Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/compiler/move-optimizer.h" |
| 6 | |
| 7 | namespace v8 { |
| 8 | namespace internal { |
| 9 | namespace compiler { |
| 10 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 11 | namespace { |
| 12 | |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 13 | struct MoveKey { |
| 14 | InstructionOperand source; |
| 15 | InstructionOperand destination; |
| 16 | }; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 17 | |
| 18 | struct MoveKeyCompare { |
| 19 | bool operator()(const MoveKey& a, const MoveKey& b) const { |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 20 | if (a.source.EqualsCanonicalized(b.source)) { |
| 21 | return a.destination.CompareCanonicalized(b.destination); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 22 | } |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 23 | return a.source.CompareCanonicalized(b.source); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 24 | } |
| 25 | }; |
| 26 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 27 | typedef ZoneMap<MoveKey, unsigned, MoveKeyCompare> MoveMap; |
| 28 | typedef ZoneSet<InstructionOperand, CompareOperandModuloType> OperandSet; |
| 29 | |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame] | 30 | bool Blocks(const OperandSet& set, const InstructionOperand& operand) { |
| 31 | if (set.find(operand) != set.end()) return true; |
| 32 | // Only FP registers on archs with non-simple aliasing need extra checks. |
| 33 | if (!operand.IsFPRegister() || kSimpleFPAliasing) return false; |
| 34 | |
| 35 | const LocationOperand& loc = LocationOperand::cast(operand); |
| 36 | MachineRepresentation rep = loc.representation(); |
| 37 | MachineRepresentation other_fp_rep = rep == MachineRepresentation::kFloat64 |
| 38 | ? MachineRepresentation::kFloat32 |
| 39 | : MachineRepresentation::kFloat64; |
| 40 | const RegisterConfiguration* config = RegisterConfiguration::Turbofan(); |
| 41 | if (config->fp_aliasing_kind() != RegisterConfiguration::COMBINE) { |
| 42 | // Overlap aliasing case. |
| 43 | return set.find(LocationOperand(loc.kind(), loc.location_kind(), |
| 44 | other_fp_rep, loc.register_code())) != |
| 45 | set.end(); |
| 46 | } |
| 47 | // Combine aliasing case. |
| 48 | int alias_base_index = -1; |
| 49 | int aliases = config->GetAliases(rep, loc.register_code(), other_fp_rep, |
| 50 | &alias_base_index); |
| 51 | while (aliases--) { |
| 52 | int aliased_reg = alias_base_index + aliases; |
| 53 | if (set.find(LocationOperand(loc.kind(), loc.location_kind(), other_fp_rep, |
| 54 | aliased_reg)) != set.end()) |
| 55 | return true; |
| 56 | } |
| 57 | return false; |
| 58 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 59 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 60 | int FindFirstNonEmptySlot(const Instruction* instr) { |
| 61 | int i = Instruction::FIRST_GAP_POSITION; |
| 62 | for (; i <= Instruction::LAST_GAP_POSITION; i++) { |
| 63 | ParallelMove* moves = instr->parallel_moves()[i]; |
| 64 | if (moves == nullptr) continue; |
| 65 | for (MoveOperands* move : *moves) { |
| 66 | if (!move->IsRedundant()) return i; |
| 67 | move->Eliminate(); |
| 68 | } |
| 69 | moves->clear(); // Clear this redundant move. |
| 70 | } |
| 71 | return i; |
| 72 | } |
| 73 | |
| 74 | } // namespace |
| 75 | |
| 76 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 77 | MoveOptimizer::MoveOptimizer(Zone* local_zone, InstructionSequence* code) |
| 78 | : local_zone_(local_zone), |
| 79 | code_(code), |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 80 | local_vector_(local_zone) {} |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 81 | |
| 82 | |
| 83 | void MoveOptimizer::Run() { |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 84 | for (Instruction* instruction : code()->instructions()) { |
| 85 | CompressGaps(instruction); |
| 86 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 87 | for (InstructionBlock* block : code()->instruction_blocks()) { |
| 88 | CompressBlock(block); |
| 89 | } |
| 90 | for (InstructionBlock* block : code()->instruction_blocks()) { |
| 91 | if (block->PredecessorCount() <= 1) continue; |
