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1 /* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 * vim: set ts=8 sw=4 et tw=79:
3 *
4 * ***** BEGIN LICENSE BLOCK *****
5 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
6 *
7 * The contents of this file are subject to the Mozilla Public License Version
8 * 1.1 (the "License"); you may not use this file except in compliance with
9 * the License. You may obtain a copy of the License at
10 * http://www.mozilla.org/MPL/
11 *
12 * Software distributed under the License is distributed on an "AS IS" basis,
13 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
14 * for the specific language governing rights and limitations under the
15 * License.
16 *
17 * The Original Code is Mozilla Communicator client code, released
18 * March 31, 1998.
19 *
20 * The Initial Developer of the Original Code is
21 * Netscape Communications Corporation.
22 * Portions created by the Initial Developer are Copyright (C) 1998
23 * the Initial Developer. All Rights Reserved.
24 *
25 * Contributor(s):
26 *
27 * Alternatively, the contents of this file may be used under the terms of
28 * either of the GNU General Public License Version 2 or later (the "GPL"),
29 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
30 * in which case the provisions of the GPL or the LGPL are applicable instead
31 * of those above. If you wish to allow use of your version of this file only
32 * under the terms of either the GPL or the LGPL, and not to allow others to
33 * use your version of this file under the terms of the MPL, indicate your
34 * decision by deleting the provisions above and replace them with the notice
35 * and other provisions required by the GPL or the LGPL. If you do not delete
36 * the provisions above, a recipient may use your version of this file under
37 * the terms of any one of the MPL, the GPL or the LGPL.
38 *
39 * ***** END LICENSE BLOCK ***** */
40
41 #ifndef jsemit_h___
42 #define jsemit_h___
43 /*
44 * JS bytecode generation.
45 */
46
47 #include "jsstddef.h"
48 #include "jstypes.h"
49 #include "jsatom.h"
50 #include "jsopcode.h"
51 #include "jsscript.h"
52 #include "jsprvtd.h"
53 #include "jspubtd.h"
54
55 JS_BEGIN_EXTERN_C
56
57 /*
58 * NB: If you add enumerators for scope statements, add them between STMT_WITH
59 * and STMT_CATCH, or you will break the STMT_TYPE_IS_SCOPE macro. If you add
60 * non-looping statement enumerators, add them before STMT_DO_LOOP or you will
61 * break the STMT_TYPE_IS_LOOP macro.
62 *
63 * Also remember to keep the statementName array in jsemit.c in sync.
64 */
65 typedef enum JSStmtType {
66 STMT_LABEL, /* labeled statement: L: s */
67 STMT_IF, /* if (then) statement */
68 STMT_ELSE, /* else clause of if statement */
69 STMT_SEQ, /* synthetic sequence of statements */
70 STMT_BLOCK, /* compound statement: { s1[;... sN] } */
71 STMT_SWITCH, /* switch statement */
72 STMT_WITH, /* with statement */
73 STMT_CATCH, /* catch block */
74 STMT_TRY, /* try block */
75 STMT_FINALLY, /* finally block */
76 STMT_SUBROUTINE, /* gosub-target subroutine body */
77 STMT_DO_LOOP, /* do/while loop statement */
78 STMT_FOR_LOOP, /* for loop statement */
79 STMT_FOR_IN_LOOP, /* for/in loop statement */
80 STMT_WHILE_LOOP, /* while loop statement */
81 STMT_LIMIT
82 } JSStmtType;
83
84 #define STMT_TYPE_IN_RANGE(t,b,e) ((uint)((t) - (b)) <= (uintN)((e) - (b)))
85
86 /*
87 * A comment on the encoding of the JSStmtType enum and type-testing macros:
88 *
89 * STMT_TYPE_MAYBE_SCOPE tells whether a statement type is always, or may
90 * become, a lexical scope. It therefore includes block and switch (the two
91 * low-numbered "maybe" scope types) and excludes with (with has dynamic scope
92 * pending the "reformed with" in ES4/JS2). It includes all try-catch-finally
93 * types, which are high-numbered maybe-scope types.
94 *
95 * STMT_TYPE_LINKS_SCOPE tells whether a JSStmtInfo of the given type eagerly
96 * links to other scoping statement info records. It excludes the two early
97 * "maybe" types, block and switch, as well as the try and both finally types,
98 * since try and the other trailing maybe-scope types don't need block scope
99 * unless they contain let declarations.
100 *
101 * We treat WITH as a static scope because it prevents lexical binding from
102 * continuing further up the static scope chain. With the lost "reformed with"
103 * proposal for ES4, we would be able to model it statically, too.
