Appearance
| 1 | namespace Syntax.Process is | |
| 2 | use Semantic.Types.Type | |
| 3 | use Semantic.Types.INTERSECTION | |
| 4 | use Symbol = Semantic.Symbols.Symbol | |
| 5 | ||
| 6 | // One call a heap fact survived on the way to a use. Narrowing is | |
| 7 | // optimistic: a call does not drop heap facts, it is recorded | |
| 8 | // against every fact live across it, and a use of the fact is | |
| 9 | // checked against the record — a crossing whose callee provably | |
| 10 | // left the fact alone is discharged, and relying on a fact with | |
| 11 | // an undischarged crossing is a compile error at the use site. | |
| 12 | class CROSSING(location: Source.LOCATION, callee: Semantic.Symbols.Function?) | |
| 13 | ||
| 14 | // The flow-analysis facts in force at one program point: the | |
| 15 | // local variables observed at a type narrower than their | |
| 16 | // declaration, the local variables known to be definitely | |
| 17 | // assigned, the local variables known to hold a value, and a | |
| 18 | // `bottom` marker for points reached only via a diverging path | |
| 19 | // (return / throw / break / continue). | |
| 20 | // | |
| 21 | // The flow pass threads a NARROW_ENV forward through a method, | |
| 22 | // copies it at branch points, and merges divergent copies with | |
| 23 | // `join`. A variable absent from `_narrows` is at its declared | |
| 24 | // type; a variable absent from `_assigned` is not known to be | |
| 25 | // definitely assigned; a variable absent from `_non_null` is not | |
| 26 | // known to hold a value. See `docs/claude/flow-sensitive-narrowing.md`. | |
| 27 | class NARROW_ENV is | |
| 28 | _narrows: Collections.MAP[Symbol, Type] | |
| 29 | ||
| 30 | // Locals definitely assigned on every path reaching this | |
| 31 | // point — the definite-assignment domain. | |
| 32 | _assigned: Collections.SET[Symbol] | |
| 33 | ||
| 34 | // Methods of the enclosing type called on `self` on every path | |
| 35 | // reaching this point - the same must-domain as `_assigned`, and | |
| 36 | // joined the same way. A constructor's field-assignment answer | |
| 37 | // follows the callees it cannot avoid reaching. | |
| 38 | _called: Collections.SET[Symbol] | |
| 39 | ||
| 40 | // Locals known to hold a value at this point — non-null for a | |
| 41 | // reference type, has-a-value for a NULLABLE[T] (`T?`) value | |
| 42 | // type. The presence domain; a possible-null-dereference | |
| 43 | // check (a later phase) consumes it. | |
| 44 | _non_null: Collections.SET[Symbol] | |
| 45 | ||
| 46 | // Member-access paths (`receiver.prop`, `receiver.a.b`) known | |
| 47 | // to hold a value at this point — the same presence domain | |
| 48 | // lifted from single symbols to re-readable paths. A path | |
| 49 | // here is narrowed optional -> non-optional at its use sites, | |
| 50 | // so `if x.y? then x.y.z fi` type-checks. Every hop is a | |
| 51 | // field or a store-free getter; the flow transfers drop paths | |
| 52 | // the moment the heap may have changed what they read. See | |
| 53 | // ACCESS_PATH. | |
| 54 | _non_null_paths: Collections.SET[ACCESS_PATH] | |
| 55 | ||
| 56 | // Member-access paths narrowed to a specific type at this | |
| 57 | // point — the type domain lifted from single symbols to | |
| 58 | // re-readable paths. A path here is loaded at the narrower | |
| 59 | // type at its use sites, so `if isa Cat(x.y) then x.y.meow() | |
| 60 | // fi` type-checks. Composed via INTERSECTION like `_narrows`, | |
| 61 | // and dropped by the same heap transfers as `_non_null_paths`. | |
| 62 | _path_narrows: Collections.MAP[ACCESS_PATH, Type] | |
| 63 | ||
| 64 | // The calls each heap fact has survived since it was last | |
| 65 | // established, one map per fact domain. A local's facts never | |
| 66 | // cross - a callee cannot reach a local - so only fields, | |
| 67 | // properties and paths take entries. Establishing a fact | |
| 68 | // afresh clears its record; an else-edge complement, which | |
| 69 | // derives from the prior narrow, inherits it instead. | |
| 70 | _non_null_crossings: Collections.MAP[Symbol, Collections.LIST[CROSSING]] | |
| 71 | _narrow_crossings: Collections.MAP[Symbol, Collections.LIST[CROSSING]] | |
| 72 | _path_presence_crossings: Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]] | |
| 73 | _path_narrow_crossings: Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]] | |
| 74 | ||
| 75 | // The crossing-log index at which each heap fact was | |
| 76 | // established, one map per fact domain mirroring the crossing | |
| 77 | // records. Adoption replays a log range onto an environment's | |
| 78 | // facts; a replayed crossing that ran before a fact's own | |
| 79 | // establishing test cannot invalidate it, and the index lets | |
| 80 | // `note_crossing_at` skip it. A fact with no recorded index is | |
| 81 | // treated as created at the start of the log, so every | |
| 82 | // replayed crossing attaches — the pre-mechanism behaviour, | |
| 83 | // and the conservative direction. | |
| 84 | _non_null_created_at: Collections.MAP[Symbol, int] | |
| 85 | _narrow_created_at: Collections.MAP[Symbol, int] | |
| 86 | _path_presence_created_at: Collections.MAP[ACCESS_PATH, int] | |
| 87 | _path_narrow_created_at: Collections.MAP[ACCESS_PATH, int] | |
| 88 | ||
| 89 | // The creation index the setters stamp on facts they establish | |
| 90 | // afresh. The condition analyzer sets it to the log count the | |
| 91 | // walk recorded at each leaf test before adding that leaf's | |
| 92 | // facts; the flow sets it to its own log count before creating | |
| 93 | // a fact mid-walk. Zero attaches everything. | |
| 94 | creation_mark: int public | |
| 95 | ||
| 96 | // True for an unreachable program point. A bottom env is the | |
| 97 | // identity element of `join` and carries no facts. | |
| 98 | is_bottom: bool public | |
| 99 | ||
| 100 | init() is | |
| 101 | _narrows = Collections.MAP[Symbol, Type]() | |
| 102 | _assigned = Collections.SET[Symbol]() | |
| 103 | _called = Collections.SET[Symbol]() | |
| 104 | _non_null = Collections.SET[Symbol]() | |
| 105 | _non_null_paths = Collections.SET[ACCESS_PATH]() | |
| 106 | _path_narrows = Collections.MAP[ACCESS_PATH, Type]() | |
| 107 | _non_null_crossings = Collections.MAP[Symbol, Collections.LIST[CROSSING]]() | |
| 108 | _narrow_crossings = Collections.MAP[Symbol, Collections.LIST[CROSSING]]() | |
| 109 | _path_presence_crossings = Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]]() | |
