| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | */ |
| 7 | |
| 8 | import {CompilerError} from '../CompilerError'; |
| 9 | import { |
| 10 | BasicBlock, |
| 11 | BlockId, |
| 12 | GeneratedSource, |
| 13 | GotoVariant, |
| 14 | HIR, |
| 15 | InstructionId, |
| 16 | Place, |
| 17 | ReactiveBlock, |
| 18 | SourceLocation, |
| 19 | } from '../HIR'; |
| 20 | import { |
| 21 | HIRFunction, |
| 22 | ReactiveBreakTerminal, |
| 23 | ReactiveContinueTerminal, |
| 24 | ReactiveFunction, |
| 25 | ReactiveInstruction, |
| 26 | ReactiveLogicalValue, |
| 27 | ReactiveSequenceValue, |
| 28 | ReactiveTerminalStatement, |
| 29 | ReactiveTerminalTargetKind, |
| 30 | ReactiveTernaryValue, |
| 31 | ReactiveValue, |
| 32 | Terminal, |
| 33 | } from '../HIR/HIR'; |
| 34 | import {assertExhaustive} from '../Utils/utils'; |
| 35 | |
| 36 | /* |
| 37 | * Converts from HIR (lower-level CFG) to ReactiveFunction, a tree representation |
| 38 | * that is closer to an AST. This pass restores the original control flow constructs, |
| 39 | * including break/continue to labeled statements. Note that this pass naively emits |
| 40 | * labels for *all* terminals: see PruneUnusedLabels which removes unnecessary labels. |
| 41 | */ |
| 42 | export function buildReactiveFunction(fn: HIRFunction): ReactiveFunction { |
| 43 | const cx = new Context(fn.body); |
| 44 | const driver = new Driver(cx); |
| 45 | const body = driver.traverseBlock(cx.block(fn.body.entry)); |
| 46 | return { |
| 47 | loc: fn.loc, |
| 48 | id: fn.id, |
| 49 | nameHint: fn.nameHint, |
| 50 | params: fn.params, |
| 51 | generator: fn.generator, |
| 52 | async: fn.async, |
| 53 | body, |
| 54 | env: fn.env, |
| 55 | directives: fn.directives, |
| 56 | }; |
| 57 | } |
| 58 | |
| 59 | class Driver { |
| 60 | cx: Context; |
| 61 | |
| 62 | constructor(cx: Context) { |
| 63 | this.cx = cx; |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * Wraps a continuation result with preceding instructions. If there are no |
| 68 | * instructions, returns the continuation as-is. Otherwise, wraps the continuation's |
| 69 | * value in a SequenceExpression with the instructions prepended. |
| 70 | */ |
| 71 | wrapWithSequence( |
| 72 | instructions: Array<ReactiveInstruction>, |
| 73 | continuation: { |
| 74 | block: BlockId; |
| 75 | value: ReactiveValue; |
| 76 | place: Place; |
| 77 | id: InstructionId; |
| 78 | }, |
| 79 | loc: SourceLocation, |
| 80 | ): {block: BlockId; value: ReactiveValue; place: Place; id: InstructionId} { |
| 81 | if (instructions.length === 0) { |
| 82 | return continuation; |
| 83 | } |
| 84 | const sequence: ReactiveSequenceValue = { |
| 85 | kind: 'SequenceExpression', |
| 86 | instructions, |
| 87 | id: continuation.id, |
| 88 | value: continuation.value, |
| 89 | loc, |
| 90 | }; |
| 91 | return { |
| 92 | block: continuation.block, |
| 93 | value: sequence, |
| 94 | place: continuation.place, |
| 95 | id: continuation.id, |
| 96 | }; |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * Extracts the result value from instructions at the end of a value block. |
| 101 | * Value blocks generally end in a StoreLocal to assign the value of the |
| 102 | * expression. These StoreLocal instructions can be pruned since we represent |
| 103 | * value blocks as compound values in ReactiveFunction (no phis). However, |
| 104 | * it's also possible to have a value block that ends in an AssignmentExpression, |
| 105 | * which we need to keep. So we only prune StoreLocal for temporaries. |
| 106 | */ |
| 107 | extractValueBlockResult( |
| 108 | instructions: BasicBlock['instructions'], |
| 109 | blockId: BlockId, |
| 110 | loc: SourceLocation, |
| 111 | ): {block: BlockId; place: Place; value: ReactiveValue; id: InstructionId} { |
| 112 | CompilerError.invariant(instructions.length !== 0, { |
| 113 | reason: `Expected non-empty instructions in extractValueBlockResult`, |
| 114 | description: null, |
| 115 | loc, |
| 116 | }); |
| 117 | const instr = instructions.at(-1)!; |
| 118 | let place: Place = instr.lvalue; |
| 119 | let value: ReactiveValue = instr.value; |
| 120 | if ( |
| 121 | value.kind === 'StoreLocal' && |
| 122 | value.lvalue.place.identifier.name === null |
| 123 | ) { |
| 124 | place = value.lvalue.place; |
| 125 | value = { |
| 126 | kind: 'LoadLocal', |
| 127 | place: value.value, |
| 128 | loc: value.value.loc, |
| 129 | }; |
| 130 | } |
| 131 | if (instructions.length === 1) { |
| 132 | return {block: blockId, place, value, id: instr.id}; |
| 133 | } |
| 134 | const sequence: ReactiveSequenceValue = { |
| 135 | kind: 'SequenceExpression', |
| 136 | instructions: instructions.slice(0, -1), |
| 137 | id: instr.id, |
| 138 | value, |
| 139 | loc, |
| 140 | }; |
| 141 | return {block: blockId, place, value: sequence, id: instr.id}; |
| 142 | } |
| 143 | |
| 144 | /* |
| 145 | * Converts the result of visitValueBlock into a SequenceExpression that includes |
| 146 | * the instruction with its lvalue. This is needed for for/for-of/for-in init/test |
| 147 | * blocks where the instruction's lvalue assignment must be preserved. |
| 148 | * |
| 149 | * This also flattens nested SequenceExpressions that can occur from MaybeThrow |
| 150 | * handling in try-catch blocks. |
| 151 | */ |
| 152 | valueBlockResultToSequence( |
| 153 | result: { |
| 154 | block: BlockId; |
| 155 | value: ReactiveValue; |
| 156 | place: Place; |
| 157 | id: InstructionId; |
| 158 | }, |
| 159 | loc: SourceLocation, |
| 160 | ): ReactiveSequenceValue { |
| 161 | // Collect all instructions from potentially nested SequenceExpressions |
| 162 | const instructions: Array<ReactiveInstruction> = []; |
| 163 | let innerValue: ReactiveValue = result.value; |
| 164 | |
| 165 | // Flatten nested SequenceExpressions |
| 166 | while (innerValue.kind === 'SequenceExpression') { |
| 167 | instructions.push(...innerValue.instructions); |
| 168 | innerValue = innerValue.value; |
| 169 | } |
| 170 | |
| 171 | /* |
| 172 | * Only add the final instruction if the innermost value is not just a LoadLocal |
| 173 | * of the same place we're storing to (which would be a no-op). |