104 */
105 #define STMT_TYPE_MAYBE_SCOPE(type) \
106 (type != STMT_WITH && \
107 STMT_TYPE_IN_RANGE(type, STMT_BLOCK, STMT_SUBROUTINE))
108
109 #define STMT_TYPE_LINKS_SCOPE(type) \
110 STMT_TYPE_IN_RANGE(type, STMT_WITH, STMT_CATCH)
111
112 #define STMT_TYPE_IS_TRYING(type) \
113 STMT_TYPE_IN_RANGE(type, STMT_TRY, STMT_SUBROUTINE)
114
115 #define STMT_TYPE_IS_LOOP(type) ((type) >= STMT_DO_LOOP)
116
117 #define STMT_MAYBE_SCOPE(stmt) STMT_TYPE_MAYBE_SCOPE((stmt)->type)
118 #define STMT_LINKS_SCOPE(stmt) (STMT_TYPE_LINKS_SCOPE((stmt)->type) || \
119 ((stmt)->flags & SIF_SCOPE))
120 #define STMT_IS_TRYING(stmt) STMT_TYPE_IS_TRYING((stmt)->type)
121 #define STMT_IS_LOOP(stmt) STMT_TYPE_IS_LOOP((stmt)->type)
122
123 typedef struct JSStmtInfo JSStmtInfo;
124
125 struct JSStmtInfo {
126 uint16 type; /* statement type */
127 uint16 flags; /* flags, see below */
128 ptrdiff_t update; /* loop update offset (top if none) */
129 ptrdiff_t breaks; /* offset of last break in loop */
130 ptrdiff_t continues; /* offset of last continue in loop */
131 union {
132 JSAtom *label; /* name of LABEL */
133 JSObject *blockObj; /* block scope object */
134 } u;
135 JSStmtInfo *down; /* info for enclosing statement */
136 JSStmtInfo *downScope; /* next enclosing lexical scope */
137 };
138
139 #define SIF_SCOPE 0x0001 /* statement has its own lexical scope */
140 #define SIF_BODY_BLOCK 0x0002 /* STMT_BLOCK type is a function body */
141 #define SIF_FOR_BLOCK 0x0004 /* for (let ...) induced block scope */
142
143 /*
144 * To reuse space in JSStmtInfo, rename breaks and continues for use during
145 * try/catch/finally code generation and backpatching. To match most common
146 * use cases, the macro argument is a struct, not a struct pointer. Only a
147 * loop, switch, or label statement info record can have breaks and continues,
148 * and only a for loop has an update backpatch chain, so it's safe to overlay
149 * these for the "trying" JSStmtTypes.
150 */
151 #define CATCHNOTE(stmt) ((stmt).update)
152 #define GOSUBS(stmt) ((stmt).breaks)
153 #define GUARDJUMP(stmt) ((stmt).continues)
154
155 #define AT_TOP_LEVEL(tc) \
156 (!(tc)->topStmt || ((tc)->topStmt->flags & SIF_BODY_BLOCK))
157
158 #define SET_STATEMENT_TOP(stmt, top) \
159 ((stmt)->update = (top), (stmt)->breaks = (stmt)->continues = (-1))
160
161 struct JSTreeContext { /* tree context for semantic checks */
162 uint16 flags; /* statement state flags, see below */
163 uint16 ngvars; /* max. no. of global variables/regexps */
164 JSStmtInfo *topStmt; /* top of statement info stack */
165 JSStmtInfo *topScopeStmt; /* top lexical scope statement */
166 JSObject *blockChain; /* compile time block scope chain (NB: one
167 deeper than the topScopeStmt/downScope
168 chain when in head of let block/expr) */
169 JSParseNode *blockNode; /* parse node for a lexical scope.
170 XXX combine with blockChain? */
171 JSAtomList decls; /* function, const, and var declarations */
172 JSParseContext *parseContext;
173
174 union {
175
176 JSFunction *fun; /* function to store argument and variable
177 names when flags & TCF_IN_FUNCTION */
178 JSObject *scopeChain; /* scope chain object for the script */
179 } u;
180
181 #ifdef JS_SCOPE_DEPTH_METER
182 uint16 scopeDepth; /* current lexical scope chain depth */
183 uint16 maxScopeDepth; /* maximum lexical scope chain depth */
184 #endif
185 };
186
187 #define TCF_IN_FUNCTION 0x01 /* parsing inside function body */
188 #define TCF_RETURN_EXPR 0x02 /* function has 'return expr;' */
189 #define TCF_RETURN_VOID 0x04 /* function has 'return;' */
190 #define TCF_IN_FOR_INIT 0x08 /* parsing init expr of for; exclude 'in' */
191 #define TCF_FUN_CLOSURE_VS_VAR 0x10 /* function and var with same name */
192 #define TCF_FUN_USES_NONLOCALS 0x20 /* function refers to non-local names */
193 #define TCF_FUN_HEAVYWEIGHT 0x40 /* function needs Call object per call */
194 #define TCF_FUN_IS_GENERATOR 0x80 /* parsed yield statement in function */
195 #define TCF_HAS_DEFXMLNS 0x100 /* default xml namespace = ...; parsed */
196 #define TCF_HAS_FUNCTION_STMT 0x200 /* block contains a function statement */
197 #define TCF_GENEXP_LAMBDA 0x400 /* flag lambda from generator expression */
198 #define TCF_COMPILE_N_GO 0x800 /* compiler-and-go mode of script, can
199 optimize name references based on scope
200 chain */
201 #define TCF_NO_SCRIPT_RVAL 0x1000 /* API caller does not want result value
202 from global script */
203 /*
204 * Flags to propagate out of the blocks.
