Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 1 | // Copyright 2011 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 | #if V8_TARGET_ARCH_X87 |
| 6 | |
| 7 | #include "src/crankshaft/x87/lithium-gap-resolver-x87.h" |
| 8 | #include "src/register-configuration.h" |
| 9 | |
| 10 | #include "src/crankshaft/x87/lithium-codegen-x87.h" |
| 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | |
| 15 | LGapResolver::LGapResolver(LCodeGen* owner) |
| 16 | : cgen_(owner), |
| 17 | moves_(32, owner->zone()), |
| 18 | source_uses_(), |
| 19 | destination_uses_(), |
| 20 | spilled_register_(-1) {} |
| 21 | |
| 22 | |
| 23 | void LGapResolver::Resolve(LParallelMove* parallel_move) { |
| 24 | DCHECK(HasBeenReset()); |
| 25 | // Build up a worklist of moves. |
| 26 | BuildInitialMoveList(parallel_move); |
| 27 | |
| 28 | for (int i = 0; i < moves_.length(); ++i) { |
| 29 | LMoveOperands move = moves_[i]; |
| 30 | // Skip constants to perform them last. They don't block other moves |
| 31 | // and skipping such moves with register destinations keeps those |
| 32 | // registers free for the whole algorithm. |
| 33 | if (!move.IsEliminated() && !move.source()->IsConstantOperand()) { |
| 34 | PerformMove(i); |
| 35 | } |
| 36 | } |
| 37 | |
| 38 | // Perform the moves with constant sources. |
| 39 | for (int i = 0; i < moves_.length(); ++i) { |
| 40 | if (!moves_[i].IsEliminated()) { |
| 41 | DCHECK(moves_[i].source()->IsConstantOperand()); |
| 42 | EmitMove(i); |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | Finish(); |
| 47 | DCHECK(HasBeenReset()); |
| 48 | } |
| 49 | |
| 50 | |
| 51 | void LGapResolver::BuildInitialMoveList(LParallelMove* parallel_move) { |
| 52 | // Perform a linear sweep of the moves to add them to the initial list of |
| 53 | // moves to perform, ignoring any move that is redundant (the source is |
| 54 | // the same as the destination, the destination is ignored and |
| 55 | // unallocated, or the move was already eliminated). |
| 56 | const ZoneList<LMoveOperands>* moves = parallel_move->move_operands(); |
| 57 | for (int i = 0; i < moves->length(); ++i) { |
| 58 | LMoveOperands move = moves->at(i); |
| 59 | if (!move.IsRedundant()) AddMove(move); |
| 60 | } |
| 61 | Verify(); |
| 62 | } |
| 63 | |
| 64 | |
| 65 | void LGapResolver::PerformMove(int index) { |
| 66 | // Each call to this function performs a move and deletes it from the move |
| 67 | // graph. We first recursively perform any move blocking this one. We |
| 68 | // mark a move as "pending" on entry to PerformMove in order to detect |
| 69 | // cycles in the move graph. We use operand swaps to resolve cycles, |
| 70 | // which means that a call to PerformMove could change any source operand |
| 71 | // in the move graph. |
| 72 | |
| 73 | DCHECK(!moves_[index].IsPending()); |
| 74 | DCHECK(!moves_[index].IsRedundant()); |
| 75 | |
| 76 | // Clear this move's destination to indicate a pending move. The actual |
| 77 | // destination is saved on the side. |
| 78 | DCHECK(moves_[index].source() != NULL); // Or else it will look eliminated. |
| 79 | LOperand* destination = moves_[index].destination(); |
| 80 | moves_[index].set_destination(NULL); |
| 81 | |
| 82 | // Perform a depth-first traversal of the move graph to resolve |
| 83 | // dependencies. Any unperformed, unpending move with a source the same |
| 84 | // as this one's destination blocks this one so recursively perform all |
| 85 | // such moves. |
| 86 | for (int i = 0; i < moves_.length(); ++i) { |
| 87 | LMoveOperands other_move = moves_[i]; |
| 88 | if (other_move.Blocks(destination) && !other_move.IsPending()) { |
| 89 | // Though PerformMove can change any source operand in the move graph, |
| 90 | // this call cannot create a blocking move via a swap (this loop does |