| 110 | _path_narrow_crossings = Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]]() | |
| 111 | _non_null_created_at = Collections.MAP[Symbol, int]() | |
| 112 | _narrow_created_at = Collections.MAP[Symbol, int]() | |
| 113 | _path_presence_created_at = Collections.MAP[ACCESS_PATH, int]() | |
| 114 | _path_narrow_created_at = Collections.MAP[ACCESS_PATH, int]() | |
| 115 | si | |
| 116 | ||
| 117 | _is_heap_fact(v: Symbol) -> bool => | |
| 118 | isa Semantic.Symbols.Field(v) \/ | |
| 119 | isa Semantic.Symbols.Property(v) \/ | |
| 120 | is_closure_assigned(v) | |
| 121 | ||
| 122 | // A local a closure body assigns is a heap fact. Facts on | |
| 123 | // other locals are never recorded as crossing a call, because | |
| 124 | // a callee cannot reach a caller's stack slot - but such a | |
| 125 | // local lives in a heap cell shared with the closure, so a | |
| 126 | // call can rewrite it, and its facts take crossings and are | |
| 127 | // judged at each leaning use exactly as a field's are. | |
| 128 | is_closure_assigned(v: Symbol) -> bool static => | |
| 129 | if let variable: Semantic.Symbols.Variable = v then | |
| 130 | variable.is_closure_assigned | |
| 131 | else | |
| 132 | false | |
| 133 | fi | |
| 134 | ||
| 135 | // Record `crossing` against every heap fact live at this | |
| 136 | // point, in every domain. | |
| 137 | // Copy `v`'s crossing records from `other` into this | |
| 138 | // environment. For an environment rebuilt fact-by-fact from | |
| 139 | // another (the loop kept-env), which would otherwise carry | |
| 140 | // the facts stripped of the crossings still owed on them. | |
| 141 | copy_crossings_of(v: Symbol, other: NARROW_ENV) is | |
| 142 | let existing: Collections.LIST[CROSSING] mut | |
| 143 | ||
| 144 | if other._non_null_crossings.try_get_value(v, existing ref) then | |
| 145 | _non_null_crossings[v] = _copied_crossings(existing) | |
| 146 | fi | |
| 147 | ||
| 148 | if other._narrow_crossings.try_get_value(v, existing ref) then | |
| 149 | _narrow_crossings[v] = _copied_crossings(existing) | |
| 150 | fi | |
| 151 | ||
| 152 | let created mut = 0 | |
| 153 | ||
| 154 | if other._non_null_created_at.try_get_value(v, created ref) then | |
| 155 | _non_null_created_at[v] = created | |
| 156 | fi | |
| 157 | ||
| 158 | if other._narrow_created_at.try_get_value(v, created ref) then | |
| 159 | _narrow_created_at[v] = created | |
| 160 | fi | |
| 161 | si | |
| 162 | ||
| 163 | // The heap facts a crossing would be attached to, narrowed | |
| 164 | // variables first and presence-only ones after, so a variable | |
| 165 | // carrying both is described by its narrow. Mirrors the | |
| 166 | // enumeration `note_crossing` performs. | |
| 167 | heap_fact_variables: Collections.Iterable[Symbol] is | |
| 168 | let result = Collections.LIST[Symbol]() | |
| 169 | ||
| 170 | if is_bottom then | |
| 171 | return result | |
| 172 | fi | |
| 173 | ||
| 174 | for v in _narrows.keys do | |
| 175 | if _is_heap_fact(v) then | |
| 176 | result.add(v) | |
| 177 | fi | |
| 178 | od | |
| 179 | ||
| 180 | for v in _non_null do | |
| 181 | if _is_heap_fact(v) /\ !_narrows.contains_key(v) then | |
| 182 | result.add(v) | |
| 183 | fi | |
| 184 | od | |
| 185 | ||
| 186 | return result | |
| 187 | si | |
| 188 | ||
| 189 | // Path analogue of `heap_fact_variables`. | |
| 190 | heap_fact_paths: Collections.Iterable[ACCESS_PATH] is | |
| 191 | let result = Collections.LIST[ACCESS_PATH]() | |
| 192 | ||
| 193 | if is_bottom then | |
| 194 | return result | |
| 195 | fi | |
| 196 | ||
| 197 | for p in _path_narrows.keys do | |
| 198 | result.add(p) | |
| 199 | od | |
| 200 | ||
| 201 | for p in _non_null_paths do | |
| 202 | if !_path_narrows.contains_key(p) then | |
| 203 | result.add(p) | |
| 204 | fi | |
| 205 | od | |
| 206 | ||
| 207 | return result | |
| 208 | si | |
| 209 | ||
| 210 | note_crossing(crossing: CROSSING) is | |
| 211 | if is_bottom then | |
| 212 | return | |
| 213 | fi | |
| 214 | ||
| 215 | for v in _non_null do | |
| 216 | if _is_heap_fact(v) then | |
| 217 | _append_crossing(_non_null_crossings, v, crossing) | |
| 218 | fi | |
| 219 | od | |
| 220 | ||
| 221 | for v in _narrows.keys do | |
| 222 | if _is_heap_fact(v) then | |
| 223 | _append_crossing(_narrow_crossings, v, crossing) | |
| 224 | fi | |
| 225 | od | |
| 226 | ||
| 227 | for p in _non_null_paths do | |
| 228 | _append_path_crossing(_path_presence_crossings, p, crossing) | |
| 229 | od | |
| 230 | ||
| 231 | for p in _path_narrows.keys do | |
| 232 | _append_path_crossing(_path_narrow_crossings, p, crossing) | |
| 233 | od | |
| 234 | si | |
| 235 | ||
| 236 | // The formation rule of the combined-solve prototype: a fact | |
| 237 | // read through a getter whose own re-read the solved relations | |
| 238 | // cannot discharge is dead at its first use, so it is not | |
| 239 | // formed. The decline is recorded as a kill at the getter's | |
| 240 | // own call, so a later solve that backs the getter re-walks | |
| 241 | // the file and the fact forms. With nothing solved the fact | |
| 242 | // forms, and its first load records the same question for the | |
| 243 | // ledger to ask after the solve. | |
| 244 | _getter_hops(target: Symbol?, path: ACCESS_PATH?) -> Collections.LIST[Semantic.Symbols.Property] static is | |
| 245 | let result = Collections.LIST[Semantic.Symbols.Property]() | |
| 246 | ||
| 247 | if let property: Semantic.Symbols.Property = target then | |
| 248 | result.add(property) | |
| 249 | fi | |
| 250 | ||
| 251 | if path? then | |
| 252 | if let property: Semantic.Symbols.Property = path.root then | |
| 253 | result.add(property) | |
| 254 | fi | |
| 255 | ||
| 256 | for m in path.members do | |
| 257 | if let property: Semantic.Symbols.Property = m then | |
| 258 | result.add(property) | |
| 259 | fi | |
| 260 | od | |
| 261 | fi | |
| 262 | ||
| 263 | return result | |
| 264 | si | |
| 265 | ||
| 266 | _declines_getter_fact(target: Symbol?, path: ACCESS_PATH?, is_presence: bool) -> bool static is | |
| 267 | if !KILL_LEDGER.can_kill_in_walk then | |
| 268 | // Nothing solved yet, so the fact forms; each getter it | |
| 269 | // reads through is recorded as a kept decision at the | |
| 270 | // getter's own call, so the re-ask after the solve | |
| 271 | // reaches the formation even when no load follows it. | |
| 272 | if let file_name = KILL_LEDGER.current_file then | |
| 273 | for getter in _getter_hops(target, path) do | |
| 274 | if let read = getter.read_function then | |