| 174 | * This happens when MaybeThrow blocks cause the sequence to already contain |
| 175 | * all the necessary instructions. |
| 176 | */ |
| 177 | const isLoadOfSamePlace = |
| 178 | innerValue.kind === 'LoadLocal' && |
| 179 | innerValue.place.identifier.id === result.place.identifier.id; |
| 180 | |
| 181 | if (!isLoadOfSamePlace) { |
| 182 | instructions.push({ |
| 183 | id: result.id, |
| 184 | lvalue: result.place, |
| 185 | value: innerValue, |
| 186 | loc, |
| 187 | }); |
| 188 | } |
| 189 | |
| 190 | return { |
| 191 | kind: 'SequenceExpression', |
| 192 | instructions, |
| 193 | id: result.id, |
| 194 | value: {kind: 'Primitive', value: undefined, loc}, |
| 195 | loc, |
| 196 | }; |
| 197 | } |
| 198 | |
| 199 | traverseBlock(block: BasicBlock): ReactiveBlock { |
| 200 | const blockValue: ReactiveBlock = []; |
| 201 | this.visitBlock(block, blockValue); |
| 202 | return blockValue; |
| 203 | } |
| 204 | |
| 205 | visitBlock(block: BasicBlock, blockValue: ReactiveBlock): void { |
| 206 | CompilerError.invariant(!this.cx.emitted.has(block.id), { |
| 207 | reason: `Cannot emit the same block twice: bb${block.id}`, |
| 208 | loc: GeneratedSource, |
| 209 | }); |
| 210 | this.cx.emitted.add(block.id); |
| 211 | for (const instruction of block.instructions) { |
| 212 | blockValue.push({ |
| 213 | kind: 'instruction', |
| 214 | instruction, |
| 215 | }); |
| 216 | } |
| 217 | |
| 218 | const terminal = block.terminal; |
| 219 | const scheduleIds = []; |
| 220 | switch (terminal.kind) { |
| 221 | case 'return': { |
| 222 | blockValue.push({ |
| 223 | kind: 'terminal', |
| 224 | terminal: { |
| 225 | kind: 'return', |
| 226 | loc: terminal.loc, |
| 227 | value: terminal.value, |
| 228 | id: terminal.id, |
| 229 | }, |
| 230 | label: null, |
| 231 | }); |
| 232 | break; |
| 233 | } |
| 234 | case 'throw': { |
| 235 | blockValue.push({ |
| 236 | kind: 'terminal', |
| 237 | terminal: { |
| 238 | kind: 'throw', |
| 239 | loc: terminal.loc, |
| 240 | value: terminal.value, |
| 241 | id: terminal.id, |
| 242 | }, |
| 243 | label: null, |
| 244 | }); |
| 245 | break; |
| 246 | } |
| 247 | case 'if': { |
| 248 | const fallthroughId = |
| 249 | this.cx.reachable(terminal.fallthrough) && |
| 250 | !this.cx.isScheduled(terminal.fallthrough) |
| 251 | ? terminal.fallthrough |
| 252 | : null; |
| 253 | const alternateId = |
| 254 | terminal.alternate !== terminal.fallthrough |
| 255 | ? terminal.alternate |
| 256 | : null; |
| 257 | |
| 258 | if (fallthroughId !== null) { |
| 259 | const scheduleId = this.cx.schedule(fallthroughId, 'if'); |
| 260 | scheduleIds.push(scheduleId); |
| 261 | } |
| 262 | |
| 263 | let consequent: ReactiveBlock | null = null; |
| 264 | if (this.cx.isScheduled(terminal.consequent)) { |
| 265 | CompilerError.invariant(false, { |
| 266 | reason: `Unexpected 'if' where the consequent is already scheduled`, |
| 267 | loc: terminal.loc, |
| 268 | }); |
| 269 | } else { |
| 270 | consequent = this.traverseBlock( |
| 271 | this.cx.ir.blocks.get(terminal.consequent)!, |
| 272 | ); |
| 273 | } |
| 274 | |
| 275 | let alternate: ReactiveBlock | null = null; |
| 276 | if (alternateId !== null) { |
| 277 | if (this.cx.isScheduled(alternateId)) { |
| 278 | CompilerError.invariant(false, { |
| 279 | reason: `Unexpected 'if' where the alternate is already scheduled`, |
| 280 | loc: terminal.loc, |
| 281 | }); |
| 282 | } else { |
| 283 | alternate = this.traverseBlock(this.cx.ir.blocks.get(alternateId)!); |
| 284 | } |
| 285 | } |
| 286 | |
| 287 | this.cx.unscheduleAll(scheduleIds); |
| 288 | blockValue.push({ |
| 289 | kind: 'terminal', |
| 290 | terminal: { |
| 291 | kind: 'if', |
| 292 | loc: terminal.loc, |
| 293 | test: terminal.test, |
| 294 | consequent: consequent ?? this.emptyBlock(), |
| 295 | alternate: alternate, |
| 296 | id: terminal.id, |
| 297 | }, |
| 298 | label: |
| 299 | fallthroughId == null |
| 300 | ? null |
| 301 | : { |
| 302 | id: fallthroughId, |
| 303 | implicit: false, |
| 304 | }, |
| 305 | }); |
| 306 | if (fallthroughId !== null) { |
| 307 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 308 | } |
| 309 | break; |
| 310 | } |
| 311 | case 'switch': { |
| 312 | const fallthroughId = |
| 313 | this.cx.reachable(terminal.fallthrough) && |
| 314 | !this.cx.isScheduled(terminal.fallthrough) |
| 315 | ? terminal.fallthrough |
| 316 | : null; |
| 317 | if (fallthroughId !== null) { |
| 318 | const scheduleId = this.cx.schedule(fallthroughId, 'switch'); |
| 319 | scheduleIds.push(scheduleId); |
| 320 | } |
| 321 | |
| 322 | const cases: Array<{ |
| 323 | test: Place | null; |
| 324 | block: ReactiveBlock; |
| 325 | }> = []; |
| 326 | [...terminal.cases].reverse().forEach((case_, _index) => { |
| 327 | const test = case_.test; |
| 328 | |
| 329 | let consequent: ReactiveBlock; |
| 330 | if (this.cx.isScheduled(case_.block)) { |
| 331 | CompilerError.invariant(case_.block === terminal.fallthrough, { |
| 332 | reason: `Unexpected 'switch' where a case is already scheduled and block is not the fallthrough`, |
| 333 | loc: terminal.loc, |
| 334 | }); |
| 335 | return; |
| 336 | } else { |
| 337 | consequent = this.traverseBlock( |
| 338 | this.cx.ir.blocks.get(case_.block)!, |
| 339 | ); |
| 340 | const scheduleId = this.cx.schedule(case_.block, 'case'); |
| 341 | scheduleIds.push(scheduleId); |
| 342 | } |
| 343 | cases.push({test, block: consequent}); |
| 344 | }); |
| 345 | cases.reverse(); |
| 346 | |
| 347 | this.cx.unscheduleAll(scheduleIds); |
| 348 | blockValue.push({ |
| 349 | kind: 'terminal', |
| 350 | terminal: { |
| 351 | kind: 'switch', |
| 352 | loc: terminal.loc, |
| 353 | test: terminal.test, |
| 354 | cases, |
| 355 | id: terminal.id, |
| 356 | }, |
| 357 | label: |
| 358 | fallthroughId == null |
| 359 | ? null |
| 360 | : { |
| 361 | id: fallthroughId, |
| 362 | implicit: false, |
| 363 | }, |
| 364 | }); |
| 365 | if (fallthroughId !== null) { |
| 366 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 367 | } |
| 368 | break; |
| 369 | } |
| 370 | case 'do-while': { |
| 371 | const fallthroughId = !this.cx.isScheduled(terminal.fallthrough) |
| 372 | ? terminal.fallthrough |