| 92 | if (!block->IsDeferred()) { |
| 93 | bool has_only_deferred = true; |
| 94 | for (RpoNumber& pred_id : block->predecessors()) { |
| 95 | if (!code()->InstructionBlockAt(pred_id)->IsDeferred()) { |
| 96 | has_only_deferred = false; |
| 97 | break; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 98 | } |
| 99 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 100 | // This would pull down common moves. If the moves occur in deferred |
| 101 | // blocks, and the closest common successor is not deferred, we lose the |
| 102 | // optimization of just spilling/filling in deferred blocks, when the |
| 103 | // current block is not deferred. |
| 104 | if (has_only_deferred) continue; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 105 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 106 | OptimizeMerge(block); |
| 107 | } |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 108 | for (Instruction* gap : code()->instructions()) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 109 | FinalizeMoves(gap); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 110 | } |
| 111 | } |
| 112 | |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 113 | void MoveOptimizer::RemoveClobberedDestinations(Instruction* instruction) { |
| 114 | if (instruction->IsCall()) return; |
| 115 | ParallelMove* moves = instruction->parallel_moves()[0]; |
| 116 | if (moves == nullptr) return; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 117 | |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 118 | DCHECK(instruction->parallel_moves()[1] == nullptr || |
| 119 | instruction->parallel_moves()[1]->empty()); |
| 120 | |
| 121 | OperandSet outputs(local_zone()); |
| 122 | OperandSet inputs(local_zone()); |
| 123 | |
| 124 | // Outputs and temps are treated together as potentially clobbering a |
| 125 | // destination operand. |
| 126 | for (size_t i = 0; i < instruction->OutputCount(); ++i) { |
| 127 | outputs.insert(*instruction->OutputAt(i)); |
| 128 | } |
| 129 | for (size_t i = 0; i < instruction->TempCount(); ++i) { |
| 130 | outputs.insert(*instruction->TempAt(i)); |
| 131 | } |
| 132 | |
| 133 | // Input operands block elisions. |
| 134 | for (size_t i = 0; i < instruction->InputCount(); ++i) { |
| 135 | inputs.insert(*instruction->InputAt(i)); |
| 136 | } |
| 137 | |
| 138 | // Elide moves made redundant by the instruction. |
| 139 | for (MoveOperands* move : *moves) { |
| 140 | if (outputs.find(move->destination()) != outputs.end() && |
| 141 | inputs.find(move->destination()) == inputs.end()) { |
| 142 | move->Eliminate(); |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | // The ret instruction makes any assignment before it unnecessary, except for |
| 147 | // the one for its input. |
| 148 | if (instruction->opcode() == ArchOpcode::kArchRet) { |
| 149 | for (MoveOperands* move : *moves) { |
| 150 | if (inputs.find(move->destination()) == inputs.end()) { |
| 151 | move->Eliminate(); |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | void MoveOptimizer::MigrateMoves(Instruction* to, Instruction* from) { |
| 158 | if (from->IsCall()) return; |
| 159 | |
| 160 | ParallelMove* from_moves = from->parallel_moves()[0]; |
| 161 | if (from_moves == nullptr || from_moves->empty()) return; |
| 162 | |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame] | 163 | OperandSet dst_cant_be(local_zone()); |
| 164 | OperandSet src_cant_be(local_zone()); |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 165 | |
| 166 | // If an operand is an input to the instruction, we cannot move assignments |
| 167 | // where it appears on the LHS. |
| 168 | for (size_t i = 0; i < from->InputCount(); ++i) { |
| 169 | dst_cant_be.insert(*from->InputAt(i)); |
| 170 | } |
| 171 | // If an operand is output to the instruction, we cannot move assignments |
| 172 | // where it appears on the RHS, because we would lose its value before the |
| 173 | // instruction. |
| 174 | // Same for temp operands. |
| 175 | // The output can't appear on the LHS because we performed |
| 176 | // RemoveClobberedDestinations for the "from" instruction. |
