LiveInterval.h revision f3bb2e65d12857f83b273f4ecab013680310bbbc
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/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 MRegisterInfo; 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 /// reg - Source reg iff val# is defined by a copy; zero otherwise. 41 /// kills - Instruction # of the kills. If a kill is an odd #, it means 42 /// the kill is a phi join point. 43 struct VNInfo { 44 unsigned id; 45 unsigned def; 46 unsigned reg; 47 SmallVector<unsigned, 4> kills; 48 VNInfo() : id(~1U), def(~1U), reg(0) {} 49 VNInfo(unsigned i, unsigned d, unsigned r) 50 : id(i), def(d), reg(r) {} 51 }; 52 53 /// LiveRange structure - This represents a simple register range in the 54 /// program, with an inclusive start point and an exclusive end point. 55 /// These ranges are rendered as [start,end). 56 struct LiveRange { 57 unsigned start; // Start point of the interval (inclusive) 58 unsigned end; // End point of the interval (exclusive) 59 VNInfo *valno; // identifier for the value contained in this interval. 60 61 LiveRange(unsigned S, unsigned E, VNInfo *V) : start(S), end(E), valno(V) { 62 assert(S < E && "Cannot create empty or backwards range"); 63 } 64 65 /// contains - Return true if the index is covered by this range. 66 /// 67 bool contains(unsigned I) const { 68 return start <= I && I < end; 69 } 70 71 bool operator<(const LiveRange &LR) const { 72 return start < LR.start || (start == LR.start && end < LR.end); 73 } 74 bool operator==(const LiveRange &LR) const { 75 return start == LR.start && end == LR.end; 76 } 77 78 void dump() const; 79 void print(std::ostream &os) const; 80 void print(std::ostream *os) const { if (os) print(*os); } 81 82 private: 83 LiveRange(); // DO NOT IMPLEMENT 84 }; 85 86 std::ostream& operator<<(std::ostream& os, const LiveRange &LR); 87 88 89 inline bool operator<(unsigned V, const LiveRange &LR) { 90 return V < LR.start; 91 } 92 93 inline bool operator<(const LiveRange &LR, unsigned V) { 94 return LR.start < V; 95 } 96 97 /// LiveInterval - This class represents some number of live ranges for a 98 /// register or value. This class also contains a bit of register allocator 99 /// state. 100 struct LiveInterval { 101 typedef SmallVector<LiveRange,4> Ranges; 102 typedef SmallVector<VNInfo*,4> VNInfoList; 103 104 unsigned reg; // the register of this interval 105 unsigned preference; // preferred register to allocate for this interval 106 float weight; // weight of this interval 107 Ranges ranges; // the ranges in which this register is live 108 VNInfoList valnos; // value#'s 109 110 public: 111 LiveInterval(unsigned Reg, float Weight) 112 : reg(Reg), preference(0), weight(Weight) { 113 } 114 115 typedef Ranges::iterator iterator; 116 iterator begin() { return ranges.begin(); } 117 iterator end() { return ranges.end(); } 118 119 typedef Ranges::const_iterator const_iterator; 120 const_iterator begin() const { return ranges.begin(); } 121 const_iterator end() const { return ranges.end(); } 122 123 typedef VNInfoList::iterator vni_iterator; 124 vni_iterator vni_begin() { return valnos.begin(); } 125 vni_iterator vni_end() { return valnos.end(); } 126 127 typedef VNInfoList::const_iterator const_vni_iterator; 128 const_vni_iterator vni_begin() const { return valnos.begin(); } 129 const_vni_iterator vni_end() const { return valnos.end(); } 130 131 /// advanceTo - Advance the specified iterator to point to the LiveRange 132 /// containing the specified position, or end() if the position is past the 133 /// end of the interval. If no LiveRange contains this position, but the 134 /// position is in a hole, this method returns an iterator pointing the the 135 /// LiveRange immediately after the hole. 136 iterator advanceTo(iterator I, unsigned Pos) { 137 if (Pos >= endNumber()) 138 return end(); 139 while (I->end <= Pos) ++I; 140 return I; 141 } 142 143 bool containsOneValue() const { return valnos.size() == 1; } 144 145 unsigned getNumValNums() const { return valnos.size(); } 146 147 /// getValNumInfo - Returns pointer to the specified val#. 