| 373 | : null; |
| 374 | const loopId = |
| 375 | !this.cx.isScheduled(terminal.loop) && |
| 376 | terminal.loop !== terminal.fallthrough |
| 377 | ? terminal.loop |
| 378 | : null; |
| 379 | const scheduleId = this.cx.scheduleLoop( |
| 380 | terminal.fallthrough, |
| 381 | terminal.test, |
| 382 | terminal.loop, |
| 383 | ); |
| 384 | scheduleIds.push(scheduleId); |
| 385 | |
| 386 | let loopBody: ReactiveBlock; |
| 387 | if (loopId) { |
| 388 | loopBody = this.traverseBlock(this.cx.ir.blocks.get(loopId)!); |
| 389 | } else { |
| 390 | CompilerError.invariant(false, { |
| 391 | reason: `Unexpected 'do-while' where the loop is already scheduled`, |
| 392 | loc: terminal.loc, |
| 393 | }); |
| 394 | } |
| 395 | |
| 396 | const testValue = this.visitValueBlock( |
| 397 | terminal.test, |
| 398 | terminal.loc, |
| 399 | ).value; |
| 400 | |
| 401 | this.cx.unscheduleAll(scheduleIds); |
| 402 | blockValue.push({ |
| 403 | kind: 'terminal', |
| 404 | terminal: { |
| 405 | kind: 'do-while', |
| 406 | loc: terminal.loc, |
| 407 | test: testValue, |
| 408 | loop: loopBody, |
| 409 | id: terminal.id, |
| 410 | }, |
| 411 | label: |
| 412 | fallthroughId == null |
| 413 | ? null |
| 414 | : { |
| 415 | id: fallthroughId, |
| 416 | implicit: false, |
| 417 | }, |
| 418 | }); |
| 419 | if (fallthroughId !== null) { |
| 420 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 421 | } |
| 422 | break; |
| 423 | } |
| 424 | case 'while': { |
| 425 | const fallthroughId = |
| 426 | this.cx.reachable(terminal.fallthrough) && |
| 427 | !this.cx.isScheduled(terminal.fallthrough) |
| 428 | ? terminal.fallthrough |
| 429 | : null; |
| 430 | const loopId = |
| 431 | !this.cx.isScheduled(terminal.loop) && |
| 432 | terminal.loop !== terminal.fallthrough |
| 433 | ? terminal.loop |
| 434 | : null; |
| 435 | const scheduleId = this.cx.scheduleLoop( |
| 436 | terminal.fallthrough, |
| 437 | terminal.test, |
| 438 | terminal.loop, |
| 439 | ); |
| 440 | scheduleIds.push(scheduleId); |
| 441 | |
| 442 | const testValue = this.visitValueBlock( |
| 443 | terminal.test, |
| 444 | terminal.loc, |
| 445 | ).value; |
| 446 | |
| 447 | let loopBody: ReactiveBlock; |
| 448 | if (loopId) { |
| 449 | loopBody = this.traverseBlock(this.cx.ir.blocks.get(loopId)!); |
| 450 | } else { |
| 451 | CompilerError.invariant(false, { |
| 452 | reason: `Unexpected 'while' where the loop is already scheduled`, |
| 453 | loc: terminal.loc, |
| 454 | }); |
| 455 | } |
| 456 | |
| 457 | this.cx.unscheduleAll(scheduleIds); |
| 458 | blockValue.push({ |
| 459 | kind: 'terminal', |
| 460 | terminal: { |
| 461 | kind: 'while', |
| 462 | loc: terminal.loc, |
| 463 | test: testValue, |
| 464 | loop: loopBody, |
| 465 | id: terminal.id, |
| 466 | }, |
| 467 | label: |
| 468 | fallthroughId == null |
| 469 | ? null |
| 470 | : { |
| 471 | id: fallthroughId, |
| 472 | implicit: false, |
| 473 | }, |
| 474 | }); |
| 475 | if (fallthroughId !== null) { |
| 476 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 477 | } |
| 478 | break; |
| 479 | } |
| 480 | case 'for': { |
| 481 | const loopId = |
| 482 | !this.cx.isScheduled(terminal.loop) && |
| 483 | terminal.loop !== terminal.fallthrough |
| 484 | ? terminal.loop |
| 485 | : null; |
| 486 | |
| 487 | const fallthroughId = !this.cx.isScheduled(terminal.fallthrough) |
| 488 | ? terminal.fallthrough |
| 489 | : null; |
| 490 | |
| 491 | const scheduleId = this.cx.scheduleLoop( |
| 492 | terminal.fallthrough, |
| 493 | terminal.update ?? terminal.test, |
| 494 | terminal.loop, |
| 495 | ); |
| 496 | scheduleIds.push(scheduleId); |
| 497 | |
| 498 | const init = this.visitValueBlock(terminal.init, terminal.loc); |
| 499 | const initValue = this.valueBlockResultToSequence(init, terminal.loc); |
| 500 | |
| 501 | const testValue = this.visitValueBlock( |
| 502 | terminal.test, |
| 503 | terminal.loc, |
| 504 | ).value; |
| 505 | |
| 506 | const updateValue = |
| 507 | terminal.update !== null |
| 508 | ? this.visitValueBlock(terminal.update, terminal.loc).value |
| 509 | : null; |
| 510 | |
| 511 | let loopBody: ReactiveBlock; |
| 512 | if (loopId) { |
| 513 | loopBody = this.traverseBlock(this.cx.ir.blocks.get(loopId)!); |
| 514 | } else { |
| 515 | CompilerError.invariant(false, { |
| 516 | reason: `Unexpected 'for' where the loop is already scheduled`, |
| 517 | loc: terminal.loc, |
| 518 | }); |
| 519 | } |
| 520 | |
| 521 | this.cx.unscheduleAll(scheduleIds); |
| 522 | blockValue.push({ |
| 523 | kind: 'terminal', |
| 524 | terminal: { |
| 525 | kind: 'for', |
| 526 | loc: terminal.loc, |
| 527 | init: initValue, |
| 528 | test: testValue, |
| 529 | update: updateValue, |
| 530 | loop: loopBody, |
| 531 | id: terminal.id, |
| 532 | }, |
| 533 | label: |
| 534 | fallthroughId == null ? null : {id: fallthroughId, implicit: false}, |
| 535 | }); |
| 536 | if (fallthroughId !== null) { |
| 537 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 538 | } |
| 539 | break; |
| 540 | } |
| 541 | case 'for-of': { |
| 542 | const loopId = |
| 543 | !this.cx.isScheduled(terminal.loop) && |
| 544 | terminal.loop !== terminal.fallthrough |
| 545 | ? terminal.loop |
| 546 | : null; |
| 547 | |
| 548 | const fallthroughId = !this.cx.isScheduled(terminal.fallthrough) |
| 549 | ? terminal.fallthrough |
| 550 | : null; |
| 551 | |
| 552 | const scheduleId = this.cx.scheduleLoop( |
| 553 | terminal.fallthrough, |
| 554 | terminal.init, |
| 555 | terminal.loop, |
| 556 | ); |
| 557 | scheduleIds.push(scheduleId); |
| 558 | |
| 559 | const init = this.visitValueBlock(terminal.init, terminal.loc); |
| 560 | const initValue = this.valueBlockResultToSequence(init, terminal.loc); |
| 561 | |
| 562 | const test = this.visitValueBlock(terminal.test, terminal.loc); |
| 563 | const testValue = this.valueBlockResultToSequence(test, terminal.loc); |
| 564 | |
| 565 | let loopBody: ReactiveBlock; |
| 566 | if (loopId) { |
| 567 | loopBody = this.traverseBlock(this.cx.ir.blocks.get(loopId)!); |
| 568 | } else { |
| 569 | CompilerError.invariant(false, { |
| 570 | reason: `Unexpected 'for-of' where the loop is already scheduled`, |
