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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 "jsparse.h"
52 #include "jsscript.h"
53 #include "jsprvtd.h"
54 #include "jspubtd.h"
55
56 JS_BEGIN_EXTERN_C
57
58 /*
59 * NB: If you add enumerators for scope statements, add them between STMT_WITH
60 * and STMT_CATCH, or you will break the STMT_TYPE_IS_SCOPE macro. If you add
61 * non-looping statement enumerators, add them before STMT_DO_LOOP or you will
62 * break the STMT_TYPE_IS_LOOP macro.
63 *
64 * Also remember to keep the statementName array in jsemit.c in sync.
65 */
66 typedef enum JSStmtType {
67 STMT_LABEL, /* labeled statement: L: s */
68 STMT_IF, /* if (then) statement */
69 STMT_ELSE, /* else clause of if statement */
70 STMT_SEQ, /* synthetic sequence of statements */
71 STMT_BLOCK, /* compound statement: { s1[;... sN] } */
72 STMT_SWITCH, /* switch statement */
73 STMT_WITH, /* with statement */
74 STMT_CATCH, /* catch block */
75 STMT_TRY, /* try block */
76 STMT_FINALLY, /* finally block */
77 STMT_SUBROUTINE, /* gosub-target subroutine body */
78 STMT_DO_LOOP, /* do/while loop statement */
79 STMT_FOR_LOOP, /* for loop statement */
80 STMT_FOR_IN_LOOP, /* for/in loop statement */
81 STMT_WHILE_LOOP, /* while loop statement */
82 STMT_LIMIT
83 } JSStmtType;
84
85 #define STMT_TYPE_IN_RANGE(t,b,e) ((uint)((t) - (b)) <= (uintN)((e) - (b)))
86
87 /*
88 * A comment on the encoding of the JSStmtType enum and type-testing macros:
89 *
90 * STMT_TYPE_MAYBE_SCOPE tells whether a statement type is always, or may
91 * become, a lexical scope. It therefore includes block and switch (the two
92 * low-numbered "maybe" scope types) and excludes with (with has dynamic scope
93 * pending the "reformed with" in ES4/JS2). It includes all try-catch-finally
94 * types, which are high-numbered maybe-scope types.
95 *
96 * STMT_TYPE_LINKS_SCOPE tells whether a JSStmtInfo of the given type eagerly
97 * links to other scoping statement info records. It excludes the two early
98 * "maybe" types, block and switch, as well as the try and both finally types,
99 * since try and the other trailing maybe-scope types don't need block scope
100 * unless they contain let declarations.
101 *
102 * We treat WITH as a static scope because it prevents lexical binding from
103 * continuing further up the static scope chain. With the lost "reformed with"
104 * proposal for ES4, we would be able to model it statically, too.
105 */
106 #define STMT_TYPE_MAYBE_SCOPE(type) \
107 (type != STMT_WITH && \
108 STMT_TYPE_IN_RANGE(type, STMT_BLOCK, STMT_SUBROUTINE))
109
110 #define STMT_TYPE_LINKS_SCOPE(type) \
111 STMT_TYPE_IN_RANGE(type, STMT_WITH, STMT_CATCH)
112
113 #define STMT_TYPE_IS_TRYING(type) \
114 STMT_TYPE_IN_RANGE(type, STMT_TRY, STMT_SUBROUTINE)
115
116 #define STMT_TYPE_IS_LOOP(type) ((type) >= STMT_DO_LOOP)
117
118 #define STMT_MAYBE_SCOPE(stmt) STMT_TYPE_MAYBE_SCOPE((stmt)->type)
119 #define STMT_LINKS_SCOPE(stmt) (STMT_TYPE_LINKS_SCOPE((stmt)->type) || \
120 ((stmt)->flags & SIF_SCOPE))
121 #define STMT_IS_TRYING(stmt) STMT_TYPE_IS_TRYING((stmt)->type)
122 #define STMT_IS_LOOP(stmt) STMT_TYPE_IS_LOOP((stmt)->type)
123
124 typedef struct JSStmtInfo JSStmtInfo;
125
126 struct JSStmtInfo {
127 uint16 type; /* statement type */
128 uint16 flags; /* flags, see below */
129 uint32 blockid; /* for simplified dominance computation */
130 ptrdiff_t update; /* loop update offset (top if none) */
131 ptrdiff_t breaks; /* offset of last break in loop */
132 ptrdiff_t continues; /* offset of last continue in loop */
133 union {
134 JSAtom *label; /* name of LABEL */
135 JSObject *blockObj; /* block scope object */
136 };
137 JSStmtInfo *down; /* info for enclosing statement */
138 JSStmtInfo *downScope; /* next enclosing lexical scope */
139 };
140
141 #define SIF_SCOPE 0x0001 /* statement has its own lexical scope */
142 #define SIF_BODY_BLOCK 0x0002 /* STMT_BLOCK type is a function body */
143 #define SIF_FOR_BLOCK 0x0004 /* for (let ...) induced block scope */
144
145 /*
146 * To reuse space in JSStmtInfo, rename breaks and continues for use during
147 * try/catch/finally code generation and backpatching. To match most common
148 * use cases, the macro argument is a struct, not a struct pointer. Only a
149 * loop, switch, or label statement info record can have breaks and continues,
150 * and only a for loop has an update backpatch chain, so it's safe to overlay
151 * these for the "trying" JSStmtTypes.