148 /// 149 inline VNInfo *getValNumInfo(unsigned ValNo) { 150 return valnos[ValNo]; 151 } 152 inline const VNInfo *getValNumInfo(unsigned ValNo) const { 153 return valnos[ValNo]; 154 } 155 156 /// copyValNumInfo - Copy the value number info for one value number to 157 /// another. 158 void copyValNumInfo(VNInfo *DstValNo, VNInfo *SrcValNo) { 159 DstValNo->def = SrcValNo->def; 160 DstValNo->reg = SrcValNo->reg; 161 DstValNo->kills = SrcValNo->kills; 162 } 163 164 /// getNextValue - Create a new value number and return it. MIIdx specifies 165 /// the instruction that defines the value number. 166 VNInfo *getNextValue(unsigned MIIdx, unsigned SrcReg) { 167#ifdef __GNUC__ 168 unsigned Alignment = __alignof__(VNInfo); 169#else 170 // FIXME: ugly. 171 unsigned Alignment = 8; 172#endif 173 VNInfo *VNI= static_cast<VNInfo*>(VNInfoAllocator.Allocate(sizeof(VNInfo), 174 Alignment)); 175 new (VNI) VNInfo(valnos.size(), MIIdx, SrcReg); 176 valnos.push_back(VNI); 177 return VNI; 178 } 179 180 /// addKillForValNum - Add a kill instruction index to the specified value 181 /// number. 182 static void addKill(VNInfo *VNI, unsigned KillIdx) { 183 SmallVector<unsigned, 4> &kills = VNI->kills; 184 if (kills.empty()) { 185 kills.push_back(KillIdx); 186 } else { 187 SmallVector<unsigned, 4>::iterator 188 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 189 kills.insert(I, KillIdx); 190 } 191 } 192 193 /// addKills - Add a number of kills into the VNInfo kill vector. If this 194 /// interval is live at a kill point, then the kill is not added. 195 void addKills(VNInfo *VNI, const SmallVector<unsigned, 4> &kills) { 196 for (unsigned i = 0, e = kills.size(); i != e; ++i) { 197 unsigned KillIdx = kills[i]; 198 if (!liveAt(KillIdx)) { 199 SmallVector<unsigned, 4>::iterator 200 I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), KillIdx); 201 VNI->kills.insert(I, KillIdx); 202 } 203 } 204 } 205 206 /// removeKill - Remove the specified kill from the list of kills of 207 /// the specified val#. 208 static bool removeKill(VNInfo *VNI, unsigned KillIdx) { 209 SmallVector<unsigned, 4> &kills = VNI->kills; 210 SmallVector<unsigned, 4>::iterator 211 I = std::lower_bound(kills.begin(), kills.end(), KillIdx); 212 if (I != kills.end() && *I == KillIdx) { 213 kills.erase(I); 214 return true; 215 } 216 return false; 217 } 218 219 /// removeKills - Remove all the kills in specified range 220 /// [Start, End] of the specified val#. 221 void removeKills(VNInfo *VNI, unsigned Start, unsigned End) { 222 SmallVector<unsigned, 4> &kills = VNI->kills; 223 SmallVector<unsigned, 4>::iterator 224 I = std::lower_bound(kills.begin(), kills.end(), Start); 225 SmallVector<unsigned, 4>::iterator 226 E = std::upper_bound(kills.begin(), kills.end(), End); 227 kills.erase(I, E); 228 } 229 230 /// MergeValueNumberInto - This method is called when two value nubmers 231 /// are found to be equivalent. This eliminates V1, replacing all 232 /// LiveRanges with the V1 value number with the V2 value number. This can 233 /// cause merging of V1/V2 values numbers and compaction of the value space. 234 void MergeValueNumberInto(VNInfo *V1, VNInfo *V2); 235 236 /// MergeInClobberRanges - For any live ranges that are not defined in the 237 /// current interval, but are defined in the Clobbers interval, mark them 238 /// used with an unknown definition value. Caller must pass in reference to 239 /// VNInfoAllocator since it will create a new val#. 240 void MergeInClobberRanges(const LiveInterval &Clobbers, 241 BumpPtrAllocator &VNInfoAllocator); 242 243 /// MergeRangesInAsValue - Merge all of the intervals in RHS into this live 244 /// interval as the specified value number. The LiveRanges in RHS are 245 /// allowed to overlap with LiveRanges in the current interval, but only if 246 /// the overlapping LiveRanges have the specified value number. 