summaryrefslogtreecommitdiff
path: root/js/src/frontend/FunctionEmitter.h
blob: f297f8e6c68b8455ee1bfe7035ea6b9cefca1423 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef frontend_FunctionEmitter_h
#define frontend_FunctionEmitter_h

#include "mozilla/Attributes.h"  // MOZ_STACK_CLASS

#include <stdint.h>  // uint16_t, uint32_t

#include "jsopcode.h"
#include "jsfun.h"                         // JSFunction

#include "frontend/DefaultEmitter.h"       // DefaultEmitter
#include "frontend/DestructuringFlavor.h"  // DestructuringFlavor
#include "frontend/EmitterScope.h"         // EmitterScope
#include "frontend/SharedContext.h"        // FunctionBox
#include "frontend/TDZCheckCache.h"        // TDZCheckCache
#include "gc/Rooting.h"                    // JS::Rooted, JS::Handle
#include "vm/String.h"                     // JSAtom

namespace js {
namespace frontend {

struct BytecodeEmitter;

// Class for emitting function declaration, expression, or method etc.
//
// This class handles the enclosing script's part (function object creation,
// declaration, etc). The content of the function script is handled by
// FunctionScriptEmitter and FunctionParamsEmitter.
//
// Usage: (check for the return value is omitted for simplicity)
//
//   `function f() {}`, non lazy script
//     FunctionEmitter fe(this, funbox_for_f, FunctionSyntaxKind::Statement,
//                        false);
//     fe.prepareForNonLazy();
//
//     // Emit script with FunctionScriptEmitter here.
//     ...
//
//     fe.emitNonLazyEnd();
//
//   `function f() {}`, lazy script
//     FunctionEmitter fe(this, funbox_for_f, FunctionSyntaxKind::Statement,
//                        false);
//     fe.emitLazy();
//
//   `function f() {}`, emitting hoisted function again
//     // See emitAgain comment for more details
//     FunctionEmitter fe(this, funbox_for_f, FunctionSyntaxKind::Statement,
//                        true);
//     fe.emitAgain();
//
//   `function f() { "use asm"; }`
//     FunctionEmitter fe(this, funbox_for_f, FunctionSyntaxKind::Statement,
//                        false);
//     fe.emitAsmJSModule();
//
class MOZ_STACK_CLASS FunctionEmitter {
  private:
    BytecodeEmitter* bce_;

    FunctionBox* funbox_;

    // Function linked from funbox_.
    JS::Rooted<JSFunction*> fun_;

    // Function's explicit name.
    JS::Rooted<JSAtom*> name_;

    FunctionSyntaxKind syntaxKind_;
    bool isHoisted_;

#ifdef DEBUG
    // The state of this emitter.
    //
    // +-------+
    // | Start |-+
    // +-------+ |
    //           |
    //   +-------+
    //   |
    //   | [non-lazy function]
    //   |   prepareForNonLazy  +---------+ emitNonLazyEnd     +-----+
    //   +--------------------->| NonLazy |---------------->+->| End |
    //   |                      +---------+                 ^  +-----+
    //   |                                                  |
    //   | [lazy function]                                  |
    //   |   emitLazy                                       |
    //   +------------------------------------------------->+
    //   |                                                  ^
    //   | [emitting hoisted function again]                |
    //   |   emitAgain                                      |
    //   +------------------------------------------------->+
    //   |                                                  ^
    //   | [asm.js module]                                  |
    //   |   emitAsmJSModule                                |
    //   +--------------------------------------------------+
    //
    enum class State {
        // The initial state.
        Start,

        // After calling prepareForNonLazy.
        NonLazy,

        // After calling emitNonLazyEnd, emitLazy, emitAgain, or emitAsmJSModule.
        End
    };
    State state_ = State::Start;
#endif

  public:
    FunctionEmitter(BytecodeEmitter* bce, FunctionBox* funbox,
                    FunctionSyntaxKind syntaxKind, bool isHoisted);

    [[nodiscard]] bool prepareForNonLazy();
    [[nodiscard]] bool emitNonLazyEnd();

    [[nodiscard]] bool emitLazy();

    [[nodiscard]] bool emitAgain();

    [[nodiscard]] bool emitAsmJSModule();

  private:
    // Common code for non-lazy and lazy functions.
    [[nodiscard]] bool interpretedCommon();

    // Emit the function declaration, expression, method etc.
    // This leaves function object on the stack for expression etc,
    // and doesn't for declaration.
    [[nodiscard]] bool emitFunction();

    // Helper methods used by emitFunction for each case.
    // `index` is the object index of the function.
    [[nodiscard]] bool emitNonHoisted(unsigned index);
    [[nodiscard]] bool emitHoisted(unsigned index);
    [[nodiscard]] bool emitTopLevelFunction(unsigned index);
    [[nodiscard]] bool emitNewTargetForArrow();
};