| 177 | for (size_t i = 0; i < from->OutputCount(); ++i) { |
| 178 | src_cant_be.insert(*from->OutputAt(i)); |
| 179 | } |
| 180 | for (size_t i = 0; i < from->TempCount(); ++i) { |
| 181 | src_cant_be.insert(*from->TempAt(i)); |
| 182 | } |
| 183 | for (MoveOperands* move : *from_moves) { |
| 184 | if (move->IsRedundant()) continue; |
| 185 | // Assume dest has a value "V". If we have a "dest = y" move, then we can't |
| 186 | // move "z = dest", because z would become y rather than "V". |
| 187 | // We assume CompressMoves has happened before this, which means we don't |
| 188 | // have more than one assignment to dest. |
| 189 | src_cant_be.insert(move->destination()); |
| 190 | } |
| 191 | |
| 192 | ZoneSet<MoveKey, MoveKeyCompare> move_candidates(local_zone()); |
| 193 | // We start with all the moves that don't have conflicting source or |
| 194 | // destination operands are eligible for being moved down. |
| 195 | for (MoveOperands* move : *from_moves) { |
| 196 | if (move->IsRedundant()) continue; |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame] | 197 | if (!Blocks(dst_cant_be, move->destination())) { |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 198 | MoveKey key = {move->source(), move->destination()}; |
| 199 | move_candidates.insert(key); |
| 200 | } |
| 201 | } |
| 202 | if (move_candidates.empty()) return; |
| 203 | |
| 204 | // Stabilize the candidate set. |
| 205 | bool changed = false; |
| 206 | do { |
| 207 | changed = false; |
| 208 | for (auto iter = move_candidates.begin(); iter != move_candidates.end();) { |
| 209 | auto current = iter; |
| 210 | ++iter; |
| 211 | InstructionOperand src = current->source; |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame] | 212 | if (Blocks(src_cant_be, src)) { |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 213 | src_cant_be.insert(current->destination); |
| 214 | move_candidates.erase(current); |
| 215 | changed = true; |
| 216 | } |
| 217 | } |
| 218 | } while (changed); |
| 219 | |
| 220 | ParallelMove to_move(local_zone()); |
| 221 | for (MoveOperands* move : *from_moves) { |
| 222 | if (move->IsRedundant()) continue; |
| 223 | MoveKey key = {move->source(), move->destination()}; |
| 224 | if (move_candidates.find(key) != move_candidates.end()) { |
| 225 | to_move.AddMove(move->source(), move->destination(), code_zone()); |
| 226 | move->Eliminate(); |
| 227 | } |
| 228 | } |
| 229 | if (to_move.empty()) return; |
| 230 | |
| 231 | ParallelMove* dest = |
| 232 | to->GetOrCreateParallelMove(Instruction::GapPosition::START, code_zone()); |
| 233 | |
| 234 | CompressMoves(&to_move, dest); |
| 235 | DCHECK(dest->empty()); |
| 236 | for (MoveOperands* m : to_move) { |
| 237 | dest->push_back(m); |
| 238 | } |
| 239 | } |
| 240 | |
| 241 | void MoveOptimizer::CompressMoves(ParallelMove* left, MoveOpVector* right) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 242 | if (right == nullptr) return; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 243 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 244 | MoveOpVector& eliminated = local_vector(); |
| 245 | DCHECK(eliminated.empty()); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 246 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 247 | if (!left->empty()) { |
| 248 | // Modify the right moves in place and collect moves that will be killed by |
| 249 | // merging the two gaps. |
| 250 | for (MoveOperands* move : *right) { |
| 251 | if (move->IsRedundant()) continue; |
| 252 | MoveOperands* to_eliminate = left->PrepareInsertAfter(move); |
| 253 | if (to_eliminate != nullptr) eliminated.push_back(to_eliminate); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 254 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 255 | // Eliminate dead moves. |
| 256 | for (MoveOperands* to_eliminate : eliminated) { |
| 257 | to_eliminate->Eliminate(); |
| 258 | } |
| 259 | eliminated.clear(); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 260 | } |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 261 | // Add all possibly modified moves from right side. |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 262 | for (MoveOperands* move : *right) { |