205 */
206 #define TCF_RETURN_FLAGS (TCF_RETURN_EXPR | TCF_RETURN_VOID)
207
208 /*
209 * Flags to propagate from FunctionBody.
210 */
211 #define TCF_FUN_FLAGS (TCF_FUN_IS_GENERATOR | \
212 TCF_FUN_HEAVYWEIGHT | \
213 TCF_FUN_USES_NONLOCALS | \
214 TCF_FUN_CLOSURE_VS_VAR)
215
216 /*
217 * Flags field, not stored in JSTreeContext.flags, for passing staticDepth
218 * into js_CompileScript.
219 */
220 #define TCF_STATIC_DEPTH_MASK 0xffff0000
221 #define TCF_GET_STATIC_DEPTH(f) ((uint32)(f) >> 16)
222 #define TCF_PUT_STATIC_DEPTH(d) ((uint16)(d) << 16)
223
224 #ifdef JS_SCOPE_DEPTH_METER
225 # define JS_SCOPE_DEPTH_METERING(code) ((void) (code))
226 #else
227 # define JS_SCOPE_DEPTH_METERING(code) ((void) 0)
228 #endif
229
230 #define TREE_CONTEXT_INIT(tc, pc) \
231 ((tc)->flags = (tc)->ngvars = 0, \
232 (tc)->topStmt = (tc)->topScopeStmt = NULL, \
233 (tc)->blockChain = NULL, \
234 ATOM_LIST_INIT(&(tc)->decls), \
235 (tc)->blockNode = NULL, \
236 (tc)->parseContext = (pc), \
237 (tc)->u.scopeChain = NULL, \
238 JS_SCOPE_DEPTH_METERING((tc)->scopeDepth = (tc)->maxScopeDepth = 0))
239
240 /*
241 * For functions TREE_CONTEXT_FINISH is called the second time to finish the
242 * extra tc created during code generation. We skip stats update in such
243 * cases.
244 */
245 #define TREE_CONTEXT_FINISH(cx, tc) \
246 JS_SCOPE_DEPTH_METERING( \
247 (tc)->maxScopeDepth == (uintN) -1 || \
248 JS_BASIC_STATS_ACCUM(&(cx)->runtime->lexicalScopeDepthStats, \
249 (tc)->maxScopeDepth))
250
251 /*
252 * Span-dependent instructions are jumps whose span (from the jump bytecode to
253 * the jump target) may require 2 or 4 bytes of immediate operand.
254 */
255 typedef struct JSSpanDep JSSpanDep;
256 typedef struct JSJumpTarget JSJumpTarget;
257
258 struct JSSpanDep {
259 ptrdiff_t top; /* offset of first bytecode in an opcode */
260 ptrdiff_t offset; /* offset - 1 within opcode of jump operand */
261 ptrdiff_t before; /* original offset - 1 of jump operand */
262 JSJumpTarget *target; /* tagged target pointer or backpatch delta */
263 };
264
265 /*
266 * Jump targets are stored in an AVL tree, for O(log(n)) lookup with targets
267 * sorted by offset from left to right, so that targets after a span-dependent
268 * instruction whose jump offset operand must be extended can be found quickly
269 * and adjusted upward (toward higher offsets).
270 */
271 struct JSJumpTarget {
272 ptrdiff_t offset; /* offset of span-dependent jump target */
273 int balance; /* AVL tree balance number */
274 JSJumpTarget *kids[2]; /* left and right AVL tree child pointers */
275 };
276
277 #define JT_LEFT 0
278 #define JT_RIGHT 1
279 #define JT_OTHER_DIR(dir) (1 - (dir))
280 #define JT_IMBALANCE(dir) (((dir) << 1) - 1)
281 #define JT_DIR(imbalance) (((imbalance) + 1) >> 1)
282
283 /*
284 * Backpatch deltas are encoded in JSSpanDep.target if JT_TAG_BIT is clear,
285 * so we can maintain backpatch chains when using span dependency records to
286 * hold jump offsets that overflow 16 bits.