| 571 | loc: terminal.loc, |
| 572 | }); |
| 573 | } |
| 574 | |
| 575 | this.cx.unscheduleAll(scheduleIds); |
| 576 | blockValue.push({ |
| 577 | kind: 'terminal', |
| 578 | terminal: { |
| 579 | kind: 'for-of', |
| 580 | loc: terminal.loc, |
| 581 | init: initValue, |
| 582 | test: testValue, |
| 583 | loop: loopBody, |
| 584 | id: terminal.id, |
| 585 | }, |
| 586 | label: |
| 587 | fallthroughId == null ? null : {id: fallthroughId, implicit: false}, |
| 588 | }); |
| 589 | if (fallthroughId !== null) { |
| 590 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 591 | } |
| 592 | break; |
| 593 | } |
| 594 | case 'for-in': { |
| 595 | const loopId = |
| 596 | !this.cx.isScheduled(terminal.loop) && |
| 597 | terminal.loop !== terminal.fallthrough |
| 598 | ? terminal.loop |
| 599 | : null; |
| 600 | |
| 601 | const fallthroughId = !this.cx.isScheduled(terminal.fallthrough) |
| 602 | ? terminal.fallthrough |
| 603 | : null; |
| 604 | |
| 605 | const scheduleId = this.cx.scheduleLoop( |
| 606 | terminal.fallthrough, |
| 607 | terminal.init, |
| 608 | terminal.loop, |
| 609 | ); |
| 610 | scheduleIds.push(scheduleId); |
| 611 | |
| 612 | const init = this.visitValueBlock(terminal.init, terminal.loc); |
| 613 | const initValue = this.valueBlockResultToSequence(init, terminal.loc); |
| 614 | |
| 615 | let loopBody: ReactiveBlock; |
| 616 | if (loopId) { |
| 617 | loopBody = this.traverseBlock(this.cx.ir.blocks.get(loopId)!); |
| 618 | } else { |
| 619 | CompilerError.invariant(false, { |
| 620 | reason: `Unexpected 'for-in' where the loop is already scheduled`, |
| 621 | loc: terminal.loc, |
| 622 | }); |
| 623 | } |
| 624 | |
| 625 | this.cx.unscheduleAll(scheduleIds); |
| 626 | blockValue.push({ |
| 627 | kind: 'terminal', |
| 628 | terminal: { |
| 629 | kind: 'for-in', |
| 630 | loc: terminal.loc, |
| 631 | init: initValue, |
| 632 | loop: loopBody, |
| 633 | id: terminal.id, |
| 634 | }, |
| 635 | label: |
| 636 | fallthroughId == null ? null : {id: fallthroughId, implicit: false}, |
| 637 | }); |
| 638 | if (fallthroughId !== null) { |
| 639 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 640 | } |
| 641 | break; |
| 642 | } |
| 643 | case 'branch': { |
| 644 | let consequent: ReactiveBlock | null = null; |
| 645 | if (this.cx.isScheduled(terminal.consequent)) { |
| 646 | const break_ = this.visitBreak( |
| 647 | terminal.consequent, |
| 648 | terminal.id, |
| 649 | terminal.loc, |
| 650 | ); |
| 651 | if (break_ !== null) { |
| 652 | consequent = [break_]; |
| 653 | } |
| 654 | } else { |
| 655 | consequent = this.traverseBlock( |
| 656 | this.cx.ir.blocks.get(terminal.consequent)!, |
| 657 | ); |
| 658 | } |
| 659 | |
| 660 | let alternate: ReactiveBlock | null = null; |
| 661 | if (this.cx.isScheduled(terminal.alternate)) { |
| 662 | CompilerError.invariant(false, { |
| 663 | reason: `Unexpected 'branch' where the alternate is already scheduled`, |
| 664 | loc: terminal.loc, |
| 665 | }); |
| 666 | } else { |
| 667 | alternate = this.traverseBlock( |
| 668 | this.cx.ir.blocks.get(terminal.alternate)!, |
| 669 | ); |
| 670 | } |
| 671 | |
| 672 | blockValue.push({ |
| 673 | kind: 'terminal', |
| 674 | terminal: { |
| 675 | kind: 'if', |
| 676 | loc: terminal.loc, |
| 677 | test: terminal.test, |
| 678 | consequent: consequent ?? this.emptyBlock(), |
| 679 | alternate: alternate, |
| 680 | id: terminal.id, |
| 681 | }, |
| 682 | label: null, |
| 683 | }); |
| 684 | |
| 685 | break; |
| 686 | } |
| 687 | case 'label': { |
| 688 | const fallthroughId = |
| 689 | this.cx.reachable(terminal.fallthrough) && |
| 690 | !this.cx.isScheduled(terminal.fallthrough) |
| 691 | ? terminal.fallthrough |
| 692 | : null; |
| 693 | if (fallthroughId !== null) { |
| 694 | const scheduleId = this.cx.schedule(fallthroughId, 'if'); |
| 695 | scheduleIds.push(scheduleId); |
| 696 | } |
| 697 | |
| 698 | let block: ReactiveBlock; |
| 699 | if (this.cx.isScheduled(terminal.block)) { |
| 700 | CompilerError.invariant(false, { |
| 701 | reason: `Unexpected 'label' where the block is already scheduled`, |
| 702 | loc: terminal.loc, |
| 703 | }); |
| 704 | } else { |
| 705 | block = this.traverseBlock(this.cx.ir.blocks.get(terminal.block)!); |
| 706 | } |
| 707 | |
| 708 | this.cx.unscheduleAll(scheduleIds); |
| 709 | blockValue.push({ |
| 710 | kind: 'terminal', |
| 711 | terminal: { |
| 712 | kind: 'label', |
| 713 | loc: terminal.loc, |
| 714 | block, |
| 715 | id: terminal.id, |
| 716 | }, |
| 717 | label: |
| 718 | fallthroughId == null ? null : {id: fallthroughId, implicit: false}, |
| 719 | }); |
| 720 | if (fallthroughId !== null) { |
| 721 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 722 | } |
| 723 | |
| 724 | break; |
| 725 | } |
| 726 | case 'sequence': |
| 727 | case 'optional': |
| 728 | case 'ternary': |
| 729 | case 'logical': { |
| 730 | const fallthroughId = |
| 731 | terminal.fallthrough !== null && |
| 732 | !this.cx.isScheduled(terminal.fallthrough) |
| 733 | ? terminal.fallthrough |
| 734 | : null; |
| 735 | if (fallthroughId !== null) { |
| 736 | const scheduleId = this.cx.schedule(fallthroughId, 'if'); |
| 737 | scheduleIds.push(scheduleId); |
| 738 | } |
| 739 | |
| 740 | const {place, value} = this.visitValueBlockTerminal(terminal); |
| 741 | this.cx.unscheduleAll(scheduleIds); |
| 742 | blockValue.push({ |
| 743 | kind: 'instruction', |
| 744 | instruction: { |
| 745 | id: terminal.id, |
| 746 | lvalue: place, |
| 747 | value, |
| 748 | loc: terminal.loc, |
| 749 | }, |
| 750 | }); |
| 751 | |
| 752 | if (fallthroughId !== null) { |
| 753 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 754 | } |
| 755 | break; |
| 756 | } |
| 757 | case 'goto': { |
| 758 | switch (terminal.variant) { |
| 759 | case GotoVariant.Break: { |
| 760 | const break_ = this.visitBreak( |
| 761 | terminal.block, |
| 762 | terminal.id, |
| 763 | terminal.loc, |
| 764 | ); |
| 765 | if (break_ !== null) { |
| 766 | blockValue.push(break_); |
| 767 | } |
| 768 | break; |
| 769 | } |
| 770 | case GotoVariant.Continue: { |
| 771 | const continue_ = this.visitContinue( |
| 772 | terminal.block, |