152 */
153 #define CATCHNOTE(stmt) ((stmt).update)
154 #define GOSUBS(stmt) ((stmt).breaks)
155 #define GUARDJUMP(stmt) ((stmt).continues)
156
157 #define SET_STATEMENT_TOP(stmt, top) \
158 ((stmt)->update = (top), (stmt)->breaks = (stmt)->continues = (-1))
159
160 #ifdef JS_SCOPE_DEPTH_METER
161 # define JS_SCOPE_DEPTH_METERING(code) ((void) (code))
162 #else
163 # define JS_SCOPE_DEPTH_METERING(code) ((void) 0)
164 #endif
165
166 struct JSTreeContext { /* tree context for semantic checks */
167 uint16 flags; /* statement state flags, see below */
168 uint16 ngvars; /* max. no. of global variables/regexps */
169 uint32 bodyid; /* block number of program/function body */
170 uint32 blockidGen; /* preincremented block number generator */
171 JSStmtInfo *topStmt; /* top of statement info stack */
172 JSStmtInfo *topScopeStmt; /* top lexical scope statement */
173 JSObject *blockChain; /* compile time block scope chain (NB: one
174 deeper than the topScopeStmt/downScope
175 chain when in head of let block/expr) */
176 JSParseNode *blockNode; /* parse node for a block with let declarations
177 (block with its own lexical scope) */
178 JSAtomList decls; /* function, const, and var declarations */
179 JSCompiler *compiler; /* ptr to common parsing and lexing data */
180
181 union {
182 JSFunction *fun; /* function to store argument and variable
183 names when flags & TCF_IN_FUNCTION */
184 JSObject *scopeChain; /* scope chain object for the script */
185 };
186
187 JSAtomList lexdeps; /* unresolved lexical name dependencies */
188 JSTreeContext *parent; /* enclosing function or global context */
189 uintN staticLevel; /* static compilation unit nesting level */
190
191 JSFunctionBox *funbox; /* null or box for function we're compiling
192 if (flags & TCF_IN_FUNCTION) and not in
193 JSCompiler::compileFunctionBody */
194 JSFunctionBox *functionList;
195
196 #ifdef JS_SCOPE_DEPTH_METER
197 uint16 scopeDepth; /* current lexical scope chain depth */
198 uint16 maxScopeDepth; /* maximum lexical scope chain depth */
199 #endif
200
201 JSTreeContext(JSCompiler *jsc)
202 : flags(0), ngvars(0), bodyid(0), blockidGen(0),
203 topStmt(NULL), topScopeStmt(NULL), blockChain(NULL), blockNode(NULL),
204 compiler(jsc), scopeChain(NULL), parent(NULL), staticLevel(0),
205 funbox(NULL), functionList(NULL)
206 {
207 JS_SCOPE_DEPTH_METERING(scopeDepth = maxScopeDepth = 0);
208 }
209
210 /*
211 * For functions the tree context is constructed and destructed a second
212 * time during code generation. To avoid a redundant stats update in such
213 * cases, we store (uintN) -1 in maxScopeDepth.
214 */
215 ~JSTreeContext() {
216 JS_SCOPE_DEPTH_METERING(maxScopeDepth == (uintN) -1 ||
217 JS_BASIC_STATS_ACCUM(&compiler
218 ->context
219 ->runtime
220 ->lexicalScopeDepthStats,
221 maxScopeDepth));
222 }
223
224 uintN blockid() { return topStmt ? topStmt->blockid : bodyid; }
225
226 bool atTopLevel() { return !topStmt || (topStmt->flags & SIF_BODY_BLOCK); }
227
228 /* Test whether we're in a statement of given type. */
229 bool inStatement(JSStmtType type);
230 };
231
232 /*
233 * Flags to propagate out of the blocks.
234 */
235 #define TCF_RETURN_FLAGS (TCF_RETURN_EXPR | TCF_RETURN_VOID)
236
237 /*
238 * TreeContext flags must fit in 16 bits, and all bits are in use now. Widening
239 * requires changing JSFunctionBox.tcflags too and repacking. Alternative fix
240 * gets rid of flags, probably starting with TCF_HAS_FUNCTION_STMT.
