ends at index-1. 323 bool liveBeforeAndAt(unsigned index) const; 324 325 /// getLiveRangeContaining - Return the live range that contains the 326 /// specified index, or null if there is none. 327 const LiveRange *getLiveRangeContaining(unsigned Idx) const { 328 const_iterator I = FindLiveRangeContaining(Idx); 329 return I == end() ? 0 : &*I; 330 } 331 332 /// FindLiveRangeContaining - Return an iterator to the live range that 333 /// contains the specified index, or end() if there is none. 334 const_iterator FindLiveRangeContaining(unsigned Idx) const; 335 336 /// FindLiveRangeContaining - Return an iterator to the live range that 337 /// contains the specified index, or end() if there is none. 338 iterator FindLiveRangeContaining(unsigned Idx); 339 340 /// findDefinedVNInfo - Find the VNInfo that's defined at the specified 341 /// index (register interval) or defined by the specified register (stack 342 /// inteval). 343 VNInfo *findDefinedVNInfo(unsigned DefIdxOrReg) const; 344 345 /// overlaps - Return true if the intersection of the two live intervals is 346 /// not empty. 347 bool overlaps(const LiveInterval& other) const { 348 return overlapsFrom(other, other.begin()); 349 } 350 351 /// overlapsFrom - Return true if the intersection of the two live intervals 352 /// is not empty. The specified iterator is a hint that we can begin 353 /// scanning the Other interval starting at I. 354 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 355 356 /// addRange - Add the specified LiveRange to this interval, merging 357 /// intervals as appropriate. This returns an iterator to the inserted live 358 /// range (which may have grown since it was inserted. 359 void addRange(LiveRange LR) { 360 addRangeFrom(LR, ranges.begin()); 361 } 362 363 /// join - Join two live intervals (this, and other) together. This applies 364 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 365 /// the intervals are not joinable, this aborts. 366 void join(LiveInterval &Other, const int *ValNoAssignments, 367 const int *RHSValNoAssignments, 368 SmallVector<VNInfo*, 16> &NewVNInfo); 369 370 /// removeRange - Remove the specified range from this interval. Note that 371 /// the range must already be in this interval in its entirety. 372 void removeRange(unsigned Start, unsigned End, bool RemoveDeadValNo = false); 373 374 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 375 removeRange(LR.start, LR.end, RemoveDeadValNo); 376 } 377 378 /// removeValNo - Remove all the ranges defined by the specified value#. 379 /// Also remove the value# from value# list. 380 void removeValNo(VNInfo *ValNo); 381 382 /// getSize - Returns the sum of sizes of all the LiveRange's. 383 /// 384 unsigned getSize() const; 385 386 bool operator<(const LiveInterval& other) const { 387 return beginNumber() < other.beginNumber(); 388 } 389 390 void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const; 391 void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const { 392 if (OS) print(*OS, TRI); 393 } 394 void dump() const; 395 396 private: 397 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 398 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd); 399 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr); 400 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 401 }; 402 403 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) { 404 LI.print(OS); 405 return OS; 406 } 407} 408 409#endif 410