| 773 | terminal.id, |
| 774 | terminal.loc, |
| 775 | ); |
| 776 | if (continue_ !== null) { |
| 777 | blockValue.push(continue_); |
| 778 | } |
| 779 | break; |
| 780 | } |
| 781 | case GotoVariant.Try: { |
| 782 | break; |
| 783 | } |
| 784 | default: { |
| 785 | assertExhaustive( |
| 786 | terminal.variant, |
| 787 | `Unexpected goto variant \`${terminal.variant}\``, |
| 788 | ); |
| 789 | } |
| 790 | } |
| 791 | break; |
| 792 | } |
| 793 | case 'maybe-throw': { |
| 794 | /* |
| 795 | * ReactiveFunction does not explicit model maybe-throw semantics, |
| 796 | * so these terminals flatten away |
| 797 | */ |
| 798 | if (!this.cx.isScheduled(terminal.continuation)) { |
| 799 | this.visitBlock( |
| 800 | this.cx.ir.blocks.get(terminal.continuation)!, |
| 801 | blockValue, |
| 802 | ); |
| 803 | } |
| 804 | break; |
| 805 | } |
| 806 | case 'try': { |
| 807 | const fallthroughId = |
| 808 | this.cx.reachable(terminal.fallthrough) && |
| 809 | !this.cx.isScheduled(terminal.fallthrough) |
| 810 | ? terminal.fallthrough |
| 811 | : null; |
| 812 | if (fallthroughId !== null) { |
| 813 | const scheduleId = this.cx.schedule(fallthroughId, 'if'); |
| 814 | scheduleIds.push(scheduleId); |
| 815 | } |
| 816 | this.cx.scheduleCatchHandler(terminal.handler); |
| 817 | |
| 818 | const block = this.traverseBlock( |
| 819 | this.cx.ir.blocks.get(terminal.block)!, |
| 820 | ); |
| 821 | const handler = this.traverseBlock( |
| 822 | this.cx.ir.blocks.get(terminal.handler)!, |
| 823 | ); |
| 824 | |
| 825 | this.cx.unscheduleAll(scheduleIds); |
| 826 | blockValue.push({ |
| 827 | kind: 'terminal', |
| 828 | label: |
| 829 | fallthroughId == null ? null : {id: fallthroughId, implicit: false}, |
| 830 | terminal: { |
| 831 | kind: 'try', |
| 832 | loc: terminal.loc, |
| 833 | block, |
| 834 | handlerBinding: terminal.handlerBinding, |
| 835 | handler, |
| 836 | id: terminal.id, |
| 837 | }, |
| 838 | }); |
| 839 | |
| 840 | if (fallthroughId !== null) { |
| 841 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 842 | } |
| 843 | break; |
| 844 | } |
| 845 | case 'pruned-scope': |
| 846 | case 'scope': { |
| 847 | const fallthroughId = !this.cx.isScheduled(terminal.fallthrough) |
| 848 | ? terminal.fallthrough |
| 849 | : null; |
| 850 | if (fallthroughId !== null) { |
| 851 | const scheduleId = this.cx.schedule(fallthroughId, 'if'); |
| 852 | scheduleIds.push(scheduleId); |
| 853 | this.cx.scopeFallthroughs.add(fallthroughId); |
| 854 | } |
| 855 | |
| 856 | let block: ReactiveBlock; |
| 857 | if (this.cx.isScheduled(terminal.block)) { |
| 858 | CompilerError.invariant(false, { |
| 859 | reason: `Unexpected 'scope' where the block is already scheduled`, |
| 860 | loc: terminal.loc, |
| 861 | }); |
| 862 | } else { |
| 863 | block = this.traverseBlock(this.cx.ir.blocks.get(terminal.block)!); |
| 864 | } |
| 865 | |
| 866 | this.cx.unscheduleAll(scheduleIds); |
| 867 | blockValue.push({ |
| 868 | kind: terminal.kind, |
| 869 | instructions: block, |
| 870 | scope: terminal.scope, |
| 871 | }); |
| 872 | if (fallthroughId !== null) { |
| 873 | this.visitBlock(this.cx.ir.blocks.get(fallthroughId)!, blockValue); |
| 874 | } |
| 875 | |
| 876 | break; |
| 877 | } |
| 878 | case 'unreachable': { |
| 879 | // noop |
| 880 | break; |
| 881 | } |
| 882 | case 'unsupported': { |
| 883 | CompilerError.invariant(false, { |
| 884 | reason: 'Unexpected unsupported terminal', |
| 885 | loc: terminal.loc, |
| 886 | }); |
| 887 | } |
| 888 | default: { |
| 889 | assertExhaustive(terminal, 'Unexpected terminal'); |
| 890 | } |
| 891 | } |
| 892 | } |
| 893 | |
| 894 | visitValueBlock( |
| 895 | blockId: BlockId, |
| 896 | loc: SourceLocation, |
| 897 | fallthrough: BlockId | null = null, |
| 898 | ): {block: BlockId; value: ReactiveValue; place: Place; id: InstructionId} { |
| 899 | const block = this.cx.ir.blocks.get(blockId)!; |
| 900 | // If we've reached the fallthrough block, stop recursing |
| 901 | if (fallthrough !== null && blockId === fallthrough) { |
| 902 | CompilerError.invariant(false, { |
| 903 | reason: 'Did not expect to reach the fallthrough of a value block', |
| 904 | description: `Reached bb${blockId}, which is the fallthrough for this value block`, |
| 905 | loc, |
| 906 | }); |
| 907 | } |
| 908 | if (block.terminal.kind === 'branch') { |
| 909 | if (block.instructions.length === 0) { |
| 910 | return { |
| 911 | block: block.id, |
| 912 | place: block.terminal.test, |
| 913 | value: { |
| 914 | kind: 'LoadLocal', |
| 915 | place: block.terminal.test, |
| 916 | loc: block.terminal.test.loc, |
| 917 | }, |
| 918 | id: block.terminal.id, |
| 919 | }; |
| 920 | } |
| 921 | return this.extractValueBlockResult(block.instructions, block.id, loc); |
| 922 | } else if (block.terminal.kind === 'goto') { |
| 923 | if (block.instructions.length === 0) { |
| 924 | CompilerError.invariant(false, { |
| 925 | reason: 'Unexpected empty block with `goto` terminal', |
| 926 | description: `Block bb${block.id} is empty`, |
| 927 | loc, |
| 928 | }); |
| 929 | } |
| 930 | return this.extractValueBlockResult(block.instructions, block.id, loc); |
| 931 | } else if (block.terminal.kind === 'maybe-throw') { |
| 932 | /* |
| 933 | * ReactiveFunction does not explicitly model maybe-throw semantics, |
| 934 | * so maybe-throw terminals in value blocks flatten away. In general |
| 935 | * we recurse to the continuation block. |
| 936 | * |
| 937 | * However, if the last portion |
| 938 | * of the value block is a potentially throwing expression, then the |
| 939 | * value block could be of the form |
| 940 | * ``` |
| 941 | * bb1: |
| 942 | * ...StoreLocal for the value block... |
| 943 | * maybe-throw continuation=bb2 |
| 944 | * bb2: |
| 945 | * goto (exit the value block) |
| 946 | * ``` |
| 947 | * |
| 948 | * Ie what would have been a StoreLocal+goto is split up because of |
| 949 | * the maybe-throw. We detect this case and return the value of the |
| 950 | * current block as the result of the value block |
| 951 | */ |
| 952 | const continuationId = block.terminal.continuation; |
| 953 | const continuationBlock = this.cx.ir.blocks.get(continuationId)!; |