// Class for emitting function script.
// Parameters are handled by FunctionParamsEmitter.
//
// Usage: (check for the return value is omitted for simplicity)
//
//   `function f(a) { expr }`
//     FunctionScriptEmitter fse(this, funbox_for_f,
//                               Some(offset_of_opening_paren),
//                               Some(offset_of_closing_brace));
//     fse.prepareForParameters();
//
//     // Emit parameters with FunctionParamsEmitter here.
//     ...
//
//     fse.prepareForBody();
//     emit(expr);
//     fse.emitEnd();
//
//     // Do NameFunctions operation here if needed.
//
//     fse.initScript();
//
class MOZ_STACK_CLASS FunctionScriptEmitter {
  private:
    BytecodeEmitter* bce_;

    FunctionBox* funbox_;

    // Scope for the function name for a named lambda.
    // None for anonymous function.
    mozilla::Maybe<EmitterScope> namedLambdaEmitterScope_;

    // Scope for function body.
    mozilla::Maybe<EmitterScope> functionEmitterScope_;

    // Scope for the extra body var.
    // None if `funbox_->hasExtraBodyVarScope() == false`.
    mozilla::Maybe<EmitterScope> extraBodyVarEmitterScope_;

    mozilla::Maybe<TDZCheckCache> tdzCache_;

    // See the comment for constructor.
    mozilla::Maybe<uint32_t> paramStart_;
    mozilla::Maybe<uint32_t> bodyEnd_;

#ifdef DEBUG
    // The state of this emitter.
    //
    // +-------+ prepareForParameters  +------------+
    // | Start |---------------------->| Parameters |-+
    // +-------+                       +------------+ |
    //                                                |
    //   +--------------------------------------------+
    //   |
    //   | prepareForBody  +------+ emitEndBody  +---------+
    //   +---------------->| Body |------------->| EndBody |-+
    //                     +------+              +---------+ |
    //                                                       |
    //     +-------------------------------------------------+
    //     |
    //     | initScript  +-----+
    //     +------------>| End |
    //                   +-----+
    enum class State {
        // The initial state.
        Start,

        // After calling prepareForParameters.
        Parameters,

        // After calling prepareForBody.
        Body,

        // After calling emitEndBody.
        EndBody,

        // After calling initScript.
        End
    };
    State state_ = State::Start;
#endif

  public:
    // Parameters are the offset in the source code for each character below:
    //
    //   function f(a, b, ...c) { ... }
    //             ^                  ^
    //             |                  |
    //             paramStart         bodyEnd
    //
    // Can be Nothing() if not available.
    FunctionScriptEmitter(BytecodeEmitter* bce, FunctionBox* funbox,
                          const mozilla::Maybe<uint32_t>& paramStart,
                          const mozilla::Maybe<uint32_t>& bodyEnd)
        : bce_(bce),
          funbox_(funbox),
          paramStart_(paramStart),
          bodyEnd_(bodyEnd) {}

    [[nodiscard]] bool prepareForParameters();
    [[nodiscard]] bool prepareForBody();
    [[nodiscard]] bool emitEndBody();

    // Initialize JSScript for this function.
    // WARNING: There shouldn't be any fallible operation for the function
    //          compilation after `initScript` call.
    //          See the comment inside JSScript::fullyInitFromEmitter for
    //          more details.
    [[nodiscard]] bool initScript();

 private:
    [[nodiscard]] bool emitExtraBodyVarScope();
};

// Class for emitting function parameters.
//
// Usage: (check for the return value is omitted for simplicity)
//
//   `function f(a, b=10, ...c) {}`
//     FunctionParamsEmitter fpe(this, funbox_for_f);
//
//     fpe.emitSimple(atom_of_a);
//
//     fpe.prepareForDefault();
//     emit(10);
//     fpe.emitDefaultEnd(atom_of_b);
//
//     fpe.emitRest(atom_of_c);
//
//   `function f([a], [b]=[1], ...[c]) {}`
//     FunctionParamsEmitter fpe(this, funbox_for_f);
//
//     fpe.prepareForDestructuring();
//     emit(destructuring_for_[a]);
//     fpe.emitDestructuringEnd();
//
//     fpe.prepareForDestructuringDefaultInitializer();
//     emit([1]);
//     fpe.prepareForDestructuringDefault();
//     emit(destructuring_for_[b]);
//     fpe.emitDestructuringDefaultEnd();
//
//     fpe.prepareForDestructuringRest();
//     emit(destructuring_for_[c]);
//     fpe.emitDestructuringRestEnd();
//
class MOZ_STACK_CLASS FunctionParamsEmitter {
  private:
    BytecodeEmitter* bce_;

    FunctionBox* funbox_;

    // The pointer to `FunctionScriptEmitter::functionEmitterScope_`,
    // passed via `BytecodeEmitter::innermostEmitterScope()`.
    EmitterScope* functionEmitterScope_;

    // The slot for the current parameter.
    // NOTE: after emitting rest parameter, this isn't incremented.
    uint16_t argSlot_ = 0;

    // DefaultEmitter for default parameter.
    mozilla::Maybe<DefaultEmitter> default_;

