/[jscoverage]/trunk/js/jsemit.h
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Revision 332 - (hide annotations)
Thu Oct 23 19:03:33 2008 UTC (13 years, 8 months ago) by siliconforks
File MIME type: text/plain
File size: 36390 byte(s)
Add SpiderMonkey from Firefox 3.1b1.

The following directories and files were removed:
correct/, correct.js
liveconnect/
nanojit/
t/
v8/
vprof/
xpconnect/
all JavaScript files (Y.js, call.js, if.js, math-partial-sums.js, md5.js, perfect.js, trace-test.js, trace.js)


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

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