LiveInterval.h revision 34cd4a484e532cc463fd5a4bf59b88d13c5467c1
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/Streams.h" 27#include <iosfwd> 28#include <vector> 29#include <cassert> 30 31namespace llvm { 32 class MachineInstr; 33 class TargetRegisterInfo; 34 struct LiveInterval; 35 36 /// VNInfo - If the value number definition is undefined (e.g. phi 37 /// merge point), it contains ~0u,x. If the value number is not in use, it 38 /// contains ~1u,x to indicate that the value # is not used. 39 /// def - Instruction # of the definition. 40 /// copy - Copy iff val# is defined by a copy; zero otherwise. 41 /// hasPHIKill - One or more of the kills are PHI nodes. 42 /// kills - Instruction # of the kills. 43 struct VNInfo { 44 unsigned id; 45 unsigned def; 46 MachineInstr *copy; 47 bool hasPHIKill; 48 SmallVector<unsigned, 4> kills; 49 VNInfo() : id(~1U), def(~1U), copy(0), hasPHIKill(false) {} 50 VNInfo(unsigned i, unsigned d, MachineInstr *c) 51 : id(i), def(d), copy(c), hasPHIKill(false) {} 52 }; 53 54 /// LiveRange structure - This represents a simple register range in the 55 /// program, with an inclusive start point and an exclusive end point. 56 /// These ranges are rendered as [start,end). 57 struct LiveRange { 58 unsigned start; // Start point of the interval (inclusive) 59 unsigned end; // End point of the interval (exclusive) 60 VNInfo *valno; // identifier for the value contained in this interval. 61 62 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) { 63 assert(S < E && "Cannot create empty or backwards range"); 64 } 65 66 /// contains - Return true if the index is covered by this range. 67 /// 68 bool contains(unsigned I) const { 69 return start <= I && I < end; 70 } 71 72 bool operator<(const LiveRange &LR) const { 73 return start < LR.start || (start == LR.start && end < LR.end); 74 } 75 bool operator==(const LiveRange &LR) const { 76 return start == LR.start && end == LR.end; 77 } 78 79 void dump() const; 80 void print(std::ostream &os) const; 81 void print(std::ostream *os) const { if (os) print(*os); } 82 83 private: 84 LiveRange(); // DO NOT IMPLEMENT 85 }; 86 87 std::ostream& operator<<(std::ostream& os, const LiveRange &LR); 88 89 90 inline bool operator<(unsigned V, const LiveRange &LR) { 91 return V < LR.start; 92 } 93 94 inline bool operator<(const LiveRange &LR, unsigned V) { 95 return LR.start < V; 96 } 97 98 /// LiveInterval - This class represents some number of live ranges for a 99 /// register or value. This class also contains a bit of register allocator 100 /// state. 101 struct LiveInterval { 102 typedef SmallVector<LiveRange,4> Ranges; 103 typedef SmallVector<VNInfo*,4> VNInfoList; 104 105 unsigned reg; // the register of this interval 106 unsigned preference; // preferred register to allocate for this interval 107 float weight; // weight of this interval 108 Ranges ranges; // the ranges in which this register is live 109 VNInfoList valnos; // value#'s 110 111 public: 112 LiveInterval(unsigned Reg, float Weight) 113 : reg(Reg), preference(0), weight(Weight) { 114 } 115 116 typedef Ranges::iterator iterator; 117 iterator begin() { return ranges.begin(); } 118 iterator end() { return ranges.end(); } 119 120 typedef Ranges::const_iterator const_iterator; 121 const_iterator begin() const { return ranges.begin(); } 122 const_iterator end() const { return ranges.end(); } 123 124 typedef VNInfoList::iterator vni_iterator; 125 vni_iterator vni_begin() { return valnos.begin(); } 126 vni_iterator vni_end() { return valnos.end(); } 127 128 typedef VNInfoList::const_iterator const_vni_iterator; 129 const_vni_iterator vni_begin() const { return valnos.begin(); } 130 const_vni_iterator vni_end() const { return valnos.end(); } 131 132 /// advanceTo - Advance the specified iterator to point to the LiveRange 133 /// containing the specified position, or end() if the position is past the 134 /// end of the interval. If no LiveRange contains this position, but the 135 /// position is in a hole, this method returns an iterator pointing the the 136 /// LiveRange immediately after the hole. 137 iterator advanceTo(iterator I, unsigned Pos) { 138 if (Pos >= endNumber()) 139 return end(); 140 while (I->end <= Pos) ++I; 141 return I; 142 } 143 144 bool containsOneValue() const { return valnos.size() == 1; } 145 146 unsigned getNumValNums() const { return (unsigned)valnos.size(); } 147 148 /// getValNumInfo - Returns pointer to the specified val#. 