    // Scope for each parameter expression.
    // Populated only when there's `eval` in parameters.
    mozilla::Maybe<EmitterScope> paramExprVarEmitterScope_;

#ifdef DEBUG
    // The state of this emitter.
    //
    // +----------------------------------------------------------+
    // |                                                          |
    // |  +-------+                                               |
    // +->| Start |-+                                             |
    //    +-------+ |                                             |
    //              |                                             |
    // +------------+                                             |
    // |                                                          |
    // | [single binding, wihtout default]                        |
    // |   emitSimple                                             |
    // +--------------------------------------------------------->+
    // |                                                          ^
    // | [single binding, with default]                           |
    // |   prepareForDefault  +---------+ emitDefaultEnd          |
    // +--------------------->| Default |------------------------>+
    // |                      +---------+                         ^
    // |                                                          |
    // | [destructuring, without default]                         |
    // |   prepareForDestructuring  +---------------+             |
    // +--------------------------->| Destructuring |-+           |
    // |                            +---------------+ |           |
    // |                                              |           |
    // |    +-----------------------------------------+           |
    // |    |                                                     |
    // |    | emitDestructuringEnd                                |
    // |    +---------------------------------------------------->+
    // |                                                          ^
    // | [destructuring, with default]                            |
    // |   prepareForDestructuringDefaultInitializer              |
    // +---------------------------------------------+            |
    // |                                             |            |
    // |    +----------------------------------------+            |
    // |    |                                                     |
    // |    |  +---------------------------------+                |
    // |    +->| DestructuringDefaultInitializer |-+              |
    // |       +---------------------------------+ |              |
    // |                                           |              |
    // |      +------------------------------------+              |
    // |      |                                                   |
    // |      | prepareForDestructuringDefault                    |
    // |      +-------------------------------+                   |
    // |                                      |                   |
    // |        +-----------------------------+                   |
    // |        |                                                 |
    // |        |  +----------------------+                       |
    // |        +->| DestructuringDefault |-+                     |
    // |           +----------------------+ |                     |
    // |                                    |                     |
    // |          +-------------------------+                     |
    // |          |                                               |
    // |          | emitDestructuringDefaultEnd                   |
    // |          +---------------------------------------------->+
    // |
    // | [single binding rest]
    // |   emitRest                                                  +-----+
    // +--------------------------------------------------------->+->| End |
    // |                                                          ^  +-----+
    // | [destructuring rest]                                     |
    // |   prepareForDestructuringRest   +-------------------+    |
    // +-------------------------------->| DestructuringRest |-+  |
    //                                   +-------------------+ |  |
    //                                                         |  |
    //    +----------------------------------------------------+  |
    //    |                                                       |
    //    | emitDestructuringRestEnd                              |
    //    +-------------------------------------------------------+
    //
    enum class State {
        // The initial state, or after emitting non-rest parameter.
        Start,

        // After calling prepareForDefault.
        Default,

        // After calling prepareForDestructuring.
        Destructuring,

        // After calling prepareForDestructuringDefaultInitializer.
        DestructuringDefaultInitializer,

        // After calling prepareForDestructuringDefault.
        DestructuringDefault,

        // After calling prepareForDestructuringRest.
        DestructuringRest,

        // After calling emitRest or emitDestructuringRestEnd.
        End,
    };
    State state_ = State::Start;
#endif

  public:
    FunctionParamsEmitter(BytecodeEmitter* bce, FunctionBox* funbox);

    // paramName is used only when there's at least one expression in the
    // paramerters (funbox_->hasParameterExprs == true).
    [[nodiscard]] bool emitSimple(JS::Handle<JSAtom*> paramName);

    [[nodiscard]] bool prepareForDefault();
    [[nodiscard]] bool emitDefaultEnd(JS::Handle<JSAtom*> paramName);

    [[nodiscard]] bool prepareForDestructuring();
    [[nodiscard]] bool emitDestructuringEnd();

    [[nodiscard]] bool prepareForDestructuringDefaultInitializer();
    [[nodiscard]] bool prepareForDestructuringDefault();
    [[nodiscard]] bool emitDestructuringDefaultEnd();

    [[nodiscard]] bool emitRest(JS::Handle<JSAtom*> paramName);

    [[nodiscard]] bool prepareForDestructuringRest();
    [[nodiscard]] bool emitDestructuringRestEnd();

    [[nodiscard]] DestructuringFlavor getDestructuringFlavor();

  private:
    // Enter/leave var scope for `eval` if necessary.
    [[nodiscard]] bool enterParameterExpressionVarScope();
    [[nodiscard]] bool leaveParameterExpressionVarScope();

    [[nodiscard]] bool prepareForInitializer();
    [[nodiscard]] bool emitInitializerEnd();

    [[nodiscard]] bool emitRestArray();

    [[nodiscard]] bool emitAssignment(JS::Handle<JSAtom*> paramName);
};

} /* namespace frontend */
} /* namespace js */

#endif /* frontend_FunctionEmitter_h */