241 */
242 #define TCF_COMPILING 0x01 /* JSTreeContext is JSCodeGenerator */
243 #define TCF_IN_FUNCTION 0x02 /* parsing inside function body */
244 #define TCF_RETURN_EXPR 0x04 /* function has 'return expr;' */
245 #define TCF_RETURN_VOID 0x08 /* function has 'return;' */
246 #define TCF_IN_FOR_INIT 0x10 /* parsing init expr of for; exclude 'in' */
247 #define TCF_FUN_SETS_OUTER_NAME 0x20 /* function set outer name (lexical or free) */
248 #define TCF_FUN_PARAM_ARGUMENTS 0x40 /* function has parameter named arguments */
249 #define TCF_FUN_USES_ARGUMENTS 0x80 /* function uses arguments except as a
250 parameter name */
251 #define TCF_FUN_HEAVYWEIGHT 0x100 /* function needs Call object per call */
252 #define TCF_FUN_IS_GENERATOR 0x200 /* parsed yield statement in function */
253 #define TCF_FUN_IS_FUNARG 0x400 /* function escapes as an argument, return
254 value, or via the heap */
255 #define TCF_HAS_FUNCTION_STMT 0x800 /* block contains a function statement */
256 #define TCF_GENEXP_LAMBDA 0x1000 /* flag lambda from generator expression */
257 #define TCF_COMPILE_N_GO 0x2000 /* compiler-and-go mode of script, can
258 optimize name references based on scope
259 chain */
260 #define TCF_NO_SCRIPT_RVAL 0x4000 /* API caller does not want result value
261 from global script */
262 #define TCF_HAS_SHARPS 0x8000 /* source contains sharp defs or uses */
263
264 /*
265 * Sticky deoptimization flags to propagate from FunctionBody.
266 */
267 #define TCF_FUN_FLAGS (TCF_FUN_SETS_OUTER_NAME | \
268 TCF_FUN_USES_ARGUMENTS | \
269 TCF_FUN_PARAM_ARGUMENTS | \
270 TCF_FUN_HEAVYWEIGHT | \
271 TCF_FUN_IS_GENERATOR | \
272 TCF_FUN_IS_FUNARG | \
273 TCF_HAS_SHARPS)
274
275 /*
276 * Flags field, not stored in JSTreeContext.flags, for passing a static level
277 * into js_CompileScript.
278 */
279 #define TCF_STATIC_LEVEL_MASK 0xffff0000
280 #define TCF_GET_STATIC_LEVEL(f) ((uint32)(f) >> 16)
281 #define TCF_PUT_STATIC_LEVEL(d) ((uint16)(d) << 16)
282
283 /*
284 * Span-dependent instructions are jumps whose span (from the jump bytecode to
285 * the jump target) may require 2 or 4 bytes of immediate operand.
286 */
287 typedef struct JSSpanDep JSSpanDep;
288 typedef struct JSJumpTarget JSJumpTarget;
289
290 struct JSSpanDep {
291 ptrdiff_t top; /* offset of first bytecode in an opcode */
292 ptrdiff_t offset; /* offset - 1 within opcode of jump operand */
293 ptrdiff_t before; /* original offset - 1 of jump operand */
294 JSJumpTarget *target; /* tagged target pointer or backpatch delta */
295 };
296
297 /*
298 * Jump targets are stored in an AVL tree, for O(log(n)) lookup with targets
299 * sorted by offset from left to right, so that targets after a span-dependent
300 * instruction whose jump offset operand must be extended can be found quickly
301 * and adjusted upward (toward higher offsets).
302 */
303 struct JSJumpTarget {
304 ptrdiff_t offset; /* offset of span-dependent jump target */
305 int balance; /* AVL tree balance number */
306 JSJumpTarget *kids[2]; /* left and right AVL tree child pointers */
307 };
308
309 #define JT_LEFT 0
310 #define JT_RIGHT 1
311 #define JT_OTHER_DIR(dir) (1 - (dir))
312 #define JT_IMBALANCE(dir) (((dir) << 1) - 1)
313 #define JT_DIR(imbalance) (((imbalance) + 1) >> 1)
314
315 /*
316 * Backpatch deltas are encoded in JSSpanDep.target if JT_TAG_BIT is clear,
317 * so we can maintain backpatch chains when using span dependency records to
318 * hold jump offsets that overflow 16 bits.