| 275 | let kill = KILL(file_name, CROSSING(getter.location, read), target, path, is_presence, false) | |
| 276 | ||
| 277 | kill.declined = true | |
| 278 | ||
| 279 | KILL_LEDGER.record(kill) | |
| 280 | fi | |
| 281 | od | |
| 282 | fi | |
| 283 | ||
| 284 | return false | |
| 285 | fi | |
| 286 | ||
| 287 | let getter = RELIANCES.first_unproven_getter(target, path, is_presence) | |
| 288 | ||
| 289 | if !getter? then | |
| 290 | return false | |
| 291 | fi | |
| 292 | ||
| 293 | if let file_name = KILL_LEDGER.current_file, property: Semantic.Symbols.Property = getter, read = property.read_function then | |
| 294 | let kill = KILL(file_name, CROSSING(getter.location, read), target, path, is_presence, true) | |
| 295 | ||
| 296 | kill.declined = true | |
| 297 | ||
| 298 | KILL_LEDGER.record(kill) | |
| 299 | fi | |
| 300 | ||
| 301 | return true | |
| 302 | si | |
| 303 | ||
| 304 | // As `note_crossing`, but for a crossing replayed from the log | |
| 305 | // at `index`: a fact established after the crossing ran cannot | |
| 306 | // have been invalidated by it — the establishing test observed | |
| 307 | // the post-call heap — so the crossing skips that fact. Facts | |
| 308 | // with no recorded creation index take every crossing, the | |
| 309 | // pre-mechanism behaviour. | |
| 310 | note_crossing_at(crossing: CROSSING, index: int) is | |
| 311 | if is_bottom then | |
| 312 | return | |
| 313 | fi | |
| 314 | ||
| 315 | // The replay-path half of the combined-solve prototype's | |
| 316 | // in-walk kill transfer: a fact the solved relations cannot | |
| 317 | // back across this call dies here instead of taking the | |
| 318 | // crossing. The active-environment half lives in | |
| 319 | // NARROWING_FLOW._apply_relations, which also restores | |
| 320 | // symbol types; an environment adopted onto is not in | |
| 321 | // force, so removal alone is enough here. | |
| 322 | if KILL_LEDGER.can_kill_in_walk then | |
| 323 | _apply_relations_to_self(crossing, index) | |
| 324 | fi | |
| 325 | ||
| 326 | for v in _non_null do | |
| 327 | if _is_heap_fact(v) /\ _created_by(_non_null_created_at, v, index) then | |
| 328 | _append_crossing(_non_null_crossings, v, crossing) | |
| 329 | fi | |
| 330 | od | |
| 331 | ||
| 332 | for v in _narrows.keys do | |
| 333 | if _is_heap_fact(v) /\ _created_by(_narrow_created_at, v, index) then | |
| 334 | _append_crossing(_narrow_crossings, v, crossing) | |
| 335 | fi | |
| 336 | od | |
| 337 | ||
| 338 | for p in _non_null_paths do | |
| 339 | if _path_created_by(_path_presence_created_at, p, index) then | |
| 340 | _append_path_crossing(_path_presence_crossings, p, crossing) | |
| 341 | fi | |
| 342 | od | |
| 343 | ||
| 344 | for p in _path_narrows.keys do | |
| 345 | if _path_created_by(_path_narrow_created_at, p, index) then | |
| 346 | _append_path_crossing(_path_narrow_crossings, p, crossing) | |
| 347 | fi | |
| 348 | od | |
| 349 | si | |
| 350 | ||
| 351 | _created_by(map: Collections.MAP[Symbol, int], v: Symbol, index: int) -> bool is | |
| 352 | let created mut = 0 | |
| 353 | ||
| 354 | if map.try_get_value(v, created ref) then | |
| 355 | return created <= index | |
| 356 | fi | |
| 357 | ||
| 358 | return true | |
| 359 | si | |
| 360 | ||
| 361 | _path_created_by(map: Collections.MAP[ACCESS_PATH, int], p: ACCESS_PATH, index: int) -> bool is | |
| 362 | let created mut = 0 | |
| 363 | ||
| 364 | if map.try_get_value(p, created ref) then | |
| 365 | return created <= index | |
| 366 | fi | |
| 367 | ||
| 368 | return true | |
| 369 | si | |
| 370 | ||
| 371 | _append_crossing( | |
| 372 | map: Collections.MAP[Symbol, Collections.LIST[CROSSING]], | |
| 373 | v: Symbol, | |
| 374 | crossing: CROSSING | |
| 375 | ) is | |
| 376 | let existing: Collections.LIST[CROSSING] mut | |
| 377 | ||
| 378 | if map.try_get_value(v, existing ref) then | |
| 379 | existing.add(crossing) | |
| 380 | else | |
| 381 | let fresh = Collections.LIST[CROSSING]() | |
| 382 | fresh.add(crossing) | |
| 383 | map[v] = fresh | |
| 384 | fi | |
| 385 | si | |
| 386 | ||
| 387 | _append_path_crossing( | |
| 388 | map: Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]], | |
| 389 | p: ACCESS_PATH, | |
| 390 | crossing: CROSSING | |
| 391 | ) is | |
| 392 | let existing: Collections.LIST[CROSSING] mut | |
| 393 | ||
| 394 | if map.try_get_value(p, existing ref) then | |
| 395 | existing.add(crossing) | |
| 396 | else | |
| 397 | let fresh = Collections.LIST[CROSSING]() | |
| 398 | fresh.add(crossing) | |
| 399 | map[p] = fresh | |
| 400 | fi | |
| 401 | si | |
| 402 | ||
| 403 | non_null_crossings_of(v: Symbol) -> Collections.LIST[CROSSING]? is | |
| 404 | let result: Collections.LIST[CROSSING] mut | |
| 405 | ||
| 406 | if _non_null_crossings.try_get_value(v, result ref) then | |
| 407 | return result | |
| 408 | fi | |
| 409 | ||
| 410 | return null | |
| 411 | si | |
| 412 | ||
| 413 | narrow_crossings_of(v: Symbol) -> Collections.LIST[CROSSING]? is | |
| 414 | let result: Collections.LIST[CROSSING] mut | |
| 415 | ||
| 416 | if _narrow_crossings.try_get_value(v, result ref) then | |
| 417 | return result | |
| 418 | fi | |
| 419 | ||
| 420 | return null | |
| 421 | si | |
| 422 | ||
| 423 | path_presence_crossings_of(p: ACCESS_PATH) -> Collections.LIST[CROSSING]? is | |
| 424 | let result: Collections.LIST[CROSSING] mut | |
| 425 | ||
| 426 | if _path_presence_crossings.try_get_value(p, result ref) then | |
| 427 | return result | |
| 428 | fi | |
| 429 | ||
| 430 | return null | |
| 431 | si | |
| 432 | ||
| 433 | path_narrow_crossings_of(p: ACCESS_PATH) -> Collections.LIST[CROSSING]? is | |
| 434 | let result: Collections.LIST[CROSSING] mut | |
| 435 | ||
| 436 | if _path_narrow_crossings.try_get_value(p, result ref) then | |
| 437 | return result | |
| 438 | fi | |
| 439 | ||
| 440 | return null | |
| 441 | si | |
| 442 | ||
| 443 | _clear_crossings(map: Collections.MAP[Symbol, Collections.LIST[CROSSING]], v: Symbol) is | |
| 444 | if map.contains_key(v) then | |
| 445 | map.remove(v) | |
| 446 | fi | |
| 447 | si | |
| 448 | ||
| 449 | _clear_path_crossings(map: Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]], p: ACCESS_PATH) is | |
| 450 | if map.contains_key(p) then | |
| 451 | map.remove(p) | |
| 452 | fi | |
| 453 | si | |
| 454 | ||
| 455 | // The unreachable environment. | |
| 456 | bottom() -> NARROW_ENV static is | |
| 457 | let e = NARROW_ENV() | |
| 458 | e.is_bottom = true | |
| 459 | return e | |
| 460 | si | |
| 461 | ||