| 954 | if ( |
| 955 | continuationBlock.instructions.length === 0 && |
| 956 | continuationBlock.terminal.kind === 'goto' |
| 957 | ) { |
| 958 | return this.extractValueBlockResult( |
| 959 | block.instructions, |
| 960 | continuationBlock.id, |
| 961 | loc, |
| 962 | ); |
| 963 | } |
| 964 | |
| 965 | const continuation = this.visitValueBlock( |
| 966 | continuationId, |
| 967 | loc, |
| 968 | fallthrough, |
| 969 | ); |
| 970 | return this.wrapWithSequence(block.instructions, continuation, loc); |
| 971 | } else { |
| 972 | /* |
| 973 | * The value block ended in a value terminal, recurse to get the value |
| 974 | * of that terminal and stitch them together in a sequence. |
| 975 | */ |
| 976 | const init = this.visitValueBlockTerminal(block.terminal); |
| 977 | const final = this.visitValueBlock(init.fallthrough, loc); |
| 978 | return this.wrapWithSequence( |
| 979 | [ |
| 980 | ...block.instructions, |
| 981 | {id: init.id, loc, lvalue: init.place, value: init.value}, |
| 982 | ], |
| 983 | final, |
| 984 | loc, |
| 985 | ); |
| 986 | } |
| 987 | } |
| 988 | |
| 989 | /* |
| 990 | * Visits the test block of a value terminal (optional, logical, ternary) and |
| 991 | * returns the result along with the branch terminal. Throws a todo error if |
| 992 | * the test block does not end in a branch terminal. |
| 993 | */ |
| 994 | visitTestBlock( |
| 995 | testBlockId: BlockId, |
| 996 | loc: SourceLocation, |
| 997 | terminalKind: string, |
| 998 | ): { |
| 999 | test: { |
| 1000 | block: BlockId; |
| 1001 | value: ReactiveValue; |
| 1002 | place: Place; |
| 1003 | id: InstructionId; |
| 1004 | }; |
| 1005 | branch: {consequent: BlockId; alternate: BlockId; loc: SourceLocation}; |
| 1006 | } { |
| 1007 | const test = this.visitValueBlock(testBlockId, loc); |
| 1008 | const testBlock = this.cx.ir.blocks.get(test.block)!; |
| 1009 | if (testBlock.terminal.kind !== 'branch') { |
| 1010 | CompilerError.invariant(false, { |
| 1011 | reason: `Expected a branch terminal for ${terminalKind} test block`, |
| 1012 | description: `Got \`${testBlock.terminal.kind}\``, |
| 1013 | loc: testBlock.terminal.loc, |
| 1014 | }); |
| 1015 | } |
| 1016 | return { |
| 1017 | test, |
| 1018 | branch: { |
| 1019 | consequent: testBlock.terminal.consequent, |
| 1020 | alternate: testBlock.terminal.alternate, |
| 1021 | loc: testBlock.terminal.loc, |
| 1022 | }, |
| 1023 | }; |
| 1024 | } |
| 1025 | |
| 1026 | visitValueBlockTerminal(terminal: Terminal): { |
| 1027 | value: ReactiveValue; |
| 1028 | place: Place; |
| 1029 | fallthrough: BlockId; |
| 1030 | id: InstructionId; |
| 1031 | } { |
| 1032 | switch (terminal.kind) { |
| 1033 | case 'sequence': { |
| 1034 | const block = this.visitValueBlock( |
| 1035 | terminal.block, |
| 1036 | terminal.loc, |
| 1037 | terminal.fallthrough, |
| 1038 | ); |
| 1039 | return { |
| 1040 | value: block.value, |
| 1041 | place: block.place, |
| 1042 | fallthrough: terminal.fallthrough, |
| 1043 | id: terminal.id, |
| 1044 | }; |
| 1045 | } |
| 1046 | case 'optional': { |
| 1047 | const {test, branch} = this.visitTestBlock( |
| 1048 | terminal.test, |
| 1049 | terminal.loc, |
| 1050 | 'optional', |
| 1051 | ); |
| 1052 | const consequent = this.visitValueBlock( |
| 1053 | branch.consequent, |
| 1054 | terminal.loc, |
| 1055 | terminal.fallthrough, |
| 1056 | ); |
| 1057 | const call: ReactiveSequenceValue = { |
| 1058 | kind: 'SequenceExpression', |
| 1059 | instructions: [ |
| 1060 | { |
| 1061 | id: test.id, |
| 1062 | loc: branch.loc, |
| 1063 | lvalue: test.place, |
| 1064 | value: test.value, |
| 1065 | }, |
| 1066 | ], |
| 1067 | id: consequent.id, |
| 1068 | value: consequent.value, |
| 1069 | loc: terminal.loc, |
| 1070 | }; |
| 1071 | return { |
| 1072 | place: {...consequent.place}, |
| 1073 | value: { |
| 1074 | kind: 'OptionalExpression', |
| 1075 | optional: terminal.optional, |
| 1076 | value: call, |
| 1077 | id: terminal.id, |
| 1078 | loc: terminal.loc, |
| 1079 | }, |
| 1080 | fallthrough: terminal.fallthrough, |
| 1081 | id: terminal.id, |
| 1082 | }; |
| 1083 | } |
| 1084 | case 'logical': { |
| 1085 | const {test, branch} = this.visitTestBlock( |
| 1086 | terminal.test, |
| 1087 | terminal.loc, |
| 1088 | 'logical', |
| 1089 | ); |
| 1090 | const leftFinal = this.visitValueBlock( |
| 1091 | branch.consequent, |
| 1092 | terminal.loc, |
| 1093 | terminal.fallthrough, |
| 1094 | ); |
| 1095 | const left: ReactiveSequenceValue = { |
| 1096 | kind: 'SequenceExpression', |
| 1097 | instructions: [ |
| 1098 | { |
| 1099 | id: test.id, |
| 1100 | loc: terminal.loc, |
| 1101 | lvalue: test.place, |
| 1102 | value: test.value, |
| 1103 | }, |
| 1104 | ], |
| 1105 | id: leftFinal.id, |
| 1106 | value: leftFinal.value, |
| 1107 | loc: terminal.loc, |
| 1108 | }; |
| 1109 | const right = this.visitValueBlock( |
| 1110 | branch.alternate, |
| 1111 | terminal.loc, |
| 1112 | terminal.fallthrough, |
| 1113 | ); |
| 1114 | const value: ReactiveLogicalValue = { |
| 1115 | kind: 'LogicalExpression', |
| 1116 | operator: terminal.operator, |
| 1117 | left: left, |
| 1118 | right: right.value, |
| 1119 | loc: terminal.loc, |
| 1120 | }; |
| 1121 | return { |
| 1122 | place: {...leftFinal.place}, |
| 1123 | value, |
| 1124 | fallthrough: terminal.fallthrough, |
| 1125 | id: terminal.id, |
| 1126 | }; |
| 1127 | } |
| 1128 | case 'ternary': { |
| 1129 | const {test, branch} = this.visitTestBlock( |
| 1130 | terminal.test, |
| 1131 | terminal.loc, |
| 1132 | 'ternary', |
| 1133 | ); |
| 1134 | const consequent = this.visitValueBlock( |
| 1135 | branch.consequent, |
| 1136 | terminal.loc, |
| 1137 | terminal.fallthrough, |
| 1138 | ); |
| 1139 | const alternate = this.visitValueBlock( |
| 1140 | branch.alternate, |
| 1141 | terminal.loc, |
| 1142 | terminal.fallthrough, |
| 1143 | ); |
| 1144 | const value: ReactiveTernaryValue = { |
| 1145 | kind: 'ConditionalExpression', |
| 1146 | test: test.value, |
| 1147 | consequent: consequent.value, |
| 1148 | alternate: alternate.value, |
| 1149 | loc: terminal.loc, |
| 1150 | }; |
| 1151 | |
| 1152 | return { |
| 1153 | place: {...consequent.place}, |