| 91 | // not miss any). Assume there is a non-blocking move with source A |
| 92 | // and this move is blocked on source B and there is a swap of A and |
| 93 | // B. Then A and B must be involved in the same cycle (or they would |
| 94 | // not be swapped). Since this move's destination is B and there is |
| 95 | // only a single incoming edge to an operand, this move must also be |
| 96 | // involved in the same cycle. In that case, the blocking move will |
| 97 | // be created but will be "pending" when we return from PerformMove. |
| 98 | PerformMove(i); |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | // We are about to resolve this move and don't need it marked as |
| 103 | // pending, so restore its destination. |
| 104 | moves_[index].set_destination(destination); |
| 105 | |
| 106 | // This move's source may have changed due to swaps to resolve cycles and |
| 107 | // so it may now be the last move in the cycle. If so remove it. |
| 108 | if (moves_[index].source()->Equals(destination)) { |
| 109 | RemoveMove(index); |
| 110 | return; |
| 111 | } |
| 112 | |
| 113 | // The move may be blocked on a (at most one) pending move, in which case |
| 114 | // we have a cycle. Search for such a blocking move and perform a swap to |
| 115 | // resolve it. |
| 116 | for (int i = 0; i < moves_.length(); ++i) { |
| 117 | LMoveOperands other_move = moves_[i]; |
| 118 | if (other_move.Blocks(destination)) { |
| 119 | DCHECK(other_move.IsPending()); |
| 120 | EmitSwap(index); |
| 121 | return; |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | // This move is not blocked. |
| 126 | EmitMove(index); |
| 127 | } |
| 128 | |
| 129 | |
| 130 | void LGapResolver::AddMove(LMoveOperands move) { |
| 131 | LOperand* source = move.source(); |
| 132 | if (source->IsRegister()) ++source_uses_[source->index()]; |
| 133 | |
| 134 | LOperand* destination = move.destination(); |
| 135 | if (destination->IsRegister()) ++destination_uses_[destination->index()]; |
| 136 | |
| 137 | moves_.Add(move, cgen_->zone()); |
| 138 | } |
| 139 | |
| 140 | |
| 141 | void LGapResolver::RemoveMove(int index) { |
| 142 | LOperand* source = moves_[index].source(); |
| 143 | if (source->IsRegister()) { |
| 144 | --source_uses_[source->index()]; |
| 145 | DCHECK(source_uses_[source->index()] >= 0); |
| 146 | } |
| 147 | |
| 148 | LOperand* destination = moves_[index].destination(); |
| 149 | if (destination->IsRegister()) { |
| 150 | --destination_uses_[destination->index()]; |
| 151 | DCHECK(destination_uses_[destination->index()] >= 0); |
| 152 | } |
| 153 | |
| 154 | moves_[index].Eliminate(); |
| 155 | } |
| 156 | |
| 157 | |
| 158 | int LGapResolver::CountSourceUses(LOperand* operand) { |
| 159 | int count = 0; |
| 160 | for (int i = 0; i < moves_.length(); ++i) { |
| 161 | if (!moves_[i].IsEliminated() && moves_[i].source()->Equals(operand)) { |
| 162 | ++count; |
| 163 | } |
| 164 | } |
| 165 | return count; |
| 166 | } |
| 167 | |
| 168 | |
| 169 | Register LGapResolver::GetFreeRegisterNot(Register reg) { |
| 170 | int skip_index = reg.is(no_reg) ? -1 : reg.code(); |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame^] | 171 | const RegisterConfiguration* config = RegisterConfiguration::Crankshaft(); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 172 | for (int i = 0; i < config->num_allocatable_general_registers(); ++i) { |
| 173 | int code = config->GetAllocatableGeneralCode(i); |
| 174 | if (source_uses_[code] == 0 && destination_uses_[code] > 0 && |
| 175 | code != skip_index) { |
| 176 | return Register::from_code(code); |
| 177 | } |
| 178 | } |
| 179 | return no_reg; |
| 180 | } |
| 181 | |
| 182 | |
| 183 | bool LGapResolver::HasBeenReset() { |
| 184 | if (!moves_.is_empty()) return false; |