| 462 | is_empty: bool => !is_bottom /\ _narrows.count == 0 | |
| 463 | count: int => _narrows.count | |
| 464 | ||
| 465 | variables: Collections.Iterable[Symbol] => _narrows.keys | |
| 466 | ||
| 467 | contains(v: Symbol) -> bool => _narrows.contains_key(v) | |
| 468 | ||
| 469 | // The narrowed type recorded for `v`, or null when `v` is | |
| 470 | // not narrowed in this environment. | |
| 471 | narrowed_type_of(v: Symbol) -> Type? is | |
| 472 | let result: Type mut | |
| 473 | ||
| 474 | if _narrows.try_get_value(v, result ref) then | |
| 475 | return result | |
| 476 | fi | |
| 477 | ||
| 478 | return null | |
| 479 | si | |
| 480 | ||
| 481 | // Record `v` as narrowed to `t` (mutating). A bottom env | |
| 482 | // ignores narrows — it stays unreachable. | |
| 483 | // | |
| 484 | // If `v` already carries a narrow `existing`, compose: | |
| 485 | // `INTERSECTION.try_create(existing, t)`. The factory: | |
| 486 | // - returns `t` when t strict-subtypes existing (refining), | |
| 487 | // - returns `existing` when existing strict-subtypes t (the | |
| 488 | // new narrow is weaker, no-op), | |
| 489 | // - returns a multi-member intersection when both are | |
| 490 | // real new facts (e.g., a class plus a sibling trait), | |
| 491 | // - returns null when the two carry unrelated concrete | |
| 492 | // identities — no runtime value can be both, so the edge | |
| 493 | // recording the narrow is statically impossible. The code | |
| 494 | // on that edge is written against the newly tested type | |
| 495 | // (`elif isa TUPLE(x) then x.elements`), so `t` replaces | |
| 496 | // the stale narrow: on an unreachable edge any view is | |
| 497 | // sound, and the tested type is the one that typechecks. | |
| 498 | // So stacked narrows like `if isa A(x) then if isa B(x)` | |
| 499 | // produce `Declared & A & B` rather than dropping A. | |
| 500 | // | |
| 501 | // Skipped when composing with an existing narrow doesn't | |
| 502 | // change the recorded type — every extra fact costs | |
| 503 | // downstream copies, joins and kill iterations for no | |
| 504 | // observable effect. A fresh record (no existing narrow) is | |
| 505 | // always kept; if it turns out to no-op against v's declared | |
| 506 | // type, the branch-entry `_apply_one` catches it. | |
| 507 | set_narrow(v: Symbol, t: Type) is | |
| 508 | if isa Semantic.Symbols.Property(v) /\ _declines_getter_fact(v, null, false) then | |
| 509 | return | |
| 510 | fi | |
| 511 | ||
| 512 | if is_bottom then | |
| 513 | return | |
| 514 | fi | |
| 515 | ||
| 516 | let existing: Type mut | |
| 517 | ||
| 518 | if _narrows.try_get_value(v, existing ref) then | |
| 519 | let composed = INTERSECTION.try_create(existing, t) | |
| 520 | ||
| 521 | if !composed? then | |
| 522 | // a fresh test superseding a statically-impossible | |
| 523 | // prior narrow: nothing of the old fact survives | |
| 524 | _narrows[v] = t | |
| 525 | _clear_crossings(_narrow_crossings, v) | |
| 526 | _narrow_created_at[v] = creation_mark | |
| 527 | return | |
| 528 | fi | |
| 529 | ||
| 530 | if composed.matches(existing) then | |
| 531 | // a re-test that alone implies the whole recorded | |
| 532 | // fact re-proves it, crossings and all | |
| 533 | if composed.matches(t) then | |
| 534 | _clear_crossings(_narrow_crossings, v) | |
| 535 | _narrow_created_at[v] = creation_mark | |
| 536 | fi | |
| 537 | ||
| 538 | return | |
| 539 | fi | |
| 540 | ||
| 541 | // composing keeps the prior component's crossings — and | |
| 542 | // its creation index: the new test observed the value, | |
| 543 | // the old fact did not — unless the new observation | |
| 544 | // alone implies the whole composition | |
| 545 | _narrows[v] = composed | |
| 546 | ||
| 547 | if composed.matches(t) then | |
| 548 | _clear_crossings(_narrow_crossings, v) | |
| 549 | _narrow_created_at[v] = creation_mark | |
| 550 | fi | |
| 551 | else | |
| 552 | _narrows[v] = t | |
| 553 | _clear_crossings(_narrow_crossings, v) | |
| 554 | _narrow_created_at[v] = creation_mark | |
| 555 | fi | |
| 556 | si | |
| 557 | ||
| 558 | // Record `t` as the narrow for `v`, discarding any existing | |
| 559 | // narrow instead of composing with it. For callers that have | |
| 560 | // already computed the absolute narrowed type — the else-edge | |
| 561 | // complement is derived from the current narrow, so it fully | |
| 562 | // supersedes it. Composition would be wrong when the complement | |
| 563 | // collapses to a supertype of the prior narrow (a concrete root | |
| 564 | // that outlives every eliminated subclass): INTERSECTION would | |
| 565 | // reinstate the wider prior narrow and the eliminated subclass | |
| 566 | // would survive. | |
| 567 | replace_narrow(v: Symbol, t: Type) is | |
| 568 | if is_bottom then | |
| 569 | return | |
| 570 | fi | |
| 571 | ||
| 572 | _narrows[v] = t | |
| 573 | // The replacement derives from the test establishing it: | |
| 574 | // crossings recorded before that test cannot invalidate it, | |
| 575 | // however much of the prior fact's record is inherited. | |
| 576 | _narrow_created_at[v] = creation_mark | |
| 577 | si | |
| 578 | ||
| 579 | // Path-keyed mirror of `replace_narrow`. | |
| 580 | replace_path_narrow(path: ACCESS_PATH, t: Type) is | |
| 581 | if is_bottom then | |
| 582 | return | |
| 583 | fi | |
| 584 | ||
| 585 | _path_narrows[path] = t | |
| 586 | _path_narrow_created_at[path] = creation_mark | |
| 587 | si | |
| 588 | ||
| 589 | // Forget any narrow for `v` (mutating) — used by the | |
| 590 | // assignment transfer function. | |
| 591 | drop_narrow(v: Symbol) is | |
| 592 | if _narrows.contains_key(v) then | |
| 593 | _narrows.remove(v) | |
| 594 | fi | |
| 595 | si | |
| 596 | ||
| 597 | // The locals definitely assigned at this point. | |
| 598 | assigned_variables: Collections.Iterable[Symbol] => _assigned | |
| 599 | ||
| 600 | // True iff `v` is definitely assigned at this point. | |
| 601 | is_assigned(v: Symbol) -> bool => _assigned.contains(v) | |
| 602 | ||
| 603 | // The methods definitely called at this point. | |
| 604 | called_methods: Collections.Iterable[Symbol] => _called | |
| 605 | ||
| 606 | is_called(f: Symbol) -> bool => _called.contains(f) | |
| 607 | ||
| 608 | set_called(f: Symbol) is | |
| 609 | _called.add(f) | |
| 610 | si | |
| 611 | ||
| 612 | // Record `v` as definitely assigned (mutating). A bottom env | |
| 613 | // ignores it — it stays unreachable. | |
| 614 | set_assigned(v: Symbol) is | |
| 615 | if is_bottom then | |
| 616 | return | |