| 1154 | value, |
| 1155 | fallthrough: terminal.fallthrough, |
| 1156 | id: terminal.id, |
| 1157 | }; |
| 1158 | } |
| 1159 | case 'maybe-throw': { |
| 1160 | CompilerError.invariant(false, { |
| 1161 | reason: `Unexpected maybe-throw in visitValueBlockTerminal - should be handled in visitValueBlock`, |
| 1162 | description: null, |
| 1163 | loc: terminal.loc, |
| 1164 | }); |
| 1165 | } |
| 1166 | case 'label': { |
| 1167 | CompilerError.throwTodo({ |
| 1168 | reason: `Support labeled statements combined with value blocks (conditional, logical, optional chaining, etc)`, |
| 1169 | description: null, |
| 1170 | loc: terminal.loc, |
| 1171 | suggestions: null, |
| 1172 | }); |
| 1173 | } |
| 1174 | default: { |
| 1175 | CompilerError.throwTodo({ |
| 1176 | reason: `Support \`${terminal.kind}\` as a value block terminal (conditional, logical, optional chaining, etc)`, |
| 1177 | description: null, |
| 1178 | loc: terminal.loc, |
| 1179 | suggestions: null, |
| 1180 | }); |
| 1181 | } |
| 1182 | } |
| 1183 | } |
| 1184 | |
| 1185 | emptyBlock(): ReactiveBlock { |
| 1186 | return []; |
| 1187 | } |
| 1188 | |
| 1189 | visitBreak( |
| 1190 | block: BlockId, |
| 1191 | id: InstructionId, |
| 1192 | loc: SourceLocation, |
| 1193 | ): ReactiveTerminalStatement<ReactiveBreakTerminal> | null { |
| 1194 | const target = this.cx.getBreakTarget(block); |
| 1195 | if (target === null) { |
| 1196 | CompilerError.invariant(false, { |
| 1197 | reason: 'Expected a break target', |
| 1198 | loc: GeneratedSource, |
| 1199 | }); |
| 1200 | } |
| 1201 | if (this.cx.scopeFallthroughs.has(target.block)) { |
| 1202 | CompilerError.invariant(target.type === 'implicit', { |
| 1203 | reason: 'Expected reactive scope to implicitly break to fallthrough', |
| 1204 | loc, |
| 1205 | }); |
| 1206 | return null; |
| 1207 | } |
| 1208 | return { |
| 1209 | kind: 'terminal', |
| 1210 | terminal: { |
| 1211 | kind: 'break', |
| 1212 | loc, |
| 1213 | target: target.block, |
| 1214 | id, |
| 1215 | targetKind: target.type, |
| 1216 | }, |
| 1217 | label: null, |
| 1218 | }; |
| 1219 | } |
| 1220 | |
| 1221 | visitContinue( |
| 1222 | block: BlockId, |
| 1223 | id: InstructionId, |
| 1224 | loc: SourceLocation, |
| 1225 | ): ReactiveTerminalStatement<ReactiveContinueTerminal> { |
| 1226 | const target = this.cx.getContinueTarget(block); |
| 1227 | CompilerError.invariant(target !== null, { |
| 1228 | reason: `Expected continue target to be scheduled for bb${block}`, |
| 1229 | loc: GeneratedSource, |
| 1230 | }); |
| 1231 | |
| 1232 | return { |
| 1233 | kind: 'terminal', |
| 1234 | terminal: { |
| 1235 | kind: 'continue', |
| 1236 | loc, |
| 1237 | target: target.block, |
| 1238 | id, |
| 1239 | targetKind: target.type, |
| 1240 | }, |
| 1241 | label: null, |
| 1242 | }; |
| 1243 | } |
| 1244 | } |
| 1245 | |
| 1246 | class Context { |
| 1247 | ir: HIR; |
| 1248 | #nextScheduleId: number = 0; |
| 1249 | |
| 1250 | /* |
| 1251 | * Used to track which blocks *have been* generated already in order to |
| 1252 | * abort if a block is generated a second time. This is an error catching |
| 1253 | * mechanism for debugging purposes, and is not used by the codegen algorithm |
| 1254 | * to drive decisions about how to emit blocks. |
| 1255 | */ |
| 1256 | emitted: Set<BlockId> = new Set(); |
| 1257 | |
| 1258 | scopeFallthroughs: Set<BlockId> = new Set(); |
| 1259 | /* |
| 1260 | * A set of blocks that are already scheduled to be emitted by eg a parent. |
| 1261 | * This allows child nodes to avoid re-emitting the same block and emit eg |
| 1262 | * a break instead. |
| 1263 | */ |
| 1264 | #scheduled: Set<BlockId> = new Set(); |
| 1265 | |
| 1266 | #catchHandlers: Set<BlockId> = new Set(); |
| 1267 | |
| 1268 | /* |
| 1269 | * Represents which control flow operations are currently in scope, with the innermost |
| 1270 | * scope last. Roughly speaking, the last ControlFlowTarget on the stack indicates where |
| 1271 | * control will implicitly transfer, such that gotos to that block can be elided. Gotos |
| 1272 | * targeting items higher up the stack may need labeled break or continue; see |
| 1273 | * getBreakTarget() and getContinueTarget() for more details. |
| 1274 | */ |
| 1275 | #controlFlowStack: Array<ControlFlowTarget> = []; |
| 1276 | |
| 1277 | constructor(ir: HIR) { |
| 1278 | this.ir = ir; |
| 1279 | } |
| 1280 | |
| 1281 | block(id: BlockId): BasicBlock { |
| 1282 | return this.ir.blocks.get(id)!; |
| 1283 | } |
| 1284 | |
| 1285 | scheduleCatchHandler(block: BlockId): void { |
| 1286 | this.#catchHandlers.add(block); |
| 1287 | } |
| 1288 | |
| 1289 | reachable(id: BlockId): boolean { |
| 1290 | const block = this.ir.blocks.get(id)!; |
| 1291 | return block.terminal.kind !== 'unreachable'; |
| 1292 | } |
| 1293 | |
| 1294 | /* |
| 1295 | * Record that the given block will be emitted (eg by the codegen of a parent node) |
| 1296 | * so that child nodes can avoid re-emitting it. |
| 1297 | */ |
| 1298 | schedule(block: BlockId, type: 'if' | 'switch' | 'case'): number { |
| 1299 | const id = this.#nextScheduleId++; |
| 1300 | CompilerError.invariant(!this.#scheduled.has(block), { |
| 1301 | reason: `Break block is already scheduled: bb${block}`, |
| 1302 | loc: GeneratedSource, |
| 1303 | }); |
| 1304 | this.#scheduled.add(block); |
| 1305 | this.#controlFlowStack.push({block, id, type}); |
| 1306 | return id; |
| 1307 | } |
| 1308 | |
| 1309 | scheduleLoop( |
| 1310 | fallthroughBlock: BlockId, |
| 1311 | continueBlock: BlockId, |
| 1312 | loopBlock: BlockId | null, |
| 1313 | ): number { |
| 1314 | const id = this.#nextScheduleId++; |
| 1315 | const ownsBlock = !this.#scheduled.has(fallthroughBlock); |
| 1316 | this.#scheduled.add(fallthroughBlock); |
| 1317 | CompilerError.invariant(!this.#scheduled.has(continueBlock), { |
| 1318 | reason: `Continue block is already scheduled: bb${continueBlock}`, |
| 1319 | loc: GeneratedSource, |
| 1320 | }); |
| 1321 | this.#scheduled.add(continueBlock); |
| 1322 | let ownsLoop = false; |
| 1323 | if (loopBlock !== null) { |
| 1324 | ownsLoop = !this.#scheduled.has(loopBlock); |