| 263 | if (move->IsRedundant()) continue; |
| 264 | left->push_back(move); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 265 | } |
| 266 | // Nuke right. |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 267 | right->clear(); |
| 268 | DCHECK(eliminated.empty()); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 269 | } |
| 270 | |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 271 | void MoveOptimizer::CompressGaps(Instruction* instruction) { |
| 272 | int i = FindFirstNonEmptySlot(instruction); |
| 273 | bool has_moves = i <= Instruction::LAST_GAP_POSITION; |
| 274 | USE(has_moves); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 275 | |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 276 | if (i == Instruction::LAST_GAP_POSITION) { |
| 277 | std::swap(instruction->parallel_moves()[Instruction::FIRST_GAP_POSITION], |
| 278 | instruction->parallel_moves()[Instruction::LAST_GAP_POSITION]); |
| 279 | } else if (i == Instruction::FIRST_GAP_POSITION) { |
| 280 | CompressMoves( |
| 281 | instruction->parallel_moves()[Instruction::FIRST_GAP_POSITION], |
| 282 | instruction->parallel_moves()[Instruction::LAST_GAP_POSITION]); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 283 | } |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 284 | // We either have no moves, or, after swapping or compressing, we have |
| 285 | // all the moves in the first gap position, and none in the second/end gap |
| 286 | // position. |
| 287 | ParallelMove* first = |
| 288 | instruction->parallel_moves()[Instruction::FIRST_GAP_POSITION]; |
| 289 | ParallelMove* last = |
| 290 | instruction->parallel_moves()[Instruction::LAST_GAP_POSITION]; |
| 291 | USE(first); |
| 292 | USE(last); |
| 293 | |
| 294 | DCHECK(!has_moves || |
| 295 | (first != nullptr && (last == nullptr || last->empty()))); |
| 296 | } |
| 297 | |
| 298 | void MoveOptimizer::CompressBlock(InstructionBlock* block) { |
| 299 | int first_instr_index = block->first_instruction_index(); |
| 300 | int last_instr_index = block->last_instruction_index(); |
| 301 | |
| 302 | // Start by removing gap assignments where the output of the subsequent |
| 303 | // instruction appears on LHS, as long as they are not needed by its input. |
| 304 | Instruction* prev_instr = code()->instructions()[first_instr_index]; |
| 305 | RemoveClobberedDestinations(prev_instr); |
| 306 | |
| 307 | for (int index = first_instr_index + 1; index <= last_instr_index; ++index) { |
| 308 | Instruction* instr = code()->instructions()[index]; |
| 309 | // Migrate to the gap of prev_instr eligible moves from instr. |
| 310 | MigrateMoves(instr, prev_instr); |
| 311 | // Remove gap assignments clobbered by instr's output. |
| 312 | RemoveClobberedDestinations(instr); |
| 313 | prev_instr = instr; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 314 | } |
| 315 | } |
| 316 | |
| 317 | |
| 318 | const Instruction* MoveOptimizer::LastInstruction( |
| 319 | const InstructionBlock* block) const { |
| 320 | return code()->instructions()[block->last_instruction_index()]; |
| 321 | } |
| 322 | |
| 323 | |
| 324 | void MoveOptimizer::OptimizeMerge(InstructionBlock* block) { |
| 325 | DCHECK(block->PredecessorCount() > 1); |
| 326 | // Ensure that the last instruction in all incoming blocks don't contain |
| 327 | // things that would prevent moving gap moves across them. |
| 328 | for (RpoNumber& pred_index : block->predecessors()) { |
| 329 | const InstructionBlock* pred = code()->InstructionBlockAt(pred_index); |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 330 | |
| 331 | // If the predecessor has more than one successor, we shouldn't attempt to |
| 332 | // move down to this block (one of the successors) any of the gap moves, |
| 333 | // because their effect may be necessary to the other successors. |
| 334 | if (pred->SuccessorCount() > 1) return; |
| 335 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 336 | const Instruction* last_instr = |
| 337 | code()->instructions()[pred->last_instruction_index()]; |
| 338 | if (last_instr->IsCall()) return; |
| 339 | if (last_instr->TempCount() != 0) return; |