| 617 | fi | |
| 618 | ||
| 619 | _assigned.add(v) | |
| 620 | si | |
| 621 | ||
| 622 | // The locals known to hold a value at this point. | |
| 623 | non_null_variables: Collections.Iterable[Symbol] => _non_null | |
| 624 | ||
| 625 | // True iff `v` is known to hold a value at this point. | |
| 626 | is_non_null(v: Symbol) -> bool => _non_null.contains(v) | |
| 627 | ||
| 628 | // Record `v` as known to hold a value (mutating). A bottom | |
| 629 | // env ignores it — it stays unreachable. | |
| 630 | // | |
| 631 | // Callers should filter out presence facts on non-optional | |
| 632 | // targets themselves: NARROW_ENV can't safely check `v.type` | |
| 633 | // here because the symbol's live type reflects whatever the | |
| 634 | // outer walk state applied, not the fresh env being built — | |
| 635 | // a redundant-looking fact recorded on a nested if body may | |
| 636 | // still be observable at the branch entry when the outer | |
| 637 | // narrow is restored. | |
| 638 | set_non_null(v: Symbol) is | |
| 639 | if isa Semantic.Symbols.Property(v) /\ _declines_getter_fact(v, null, true) then | |
| 640 | return | |
| 641 | fi | |
| 642 | ||
| 643 | if is_bottom then | |
| 644 | return | |
| 645 | fi | |
| 646 | ||
| 647 | _non_null.add(v) | |
| 648 | _clear_crossings(_non_null_crossings, v) | |
| 649 | _non_null_created_at[v] = creation_mark | |
| 650 | si | |
| 651 | ||
| 652 | // Forget that `v` is known to hold a value (mutating) — used | |
| 653 | // by the assignment transfer function. | |
| 654 | drop_non_null(v: Symbol) is | |
| 655 | if _non_null.contains(v) then | |
| 656 | _non_null.remove(v) | |
| 657 | fi | |
| 658 | si | |
| 659 | ||
| 660 | // The member-access paths known to hold a value at this point. | |
| 661 | non_null_paths: Collections.Iterable[ACCESS_PATH] => _non_null_paths | |
| 662 | ||
| 663 | // True iff `path` is known to hold a value at this point. | |
| 664 | is_non_null_path(path: ACCESS_PATH) -> bool => _non_null_paths.contains(path) | |
| 665 | ||
| 666 | // Record `path` as known to hold a value (mutating). A bottom | |
| 667 | // env ignores it — it stays unreachable. | |
| 668 | set_non_null_path(path: ACCESS_PATH) is | |
| 669 | if path.has_getter_hop /\ _declines_getter_fact(null, path, true) then | |
| 670 | return | |
| 671 | fi | |
| 672 | ||
| 673 | if is_bottom then | |
| 674 | return | |
| 675 | fi | |
| 676 | ||
| 677 | _non_null_paths.add(path) | |
| 678 | _clear_path_crossings(_path_presence_crossings, path) | |
| 679 | _path_presence_created_at[path] = creation_mark | |
| 680 | si | |
| 681 | ||
| 682 | // The member-access paths carrying a type narrow at this point. | |
| 683 | narrowed_paths: Collections.Iterable[ACCESS_PATH] => _path_narrows.keys | |
| 684 | ||
| 685 | // The narrowed type recorded for `path`, or null when it is | |
| 686 | // not narrowed in this environment. | |
| 687 | narrowed_type_of_path(path: ACCESS_PATH) -> Type? is | |
| 688 | let result: Type mut | |
| 689 | ||
| 690 | if _path_narrows.try_get_value(path, result ref) then | |
| 691 | return result | |
| 692 | fi | |
| 693 | ||
| 694 | return null | |
| 695 | si | |
| 696 | ||
| 697 | // Record `path` as narrowed to `t` (mutating). Bottom env | |
| 698 | // ignores it. Stacks like `set_narrow` — a prior narrow on | |
| 699 | // the same path composes with `t` via INTERSECTION, and an | |
| 700 | // unrelated-concretes pair (statically-impossible test edge) | |
| 701 | // replaces the stale narrow with `t` for the same reason. | |
| 702 | set_path_narrow(path: ACCESS_PATH, t: Type) is | |
| 703 | if path.has_getter_hop /\ _declines_getter_fact(null, path, false) then | |
| 704 | return | |
| 705 | fi | |
| 706 | ||
| 707 | if is_bottom then | |
| 708 | return | |
| 709 | fi | |
| 710 | ||
| 711 | let existing: Type mut | |
| 712 | ||
| 713 | if _path_narrows.try_get_value(path, existing ref) then | |
| 714 | let composed = INTERSECTION.try_create(existing, t) | |
| 715 | ||
| 716 | _path_narrows[path] = if composed? then composed else t fi | |
| 717 | ||
| 718 | if !composed? \/ composed.matches(t) then | |
| 719 | _clear_path_crossings(_path_narrow_crossings, path) | |
| 720 | _path_narrow_created_at[path] = creation_mark | |
| 721 | fi | |
| 722 | else | |
| 723 | _path_narrows[path] = t | |
| 724 | _clear_path_crossings(_path_narrow_crossings, path) | |
| 725 | _path_narrow_created_at[path] = creation_mark | |
| 726 | fi | |
| 727 | si | |
| 728 | ||
| 729 | // Forget every tracked path — the call transfer: a | |
| 730 | // possibly-storing callee may have changed anything a path | |
| 731 | // reads. Same reasoning for path type narrows. | |
| 732 | drop_all_paths() is | |
| 733 | _non_null_paths.clear() | |
| 734 | _path_narrows.clear() | |
| 735 | si | |
| 736 | ||
| 737 | // Forget every path that reads through a property getter — | |
| 738 | // the heap-store transfer: a store anywhere can change what a | |
| 739 | // getter returns. Fields-only paths survive; a store to a | |
| 740 | // field they read through is handled by drop_paths_through. | |
| 741 | // Applies to both presence and type-narrow slots. | |
| 742 | drop_getter_paths() is | |
| 743 | let doomed = Collections.LIST[ACCESS_PATH]() | |
| 744 | ||
| 745 | for p in _non_null_paths do | |
| 746 | if p.has_getter_hop then | |
| 747 | doomed.add(p) | |
| 748 | fi | |
| 749 | od | |
| 750 | ||
| 751 | for p in doomed do | |
| 752 | _non_null_paths.remove(p) | |
| 753 | od | |
| 754 | ||
| 755 | let doomed_narrows = Collections.LIST[ACCESS_PATH]() | |
| 756 | ||
| 757 | for p in _path_narrows.keys do | |
| 758 | if p.has_getter_hop then | |
| 759 | doomed_narrows.add(p) | |
| 760 | fi | |
| 761 | od | |
| 762 | ||
| 763 | for p in doomed_narrows do | |
| 764 | _path_narrows.remove(p) | |
| 765 | od | |
| 766 | si | |
| 767 | ||
| 768 | // Remove every fact the solved relations cannot back across | |
| 769 | // this crossing, recording each kill for the ledger. | |
| 770 | _apply_relations_to_self(crossing: CROSSING, index: int) is | |
| 771 | let doomed_narrows = Collections.LIST[Symbol]() | |
| 772 | ||
| 773 | for v in _narrows.keys do | |
| 774 | if | |
| 775 | _is_heap_fact(v) /\ | |
| 776 | _created_by(_narrow_created_at, v, index) /\ | |
| 777 | !RELIANCES.crossing_discharged(crossing, v, null, false) | |
| 778 | then | |
| 779 | let kill = KILL(crossing.location.file_name, crossing, v, null, false, true) | |
| 780 | ||
| 781 | kill.narrowed_type = narrowed_type_of(v) | |
| 782 | ||