319 */
320 #define JT_TAG_BIT ((jsword) 1)
321 #define JT_UNTAG_SHIFT 1
322 #define JT_SET_TAG(jt) ((JSJumpTarget *)((jsword)(jt) | JT_TAG_BIT))
323 #define JT_CLR_TAG(jt) ((JSJumpTarget *)((jsword)(jt) & ~JT_TAG_BIT))
324 #define JT_HAS_TAG(jt) ((jsword)(jt) & JT_TAG_BIT)
325
326 #define BITS_PER_PTRDIFF (sizeof(ptrdiff_t) * JS_BITS_PER_BYTE)
327 #define BITS_PER_BPDELTA (BITS_PER_PTRDIFF - 1 - JT_UNTAG_SHIFT)
328 #define BPDELTA_MAX (((ptrdiff_t)1 << BITS_PER_BPDELTA) - 1)
329 #define BPDELTA_TO_JT(bp) ((JSJumpTarget *)((bp) << JT_UNTAG_SHIFT))
330 #define JT_TO_BPDELTA(jt) ((ptrdiff_t)((jsword)(jt) >> JT_UNTAG_SHIFT))
331
332 #define SD_SET_TARGET(sd,jt) ((sd)->target = JT_SET_TAG(jt))
333 #define SD_GET_TARGET(sd) (JS_ASSERT(JT_HAS_TAG((sd)->target)), \
334 JT_CLR_TAG((sd)->target))
335 #define SD_SET_BPDELTA(sd,bp) ((sd)->target = BPDELTA_TO_JT(bp))
336 #define SD_GET_BPDELTA(sd) (JS_ASSERT(!JT_HAS_TAG((sd)->target)), \
337 JT_TO_BPDELTA((sd)->target))
338
339 /* Avoid asserting twice by expanding SD_GET_TARGET in the "then" clause. */
340 #define SD_SPAN(sd,pivot) (SD_GET_TARGET(sd) \
341 ? JT_CLR_TAG((sd)->target)->offset - (pivot) \
342 : 0)
343
344 typedef struct JSTryNode JSTryNode;
345
346 struct JSTryNode {
347 JSTryNote note;
348 JSTryNode *prev;
349 };
350
351 struct JSCGObjectList {
352 uint32 length; /* number of emitted so far objects */
353 JSObjectBox *lastbox; /* last emitted object */
354
355 JSCGObjectList() : length(0), lastbox(NULL) {}
356
357 uintN index(JSObjectBox *objbox);
358 void finish(JSObjectArray *array);
359 };
360
361 struct JSCodeGenerator : public JSTreeContext
362 {
363 JSArenaPool *codePool; /* pointer to thread code arena pool */
364 JSArenaPool *notePool; /* pointer to thread srcnote arena pool */
365 void *codeMark; /* low watermark in cg->codePool */
366 void *noteMark; /* low watermark in cg->notePool */
367
368 struct {
369 jsbytecode *base; /* base of JS bytecode vector */
370 jsbytecode *limit; /* one byte beyond end of bytecode */
371 jsbytecode *next; /* pointer to next free bytecode */
372 jssrcnote *notes; /* source notes, see below */
373 uintN noteCount; /* number of source notes so far */
374 uintN noteMask; /* growth increment for notes */
375 ptrdiff_t lastNoteOffset; /* code offset for last source note */
376 uintN currentLine; /* line number for tree-based srcnote gen */
377 } prolog, main, *current;
378
379 JSAtomList atomList; /* literals indexed for mapping */
380 uintN firstLine; /* first line, for js_NewScriptFromCG */
381
382 intN stackDepth; /* current stack depth in script frame */
383 uintN maxStackDepth; /* maximum stack depth so far */
384
385 uintN ntrynotes; /* number of allocated so far try notes */
386 JSTryNode *lastTryNode; /* the last allocated try node */
387
388 JSSpanDep *spanDeps; /* span dependent instruction records */
389 JSJumpTarget *jumpTargets; /* AVL tree of jump target offsets */
390 JSJumpTarget *jtFreeList; /* JT_LEFT-linked list of free structs */
391 uintN numSpanDeps; /* number of span dependencies */
392 uintN numJumpTargets; /* number of jump targets */
393 ptrdiff_t spanDepTodo; /* offset from main.base of potentially
394 unoptimized spandeps */
395
396 uintN arrayCompDepth; /* stack depth of array in comprehension */
397
398 uintN emitLevel; /* js_EmitTree recursion level */
399 JSAtomList constList; /* compile time constants */
400
401 JSCGObjectList objectList; /* list of emitted objects */
402 JSCGObjectList regexpList; /* list of emitted regexp that will be
403 cloned during execution */
404
405 JSAtomList upvarList; /* map of atoms to upvar indexes */
406 JSUpvarArray upvarMap; /* indexed upvar pairs (JS_realloc'ed) */
407
408 /*
409 * Initialize cg to allocate bytecode space from codePool, source note
410 * space from notePool, and all other arena-allocated temporaries from
411 * jsc->context->tempPool.
412 */
413 JSCodeGenerator(JSCompiler *jsc,
414 JSArenaPool *codePool, JSArenaPool *notePool,
415 uintN lineno);
416
417 /*
418 * Release cg->codePool, cg->notePool, and compiler->context->tempPool to
419 * marks set by JSCodeGenerator's ctor. Note that cgs are magic: they own
420 * the arena pool "tops-of-stack" space above their codeMark, noteMark, and
421 * tempMark points. This means you cannot alloc from tempPool and save the
422 * pointer beyond the next JSCodeGenerator destructor call.
