1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 * vim: set ts=8 sw=4 et tw=79:
4 * ***** BEGIN LICENSE BLOCK *****
5 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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/
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
17 * The Original Code is Mozilla Communicator client code, released
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.
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
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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.
39 * ***** END LICENSE BLOCK ***** */
44 * JS bytecode generation.
57 * NB: If you add enumerators for scope statements, add them between STMT_WITH
58 * and STMT_CATCH, or you will break the STMT_TYPE_IS_SCOPE macro. If you add
59 * non-looping statement enumerators, add them before STMT_DO_LOOP or you will
60 * break the STMT_TYPE_IS_LOOP macro.
62 * Also remember to keep the statementName array in jsemit.c in sync.
64 typedef enum JSStmtType {
65 STMT_LABEL, /* labeled statement: L: s */
66 STMT_IF, /* if (then) statement */
67 STMT_ELSE, /* else clause of if statement */
68 STMT_SEQ, /* synthetic sequence of statements */
69 STMT_BLOCK, /* compound statement: { s1[;... sN] } */
70 STMT_SWITCH, /* switch statement */
71 STMT_WITH, /* with statement */
72 STMT_CATCH, /* catch block */
73 STMT_TRY, /* try block */
74 STMT_FINALLY, /* finally block */
75 STMT_SUBROUTINE, /* gosub-target subroutine body */
76 STMT_DO_LOOP, /* do/while loop statement */
77 STMT_FOR_LOOP, /* for loop statement */
78 STMT_FOR_IN_LOOP, /* for/in loop statement */
79 STMT_WHILE_LOOP, /* while loop statement */
83 #define STMT_TYPE_IN_RANGE(t,b,e) ((uint)((t) - (b)) <= (uintN)((e) - (b)))
86 * A comment on the encoding of the JSStmtType enum and type-testing macros:
88 * STMT_TYPE_MAYBE_SCOPE tells whether a statement type is always, or may
89 * become, a lexical scope. It therefore includes block and switch (the two
90 * low-numbered "maybe" scope types) and excludes with (with has dynamic scope
91 * pending the "reformed with" in ES4/JS2). It includes all try-catch-finally
92 * types, which are high-numbered maybe-scope types.
94 * STMT_TYPE_LINKS_SCOPE tells whether a JSStmtInfo of the given type eagerly
95 * links to other scoping statement info records. It excludes the two early
96 * "maybe" types, block and switch, as well as the try and both finally types,
97 * since try and the other trailing maybe-scope types don't need block scope
98 * unless they contain let declarations.
100 * We treat WITH as a static scope because it prevents lexical binding from
101 * continuing further up the static scope chain. With the lost "reformed with"
102 * proposal for ES4, we would be able to model it statically, too.
104 #define STMT_TYPE_MAYBE_SCOPE(type) \
105 (type != STMT_WITH && \
106 STMT_TYPE_IN_RANGE(type, STMT_BLOCK, STMT_SUBROUTINE))
108 #define STMT_TYPE_LINKS_SCOPE(type) \
109 STMT_TYPE_IN_RANGE(type, STMT_WITH, STMT_CATCH)
111 #define STMT_TYPE_IS_TRYING(type) \
112 STMT_TYPE_IN_RANGE(type, STMT_TRY, STMT_SUBROUTINE)
114 #define STMT_TYPE_IS_LOOP(type) ((type) >= STMT_DO_LOOP)
116 #define STMT_MAYBE_SCOPE(stmt) STMT_TYPE_MAYBE_SCOPE((stmt)->type)
117 #define STMT_LINKS_SCOPE(stmt) (STMT_TYPE_LINKS_SCOPE((stmt)->type) || \
118 ((stmt)->flags & SIF_SCOPE))
119 #define STMT_IS_TRYING(stmt) STMT_TYPE_IS_TRYING((stmt)->type)
120 #define STMT_IS_LOOP(stmt) STMT_TYPE_IS_LOOP((stmt)->type)
122 typedef struct JSStmtInfo JSStmtInfo;
125 uint16 type; /* statement type */
126 uint16 flags; /* flags, see below */
127 uint32 blockid; /* for simplified dominance computation */
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 */
132 JSAtom *label; /* name of LABEL */
133 JSObjectBox *blockBox; /* block scope object */
135 JSStmtInfo *down; /* info for enclosing statement */
136 JSStmtInfo *downScope; /* next enclosing lexical scope */
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 */
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.