| 783 | KILL_LEDGER.record(kill) | |
| 784 | doomed_narrows.add(v) | |
| 785 | fi | |
| 786 | od | |
| 787 | ||
| 788 | for v in doomed_narrows do | |
| 789 | drop_narrow(v) | |
| 790 | od | |
| 791 | ||
| 792 | let doomed_presence = Collections.LIST[Symbol]() | |
| 793 | ||
| 794 | for v in _non_null do | |
| 795 | if | |
| 796 | _is_heap_fact(v) /\ | |
| 797 | _created_by(_non_null_created_at, v, index) /\ | |
| 798 | !RELIANCES.crossing_discharged(crossing, v, null, true) | |
| 799 | then | |
| 800 | KILL_LEDGER.record(KILL(crossing.location.file_name, crossing, v, null, true, true)) | |
| 801 | doomed_presence.add(v) | |
| 802 | fi | |
| 803 | od | |
| 804 | ||
| 805 | for v in doomed_presence do | |
| 806 | drop_non_null(v) | |
| 807 | od | |
| 808 | ||
| 809 | let doomed_paths = Collections.LIST[ACCESS_PATH]() | |
| 810 | ||
| 811 | for p in _non_null_paths do | |
| 812 | if | |
| 813 | _path_created_by(_path_presence_created_at, p, index) /\ | |
| 814 | !RELIANCES.crossing_discharged(crossing, null, p, true) | |
| 815 | then | |
| 816 | KILL_LEDGER.record(KILL(crossing.location.file_name, crossing, null, p, true, true)) | |
| 817 | doomed_paths.add(p) | |
| 818 | fi | |
| 819 | od | |
| 820 | ||
| 821 | for p in _path_narrows.keys do | |
| 822 | if | |
| 823 | _path_created_by(_path_narrow_created_at, p, index) /\ | |
| 824 | !RELIANCES.crossing_discharged(crossing, null, p, false) | |
| 825 | then | |
| 826 | let kill = KILL(crossing.location.file_name, crossing, null, p, false, true) | |
| 827 | ||
| 828 | kill.narrowed_type = narrowed_type_of_path(p) | |
| 829 | ||
| 830 | KILL_LEDGER.record(kill) | |
| 831 | doomed_paths.add(p) | |
| 832 | fi | |
| 833 | od | |
| 834 | ||
| 835 | for p in doomed_paths do | |
| 836 | drop_path(p) | |
| 837 | od | |
| 838 | si | |
| 839 | ||
| 840 | // Forget one exact path, both slots — the in-walk kill | |
| 841 | // transfer drops a single fact rather than a class of them. | |
| 842 | drop_path(path: ACCESS_PATH) is | |
| 843 | _non_null_paths.remove(path) | |
| 844 | _path_narrows.remove(path) | |
| 845 | si | |
| 846 | ||
| 847 | // Forget every path that reads through `member` at any hop — | |
| 848 | // the member-store transfer. Keyed on the member symbol, not | |
| 849 | // the written receiver, so a store through an aliased | |
| 850 | // receiver still invalidates. Applies to both presence and | |
| 851 | // type-narrow slots. | |
| 852 | drop_paths_through(member: Symbol) is | |
| 853 | let doomed = Collections.LIST[ACCESS_PATH]() | |
| 854 | ||
| 855 | for p in _non_null_paths do | |
| 856 | if p.contains_member(member) then | |
| 857 | doomed.add(p) | |
| 858 | fi | |
| 859 | od | |
| 860 | ||
| 861 | for p in doomed do | |
| 862 | _non_null_paths.remove(p) | |
| 863 | od | |
| 864 | ||
| 865 | let doomed_narrows = Collections.LIST[ACCESS_PATH]() | |
| 866 | ||
| 867 | for p in _path_narrows.keys do | |
| 868 | if p.contains_member(member) then | |
| 869 | doomed_narrows.add(p) | |
| 870 | fi | |
| 871 | od | |
| 872 | ||
| 873 | for p in doomed_narrows do | |
| 874 | _path_narrows.remove(p) | |
| 875 | od | |
| 876 | si | |
| 877 | ||
| 878 | // Forget every tracked path rooted at `root` — used when the | |
| 879 | // root is reassigned, which redirects every `root.…` path. | |
| 880 | // Applies to both presence and type-narrow slots. | |
| 881 | drop_paths_rooted_at(root: Symbol) is | |
| 882 | let doomed = Collections.LIST[ACCESS_PATH]() | |
| 883 | ||
| 884 | for p in _non_null_paths do | |
| 885 | if p.root == root then | |
| 886 | doomed.add(p) | |
| 887 | fi | |
| 888 | od | |
| 889 | ||
| 890 | for p in doomed do | |
| 891 | _non_null_paths.remove(p) | |
| 892 | od | |
| 893 | ||
| 894 | let doomed_narrows = Collections.LIST[ACCESS_PATH]() | |
| 895 | ||
| 896 | for p in _path_narrows.keys do | |
| 897 | if p.root == root then | |
| 898 | doomed_narrows.add(p) | |
| 899 | fi | |
| 900 | od | |
| 901 | ||
| 902 | for p in doomed_narrows do | |
| 903 | _path_narrows.remove(p) | |
| 904 | od | |
| 905 | si | |
| 906 | ||
| 907 | // Forget every fact a heap mutation can invalidate: narrows | |
| 908 | // and presence facts keyed on fields or properties, and every | |
| 909 | // member-access path. Local-variable facts survive — a callee | |
| 910 | // cannot reach a local. Used by controlled walks whose branch | |
| 911 | // environments derive from a snapshot taken before the walk: | |
| 912 | // when the walk killed heap facts, the snapshot's heap facts | |
| 913 | // cannot be trusted on the edges built from it. | |
| 914 | drop_heap_facts() is | |
| 915 | let stale = Collections.LIST[Symbol]() | |
| 916 | ||
| 917 | for v in _narrows.keys do | |
| 918 | if isa Semantic.Symbols.Field(v) \/ isa Semantic.Symbols.Property(v) then | |
| 919 | stale.add(v) | |
| 920 | fi | |
| 921 | od | |
| 922 | ||
| 923 | for v in stale do | |
| 924 | _narrows.remove(v) | |
| 925 | od | |
| 926 | ||
| 927 | let stale_presence = Collections.LIST[Symbol]() | |
| 928 | ||
| 929 | for v in _non_null do | |
| 930 | if isa Semantic.Symbols.Field(v) \/ isa Semantic.Symbols.Property(v) then | |
| 931 | stale_presence.add(v) | |
| 932 | fi | |
| 933 | od | |
| 934 | ||
| 935 | for v in stale_presence do | |
| 936 | _non_null.remove(v) | |
| 937 | od | |
| 938 | ||
| 939 | _non_null_paths.clear() | |
| 940 | _path_narrows.clear() | |
| 941 | _non_null_crossings.clear() | |
| 942 | _narrow_crossings.clear() | |
| 943 | _path_presence_crossings.clear() | |
| 944 | _path_narrow_crossings.clear() | |
| 945 | _non_null_created_at.clear() | |
| 946 | _narrow_created_at.clear() | |
| 947 | _path_presence_created_at.clear() | |
| 948 | _path_narrow_created_at.clear() | |
| 949 | si | |
| 950 | ||
| 951 | copy() -> NARROW_ENV is | |
| 952 | let e = NARROW_ENV() | |
| 953 | e.is_bottom = is_bottom | |
| 954 | ||
| 955 | for v in _narrows.keys do | |
| 956 | e._narrows[v] = _narrows[v] | |
| 957 | od | |
| 958 | ||
| 959 | for v in _assigned do | |
| 960 | e._assigned.add(v) | |
| 961 | od | |
| 962 | ||
| 963 | for f in _called do | |
| 964 | e._called.add(f) | |
| 965 | od | |
| 966 | ||
| 967 | for v in _non_null do | |
| 968 | e._non_null.add(v) | |
| 969 | od | |
| 970 | ||
| 971 | for p in _non_null_paths do | |
| 972 | e._non_null_paths.add(p) | |
| 973 | od | |
| 974 | ||
| 975 | for p in _path_narrows.keys do | |
| 976 | e._path_narrows[p] = _path_narrows[p] | |
| 977 | od | |
| 978 | ||
| 979 | for v in _non_null_crossings.keys do | |