423 */
424 ~JSCodeGenerator();
425 };
426
427 #define CG_TS(cg) TS((cg)->compiler)
428
429 #define CG_BASE(cg) ((cg)->current->base)
430 #define CG_LIMIT(cg) ((cg)->current->limit)
431 #define CG_NEXT(cg) ((cg)->current->next)
432 #define CG_CODE(cg,offset) (CG_BASE(cg) + (offset))
433 #define CG_OFFSET(cg) PTRDIFF(CG_NEXT(cg), CG_BASE(cg), jsbytecode)
434
435 #define CG_NOTES(cg) ((cg)->current->notes)
436 #define CG_NOTE_COUNT(cg) ((cg)->current->noteCount)
437 #define CG_NOTE_MASK(cg) ((cg)->current->noteMask)
438 #define CG_LAST_NOTE_OFFSET(cg) ((cg)->current->lastNoteOffset)
439 #define CG_CURRENT_LINE(cg) ((cg)->current->currentLine)
440
441 #define CG_PROLOG_BASE(cg) ((cg)->prolog.base)
442 #define CG_PROLOG_LIMIT(cg) ((cg)->prolog.limit)
443 #define CG_PROLOG_NEXT(cg) ((cg)->prolog.next)
444 #define CG_PROLOG_CODE(cg,poff) (CG_PROLOG_BASE(cg) + (poff))
445 #define CG_PROLOG_OFFSET(cg) PTRDIFF(CG_PROLOG_NEXT(cg), CG_PROLOG_BASE(cg),\
446 jsbytecode)
447
448 #define CG_SWITCH_TO_MAIN(cg) ((cg)->current = &(cg)->main)
449 #define CG_SWITCH_TO_PROLOG(cg) ((cg)->current = &(cg)->prolog)
450
451 /*
452 * Emit one bytecode.
453 */
454 extern ptrdiff_t
455 js_Emit1(JSContext *cx, JSCodeGenerator *cg, JSOp op);
456
457 /*
458 * Emit two bytecodes, an opcode (op) with a byte of immediate operand (op1).
459 */
460 extern ptrdiff_t
461 js_Emit2(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1);
462
463 /*
464 * Emit three bytecodes, an opcode with two bytes of immediate operands.
465 */
466 extern ptrdiff_t
467 js_Emit3(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1,
468 jsbytecode op2);
469
470 /*
471 * Emit (1 + extra) bytecodes, for N bytes of op and its immediate operand.
472 */
473 extern ptrdiff_t
474 js_EmitN(JSContext *cx, JSCodeGenerator *cg, JSOp op, size_t extra);
475
476 /*
477 * Unsafe macro to call js_SetJumpOffset and return false if it does.
478 */
479 #define CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx,cg,pc,off,BAD_EXIT) \
480 JS_BEGIN_MACRO \
481 if (!js_SetJumpOffset(cx, cg, pc, off)) { \
482 BAD_EXIT; \
483 } \
484 JS_END_MACRO
485
486 #define CHECK_AND_SET_JUMP_OFFSET(cx,cg,pc,off) \
487 CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx,cg,pc,off,return JS_FALSE)
488
489 #define CHECK_AND_SET_JUMP_OFFSET_AT_CUSTOM(cx,cg,off,BAD_EXIT) \
490 CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx, cg, CG_CODE(cg,off), \
491 CG_OFFSET(cg) - (off), BAD_EXIT)
492
493 #define CHECK_AND_SET_JUMP_OFFSET_AT(cx,cg,off) \
494 CHECK_AND_SET_JUMP_OFFSET_AT_CUSTOM(cx, cg, off, return JS_FALSE)
495
496 extern JSBool
497 js_SetJumpOffset(JSContext *cx, JSCodeGenerator *cg, jsbytecode *pc,
498 ptrdiff_t off);
499
500 /*
501 * Push the C-stack-allocated struct at stmt onto the stmtInfo stack.
502 */
503 extern void
504 js_PushStatement(JSTreeContext *tc, JSStmtInfo *stmt, JSStmtType type,
505 ptrdiff_t top);
506
507 /*
508 * Push a block scope statement and link blockObj into tc->blockChain. To pop
509 * this statement info record, use js_PopStatement as usual, or if appropriate
510 * (if generating code), js_PopStatementCG.
511 */
512 extern void
513 js_PushBlockScope(JSTreeContext *tc, JSStmtInfo *stmt, JSObject *blockObj,
514 ptrdiff_t top);
515
516 /*
517 * Pop tc->topStmt. If the top JSStmtInfo struct is not stack-allocated, it
518 * is up to the caller to free it.
519 */
520 extern void
521 js_PopStatement(JSTreeContext *tc);
522
523 /*
524 * Like js_PopStatement(cg), also patch breaks and continues unless the top
525 * statement info record represents a try-catch-finally suite. May fail if a
526 * jump offset overflows.
527 */
528 extern JSBool
529 js_PopStatementCG(JSContext *cx, JSCodeGenerator *cg);
530
531 /*
532 * Define and lookup a primitive jsval associated with the const named by atom.
533 * js_DefineCompileTimeConstant analyzes the constant-folded initializer at pn
534 * and saves the const's value in cg->constList, if it can be used at compile
535 * time. It returns true unless an error occurred.