151 #define CATCHNOTE(stmt) ((stmt).update)
152 #define GOSUBS(stmt) ((stmt).breaks)
153 #define GUARDJUMP(stmt) ((stmt).continues)
155 #define SET_STATEMENT_TOP(stmt, top) \
156 ((stmt)->update = (top), (stmt)->breaks = (stmt)->continues = (-1))
158 #ifdef JS_SCOPE_DEPTH_METER
159 # define JS_SCOPE_DEPTH_METERING(code) ((void) (code))
160 # define JS_SCOPE_DEPTH_METERING_IF(cond, code) ((cond) ? (void) (code) : (void) 0)
162 # define JS_SCOPE_DEPTH_METERING(code) ((void) 0)
163 # define JS_SCOPE_DEPTH_METERING_IF(code, x) ((void) 0)
166 #define TCF_COMPILING 0x01 /* JSTreeContext is JSCodeGenerator */
167 #define TCF_IN_FUNCTION 0x02 /* parsing inside function body */
168 #define TCF_RETURN_EXPR 0x04 /* function has 'return expr;' */
169 #define TCF_RETURN_VOID 0x08 /* function has 'return;' */
170 #define TCF_IN_FOR_INIT 0x10 /* parsing init expr of for; exclude 'in' */
171 #define TCF_FUN_SETS_OUTER_NAME 0x20 /* function set outer name (lexical or free) */
172 #define TCF_FUN_PARAM_ARGUMENTS 0x40 /* function has parameter named arguments */
173 #define TCF_FUN_USES_ARGUMENTS 0x80 /* function uses arguments except as a
175 #define TCF_FUN_HEAVYWEIGHT 0x100 /* function needs Call object per call */
176 #define TCF_FUN_IS_GENERATOR 0x200 /* parsed yield statement in function */
177 #define TCF_FUN_USES_OWN_NAME 0x400 /* named function expression that uses its
179 #define TCF_HAS_FUNCTION_STMT 0x800 /* block contains a function statement */
180 #define TCF_GENEXP_LAMBDA 0x1000 /* flag lambda from generator expression */
181 #define TCF_COMPILE_N_GO 0x2000 /* compile-and-go mode of script, can
182 optimize name references based on scope
184 #define TCF_NO_SCRIPT_RVAL 0x4000 /* API caller does not want result value
185 from global script */
186 #define TCF_HAS_SHARPS 0x8000 /* source contains sharp defs or uses */
189 * Set when parsing a declaration-like destructuring pattern. This
190 * flag causes PrimaryExpr to create PN_NAME parse nodes for variable
191 * references which are not hooked into any definition's use chain,
192 * added to any tree context's AtomList, etc. etc. CheckDestructuring
193 * will do that work later.
195 * The comments atop CheckDestructuring explain the distinction
196 * between assignment-like and declaration-like destructuring
197 * patterns, and why they need to be treated differently.
199 #define TCF_DECL_DESTRUCTURING 0x10000
202 * A request flag passed to Compiler::compileScript and then down via
203 * JSCodeGenerator to js_NewScriptFromCG, from script_compile_sub and any
204 * kindred functions that need to make mutable scripts (even empty ones;
205 * i.e., they can't share the const JSScript::emptyScript() singleton).
207 #define TCF_NEED_MUTABLE_SCRIPT 0x20000
210 * This function/global/eval code body contained a Use Strict Directive. Treat
211 * certain strict warnings as errors, and forbid the use of 'with'. See also
212 * TSF_STRICT_MODE_CODE, JSScript::strictModeCode, and JSREPORT_STRICT_ERROR.
214 #define TCF_STRICT_MODE_CODE 0x40000
216 /* bit 0x80000 is unused */
219 * Flag signifying that the current function seems to be a constructor that
220 * sets this.foo to define "methods", at least one of which can't be a null
221 * closure, so we should avoid over-specializing property cache entries and
222 * trace inlining guards to method function object identity, which will vary
225 #define TCF_FUN_UNBRAND_THIS 0x100000
228 * "Module pattern", i.e., a lambda that is immediately applied and the whole
229 * of an expression statement.