| 980 | e._non_null_crossings[v] = _copied_crossings(_non_null_crossings[v]) | |
| 981 | od | |
| 982 | ||
| 983 | for v in _narrow_crossings.keys do | |
| 984 | e._narrow_crossings[v] = _copied_crossings(_narrow_crossings[v]) | |
| 985 | od | |
| 986 | ||
| 987 | for p in _path_presence_crossings.keys do | |
| 988 | e._path_presence_crossings[p] = _copied_crossings(_path_presence_crossings[p]) | |
| 989 | od | |
| 990 | ||
| 991 | for p in _path_narrow_crossings.keys do | |
| 992 | e._path_narrow_crossings[p] = _copied_crossings(_path_narrow_crossings[p]) | |
| 993 | od | |
| 994 | ||
| 995 | for v in _non_null_created_at.keys do | |
| 996 | e._non_null_created_at[v] = _non_null_created_at[v] | |
| 997 | od | |
| 998 | ||
| 999 | for v in _narrow_created_at.keys do | |
| 1000 | e._narrow_created_at[v] = _narrow_created_at[v] | |
| 1001 | od | |
| 1002 | ||
| 1003 | for p in _path_presence_created_at.keys do | |
| 1004 | e._path_presence_created_at[p] = _path_presence_created_at[p] | |
| 1005 | od | |
| 1006 | ||
| 1007 | for p in _path_narrow_created_at.keys do | |
| 1008 | e._path_narrow_created_at[p] = _path_narrow_created_at[p] | |
| 1009 | od | |
| 1010 | ||
| 1011 | return e | |
| 1012 | si | |
| 1013 | ||
| 1014 | // Carry another env's crossing records into this one — used | |
| 1015 | // by the flow's set_env, which rebuilds the applied env | |
| 1016 | // through the set_* methods, whose establishment semantics | |
| 1017 | // would otherwise clear the records at every branch entry. | |
| 1018 | adopt_crossings_from(source: NARROW_ENV) is | |
| 1019 | for v in source._non_null_crossings.keys do | |
| 1020 | _non_null_crossings[v] = _copied_crossings(source._non_null_crossings[v]) | |
| 1021 | od | |
| 1022 | ||
| 1023 | for v in source._narrow_crossings.keys do | |
| 1024 | _narrow_crossings[v] = _copied_crossings(source._narrow_crossings[v]) | |
| 1025 | od | |
| 1026 | ||
| 1027 | for p in source._path_presence_crossings.keys do | |
| 1028 | _path_presence_crossings[p] = _copied_crossings(source._path_presence_crossings[p]) | |
| 1029 | od | |
| 1030 | ||
| 1031 | for p in source._path_narrow_crossings.keys do | |
| 1032 | _path_narrow_crossings[p] = _copied_crossings(source._path_narrow_crossings[p]) | |
| 1033 | od | |
| 1034 | si | |
| 1035 | ||
| 1036 | // Carry another env's fact creation indexes into this one — | |
| 1037 | // paired with `adopt_crossings_from` in the flow's set_env, so | |
| 1038 | // a rebuilt environment keeps the indexes its facts were | |
| 1039 | // established under. | |
| 1040 | adopt_creation_marks_from(source: NARROW_ENV) is | |
| 1041 | for v in source._non_null_created_at.keys do | |
| 1042 | _non_null_created_at[v] = source._non_null_created_at[v] | |
| 1043 | od | |
| 1044 | ||
| 1045 | for v in source._narrow_created_at.keys do | |
| 1046 | _narrow_created_at[v] = source._narrow_created_at[v] | |
| 1047 | od | |
| 1048 | ||
| 1049 | for p in source._path_presence_created_at.keys do | |
| 1050 | _path_presence_created_at[p] = source._path_presence_created_at[p] | |
| 1051 | od | |
| 1052 | ||
| 1053 | for p in source._path_narrow_created_at.keys do | |
| 1054 | _path_narrow_created_at[p] = source._path_narrow_created_at[p] | |
| 1055 | od | |
| 1056 | si | |
| 1057 | ||
| 1058 | _copied_crossings(crossings: Collections.LIST[CROSSING]) -> Collections.LIST[CROSSING] static is | |
| 1059 | let result = Collections.LIST[CROSSING]() | |
| 1060 | ||
| 1061 | for c in crossings do | |
| 1062 | result.add(c) | |
| 1063 | od | |
| 1064 | ||
| 1065 | return result | |
| 1066 | si | |
| 1067 | ||
| 1068 | // A copy carrying only the definite-assignment facts — no | |
| 1069 | // narrows, reachable. Used where the narrowing facts must be | |
| 1070 | // discarded conservatively (after a try statement) but | |
| 1071 | // assignments made before it still hold. | |
| 1072 | with_only_assigned() -> NARROW_ENV is | |
| 1073 | let e = NARROW_ENV() | |
| 1074 | ||
| 1075 | for v in _assigned do | |
| 1076 | e._assigned.add(v) | |
| 1077 | od | |
| 1078 | ||
| 1079 | for f in _called do | |
| 1080 | e._called.add(f) | |
| 1081 | od | |
| 1082 | ||
| 1083 | return e | |
| 1084 | si | |
| 1085 | ||
| 1086 | // A copy carrying the definite-assignment facts and, of the | |
| 1087 | // narrowing facts, those on stack locals that `keep` accepts. | |
| 1088 | // Used for the entry to a finally body, which runs on every | |
| 1089 | // path out of its try: a fact proven before the try still | |
| 1090 | // holds there unless the try writes what it was proven on. | |
| 1091 | // Heap facts are left out - a call anywhere in the try can | |
| 1092 | // invalidate one, and the crossings that would judge that | |
| 1093 | // were recorded in the body's environment rather than this | |
| 1094 | // one. | |
| 1095 | with_only_assigned_and_kept_locals(keep: (Symbol) -> bool) -> NARROW_ENV is | |
| 1096 | let e = with_only_assigned() | |
| 1097 | ||
| 1098 | for v in _non_null do | |
| 1099 | if !_is_heap_fact(v) /\ keep(v) then | |
| 1100 | e.set_non_null(v) | |
| 1101 | fi | |
| 1102 | od | |
| 1103 | ||
| 1104 | for v in _narrows.keys do | |
| 1105 | if !_is_heap_fact(v) /\ keep(v) then | |
| 1106 | if let t = narrowed_type_of(v) then | |
| 1107 | e.set_narrow(v, t) | |
| 1108 | fi | |
| 1109 | fi | |
| 1110 | od | |
| 1111 | ||
| 1112 | return e | |
| 1113 | si | |
| 1114 | ||
| 1115 | // Merge two environments at a control-flow merge point. | |
| 1116 | // `bottom` is the identity (a diverging branch contributes | |
| 1117 | // nothing). Every domain merges by intersection: a variable | |
| 1118 | // survives the narrowing merge only when narrowed in BOTH | |
| 1119 | // inputs (merged type = least upper bound); a variable is | |
| 1120 | // definitely assigned after the merge only when assigned in | |
| 1121 | // BOTH inputs; likewise known-non-null only when in both. | |
| 1122 | join(a: NARROW_ENV, b: NARROW_ENV) -> NARROW_ENV static is | |
| 1123 | if a.is_bottom then | |
| 1124 | return b.copy() | |
| 1125 | fi | |
| 1126 | ||
| 1127 | if b.is_bottom then | |
| 1128 | return a.copy() | |
| 1129 | fi | |
| 1130 | ||
| 1131 | let result = NARROW_ENV() | |
| 1132 | ||
| 1133 | for v in a.variables do | |
| 1134 | if let ta = a.narrowed_type_of(v), tb = b.narrowed_type_of(v) then | |
| 1135 | // Two narrows over the same closed root join by | |
| 1136 | // subtype-set union — exact, and it keeps the | |
| 1137 | // optional flag when either edge can be null. | |
| 1138 | // The general LUB is the fallback for every | |