536 *
537 * If the initializer's value could not be saved, js_DefineCompileTimeConstant
538 * calls will return the undefined value. js_DefineCompileTimeConstant tries
539 * to find a const value memorized for atom, returning true with *vp set to a
540 * value other than undefined if the constant was found, true with *vp set to
541 * JSVAL_VOID if not found, and false on error.
542 */
543 extern JSBool
544 js_DefineCompileTimeConstant(JSContext *cx, JSCodeGenerator *cg, JSAtom *atom,
545 JSParseNode *pn);
546
547 /*
548 * Find a lexically scoped variable (one declared by let, catch, or an array
549 * comprehension) named by atom, looking in tc's compile-time scopes.
550 *
551 * If a WITH statement is reached along the scope stack, return its statement
552 * info record, so callers can tell that atom is ambiguous. If slotp is not
553 * null, then if atom is found, set *slotp to its stack slot, otherwise to -1.
554 * This means that if slotp is not null, all the block objects on the lexical
555 * scope chain must have had their depth slots computed by the code generator,
556 * so the caller must be under js_EmitTree.
557 *
558 * In any event, directly return the statement info record in which atom was
559 * found. Otherwise return null.
560 */
561 extern JSStmtInfo *
562 js_LexicalLookup(JSTreeContext *tc, JSAtom *atom, jsint *slotp,
563 JSStmtInfo *stmt = NULL);
564
565 /*
566 * Emit code into cg for the tree rooted at pn.
567 */
568 extern JSBool
569 js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn);
570
571 /*
572 * Emit function code using cg for the tree rooted at body.
573 */
574 extern JSBool
575 js_EmitFunctionScript(JSContext *cx, JSCodeGenerator *cg, JSParseNode *body);
576
577 /*
578 * Source notes generated along with bytecode for decompiling and debugging.
579 * A source note is a uint8 with 5 bits of type and 3 of offset from the pc of
580 * the previous note. If 3 bits of offset aren't enough, extended delta notes
581 * (SRC_XDELTA) consisting of 2 set high order bits followed by 6 offset bits
582 * are emitted before the next note. Some notes have operand offsets encoded
583 * immediately after them, in note bytes or byte-triples.
584 *
585 * Source Note Extended Delta
586 * +7-6-5-4-3+2-1-0+ +7-6-5+4-3-2-1-0+
587 * |note-type|delta| |1 1| ext-delta |
588 * +---------+-----+ +---+-----------+
589 *
590 * At most one "gettable" note (i.e., a note of type other than SRC_NEWLINE,
591 * SRC_SETLINE, and SRC_XDELTA) applies to a given bytecode.
592 *
593 * NB: the js_SrcNoteSpec array in jsemit.c is indexed by this enum, so its
594 * initializers need to match the order here.
595 *
596 * Note on adding new source notes: every pair of bytecodes (A, B) where A and
597 * B have disjoint sets of source notes that could apply to each bytecode may
598 * reuse the same note type value for two notes (snA, snB) that have the same
599 * arity, offsetBias, and isSpanDep initializers in js_SrcNoteSpec. This is
600 * why SRC_IF and SRC_INITPROP have the same value below. For bad historical
601 * reasons, some bytecodes below that could be overlayed have not been, but
602 * before using SRC_EXTENDED, consider compressing the existing note types.
603 *
604 * Don't forget to update JSXDR_BYTECODE_VERSION in jsxdrapi.h for all such
605 * incompatible source note or other bytecode changes.