| 185 | if (spilled_register_ >= 0) return false; |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame^] | 186 | const RegisterConfiguration* config = RegisterConfiguration::Crankshaft(); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 187 | for (int i = 0; i < config->num_allocatable_general_registers(); ++i) { |
| 188 | int code = config->GetAllocatableGeneralCode(i); |
| 189 | if (source_uses_[code] != 0) return false; |
| 190 | if (destination_uses_[code] != 0) return false; |
| 191 | } |
| 192 | return true; |
| 193 | } |
| 194 | |
| 195 | |
| 196 | void LGapResolver::Verify() { |
| 197 | #ifdef ENABLE_SLOW_DCHECKS |
| 198 | // No operand should be the destination for more than one move. |
| 199 | for (int i = 0; i < moves_.length(); ++i) { |
| 200 | LOperand* destination = moves_[i].destination(); |
| 201 | for (int j = i + 1; j < moves_.length(); ++j) { |
| 202 | SLOW_DCHECK(!destination->Equals(moves_[j].destination())); |
| 203 | } |
| 204 | } |
| 205 | #endif |
| 206 | } |
| 207 | |
| 208 | |
| 209 | #define __ ACCESS_MASM(cgen_->masm()) |
| 210 | |
| 211 | void LGapResolver::Finish() { |
| 212 | if (spilled_register_ >= 0) { |
| 213 | __ pop(Register::from_code(spilled_register_)); |
| 214 | spilled_register_ = -1; |
| 215 | } |
| 216 | moves_.Rewind(0); |
| 217 | } |
| 218 | |
| 219 | |
| 220 | void LGapResolver::EnsureRestored(LOperand* operand) { |
| 221 | if (operand->IsRegister() && operand->index() == spilled_register_) { |
| 222 | __ pop(Register::from_code(spilled_register_)); |
| 223 | spilled_register_ = -1; |
| 224 | } |
| 225 | } |
| 226 | |
| 227 | |
| 228 | Register LGapResolver::EnsureTempRegister() { |
| 229 | // 1. We may have already spilled to create a temp register. |
| 230 | if (spilled_register_ >= 0) { |
| 231 | return Register::from_code(spilled_register_); |
| 232 | } |
| 233 | |
| 234 | // 2. We may have a free register that we can use without spilling. |
| 235 | Register free = GetFreeRegisterNot(no_reg); |
| 236 | if (!free.is(no_reg)) return free; |
| 237 | |
| 238 | // 3. Prefer to spill a register that is not used in any remaining move |
| 239 | // because it will not need to be restored until the end. |
Ben Murdoch | 61f157c | 2016-09-16 13:49:30 +0100 | [diff] [blame^] | 240 | const RegisterConfiguration* config = RegisterConfiguration::Crankshaft(); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 241 | for (int i = 0; i < config->num_allocatable_general_registers(); ++i) { |
| 242 | int code = config->GetAllocatableGeneralCode(i); |
| 243 | if (source_uses_[code] == 0 && destination_uses_[code] == 0) { |
| 244 | Register scratch = Register::from_code(code); |
| 245 | __ push(scratch); |
| 246 | spilled_register_ = code; |
| 247 | return scratch; |
| 248 | } |
| 249 | } |
| 250 | |
| 251 | // 4. Use an arbitrary register. Register 0 is as arbitrary as any other. |
| 252 | spilled_register_ = config->GetAllocatableGeneralCode(0); |
| 253 | Register scratch = Register::from_code(spilled_register_); |
| 254 | __ push(scratch); |
| 255 | return scratch; |
| 256 | } |
| 257 | |
| 258 | |
| 259 | void LGapResolver::EmitMove(int index) { |
| 260 | LOperand* source = moves_[index].source(); |
| 261 | LOperand* destination = moves_[index].destination(); |
| 262 | EnsureRestored(source); |
| 263 | EnsureRestored(destination); |
| 264 | |
| 265 | // Dispatch on the source and destination operand kinds. Not all |
| 266 | // combinations are possible. |
| 267 | if (source->IsRegister()) { |
| 268 | DCHECK(destination->IsRegister() || destination->IsStackSlot()); |
| 269 | Register src = cgen_->ToRegister(source); |
| 270 | Operand dst = cgen_->ToOperand(destination); |
| 271 | __ mov(dst, src); |
| 272 | |
| 273 | } else if (source->IsStackSlot()) { |
| 274 | DCHECK(destination->IsRegister() || destination->IsStackSlot()); |
| 275 | Operand src = cgen_->ToOperand(source); |
| 276 | if (destination->IsRegister()) { |