287 */
288 #define JT_TAG_BIT ((jsword) 1)
289 #define JT_UNTAG_SHIFT 1
290 #define JT_SET_TAG(jt) ((JSJumpTarget *)((jsword)(jt) | JT_TAG_BIT))
291 #define JT_CLR_TAG(jt) ((JSJumpTarget *)((jsword)(jt) & ~JT_TAG_BIT))
292 #define JT_HAS_TAG(jt) ((jsword)(jt) & JT_TAG_BIT)
293
294 #define BITS_PER_PTRDIFF (sizeof(ptrdiff_t) * JS_BITS_PER_BYTE)
295 #define BITS_PER_BPDELTA (BITS_PER_PTRDIFF - 1 - JT_UNTAG_SHIFT)
296 #define BPDELTA_MAX (((ptrdiff_t)1 << BITS_PER_BPDELTA) - 1)
297 #define BPDELTA_TO_JT(bp) ((JSJumpTarget *)((bp) << JT_UNTAG_SHIFT))
298 #define JT_TO_BPDELTA(jt) ((ptrdiff_t)((jsword)(jt) >> JT_UNTAG_SHIFT))
299
300 #define SD_SET_TARGET(sd,jt) ((sd)->target = JT_SET_TAG(jt))
301 #define SD_GET_TARGET(sd) (JS_ASSERT(JT_HAS_TAG((sd)->target)), \
302 JT_CLR_TAG((sd)->target))
303 #define SD_SET_BPDELTA(sd,bp) ((sd)->target = BPDELTA_TO_JT(bp))
304 #define SD_GET_BPDELTA(sd) (JS_ASSERT(!JT_HAS_TAG((sd)->target)), \
305 JT_TO_BPDELTA((sd)->target))
306
307 /* Avoid asserting twice by expanding SD_GET_TARGET in the "then" clause. */
308 #define SD_SPAN(sd,pivot) (SD_GET_TARGET(sd) \
309 ? JT_CLR_TAG((sd)->target)->offset - (pivot) \
310 : 0)
311
312 typedef struct JSTryNode JSTryNode;
313
314 struct JSTryNode {
315 JSTryNote note;
316 JSTryNode *prev;
317 };
318
319 typedef struct JSEmittedObjectList {
320 uint32 length; /* number of emitted so far objects */
321 JSParsedObjectBox *lastPob; /* last emitted object */
322 } JSEmittedObjectList;
323
324 extern void
325 FinishParsedObjects(JSEmittedObjectList *emittedList, JSObjectArray *objectMap);
326
327 struct JSCodeGenerator {
328 JSTreeContext treeContext; /* base state: statement info stack, etc. */
329
330 JSArenaPool *codePool; /* pointer to thread code arena pool */
331 JSArenaPool *notePool; /* pointer to thread srcnote arena pool */
332 void *codeMark; /* low watermark in cg->codePool */
333 void *noteMark; /* low watermark in cg->notePool */
334
335 struct {
336 jsbytecode *base; /* base of JS bytecode vector */
337 jsbytecode *limit; /* one byte beyond end of bytecode */
338 jsbytecode *next; /* pointer to next free bytecode */
339 jssrcnote *notes; /* source notes, see below */
340 uintN noteCount; /* number of source notes so far */
341 uintN noteMask; /* growth increment for notes */
342 ptrdiff_t lastNoteOffset; /* code offset for last source note */
343 uintN currentLine; /* line number for tree-based srcnote gen */
344 } prolog, main, *current;
345
346 JSAtomList atomList; /* literals indexed for mapping */
347 uintN firstLine; /* first line, for js_NewScriptFromCG */
348
349 intN stackDepth; /* current stack depth in script frame */
350 uintN maxStackDepth; /* maximum stack depth so far */
351
352 uintN ntrynotes; /* number of allocated so far try notes */
353 JSTryNode *lastTryNode; /* the last allocated try node */
354
355 JSSpanDep *spanDeps; /* span dependent instruction records */
356 JSJumpTarget *jumpTargets; /* AVL tree of jump target offsets */
357 JSJumpTarget *jtFreeList; /* JT_LEFT-linked list of free structs */
358 uintN numSpanDeps; /* number of span dependencies */
359 uintN numJumpTargets; /* number of jump targets */
360 ptrdiff_t spanDepTodo; /* offset from main.base of potentially
361 unoptimized spandeps */
362
363 uintN arrayCompDepth; /* stack depth of array in comprehension */
364
365 uintN emitLevel; /* js_EmitTree recursion level */
366 JSAtomList constList; /* compile time constants */
367
368 JSEmittedObjectList objectList; /* list of emitted so far objects */
369 JSEmittedObjectList regexpList; /* list of emitted so far regexp
370 that will be cloned during execution */
371
372 uintN staticDepth; /* static frame chain depth */
373 JSAtomList upvarList; /* map of atoms to upvar indexes */
374 JSUpvarArray upvarMap; /* indexed upvar pairs (JS_realloc'ed) */
375 JSCodeGenerator *parent; /* enclosing function or global context */
376 };
377
378 #define CG_TS(cg) TS((cg)->treeContext.parseContext)
379
380 #define CG_BASE(cg) ((cg)->current->base)
381 #define CG_LIMIT(cg) ((cg)->current->limit)
382 #define CG_NEXT(cg) ((cg)->current->next)
383 #define CG_CODE(cg,offset) (CG_BASE(cg) + (offset))
384 #define CG_OFFSET(cg) PTRDIFF(CG_NEXT(cg), CG_BASE(cg), jsbytecode)
385
386 #define CG_NOTES(cg) ((cg)->current->notes)
387 #define CG_NOTE_COUNT(cg) ((cg)->current->noteCount)
388 #define CG_NOTE_MASK(cg) ((cg)->current->noteMask)
389 #define CG_LAST_NOTE_OFFSET(cg) ((cg)->current->lastNoteOffset)
390 #define CG_CURRENT_LINE(cg) ((cg)->current->currentLine)
391
392 #define CG_PROLOG_BASE(cg) ((cg)->prolog.base)
393 #define CG_PROLOG_LIMIT(cg) ((cg)->prolog.limit)
394 #define CG_PROLOG_NEXT(cg) ((cg)->prolog.next)
395 #define CG_PROLOG_CODE(cg,poff) (CG_PROLOG_BASE(cg) + (poff))
396 #define CG_PROLOG_OFFSET(cg) PTRDIFF(CG_PROLOG_NEXT(cg), CG_PROLOG_BASE(cg),\
397 jsbytecode)
398
399 #define CG_SWITCH_TO_MAIN(cg) ((cg)->current = &(cg)->main)
400 #define CG_SWITCH_TO_PROLOG(cg) ((cg)->current = &(cg)->prolog)
401
402 /*
403 * Initialize cg to allocate bytecode space from codePool, source note space
404 * from notePool, and all other arena-allocated temporaries from cx->tempPool.