606 */
607 typedef enum JSSrcNoteType {
608 SRC_NULL = 0, /* terminates a note vector */
609 SRC_IF = 1, /* JSOP_IFEQ bytecode is from an if-then */
610 SRC_BREAK = 1, /* JSOP_GOTO is a break */
611 SRC_INITPROP = 1, /* disjoint meaning applied to JSOP_INITELEM or
612 to an index label in a regular (structuring)
613 or a destructuring object initialiser */
614 SRC_GENEXP = 1, /* JSOP_LAMBDA from generator expression */
615 SRC_IF_ELSE = 2, /* JSOP_IFEQ bytecode is from an if-then-else */
616 SRC_FOR_IN = 2, /* JSOP_GOTO to for-in loop condition from
617 before loop (same arity as SRC_IF_ELSE) */
618 SRC_FOR = 3, /* JSOP_NOP or JSOP_POP in for(;;) loop head */
619 SRC_WHILE = 4, /* JSOP_GOTO to for or while loop condition
620 from before loop, else JSOP_NOP at top of
621 do-while loop */
622 SRC_CONTINUE = 5, /* JSOP_GOTO is a continue, not a break;
623 also used on JSOP_ENDINIT if extra comma
624 at end of array literal: [1,2,,];
625 JSOP_DUP continuing destructuring pattern */
626 SRC_DECL = 6, /* type of a declaration (var, const, let*) */
627 SRC_DESTRUCT = 6, /* JSOP_DUP starting a destructuring assignment
628 operation, with SRC_DECL_* offset operand */
629 SRC_PCDELTA = 7, /* distance forward from comma-operator to
630 next POP, or from CONDSWITCH to first CASE
631 opcode, etc. -- always a forward delta */
632 SRC_GROUPASSIGN = 7, /* SRC_DESTRUCT variant for [a, b] = [c, d] */
633 SRC_ASSIGNOP = 8, /* += or another assign-op follows */
634 SRC_COND = 9, /* JSOP_IFEQ is from conditional ?: operator */
635 SRC_BRACE = 10, /* mandatory brace, for scope or to avoid
636 dangling else */
637 SRC_HIDDEN = 11, /* opcode shouldn't be decompiled */
638 SRC_PCBASE = 12, /* distance back from annotated getprop or
639 setprop op to left-most obj.prop.subprop
640 bytecode -- always a backward delta */
641 SRC_LABEL = 13, /* JSOP_NOP for label: with atomid immediate */
642 SRC_LABELBRACE = 14, /* JSOP_NOP for label: {...} begin brace */
643 SRC_ENDBRACE = 15, /* JSOP_NOP for label: {...} end brace */
644 SRC_BREAK2LABEL = 16, /* JSOP_GOTO for 'break label' with atomid */
645 SRC_CONT2LABEL = 17, /* JSOP_GOTO for 'continue label' with atomid */
646 SRC_SWITCH = 18, /* JSOP_*SWITCH with offset to end of switch,
647 2nd off to first JSOP_CASE if condswitch */
648 SRC_FUNCDEF = 19, /* JSOP_NOP for function f() with atomid */
649 SRC_CATCH = 20, /* catch block has guard */
650 SRC_EXTENDED = 21, /* extended source note, 32-159, in next byte */
651 SRC_NEWLINE = 22, /* bytecode follows a source newline */
652 SRC_SETLINE = 23, /* a file-absolute source line number note */
653 SRC_XDELTA = 24 /* 24-31 are for extended delta notes */
654 } JSSrcNoteType;
655
656 /*
657 * Constants for the SRC_DECL source note. Note that span-dependent bytecode
658 * selection means that any SRC_DECL offset greater than SRC_DECL_LET may need
659 * to be adjusted, but these "offsets" are too small to span a span-dependent
660 * instruction, so can be used to denote distinct declaration syntaxes to the
661 * decompiler.
662 *
663 * NB: the var_prefix array in jsopcode.c depends on these dense indexes from
664 * SRC_DECL_VAR through SRC_DECL_LET.
665 */
666 #define SRC_DECL_VAR 0
667 #define SRC_DECL_CONST 1
668 #define SRC_DECL_LET 2
669 #define SRC_DECL_NONE 3
670
671 #define SN_TYPE_BITS 5
672 #define SN_DELTA_BITS 3
673 #define SN_XDELTA_BITS 6
674 #define SN_TYPE_MASK (JS_BITMASK(SN_TYPE_BITS) << SN_DELTA_BITS)
675 #define SN_DELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_DELTA_BITS))
676 #define SN_XDELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_XDELTA_BITS))
677
678 #define SN_MAKE_NOTE(sn,t,d) (*(sn) = (jssrcnote) \
679 (((t) << SN_DELTA_BITS) \
680 | ((d) & SN_DELTA_MASK)))
681 #define SN_MAKE_XDELTA(sn,d) (*(sn) = (jssrcnote) \
682 ((SRC_XDELTA << SN_DELTA_BITS) \
683 | ((d) & SN_XDELTA_MASK)))
684
685 #define SN_IS_XDELTA(sn) ((*(sn) >> SN_DELTA_BITS) >= SRC_XDELTA)
686 #define SN_TYPE(sn) ((JSSrcNoteType)(SN_IS_XDELTA(sn) \
687 ? SRC_XDELTA \
688 : *(sn) >> SN_DELTA_BITS))
689 #define SN_SET_TYPE(sn,type) SN_MAKE_NOTE(sn, type, SN_DELTA(sn))
690 #define SN_IS_GETTABLE(sn) (SN_TYPE(sn) < SRC_NEWLINE)
691
692 #define SN_DELTA(sn) ((ptrdiff_t)(SN_IS_XDELTA(sn) \
693 ? *(sn) & SN_XDELTA_MASK \
694 : *(sn) & SN_DELTA_MASK))
695 #define SN_SET_DELTA(sn,delta) (SN_IS_XDELTA(sn) \
696 ? SN_MAKE_XDELTA(sn, delta) \
697 : SN_MAKE_NOTE(sn, SN_TYPE(sn), delta))
698
699 #define SN_DELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_DELTA_BITS))
700 #define SN_XDELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_XDELTA_BITS))
701
702 /*
703 * Offset fields follow certain notes and are frequency-encoded: an offset in
704 * [0,0x7f] consumes one byte, an offset in [0x80,0x7fffff] takes three, and
705 * the high bit of the first byte is set.