149 /// 150 inline VNInfo *getValNumInfo(unsigned ValNo) { 151 return valnos[ValNo]; 152 } 153 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 154 return valnos[ValNo]; 155 } 156 157 /// copyValNumInfo - Copy the value number info for one value number to 158 /// another. 159 void copyValNumInfo(VNInfo *DstValNo, const VNInfo *SrcValNo) { 160 DstValNo->def = SrcValNo->def; 161 DstValNo->copy = SrcValNo->copy; 162 DstValNo->hasPHIKill = SrcValNo->hasPHIKill; 163 DstValNo->kills = SrcValNo->kills; 164 } 165 166 /// getNextValue - Create a new value number and return it. MIIdx specifies 167 /// the instruction that defines the value number. 168 VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI, 169 BumpPtrAllocator &VNInfoAllocator) { 170#ifdef __GNUC__ 171 unsigned Alignment = (unsigned)__alignof__(VNInfo); 172#else 173 // FIXME: ugly. 174 unsigned Alignment = 8; 175#endif 176 VNInfo *VNI = 177 static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo), 178 Alignment)); 179 new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, CopyMI); 180 valnos.push_back(VNI); 181 return VNI; 182 } 183 184 /// addKillForValNum - Add a kill instruction index to the specified value 185 /// number. 186 static void addKill(VNInfo *VNI, unsigned KillIdx) { 187 SmallVector<unsigned, 4> &kills = VNI->kills; 188 if (kills.empty()) { 189 kills.push_back(KillIdx); 190 } else { 191 SmallVector<unsigned, 4>::iterator 192 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 193 kills.insert(I, KillIdx); 194 } 195 } 196 197 /// addKills - Add a number of kills into the VNInfo kill vector. If this 198 /// interval is live at a kill point, then the kill is not added. 199 void addKills(VNInfo *VNI, const SmallVector<unsigned, 4> &kills) { 200 for (unsigned i = 0, e = static_cast<unsigned>(kills.size()); 201 i != e; ++i) { 202 unsigned KillIdx = kills[i]; 203 if (!liveBeforeAndAt(KillIdx)) { 204 SmallVector<unsigned, 4>::iterator 205 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), KillIdx); 206 VNI->kills.insert(I, KillIdx); 207 } 208 } 209 } 210 211 /// removeKill - Remove the specified kill from the list of kills of 212 /// the specified val#. 213 static bool removeKill(VNInfo *VNI, unsigned KillIdx) { 214 SmallVector<unsigned, 4> &kills = VNI->kills; 215 SmallVector<unsigned, 4>::iterator 216 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 217 if (I != kills.end() && *I == KillIdx) { 218 kills.erase(I); 219 return true; 220 } 221 return false; 222 } 223 224 /// removeKills - Remove all the kills in specified range 225 /// [Start, End] of the specified val#. 226 void removeKills(VNInfo *VNI, unsigned Start, unsigned End) { 227 SmallVector<unsigned, 4> &kills = VNI->kills; 228 SmallVector<unsigned, 4>::iterator 229 I = std::lower_bound(kills.begin(), kills.end(), Start); 230 SmallVector<unsigned, 4>::iterator 231 E = std::upper_bound(kills.begin(), kills.end(), End); 232 kills.erase(I, E); 233 } 234 235 /// isKill - Return true if the specified index is a kill of the 236 /// specified val#. 237 bool isKill(const VNInfo *VNI, unsigned KillIdx) const { 238 const SmallVector<unsigned, 4> &kills = VNI->kills; 239 SmallVector<unsigned, 4>::const_iterator 240 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 241 return I != kills.end() && *I == KillIdx; 242 } 243 244 /// MergeValueNumberInto - This method is called when two value nubmers 245 /// are found to be equivalent. This eliminates V1, replacing all 246 /// LiveRanges with the V1 value number with the V2 value number. This can 247 /// cause merging of V1/V2 values numbers and compaction of the value space. 248 void MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 249 250 /// MergeInClobberRanges - For any live ranges that are not defined in the 251 /// current interval, but are defined in the Clobbers interval, mark them 252 /// used with an unknown definition value. Caller must pass in reference to 253 /// VNInfoAllocator since it will create a new val#. 254 void MergeInClobberRanges(const LiveInterval &Clobbers, 255 BumpPtrAllocator &VNInfoAllocator); 256 257 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 258 /// in RHS into this live interval as the specified value number. 259 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 260 /// current interval, it will replace the value numbers of the overlaped 261 /// live ranges with the specified value number. 262 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 263 264 /// MergeValueInAsValue - Merge all of the live ranges of a specific val# 265 /// in RHS into this live interval as the specified value number. 