231 #define TCF_FUN_MODULE_PATTERN 0x200000
234 * Flag to prevent a non-escaping function from being optimized into a null
235 * closure (i.e., a closure that needs only its global object for free variable
236 * resolution), because this function contains a closure that needs one or more
237 * scope objects surrounding it (i.e., a Call object for an outer heavyweight
238 * function). See bug 560234.
240 #define TCF_FUN_ENTRAINS_SCOPES 0x400000
242 /* The function calls 'eval'. */
243 #define TCF_FUN_CALLS_EVAL 0x800000
245 /* The function mutates a positional (non-destructuring) parameter. */
246 #define TCF_FUN_MUTATES_PARAMETER 0x1000000
249 * Compiling an eval() script.
251 #define TCF_COMPILE_FOR_EVAL 0x2000000
254 * The function or a function that encloses it may define new local names
255 * at runtime through means other than calling eval.
257 #define TCF_FUN_MIGHT_ALIAS_LOCALS 0x4000000
260 * The script contains singleton initialiser JSOP_OBJECT.
262 #define TCF_HAS_SINGLETONS 0x8000000
265 * Some enclosing scope is a with-statement or E4X filter-expression.
267 #define TCF_IN_WITH 0x10000000
270 * Flags to check for return; vs. return expr; in a function.
272 #define TCF_RETURN_FLAGS (TCF_RETURN_EXPR | TCF_RETURN_VOID)
275 * Sticky deoptimization flags to propagate from FunctionBody.
277 #define TCF_FUN_FLAGS (TCF_FUN_SETS_OUTER_NAME | \
278 TCF_FUN_USES_ARGUMENTS | \
279 TCF_FUN_PARAM_ARGUMENTS | \
280 TCF_FUN_HEAVYWEIGHT | \
281 TCF_FUN_IS_GENERATOR | \
282 TCF_FUN_USES_OWN_NAME | \
284 TCF_FUN_CALLS_EVAL | \
285 TCF_FUN_MIGHT_ALIAS_LOCALS | \
286 TCF_FUN_MUTATES_PARAMETER | \
287 TCF_STRICT_MODE_CODE)
289 struct JSTreeContext { /* tree context for semantic checks */
290 uint32 flags; /* statement state flags, see above */
291 uint32 bodyid; /* block number of program/function body */
292 uint32 blockidGen; /* preincremented block number generator */
293 JSStmtInfo *topStmt; /* top of statement info stack */
294 JSStmtInfo *topScopeStmt; /* top lexical scope statement */
295 JSObjectBox *blockChainBox; /* compile time block scope chain (NB: one
296 deeper than the topScopeStmt/downScope
297 chain when in head of let block/expr) */
298 JSParseNode *blockNode; /* parse node for a block with let declarations
299 (block with its own lexical scope) */
300 JSAtomList decls; /* function, const, and var declarations */
301 js::Parser *parser; /* ptr to common parsing and lexing data */
305 JSFunction *fun_; /* function to store argument and variable
306 names when flags & TCF_IN_FUNCTION */
307 JSObject *scopeChain_; /* scope chain object for the script */
311 JSFunction *fun() const {
312 JS_ASSERT(inFunction());
315 void setFunction(JSFunction *fun) {
316 JS_ASSERT(inFunction());
319 JSObject *scopeChain() const {
320 JS_ASSERT(!inFunction());
323 void setScopeChain(JSObject *scopeChain) {
324 JS_ASSERT(!inFunction());
325 scopeChain_ = scopeChain;
328 JSAtomList lexdeps; /* unresolved lexical name dependencies */
329 JSTreeContext *parent; /* enclosing function or global context */
330 uintN staticLevel; /* static compilation unit nesting level */
332 JSFunctionBox *funbox; /* null or box for function we're compiling
333 if (flags & TCF_IN_FUNCTION) and not in
334 Compiler::compileFunctionBody */
335 JSFunctionBox *functionList;
337 JSParseNode *innermostWith; /* innermost WITH parse node */
339 js::Bindings bindings; /* bindings in this code, including
340 arguments if we're compiling a function */
342 #ifdef JS_SCOPE_DEPTH_METER
343 uint16 scopeDepth; /* current lexical scope chain depth */
344 uint16 maxScopeDepth; /* maximum lexical scope chain depth */
347 void trace(JSTracer *trc);
349 JSTreeContext(js::Parser *prs)
350 : flags(0), bodyid(0), blockidGen(0), topStmt(NULL), topScopeStmt(NULL),
351 blockChainBox(NULL), blockNode(NULL), parser(prs), scopeChain_(NULL), parent(prs->tc),
352 staticLevel(0), funbox(NULL), functionList(NULL), innermostWith(NULL), bindings(prs->context),
356 JS_SCOPE_DEPTH_METERING(scopeDepth = maxScopeDepth = 0);
360 * For functions the tree context is constructed and destructed a second
361 * time during code generation. To avoid a redundant stats update in such
362 * cases, we store uint16(-1) in maxScopeDepth.