| 277 | Register dst = cgen_->ToRegister(destination); |
| 278 | __ mov(dst, src); |
| 279 | } else { |
| 280 | // Spill on demand to use a temporary register for memory-to-memory |
| 281 | // moves. |
| 282 | Register tmp = EnsureTempRegister(); |
| 283 | Operand dst = cgen_->ToOperand(destination); |
| 284 | __ mov(tmp, src); |
| 285 | __ mov(dst, tmp); |
| 286 | } |
| 287 | |
| 288 | } else if (source->IsConstantOperand()) { |
| 289 | LConstantOperand* constant_source = LConstantOperand::cast(source); |
| 290 | if (destination->IsRegister()) { |
| 291 | Register dst = cgen_->ToRegister(destination); |
| 292 | Representation r = cgen_->IsSmi(constant_source) |
| 293 | ? Representation::Smi() : Representation::Integer32(); |
| 294 | if (cgen_->IsInteger32(constant_source)) { |
| 295 | __ Move(dst, cgen_->ToImmediate(constant_source, r)); |
| 296 | } else { |
| 297 | __ LoadObject(dst, cgen_->ToHandle(constant_source)); |
| 298 | } |
| 299 | } else if (destination->IsDoubleRegister()) { |
| 300 | double v = cgen_->ToDouble(constant_source); |
| 301 | uint64_t int_val = bit_cast<uint64_t, double>(v); |
| 302 | int32_t lower = static_cast<int32_t>(int_val); |
| 303 | int32_t upper = static_cast<int32_t>(int_val >> kBitsPerInt); |
| 304 | __ push(Immediate(upper)); |
| 305 | __ push(Immediate(lower)); |
| 306 | X87Register dst = cgen_->ToX87Register(destination); |
| 307 | cgen_->X87Mov(dst, MemOperand(esp, 0)); |
| 308 | __ add(esp, Immediate(kDoubleSize)); |
| 309 | } else { |
| 310 | DCHECK(destination->IsStackSlot()); |
| 311 | Operand dst = cgen_->ToOperand(destination); |
| 312 | Representation r = cgen_->IsSmi(constant_source) |
| 313 | ? Representation::Smi() : Representation::Integer32(); |
| 314 | if (cgen_->IsInteger32(constant_source)) { |
| 315 | __ Move(dst, cgen_->ToImmediate(constant_source, r)); |
| 316 | } else { |
| 317 | Register tmp = EnsureTempRegister(); |
| 318 | __ LoadObject(tmp, cgen_->ToHandle(constant_source)); |
| 319 | __ mov(dst, tmp); |
| 320 | } |
| 321 | } |
| 322 | |
| 323 | } else if (source->IsDoubleRegister()) { |
| 324 | // load from the register onto the stack, store in destination, which must |
| 325 | // be a double stack slot in the non-SSE2 case. |
| 326 | if (destination->IsDoubleStackSlot()) { |
| 327 | Operand dst = cgen_->ToOperand(destination); |
| 328 | X87Register src = cgen_->ToX87Register(source); |
| 329 | cgen_->X87Mov(dst, src); |
| 330 | } else { |
| 331 | X87Register dst = cgen_->ToX87Register(destination); |
| 332 | X87Register src = cgen_->ToX87Register(source); |
| 333 | cgen_->X87Mov(dst, src); |
| 334 | } |
| 335 | } else if (source->IsDoubleStackSlot()) { |
| 336 | // load from the stack slot on top of the floating point stack, and then |
| 337 | // store in destination. If destination is a double register, then it |
| 338 | // represents the top of the stack and nothing needs to be done. |
| 339 | if (destination->IsDoubleStackSlot()) { |
| 340 | Register tmp = EnsureTempRegister(); |
| 341 | Operand src0 = cgen_->ToOperand(source); |
| 342 | Operand src1 = cgen_->HighOperand(source); |
| 343 | Operand dst0 = cgen_->ToOperand(destination); |
| 344 | Operand dst1 = cgen_->HighOperand(destination); |
| 345 | __ mov(tmp, src0); // Then use tmp to copy source to destination. |
| 346 | __ mov(dst0, tmp); |
| 347 | __ mov(tmp, src1); |
| 348 | __ mov(dst1, tmp); |
| 349 | } else { |
| 350 | Operand src = cgen_->ToOperand(source); |
| 351 | X87Register dst = cgen_->ToX87Register(destination); |
| 352 | cgen_->X87Mov(dst, src); |
| 353 | } |
| 354 | } else { |
| 355 | UNREACHABLE(); |
| 356 | } |
| 357 | |
| 358 | RemoveMove(index); |
| 359 | } |
| 360 | |
| 361 | |
| 362 | void LGapResolver::EmitSwap(int index) { |
| 363 | LOperand* source = moves_[index].source(); |