| 340 | if (last_instr->OutputCount() != 0) return; |
| 341 | for (size_t i = 0; i < last_instr->InputCount(); ++i) { |
| 342 | const InstructionOperand* op = last_instr->InputAt(i); |
| 343 | if (!op->IsConstant() && !op->IsImmediate()) return; |
| 344 | } |
| 345 | } |
| 346 | // TODO(dcarney): pass a ZonePool down for this? |
| 347 | MoveMap move_map(local_zone()); |
| 348 | size_t correct_counts = 0; |
| 349 | // Accumulate set of shared moves. |
| 350 | for (RpoNumber& pred_index : block->predecessors()) { |
| 351 | const InstructionBlock* pred = code()->InstructionBlockAt(pred_index); |
| 352 | const Instruction* instr = LastInstruction(pred); |
| 353 | if (instr->parallel_moves()[0] == nullptr || |
| 354 | instr->parallel_moves()[0]->empty()) { |
| 355 | return; |
| 356 | } |
| 357 | for (const MoveOperands* move : *instr->parallel_moves()[0]) { |
| 358 | if (move->IsRedundant()) continue; |
| 359 | InstructionOperand src = move->source(); |
| 360 | InstructionOperand dst = move->destination(); |
| 361 | MoveKey key = {src, dst}; |
| 362 | auto res = move_map.insert(std::make_pair(key, 1)); |
| 363 | if (!res.second) { |
| 364 | res.first->second++; |
| 365 | if (res.first->second == block->PredecessorCount()) { |
| 366 | correct_counts++; |
| 367 | } |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 368 | } |
| 369 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 370 | } |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 371 | if (move_map.empty() || correct_counts == 0) return; |
| 372 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 373 | // Find insertion point. |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 374 | Instruction* instr = code()->instructions()[block->first_instruction_index()]; |
| 375 | |
| 376 | if (correct_counts != move_map.size()) { |
| 377 | // Moves that are unique to each predecessor won't be pushed to the common |
| 378 | // successor. |
| 379 | OperandSet conflicting_srcs(local_zone()); |
| 380 | for (auto iter = move_map.begin(), end = move_map.end(); iter != end;) { |
| 381 | auto current = iter; |
| 382 | ++iter; |
| 383 | if (current->second != block->PredecessorCount()) { |
| 384 | InstructionOperand dest = current->first.destination; |
| 385 | // Not all the moves in all the gaps are the same. Maybe some are. If |
| 386 | // there are such moves, we could move them, but the destination of the |
| 387 | // moves staying behind can't appear as a source of a common move, |
| 388 | // because the move staying behind will clobber this destination. |
| 389 | conflicting_srcs.insert(dest); |
| 390 | move_map.erase(current); |
| 391 | } |
| 392 | } |
| 393 | |
| 394 | bool changed = false; |
| 395 | do { |
| 396 | // If a common move can't be pushed to the common successor, then its |
| 397 | // destination also can't appear as source to any move being pushed. |
| 398 | changed = false; |
| 399 | for (auto iter = move_map.begin(), end = move_map.end(); iter != end;) { |
| 400 | auto current = iter; |
| 401 | ++iter; |
| 402 | DCHECK_EQ(block->PredecessorCount(), current->second); |
| 403 | if (conflicting_srcs.find(current->first.source) != |
| 404 | conflicting_srcs.end()) { |
| 405 | conflicting_srcs.insert(current->first.destination); |
| 406 | move_map.erase(current); |
| 407 | changed = true; |
| 408 | } |
| 409 | } |
| 410 | } while (changed); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 411 | } |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 412 | |
| 413 | if (move_map.empty()) return; |
| 414 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 415 | DCHECK_NOT_NULL(instr); |
| 416 | bool gap_initialized = true; |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 417 | if (instr->parallel_moves()[0] != nullptr && |
| 418 | !instr->parallel_moves()[0]->empty()) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 419 | // Will compress after insertion. |
| 420 | gap_initialized = false; |
| 421 | std::swap(instr->parallel_moves()[0], instr->parallel_moves()[1]); |
| 422 | } |
| 423 | ParallelMove* moves = instr->GetOrCreateParallelMove( |