247 void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo); 248 249 bool empty() const { return ranges.empty(); } 250 251 /// beginNumber - Return the lowest numbered slot covered by interval. 252 unsigned beginNumber() const { 253 assert(!empty() && "empty interval for register"); 254 return ranges.front().start; 255 } 256 257 /// endNumber - return the maximum point of the interval of the whole, 258 /// exclusive. 259 unsigned endNumber() const { 260 assert(!empty() && "empty interval for register"); 261 return ranges.back().end; 262 } 263 264 bool expiredAt(unsigned index) const { 265 return index >= endNumber(); 266 } 267 268 bool liveAt(unsigned index) const; 269 270 /// getLiveRangeContaining - Return the live range that contains the 271 /// specified index, or null if there is none. 272 const LiveRange *getLiveRangeContaining(unsigned Idx) const { 273 const_iterator I = FindLiveRangeContaining(Idx); 274 return I == end() ? 0 : &*I; 275 } 276 277 /// FindLiveRangeContaining - Return an iterator to the live range that 278 /// contains the specified index, or end() if there is none. 279 const_iterator FindLiveRangeContaining(unsigned Idx) const; 280 281 /// FindLiveRangeContaining - Return an iterator to the live range that 282 /// contains the specified index, or end() if there is none. 283 iterator FindLiveRangeContaining(unsigned Idx); 284 285 /// getOverlapingRanges - Given another live interval which is defined as a 286 /// copy from this one, return a list of all of the live ranges where the 287 /// two overlap and have different value numbers. 288 void getOverlapingRanges(const LiveInterval &Other, unsigned CopyIdx, 289 std::vector<LiveRange*> &Ranges); 290 291 /// overlaps - Return true if the intersection of the two live intervals is 292 /// not empty. 293 bool overlaps(const LiveInterval& other) const { 294 return overlapsFrom(other, other.begin()); 295 } 296 297 /// overlapsFrom - Return true if the intersection of the two live intervals 298 /// is not empty. The specified iterator is a hint that we can begin 299 /// scanning the Other interval starting at I. 300 bool overlapsFrom(const LiveInterval& other, const_iterator I) const; 301 302 /// addRange - Add the specified LiveRange to this interval, merging 303 /// intervals as appropriate. This returns an iterator to the inserted live 304 /// range (which may have grown since it was inserted. 305 void addRange(LiveRange LR) { 306 addRangeFrom(LR, ranges.begin()); 307 } 308 309 /// join - Join two live intervals (this, and other) together. This applies 310 /// mappings to the value numbers in the LHS/RHS intervals as specified. If 311 /// the intervals are not joinable, this aborts. 312 void join(LiveInterval &Other, int *ValNoAssignments, 313 int *RHSValNoAssignments, SmallVector<VNInfo*, 16> &NewVNInfo); 314 315 /// removeRange - Remove the specified range from this interval. Note that 316 /// the range must already be in this interval in its entirety. 317 void removeRange(unsigned Start, unsigned End); 318 319 void removeRange(LiveRange LR) { 320 removeRange(LR.start, LR.end); 321 } 322 323 /// getSize - Returns the sum of sizes of all the LiveRange's. 324 /// 325 unsigned getSize() const; 326 327 bool operator<(const LiveInterval& other) const { 328 return beginNumber() < other.beginNumber(); 329 } 330 331 void print(std::ostream &OS, const MRegisterInfo *MRI = 0) const; 332 void print(std::ostream *OS, const MRegisterInfo *MRI = 0) const { 333 if (OS) print(*OS, MRI); 334 } 335 void dump() const; 336 337 private: 338 Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From); 339 void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd); 340 Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr); 341 LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT 342 }; 343 344 inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) { 345 LI.print(OS); 346 return OS; 347 } 348} 349 350#endif 351