| 364 | LOperand* destination = moves_[index].destination(); |
| 365 | EnsureRestored(source); |
| 366 | EnsureRestored(destination); |
| 367 | |
| 368 | // Dispatch on the source and destination operand kinds. Not all |
| 369 | // combinations are possible. |
| 370 | if (source->IsRegister() && destination->IsRegister()) { |
| 371 | // Register-register. |
| 372 | Register src = cgen_->ToRegister(source); |
| 373 | Register dst = cgen_->ToRegister(destination); |
| 374 | __ xchg(dst, src); |
| 375 | |
| 376 | } else if ((source->IsRegister() && destination->IsStackSlot()) || |
| 377 | (source->IsStackSlot() && destination->IsRegister())) { |
| 378 | // Register-memory. Use a free register as a temp if possible. Do not |
| 379 | // spill on demand because the simple spill implementation cannot avoid |
| 380 | // spilling src at this point. |
| 381 | Register tmp = GetFreeRegisterNot(no_reg); |
| 382 | Register reg = |
| 383 | cgen_->ToRegister(source->IsRegister() ? source : destination); |
| 384 | Operand mem = |
| 385 | cgen_->ToOperand(source->IsRegister() ? destination : source); |
| 386 | if (tmp.is(no_reg)) { |
| 387 | __ xor_(reg, mem); |
| 388 | __ xor_(mem, reg); |
| 389 | __ xor_(reg, mem); |
| 390 | } else { |
| 391 | __ mov(tmp, mem); |
| 392 | __ mov(mem, reg); |
| 393 | __ mov(reg, tmp); |
| 394 | } |
| 395 | |
| 396 | } else if (source->IsStackSlot() && destination->IsStackSlot()) { |
| 397 | // Memory-memory. Spill on demand to use a temporary. If there is a |
| 398 | // free register after that, use it as a second temporary. |
| 399 | Register tmp0 = EnsureTempRegister(); |
| 400 | Register tmp1 = GetFreeRegisterNot(tmp0); |
| 401 | Operand src = cgen_->ToOperand(source); |
| 402 | Operand dst = cgen_->ToOperand(destination); |
| 403 | if (tmp1.is(no_reg)) { |
| 404 | // Only one temp register available to us. |
| 405 | __ mov(tmp0, dst); |
| 406 | __ xor_(tmp0, src); |
| 407 | __ xor_(src, tmp0); |
| 408 | __ xor_(tmp0, src); |
| 409 | __ mov(dst, tmp0); |
| 410 | } else { |
| 411 | __ mov(tmp0, dst); |
| 412 | __ mov(tmp1, src); |
| 413 | __ mov(dst, tmp1); |
| 414 | __ mov(src, tmp0); |
| 415 | } |
| 416 | } else { |
| 417 | // No other combinations are possible. |
| 418 | UNREACHABLE(); |
| 419 | } |
| 420 | |
| 421 | // The swap of source and destination has executed a move from source to |
| 422 | // destination. |
| 423 | RemoveMove(index); |
| 424 | |
| 425 | // Any unperformed (including pending) move with a source of either |
| 426 | // this move's source or destination needs to have their source |
| 427 | // changed to reflect the state of affairs after the swap. |
| 428 | for (int i = 0; i < moves_.length(); ++i) { |
| 429 | LMoveOperands other_move = moves_[i]; |
| 430 | if (other_move.Blocks(source)) { |
| 431 | moves_[i].set_source(destination); |
| 432 | } else if (other_move.Blocks(destination)) { |
| 433 | moves_[i].set_source(source); |
| 434 | } |
| 435 | } |
| 436 | |
| 437 | // In addition to swapping the actual uses as sources, we need to update |
| 438 | // the use counts. |
| 439 | if (source->IsRegister() && destination->IsRegister()) { |
| 440 | int temp = source_uses_[source->index()]; |
| 441 | source_uses_[source->index()] = source_uses_[destination->index()]; |
| 442 | source_uses_[destination->index()] = temp; |
| 443 | } else if (source->IsRegister()) { |
| 444 | // We don't have use counts for non-register operands like destination. |
| 445 | // Compute those counts now. |
| 446 | source_uses_[source->index()] = CountSourceUses(source); |
| 447 | } else if (destination->IsRegister()) { |
| 448 | source_uses_[destination->index()] = CountSourceUses(destination); |
| 449 | } |
| 450 | } |
| 451 | |
| 452 | #undef __ |
| 453 | |
| 454 | } // namespace internal |
| 455 | } // namespace v8 |
| 456 | |
| 457 | #endif // V8_TARGET_ARCH_X87 |