405 */
406 extern JS_FRIEND_API(void)
407 js_InitCodeGenerator(JSContext *cx, JSCodeGenerator *cg, JSParseContext *pc,
408 JSArenaPool *codePool, JSArenaPool *notePool,
409 uintN lineno);
410
411 /*
412 * Release cg->codePool, cg->notePool, and cx->tempPool to marks set by
413 * js_InitCodeGenerator. Note that cgs are magic: they own the arena pool
414 * "tops-of-stack" space above their codeMark, noteMark, and tempMark points.
415 * This means you cannot alloc from tempPool and save the pointer beyond the
416 * next JS_FinishCodeGenerator.
417 */
418 extern JS_FRIEND_API(void)
419 js_FinishCodeGenerator(JSContext *cx, JSCodeGenerator *cg);
420
421 /*
422 * Emit one bytecode.
423 */
424 extern ptrdiff_t
425 js_Emit1(JSContext *cx, JSCodeGenerator *cg, JSOp op);
426
427 /*
428 * Emit two bytecodes, an opcode (op) with a byte of immediate operand (op1).
429 */
430 extern ptrdiff_t
431 js_Emit2(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1);
432
433 /*
434 * Emit three bytecodes, an opcode with two bytes of immediate operands.
435 */
436 extern ptrdiff_t
437 js_Emit3(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1,
438 jsbytecode op2);
439
440 /*
441 * Emit (1 + extra) bytecodes, for N bytes of op and its immediate operand.
442 */
443 extern ptrdiff_t
444 js_EmitN(JSContext *cx, JSCodeGenerator *cg, JSOp op, size_t extra);
445
446 /*
447 * Unsafe macro to call js_SetJumpOffset and return false if it does.
448 */
449 #define CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx,cg,pc,off,BAD_EXIT) \
450 JS_BEGIN_MACRO \
451 if (!js_SetJumpOffset(cx, cg, pc, off)) { \
452 BAD_EXIT; \
453 } \
454 JS_END_MACRO
455
456 #define CHECK_AND_SET_JUMP_OFFSET(cx,cg,pc,off) \
457 CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx,cg,pc,off,return JS_FALSE)
458
459 #define CHECK_AND_SET_JUMP_OFFSET_AT_CUSTOM(cx,cg,off,BAD_EXIT) \
460 CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx, cg, CG_CODE(cg,off), \
461 CG_OFFSET(cg) - (off), BAD_EXIT)
462
463 #define CHECK_AND_SET_JUMP_OFFSET_AT(cx,cg,off) \
464 CHECK_AND_SET_JUMP_OFFSET_AT_CUSTOM(cx, cg, off, return JS_FALSE)
465
466 extern JSBool
467 js_SetJumpOffset(JSContext *cx, JSCodeGenerator *cg, jsbytecode *pc,
468 ptrdiff_t off);
469
470 /* Test whether we're in a statement of given type. */
471 extern JSBool
472 js_InStatement(JSTreeContext *tc, JSStmtType type);
473
474 /* Test whether we're in a with statement. */
475 #define js_InWithStatement(tc) js_InStatement(tc, STMT_WITH)
476
477 /*
478 * Push the C-stack-allocated struct at stmt onto the stmtInfo stack.
479 */
480 extern void
481 js_PushStatement(JSTreeContext *tc, JSStmtInfo *stmt, JSStmtType type,
482 ptrdiff_t top);
483
484 /*
485 * Push a block scope statement and link blockObj into tc->blockChain. To pop
486 * this statement info record, use js_PopStatement as usual, or if appropriate
487 * (if generating code), js_PopStatementCG.
488 */
489 extern void
490 js_PushBlockScope(JSTreeContext *tc, JSStmtInfo *stmt, JSObject *blockObj,
491 ptrdiff_t top);
492
493 /*
494 * Pop tc->topStmt. If the top JSStmtInfo struct is not stack-allocated, it
495 * is up to the caller to free it.
496 */
497 extern void
498 js_PopStatement(JSTreeContext *tc);
499
500 /*
501 * Like js_PopStatement(&cg->treeContext), also patch breaks and continues
502 * unless the top statement info record represents a try-catch-finally suite.