706 */
707 #define SN_3BYTE_OFFSET_FLAG 0x80
708 #define SN_3BYTE_OFFSET_MASK 0x7f
709
710 typedef struct JSSrcNoteSpec {
711 const char *name; /* name for disassembly/debugging output */
712 int8 arity; /* number of offset operands */
713 uint8 offsetBias; /* bias of offset(s) from annotated pc */
714 int8 isSpanDep; /* 1 or -1 if offsets could span extended ops,
715 0 otherwise; sign tells span direction */
716 } JSSrcNoteSpec;
717
718 extern JS_FRIEND_DATA(JSSrcNoteSpec) js_SrcNoteSpec[];
719 extern JS_FRIEND_API(uintN) js_SrcNoteLength(jssrcnote *sn);
720
721 #define SN_LENGTH(sn) ((js_SrcNoteSpec[SN_TYPE(sn)].arity == 0) ? 1 \
722 : js_SrcNoteLength(sn))
723 #define SN_NEXT(sn) ((sn) + SN_LENGTH(sn))
724
725 /* A source note array is terminated by an all-zero element. */
726 #define SN_MAKE_TERMINATOR(sn) (*(sn) = SRC_NULL)
727 #define SN_IS_TERMINATOR(sn) (*(sn) == SRC_NULL)
728
729 /*
730 * Append a new source note of the given type (and therefore size) to cg's
731 * notes dynamic array, updating cg->noteCount. Return the new note's index
732 * within the array pointed at by cg->current->notes. Return -1 if out of
733 * memory.
734 */
735 extern intN
736 js_NewSrcNote(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type);
737
738 extern intN
739 js_NewSrcNote2(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type,
740 ptrdiff_t offset);
741
742 extern intN
743 js_NewSrcNote3(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type,
744 ptrdiff_t offset1, ptrdiff_t offset2);
745
746 /*
747 * NB: this function can add at most one extra extended delta note.
748 */
749 extern jssrcnote *
750 js_AddToSrcNoteDelta(JSContext *cx, JSCodeGenerator *cg, jssrcnote *sn,
751 ptrdiff_t delta);
752
753 /*
754 * Get and set the offset operand identified by which (0 for the first, etc.).
755 */
756 extern JS_FRIEND_API(ptrdiff_t)
757 js_GetSrcNoteOffset(jssrcnote *sn, uintN which);
758
759 extern JSBool
760 js_SetSrcNoteOffset(JSContext *cx, JSCodeGenerator *cg, uintN index,
761 uintN which, ptrdiff_t offset);
762
763 /*
764 * Finish taking source notes in cx's notePool, copying final notes to the new
765 * stable store allocated by the caller and passed in via notes. Return false
766 * on malloc failure, which means this function reported an error.
767 *
768 * To compute the number of jssrcnotes to allocate and pass in via notes, use
769 * the CG_COUNT_FINAL_SRCNOTES macro. This macro knows a lot about details of
770 * js_FinishTakingSrcNotes, SO DON'T CHANGE jsemit.c's js_FinishTakingSrcNotes
771 * FUNCTION WITHOUT CHECKING WHETHER THIS MACRO NEEDS CORRESPONDING CHANGES!
772 */
773 #define CG_COUNT_FINAL_SRCNOTES(cg, cnt) \
774 JS_BEGIN_MACRO \
775 ptrdiff_t diff_ = CG_PROLOG_OFFSET(cg) - (cg)->prolog.lastNoteOffset; \
776 cnt = (cg)->prolog.noteCount + (cg)->main.noteCount + 1; \
777 if ((cg)->prolog.noteCount && \
778 (cg)->prolog.currentLine != (cg)->firstLine) { \
779 if (diff_ > SN_DELTA_MASK) \
780 cnt += JS_HOWMANY(diff_ - SN_DELTA_MASK, SN_XDELTA_MASK); \
781 cnt += 2 + (((cg)->firstLine > SN_3BYTE_OFFSET_MASK) << 1); \
782 } else if (diff_ > 0) { \
783 if (cg->main.noteCount) { \
784 jssrcnote *sn_ = (cg)->main.notes; \
785 diff_ -= SN_IS_XDELTA(sn_) \
786 ? SN_XDELTA_MASK - (*sn_ & SN_XDELTA_MASK) \
787 : SN_DELTA_MASK - (*sn_ & SN_DELTA_MASK); \
788 } \
789 if (diff_ > 0) \
790 cnt += JS_HOWMANY(diff_, SN_XDELTA_MASK); \
791 } \
792 JS_END_MACRO
793
794 extern JSBool
795 js_FinishTakingSrcNotes(JSContext *cx, JSCodeGenerator *cg, jssrcnote *notes);
796
797 extern void
798 js_FinishTakingTryNotes(JSCodeGenerator *cg, JSTryNoteArray *array);
799
800 JS_END_EXTERN_C
801
802 #endif /* jsemit_h___ */

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