| 1325 | this.#scheduled.add(loopBlock); |
| 1326 | } |
| 1327 | |
| 1328 | this.#controlFlowStack.push({ |
| 1329 | block: fallthroughBlock, |
| 1330 | ownsBlock, |
| 1331 | id, |
| 1332 | type: 'loop', |
| 1333 | continueBlock, |
| 1334 | loopBlock, |
| 1335 | ownsLoop, |
| 1336 | }); |
| 1337 | return id; |
| 1338 | } |
| 1339 | |
| 1340 | // Removes a block that was scheduled; must be called after that block is emitted. |
| 1341 | unschedule(scheduleId: number): void { |
| 1342 | const last = this.#controlFlowStack.pop(); |
| 1343 | CompilerError.invariant(last !== undefined && last.id === scheduleId, { |
| 1344 | reason: 'Can only unschedule the last target', |
| 1345 | loc: GeneratedSource, |
| 1346 | }); |
| 1347 | if (last.type !== 'loop' || last.ownsBlock !== null) { |
| 1348 | this.#scheduled.delete(last.block); |
| 1349 | } |
| 1350 | if (last.type === 'loop') { |
| 1351 | this.#scheduled.delete(last.continueBlock); |
| 1352 | if (last.ownsLoop && last.loopBlock !== null) { |
| 1353 | this.#scheduled.delete(last.loopBlock); |
| 1354 | } |
| 1355 | } |
| 1356 | } |
| 1357 | |
| 1358 | /* |
| 1359 | * Helper to unschedule multiple scheduled blocks. The ids should be in |
| 1360 | * the order in which they were scheduled, ie most recently scheduled last. |
| 1361 | */ |
| 1362 | unscheduleAll(scheduleIds: Array<number>): void { |
| 1363 | for (let i = scheduleIds.length - 1; i >= 0; i--) { |
| 1364 | this.unschedule(scheduleIds[i]!); |
| 1365 | } |
| 1366 | } |
| 1367 | |
| 1368 | // Check if the given @param block is scheduled or not. |
| 1369 | isScheduled(block: BlockId): boolean { |
| 1370 | return this.#scheduled.has(block) || this.#catchHandlers.has(block); |
| 1371 | } |
| 1372 | |
| 1373 | /* |
| 1374 | * Given the current control flow stack, determines how a `break` to the given @param block |
| 1375 | * must be emitted. Returns as follows: |
| 1376 | * - 'implicit' if control would implicitly transfer to that block |
| 1377 | * - 'labeled' if a labeled break is required to transfer control to that block |
| 1378 | * - 'unlabeled' if an unlabeled break would transfer to that block |
| 1379 | * - null if there is no information for this block |
| 1380 | * |
| 1381 | * The returned 'block' value should be used as the label if necessary. |
| 1382 | */ |
| 1383 | getBreakTarget(block: BlockId): { |
| 1384 | block: BlockId; |
| 1385 | type: ReactiveTerminalTargetKind; |
| 1386 | } { |
| 1387 | let hasPrecedingLoop = false; |
| 1388 | for (let i = this.#controlFlowStack.length - 1; i >= 0; i--) { |
| 1389 | const target = this.#controlFlowStack[i]!; |
| 1390 | if (target.block === block) { |
| 1391 | let type: ReactiveTerminalTargetKind; |
| 1392 | if (target.type === 'loop') { |
| 1393 | /* |
| 1394 | * breaking out of a loop requires an explicit break, |
| 1395 | * but only requires a label if breaking past the innermost loop. |
| 1396 | */ |
| 1397 | type = hasPrecedingLoop ? 'labeled' : 'unlabeled'; |
| 1398 | } else if (i === this.#controlFlowStack.length - 1) { |
| 1399 | /* |
| 1400 | * breaking to the last break point, which is where control will transfer |
| 1401 | * implicitly |
| 1402 | */ |
| 1403 | type = 'implicit'; |
| 1404 | } else { |
| 1405 | // breaking somewhere else requires an explicit break |
| 1406 | type = 'labeled'; |
| 1407 | } |
| 1408 | return { |
| 1409 | block: target.block, |
| 1410 | type, |
| 1411 | }; |
| 1412 | } |
| 1413 | hasPrecedingLoop ||= target.type === 'loop'; |
| 1414 | } |
| 1415 | |
| 1416 | CompilerError.invariant(false, { |
| 1417 | reason: 'Expected a break target', |
| 1418 | loc: GeneratedSource, |
| 1419 | }); |
| 1420 | } |
| 1421 | |
| 1422 | /* |
| 1423 | * Given the current control flow stack, determines how a `continue` to the given @param block |
| 1424 | * must be emitted. Returns as follows: |
| 1425 | * - 'implicit' if control would implicitly continue to that block |
| 1426 | * - 'labeled' if a labeled continue is required to continue to that block |
| 1427 | * - 'unlabeled' if an unlabeled continue would transfer to that block |
| 1428 | * - null if there is no information for this block |
| 1429 | * |
| 1430 | * The returned 'block' value should be used as the label if necessary. |
| 1431 | */ |
| 1432 | getContinueTarget( |
| 1433 | block: BlockId, |
| 1434 | ): {block: BlockId; type: ReactiveTerminalTargetKind} | null { |
| 1435 | let hasPrecedingLoop = false; |
| 1436 | for (let i = this.#controlFlowStack.length - 1; i >= 0; i--) { |
| 1437 | const target = this.#controlFlowStack[i]!; |
| 1438 | if (target.type == 'loop' && target.continueBlock === block) { |
| 1439 | let type: ReactiveTerminalTargetKind; |
| 1440 | if (hasPrecedingLoop) { |
| 1441 | /* |
| 1442 | * continuing to a loop that is not the innermost loop always requires |
| 1443 | * a label |
| 1444 | */ |
| 1445 | type = 'labeled'; |
| 1446 | } else if (i === this.#controlFlowStack.length - 1) { |
| 1447 | /* |
| 1448 | * continuing to the last break point, which is where control will |
| 1449 | * transfer to naturally |
| 1450 | */ |
| 1451 | type = 'implicit'; |
| 1452 | } else { |
| 1453 | /* |
| 1454 | * the continue is inside some conditional logic, requires an explicit |
| 1455 | * continue |
| 1456 | */ |
| 1457 | type = 'unlabeled'; |
| 1458 | } |
| 1459 | return { |
| 1460 | block: target.block, |
| 1461 | type, |
| 1462 | }; |
| 1463 | } |
| 1464 | hasPrecedingLoop ||= target.type === 'loop'; |
| 1465 | } |
| 1466 | return null; |
| 1467 | } |
| 1468 | |
| 1469 | debugBreakTargets(): Array<ControlFlowTarget> { |
| 1470 | return this.#controlFlowStack.map(target => ({...target})); |
| 1471 | } |
| 1472 | } |
| 1473 | |
| 1474 | type ControlFlowTarget = |
| 1475 | | {type: 'if'; block: BlockId; id: number} |
| 1476 | | {type: 'switch'; block: BlockId; id: number} |
| 1477 | | {type: 'case'; block: BlockId; id: number} |
| 1478 | | { |
| 1479 | type: 'loop'; |
| 1480 | block: BlockId; |
| 1481 | ownsBlock: boolean; |
| 1482 | continueBlock: BlockId; |
| 1483 | loopBlock: BlockId | null; |
| 1484 | ownsLoop: boolean; |
| 1485 | id: number; |
| 1486 | }; |