503 * May fail if a jump offset overflows.
504 */
505 extern JSBool
506 js_PopStatementCG(JSContext *cx, JSCodeGenerator *cg);
507
508 /*
509 * Define and lookup a primitive jsval associated with the const named by atom.
510 * js_DefineCompileTimeConstant analyzes the constant-folded initializer at pn
511 * and saves the const's value in cg->constList, if it can be used at compile
512 * time. It returns true unless an error occurred.
513 *
514 * If the initializer's value could not be saved, js_DefineCompileTimeConstant
515 * calls will return the undefined value. js_DefineCompileTimeConstant tries
516 * to find a const value memorized for atom, returning true with *vp set to a
517 * value other than undefined if the constant was found, true with *vp set to
518 * JSVAL_VOID if not found, and false on error.
519 */
520 extern JSBool
521 js_DefineCompileTimeConstant(JSContext *cx, JSCodeGenerator *cg, JSAtom *atom,
522 JSParseNode *pn);
523
524 /*
525 * Find a lexically scoped variable (one declared by let, catch, or an array
526 * comprehension) named by atom, looking in tc's compile-time scopes.
527 *
528 * If a WITH statement is reached along the scope stack, return its statement
529 * info record, so callers can tell that atom is ambiguous. If slotp is not
530 * null, then if atom is found, set *slotp to its stack slot, otherwise to -1.
531 * This means that if slotp is not null, all the block objects on the lexical
532 * scope chain must have had their depth slots computed by the code generator,
533 * so the caller must be under js_EmitTree.
534 *
535 * In any event, directly return the statement info record in which atom was
536 * found. Otherwise return null.
537 */
538 extern JSStmtInfo *
539 js_LexicalLookup(JSTreeContext *tc, JSAtom *atom, jsint *slotp);
540
541 /*
542 * Emit code into cg for the tree rooted at pn.
543 */
544 extern JSBool
545 js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn);
546
547 /*
548 * Emit function code using cg for the tree rooted at body.
549 */
550 extern JSBool
551 js_EmitFunctionScript(JSContext *cx, JSCodeGenerator *cg, JSParseNode *body);
552
553 /*
554 * Source notes generated along with bytecode for decompiling and debugging.
555 * A source note is a uint8 with 5 bits of type and 3 of offset from the pc of
556 * the previous note. If 3 bits of offset aren't enough, extended delta notes
557 * (SRC_XDELTA) consisting of 2 set high order bits followed by 6 offset bits
558 * are emitted before the next note. Some notes have operand offsets encoded
559 * immediately after them, in note bytes or byte-triples.
560 *
561 * Source Note Extended Delta
562 * +7-6-5-4-3+2-1-0+ +7-6-5+4-3-2-1-0+
563 * |note-type|delta| |1 1| ext-delta |
564 * +---------+-----+ +---+-----------+
565 *
566 * At most one "gettable" note (i.e., a note of type other than SRC_NEWLINE,
567 * SRC_SETLINE, and SRC_XDELTA) applies to a given bytecode.
568 *
569 * NB: the js_SrcNoteSpec array in jsemit.c is indexed by this enum, so its
570 * initializers need to match the order here.
571 *
572 * Note on adding new source notes: every pair of bytecodes (A, B) where A and
573 * B have disjoint sets of source notes that could apply to each bytecode may
574 * reuse the same note type value for two notes (snA, snB) that have the same
575 * arity, offsetBias, and isSpanDep initializers in js_SrcNoteSpec. This is
576 * why SRC_IF and SRC_INITPROP have the same value below. For bad historical
577 * reasons, some bytecodes below that could be overlayed have not been, but
578 * before using SRC_EXTENDED, consider compressing the existing note types.
579 *
580 * Don't forget to update JSXDR_BYTECODE_VERSION in jsxdrapi.h for all such
581 * incompatible source note or other bytecode changes.