266 /// The LiveRanges in RHS are allowed to overlap with LiveRanges in the 267 /// current interval, but only if the overlapping LiveRanges have the 268 /// specified value number. 269 void MergeValueInAsValue(const LiveInterval &RHS, 270 const VNInfo *RHSValNo, VNInfo *LHSValNo); 271 272 /// Copy - Copy the specified live interval. This copies all the fields 273 /// except for the register of the interval. 274 void Copy(const LiveInterval &RHS, BumpPtrAllocator &VNInfoAllocator); 275 276 bool empty() const { return ranges.empty(); } 277 278 /// beginNumber - Return the lowest numbered slot covered by interval. 279 unsigned beginNumber() const { 280 if (empty()) 281 return 0; 282 return ranges.front().start; 283 } 284 285 /// endNumber - return the maximum point of the interval of the whole, 286 /// exclusive. 287 unsigned endNumber() const { 288 if (empty()) 289 return 0; 290 return ranges.back().end; 291 } 292 293 bool expiredAt(unsigned index) const { 294 return index >= endNumber(); 295 } 296 297 bool liveAt(unsigned index) const; 298 299 // liveBeforeAndAt - Check if the interval is live at the index and the 300 // index just before it. If index is liveAt, check if it starts a new live 301 // range.If it does, then check if the previous live range ends at index-1. 302 bool liveBeforeAndAt(unsigned index) const; 303 304 /// getLiveRangeContaining - Return the live range that contains the 305 /// specified index, or null if there is none. 306 const LiveRange *getLiveRangeContaining(unsigned Idx) const { 307 const_iterator I = FindLiveRangeContaining(Idx); 308 return I == end() ? 0 : &*I; 309 } 310 311 /// FindLiveRangeContaining - Return an iterator to the live range that 312 /// contains the specified index, or end() if there is none. 313 const_iterator FindLiveRangeContaining(unsigned Idx) const; 314 315 /// FindLiveRangeContaining - Return an iterator to the live range that 316 /// contains the specified index, or end() if there is none. 317 iterator FindLiveRangeContaining(unsigned Idx); 318 319 /// overlaps - Return true if the intersection of the two live intervals is 320 /// not empty. 321 bool overlaps(const LiveInterval& other) const { 322 return overlapsFrom(other, other.begin()); 323 } 324 325 /// overlapsFrom - Return true if the intersection of the two live intervals 326 /// is not empty. The specified iterator is a hint that we can begin 327 /// scanning the Other interval starting at I. 328 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 329 330 /// addRange - Add the specified LiveRange to this interval, merging 331 /// intervals as appropriate. This returns an iterator to the inserted live 332 /// range (which may have grown since it was inserted. 333 void addRange(LiveRange LR) { 334 addRangeFrom(LR, ranges.begin()); 335 } 336 337 /// join - Join two live intervals (this, and other) together. This applies 338 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 339 /// the intervals are not joinable, this aborts. 340 void join(LiveInterval &Other, const int *ValNoAssignments, 341 const int *RHSValNoAssignments, 342 SmallVector<VNInfo*, 16> &NewVNInfo); 343 344 /// removeRange - Remove the specified range from this interval. Note that 345 /// the range must already be in this interval in its entirety. 346 void removeRange(unsigned Start, unsigned End, bool RemoveDeadValNo = false); 347 348 void removeRange(LiveRange LR, bool RemoveDeadValNo = false) { 349 removeRange(LR.start, LR.end, RemoveDeadValNo); 350 } 351 352 /// removeValNo - Remove all the ranges defined by the specified value#. 353 /// Also remove the value# from value# list. 354 void removeValNo(VNInfo *ValNo); 355 356 /// getSize - Returns the sum of sizes of all the LiveRange's. 357 /// 358 unsigned getSize() const; 359 360 bool operator<(const LiveInterval& other) const { 361 return beginNumber() < other.beginNumber(); 362 } 363 364 void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const; 365 void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const { 366 if (OS) print(*OS, TRI); 367 } 368 void dump() const; 369 370 private: 371 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 372 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd); 373 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr); 374 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 375 }; 376 377 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) { 378 LI.print(OS); 379 return OS; 380 } 381} 382 383#endif 384