| 1139 | // other shape. | |
| 1140 | let merged mut = Semantic.Types.ONE_OF.try_join(ta, tb) | |
| 1141 | ||
| 1142 | if !merged? then | |
| 1143 | let lub = Semantic.LEAST_UPPER_BOUND_MAP() | |
| 1144 | lub.add(ta) | |
| 1145 | lub.add(tb) | |
| 1146 | ||
| 1147 | merged = lub.get_result() | |
| 1148 | fi | |
| 1149 | ||
| 1150 | if merged? then | |
| 1151 | result.set_narrow(v, merged) | |
| 1152 | fi | |
| 1153 | fi | |
| 1154 | od | |
| 1155 | ||
| 1156 | for v in a.assigned_variables do | |
| 1157 | if b.is_assigned(v) then | |
| 1158 | result.set_assigned(v) | |
| 1159 | fi | |
| 1160 | od | |
| 1161 | ||
| 1162 | for f in a.called_methods do | |
| 1163 | if b.is_called(f) then | |
| 1164 | result.set_called(f) | |
| 1165 | fi | |
| 1166 | od | |
| 1167 | ||
| 1168 | for v in a.non_null_variables do | |
| 1169 | if b.is_non_null(v) then | |
| 1170 | result.set_non_null(v) | |
| 1171 | fi | |
| 1172 | od | |
| 1173 | ||
| 1174 | for p in a.non_null_paths do | |
| 1175 | if b.is_non_null_path(p) then | |
| 1176 | result.set_non_null_path(p) | |
| 1177 | fi | |
| 1178 | od | |
| 1179 | ||
| 1180 | for p in a.narrowed_paths do | |
| 1181 | if let ta = a.narrowed_type_of_path(p), tb = b.narrowed_type_of_path(p) then | |
| 1182 | // Two narrows over the same closed root join by | |
| 1183 | // subtype-set union — mirrors the symbol case. | |
| 1184 | let merged mut = Semantic.Types.ONE_OF.try_join(ta, tb) | |
| 1185 | ||
| 1186 | if !merged? then | |
| 1187 | let lub = Semantic.LEAST_UPPER_BOUND_MAP() | |
| 1188 | lub.add(ta) | |
| 1189 | lub.add(tb) | |
| 1190 | ||
| 1191 | merged = lub.get_result() | |
| 1192 | fi | |
| 1193 | ||
| 1194 | if merged? then | |
| 1195 | result.set_path_narrow(p, merged) | |
| 1196 | fi | |
| 1197 | fi | |
| 1198 | od | |
| 1199 | ||
| 1200 | // A fact that survives the merge survived every crossing | |
| 1201 | // on either edge, so its record is the union of both. | |
| 1202 | // The set_* calls above cleared the result's entries, so | |
| 1203 | // the union is written afterwards. | |
| 1204 | for v in result._non_null do | |
| 1205 | _merge_crossings(result._non_null_crossings, v, a.non_null_crossings_of(v), b.non_null_crossings_of(v)) | |
| 1206 | result._non_null_created_at[v] = _merged_created(a._non_null_created_at, b._non_null_created_at, v) | |
| 1207 | od | |
| 1208 | ||
| 1209 | for v in result._narrows.keys do | |
| 1210 | _merge_crossings(result._narrow_crossings, v, a.narrow_crossings_of(v), b.narrow_crossings_of(v)) | |
| 1211 | result._narrow_created_at[v] = _merged_created(a._narrow_created_at, b._narrow_created_at, v) | |
| 1212 | od | |
| 1213 | ||
| 1214 | for p in result._non_null_paths do | |
| 1215 | _merge_path_crossings(result._path_presence_crossings, p, a.path_presence_crossings_of(p), b.path_presence_crossings_of(p)) | |
| 1216 | result._path_presence_created_at[p] = _merged_path_created(a._path_presence_created_at, b._path_presence_created_at, p) | |
| 1217 | od | |
| 1218 | ||
| 1219 | for p in result._path_narrows.keys do | |
| 1220 | _merge_path_crossings(result._path_narrow_crossings, p, a.path_narrow_crossings_of(p), b.path_narrow_crossings_of(p)) | |
| 1221 | result._path_narrow_created_at[p] = _merged_path_created(a._path_narrow_created_at, b._path_narrow_created_at, p) | |
| 1222 | od | |
| 1223 | ||
| 1224 | return result | |
| 1225 | si | |
| 1226 | ||
| 1227 | // The creation index of a fact surviving a join: the earlier | |
| 1228 | // edge's index when both edges record one, zero otherwise — a | |
| 1229 | // side with no recorded index may have carried the fact since | |
| 1230 | // the start of the log, and the merged record inherits its | |
| 1231 | // crossings, so nothing may be filtered. | |
| 1232 | _merged_created( | |
| 1233 | from_a: Collections.MAP[Symbol, int], | |
| 1234 | from_b: Collections.MAP[Symbol, int], | |
| 1235 | v: Symbol | |
| 1236 | ) -> int static is | |
| 1237 | let mark_a mut = 0 | |
| 1238 | let mark_b mut = 0 | |
| 1239 | ||
| 1240 | if from_a.try_get_value(v, mark_a ref) /\ from_b.try_get_value(v, mark_b ref) then | |
| 1241 | return if mark_a < mark_b then mark_a else mark_b fi | |
| 1242 | fi | |
| 1243 | ||
| 1244 | return 0 | |
| 1245 | si | |
| 1246 | ||
| 1247 | _merged_path_created( | |
| 1248 | from_a: Collections.MAP[ACCESS_PATH, int], | |
| 1249 | from_b: Collections.MAP[ACCESS_PATH, int], | |
| 1250 | p: ACCESS_PATH | |
| 1251 | ) -> int static is | |
| 1252 | let mark_a mut = 0 | |
| 1253 | let mark_b mut = 0 | |
| 1254 | ||
| 1255 | if from_a.try_get_value(p, mark_a ref) /\ from_b.try_get_value(p, mark_b ref) then | |
| 1256 | return if mark_a < mark_b then mark_a else mark_b fi | |
| 1257 | fi | |
| 1258 | ||
| 1259 | return 0 | |
| 1260 | si | |
| 1261 | ||
| 1262 | _merge_crossings( | |
| 1263 | map: Collections.MAP[Symbol, Collections.LIST[CROSSING]], | |
| 1264 | v: Symbol, | |
| 1265 | from_a: Collections.LIST[CROSSING]?, | |
| 1266 | from_b: Collections.LIST[CROSSING]? | |
| 1267 | ) static is | |
| 1268 | let merged = _merged_crossing_lists(from_a, from_b) | |
| 1269 | ||
| 1270 | if merged? then | |
| 1271 | map[v] = merged | |
| 1272 | fi | |
| 1273 | si | |
| 1274 | ||
| 1275 | _merge_path_crossings( | |
| 1276 | map: Collections.MAP[ACCESS_PATH, Collections.LIST[CROSSING]], | |
| 1277 | p: ACCESS_PATH, | |
| 1278 | from_a: Collections.LIST[CROSSING]?, | |
| 1279 | from_b: Collections.LIST[CROSSING]? | |
| 1280 | ) static is | |
| 1281 | let merged = _merged_crossing_lists(from_a, from_b) | |
| 1282 | ||
| 1283 | if merged? then | |
| 1284 | map[p] = merged | |
| 1285 | fi | |
| 1286 | si | |
| 1287 | ||
| 1288 | _merged_crossing_lists( | |
| 1289 | from_a: Collections.LIST[CROSSING]?, | |
| 1290 | from_b: Collections.LIST[CROSSING]? | |
| 1291 | ) -> Collections.LIST[CROSSING]? static is | |
| 1292 | if !from_a? /\ !from_b? then | |
| 1293 | return null | |
| 1294 | fi | |
| 1295 | ||
| 1296 | let merged = Collections.LIST[CROSSING]() | |
| 1297 | ||
| 1298 | if from_a? then | |
| 1299 | for c in from_a do | |
| 1300 | merged.add(c) | |
| 1301 | od | |
| 1302 | fi | |
| 1303 | ||
| 1304 | if from_b? then | |
| 1305 | for c in from_b do | |
| 1306 | // both edges usually share the pre-branch prefix; | |
| 1307 | // skip exact duplicates so the record stays small | |
| 1308 | if !merged.contains(c) then | |
| 1309 | merged.add(c) | |
| 1310 | fi | |
| 1311 | od | |
| 1312 | fi | |
| 1313 | ||
| 1314 | return merged | |
| 1315 | si | |
| 1316 | si | |
| 1317 | si |