582 */
583 typedef enum JSSrcNoteType {
584 SRC_NULL = 0, /* terminates a note vector */
585 SRC_IF = 1, /* JSOP_IFEQ bytecode is from an if-then */
586 SRC_BREAK = 1, /* JSOP_GOTO is a break */
587 SRC_INITPROP = 1, /* disjoint meaning applied to JSOP_INITELEM or
588 to an index label in a regular (structuring)
589 or a destructuring object initialiser */
590 SRC_GENEXP = 1, /* JSOP_ANONFUNOBJ from generator expression */
591 SRC_IF_ELSE = 2, /* JSOP_IFEQ bytecode is from an if-then-else */
592 SRC_FOR_IN = 2, /* JSOP_GOTO to for-in loop condition from
593 before loop (same arity as SRC_IF_ELSE) */
594 SRC_FOR = 3, /* JSOP_NOP or JSOP_POP in for(;;) loop head */
595 SRC_WHILE = 4, /* JSOP_GOTO to for or while loop condition
596 from before loop, else JSOP_NOP at top of
597 do-while loop */
598 SRC_CONTINUE = 5, /* JSOP_GOTO is a continue, not a break;
599 also used on JSOP_ENDINIT if extra comma
600 at end of array literal: [1,2,,] */
601 SRC_DECL = 6, /* type of a declaration (var, const, let*) */
602 SRC_DESTRUCT = 6, /* JSOP_DUP starting a destructuring assignment
603 operation, with SRC_DECL_* offset operand */
604 SRC_PCDELTA = 7, /* distance forward from comma-operator to
605 next POP, or from CONDSWITCH to first CASE
606 opcode, etc. -- always a forward delta */
607 SRC_GROUPASSIGN = 7, /* SRC_DESTRUCT variant for [a, b] = [c, d] */
608 SRC_ASSIGNOP = 8, /* += or another assign-op follows */
609 SRC_COND = 9, /* JSOP_IFEQ is from conditional ?: operator */
610 SRC_BRACE = 10, /* mandatory brace, for scope or to avoid
611 dangling else */
612 SRC_HIDDEN = 11, /* opcode shouldn't be decompiled */
613 SRC_PCBASE = 12, /* distance back from annotated getprop or
614 setprop op to left-most obj.prop.subprop
615 bytecode -- always a backward delta */
616 SRC_LABEL = 13, /* JSOP_NOP for label: with atomid immediate */
617 SRC_LABELBRACE = 14, /* JSOP_NOP for label: {...} begin brace */
618 SRC_ENDBRACE = 15, /* JSOP_NOP for label: {...} end brace */
619 SRC_BREAK2LABEL = 16, /* JSOP_GOTO for 'break label' with atomid */
620 SRC_CONT2LABEL = 17, /* JSOP_GOTO for 'continue label' with atomid */
621 SRC_SWITCH = 18, /* JSOP_*SWITCH with offset to end of switch,
622 2nd off to first JSOP_CASE if condswitch */
623 SRC_FUNCDEF = 19, /* JSOP_NOP for function f() with atomid */
624 SRC_CATCH = 20, /* catch block has guard */
625 SRC_EXTENDED = 21, /* extended source note, 32-159, in next byte */
626 SRC_NEWLINE = 22, /* bytecode follows a source newline */
627 SRC_SETLINE = 23, /* a file-absolute source line number note */
628 SRC_XDELTA = 24 /* 24-31 are for extended delta notes */
629 } JSSrcNoteType;
630
631 /*
632 * Constants for the SRC_DECL source note. Note that span-dependent bytecode
633 * selection means that any SRC_DECL offset greater than SRC_DECL_LET may need
634 * to be adjusted, but these "offsets" are too small to span a span-dependent
635 * instruction, so can be used to denote distinct declaration syntaxes to the
636 * decompiler.
637 *
638 * NB: the var_prefix array in jsopcode.c depends on these dense indexes from
639 * SRC_DECL_VAR through SRC_DECL_LET.
640 */
641 #define SRC_DECL_VAR 0
642 #define SRC_DECL_CONST 1
643 #define SRC_DECL_LET 2
644 #define SRC_DECL_NONE 3
645
646 #define SN_TYPE_BITS 5
647 #define SN_DELTA_BITS 3
648 #define SN_XDELTA_BITS 6
649 #define SN_TYPE_MASK (JS_BITMASK(SN_TYPE_BITS) << SN_DELTA_BITS)
650 #define SN_DELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_DELTA_BITS))
651 #define SN_XDELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_XDELTA_BITS))
652
653 #define SN_MAKE_NOTE(sn,t,d) (*(sn) = (jssrcnote) \
654 (((t) << SN_DELTA_BITS) \
655 | ((d) & SN_DELTA_MASK)))
656 #define SN_MAKE_XDELTA(sn,d) (*(sn) = (jssrcnote) \
657 ((SRC_XDELTA << SN_DELTA_BITS) \
658 | ((d) & SN_XDELTA_MASK)))
659
660 #define SN_IS_XDELTA(sn) ((*(sn) >> SN_DELTA_BITS) >= SRC_XDELTA)
661 #define SN_TYPE(sn) ((JSSrcNoteType)(SN_IS_XDELTA(sn) \
662 ? SRC_XDELTA \
663 : *(sn) >> SN_DELTA_BITS))
664 #define SN_SET_TYPE(sn,type) SN_MAKE_NOTE(sn, type, SN_DELTA(sn))
665 #define SN_IS_GETTABLE(sn) (SN_TYPE(sn) < SRC_NEWLINE)
666
667 #define SN_DELTA(sn) ((ptrdiff_t)(SN_IS_XDELTA(sn) \
668 ? *(sn) & SN_XDELTA_MASK \
669 : *(sn) & SN_DELTA_MASK))
670 #define SN_SET_DELTA(sn,delta) (SN_IS_XDELTA(sn) \
671 ? SN_MAKE_XDELTA(sn, delta) \
672 : SN_MAKE_NOTE(sn, SN_TYPE(sn), delta))
673
674 #define SN_DELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_DELTA_BITS))
675 #define SN_XDELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_XDELTA_BITS))
676
677 /*
678 * Offset fields follow certain notes and are frequency-encoded: an offset in
679 * [0,0x7f] consumes one byte, an offset in [0x80,0x7fffff] takes three, and
680 * the high bit of the first byte is set.