| 424 | static_cast<Instruction::GapPosition>(0), code_zone()); |
| 425 | // Delete relevant entries in predecessors and move everything to block. |
| 426 | bool first_iteration = true; |
| 427 | for (RpoNumber& pred_index : block->predecessors()) { |
| 428 | const InstructionBlock* pred = code()->InstructionBlockAt(pred_index); |
| 429 | for (MoveOperands* move : *LastInstruction(pred)->parallel_moves()[0]) { |
| 430 | if (move->IsRedundant()) continue; |
| 431 | MoveKey key = {move->source(), move->destination()}; |
| 432 | auto it = move_map.find(key); |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 433 | if (it != move_map.end()) { |
| 434 | if (first_iteration) { |
| 435 | moves->AddMove(move->source(), move->destination()); |
| 436 | } |
| 437 | move->Eliminate(); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 438 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 439 | } |
| 440 | first_iteration = false; |
| 441 | } |
| 442 | // Compress. |
| 443 | if (!gap_initialized) { |
| 444 | CompressMoves(instr->parallel_moves()[0], instr->parallel_moves()[1]); |
| 445 | } |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 446 | CompressBlock(block); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 447 | } |
| 448 | |
| 449 | |
| 450 | namespace { |
| 451 | |
| 452 | bool IsSlot(const InstructionOperand& op) { |
| 453 | return op.IsStackSlot() || op.IsDoubleStackSlot(); |
| 454 | } |
| 455 | |
| 456 | |
| 457 | bool LoadCompare(const MoveOperands* a, const MoveOperands* b) { |
| 458 | if (!a->source().EqualsCanonicalized(b->source())) { |
| 459 | return a->source().CompareCanonicalized(b->source()); |
| 460 | } |
| 461 | if (IsSlot(a->destination()) && !IsSlot(b->destination())) return false; |
| 462 | if (!IsSlot(a->destination()) && IsSlot(b->destination())) return true; |
| 463 | return a->destination().CompareCanonicalized(b->destination()); |
| 464 | } |
| 465 | |
| 466 | } // namespace |
| 467 | |
| 468 | |
| 469 | // Split multiple loads of the same constant or stack slot off into the second |
| 470 | // slot and keep remaining moves in the first slot. |
| 471 | void MoveOptimizer::FinalizeMoves(Instruction* instr) { |
| 472 | MoveOpVector& loads = local_vector(); |
| 473 | DCHECK(loads.empty()); |
| 474 | |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 475 | ParallelMove* parallel_moves = instr->parallel_moves()[0]; |
| 476 | if (parallel_moves == nullptr) return; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 477 | // Find all the loads. |
Ben Murdoch | 097c5b2 | 2016-05-18 11:27:45 +0100 | [diff] [blame] | 478 | for (MoveOperands* move : *parallel_moves) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 479 | if (move->IsRedundant()) continue; |
| 480 | if (move->source().IsConstant() || IsSlot(move->source())) { |
| 481 | loads.push_back(move); |
| 482 | } |
| 483 | } |
| 484 | if (loads.empty()) return; |
| 485 | // Group the loads by source, moving the preferred destination to the |
| 486 | // beginning of the group. |
| 487 | std::sort(loads.begin(), loads.end(), LoadCompare); |
| 488 | MoveOperands* group_begin = nullptr; |
| 489 | for (MoveOperands* load : loads) { |
| 490 | // New group. |
| 491 | if (group_begin == nullptr || |
| 492 | !load->source().EqualsCanonicalized(group_begin->source())) { |
| 493 | group_begin = load; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 494 | continue; |
| 495 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 496 | // Nothing to be gained from splitting here. |
| 497 | if (IsSlot(group_begin->destination())) continue; |
| 498 | // Insert new move into slot 1. |
| 499 | ParallelMove* slot_1 = instr->GetOrCreateParallelMove( |
| 500 | static_cast<Instruction::GapPosition>(1), code_zone()); |
| 501 | slot_1->AddMove(group_begin->destination(), load->destination()); |
| 502 | load->Eliminate(); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 503 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 504 | loads.clear(); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 505 | } |
| 506 | |
| 507 | } // namespace compiler |
| 508 | } // namespace internal |
| 509 | } // namespace v8 |