681 */
682 #define SN_3BYTE_OFFSET_FLAG 0x80
683 #define SN_3BYTE_OFFSET_MASK 0x7f
684
685 typedef struct JSSrcNoteSpec {
686 const char *name; /* name for disassembly/debugging output */
687 int8 arity; /* number of offset operands */
688 uint8 offsetBias; /* bias of offset(s) from annotated pc */
689 int8 isSpanDep; /* 1 or -1 if offsets could span extended ops,
690 0 otherwise; sign tells span direction */
691 } JSSrcNoteSpec;
692
693 extern JS_FRIEND_DATA(JSSrcNoteSpec) js_SrcNoteSpec[];
694 extern JS_FRIEND_API(uintN) js_SrcNoteLength(jssrcnote *sn);
695
696 #define SN_LENGTH(sn) ((js_SrcNoteSpec[SN_TYPE(sn)].arity == 0) ? 1 \
697 : js_SrcNoteLength(sn))
698 #define SN_NEXT(sn) ((sn) + SN_LENGTH(sn))
699
700 /* A source note array is terminated by an all-zero element. */
701 #define SN_MAKE_TERMINATOR(sn) (*(sn) = SRC_NULL)
702 #define SN_IS_TERMINATOR(sn) (*(sn) == SRC_NULL)
703
704 /*
705 * Append a new source note of the given type (and therefore size) to cg's
706 * notes dynamic array, updating cg->noteCount. Return the new note's index
707 * within the array pointed at by cg->current->notes. Return -1 if out of
708 * memory.
709 */
710 extern intN
711 js_NewSrcNote(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type);
712
713 extern intN
714 js_NewSrcNote2(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type,
715 ptrdiff_t offset);
716
717 extern intN
718 js_NewSrcNote3(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type,
719 ptrdiff_t offset1, ptrdiff_t offset2);
720
721 /*
722 * NB: this function can add at most one extra extended delta note.
723 */
724 extern jssrcnote *
725 js_AddToSrcNoteDelta(JSContext *cx, JSCodeGenerator *cg, jssrcnote *sn,
726 ptrdiff_t delta);
727
728 /*
729 * Get and set the offset operand identified by which (0 for the first, etc.).
730 */
731 extern JS_FRIEND_API(ptrdiff_t)
732 js_GetSrcNoteOffset(jssrcnote *sn, uintN which);
733
734 extern JSBool
735 js_SetSrcNoteOffset(JSContext *cx, JSCodeGenerator *cg, uintN index,
736 uintN which, ptrdiff_t offset);
737
738 /*
739 * Finish taking source notes in cx's notePool, copying final notes to the new
740 * stable store allocated by the caller and passed in via notes. Return false
741 * on malloc failure, which means this function reported an error.
742 *
743 * To compute the number of jssrcnotes to allocate and pass in via notes, use
744 * the CG_COUNT_FINAL_SRCNOTES macro. This macro knows a lot about details of
745 * js_FinishTakingSrcNotes, SO DON'T CHANGE jsemit.c's js_FinishTakingSrcNotes
746 * FUNCTION WITHOUT CHECKING WHETHER THIS MACRO NEEDS CORRESPONDING CHANGES!
747 */
748 #define CG_COUNT_FINAL_SRCNOTES(cg, cnt) \
749 JS_BEGIN_MACRO \
750 ptrdiff_t diff_ = CG_PROLOG_OFFSET(cg) - (cg)->prolog.lastNoteOffset; \
751 cnt = (cg)->prolog.noteCount + (cg)->main.noteCount + 1; \
752 if ((cg)->prolog.noteCount && \
753 (cg)->prolog.currentLine != (cg)->firstLine) { \
754 if (diff_ > SN_DELTA_MASK) \
755 cnt += JS_HOWMANY(diff_ - SN_DELTA_MASK, SN_XDELTA_MASK); \
756 cnt += 2 + (((cg)->firstLine > SN_3BYTE_OFFSET_MASK) << 1); \
757 } else if (diff_ > 0) { \
758 if (cg->main.noteCount) { \
759 jssrcnote *sn_ = (cg)->main.notes; \
760 diff_ -= SN_IS_XDELTA(sn_) \
761 ? SN_XDELTA_MASK - (*sn_ & SN_XDELTA_MASK) \
762 : SN_DELTA_MASK - (*sn_ & SN_DELTA_MASK); \
763 } \
764 if (diff_ > 0) \
765 cnt += JS_HOWMANY(diff_, SN_XDELTA_MASK); \
766 } \
767 JS_END_MACRO
768
769 extern JSBool
770 js_FinishTakingSrcNotes(JSContext *cx, JSCodeGenerator *cg, jssrcnote *notes);
771
772 extern void
773 js_FinishTakingTryNotes(JSCodeGenerator *cg, JSTryNoteArray *array);
774
775 JS_END_EXTERN_C
776
777 #endif /* jsemit_h___ */

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