365 parser->tc = this->parent;
366 JS_SCOPE_DEPTH_METERING_IF((maxScopeDepth != uint16(-1)),
367 JS_BASIC_STATS_ACCUM(&parser
370 ->lexicalScopeDepthStats,
374 uintN blockid() { return topStmt ? topStmt->blockid : bodyid; }
376 JSObject *blockChain() {
377 return blockChainBox ? blockChainBox->object : NULL;
381 * True if we are at the topmost level of a entire script or function body.
382 * For example, while parsing this code we would encounter f1 and f2 at
383 * body level, but we would not encounter f3 or f4 at body level:
385 * function f1() { function f2() { } }
386 * if (cond) { function f3() { if (cond) { function f4() { } } } }
388 bool atBodyLevel() { return !topStmt || (topStmt->flags & SIF_BODY_BLOCK); }
390 /* Test whether we're in a statement of given type. */
391 bool inStatement(JSStmtType type);
393 bool inStrictMode() const {
394 return flags & TCF_STRICT_MODE_CODE;
397 inline bool needStrictChecks();
400 * sharpSlotBase is -1 or first slot of pair for [sharpArray, sharpDepth].
401 * The parser calls ensureSharpSlots to allocate these two stack locals.
404 bool ensureSharpSlots();
406 js::Compiler *compiler() { return (js::Compiler *)parser; }
408 // Return true there is a generator function within |skip| lexical scopes
409 // (going upward) from this context's lexical scope. Always return true if
410 // this context is itself a generator.
411 bool skipSpansGenerator(unsigned skip);
413 bool compileAndGo() const { return flags & TCF_COMPILE_N_GO; }
414 bool inFunction() const { return flags & TCF_IN_FUNCTION; }
416 bool compiling() const { return flags & TCF_COMPILING; }
417 inline JSCodeGenerator *asCodeGenerator();
419 bool usesArguments() const {
420 return flags & TCF_FUN_USES_ARGUMENTS;
423 void noteCallsEval() {
424 flags |= TCF_FUN_CALLS_EVAL;
427 bool callsEval() const {
428 return flags & TCF_FUN_CALLS_EVAL;
431 void noteMightAliasLocals() {
432 flags |= TCF_FUN_MIGHT_ALIAS_LOCALS;
435 bool mightAliasLocals() const {
436 return flags & TCF_FUN_MIGHT_ALIAS_LOCALS;
439 void noteParameterMutation() {
440 JS_ASSERT(inFunction());
441 flags |= TCF_FUN_MUTATES_PARAMETER;
444 bool mutatesParameter() const {
445 JS_ASSERT(inFunction());
446 return flags & TCF_FUN_MUTATES_PARAMETER;
449 void noteArgumentsUse() {
450 JS_ASSERT(inFunction());
451 flags |= TCF_FUN_USES_ARGUMENTS;
453 funbox->node->pn_dflags |= PND_FUNARG;
456 bool needsEagerArguments() const {
457 return inStrictMode() && ((usesArguments() && mutatesParameter()) || callsEval());
462 * Return true if we need to check for conditions that elicit
463 * JSOPTION_STRICT warnings or strict mode errors.
465 inline bool JSTreeContext::needStrictChecks() {
466 return parser->context->hasStrictOption() || inStrictMode();
470 * Span-dependent instructions are jumps whose span (from the jump bytecode to
471 * the jump target) may require 2 or 4 bytes of immediate operand.
473 typedef struct JSSpanDep JSSpanDep;
474 typedef struct JSJumpTarget JSJumpTarget;
477 ptrdiff_t top; /* offset of first bytecode in an opcode */
478 ptrdiff_t offset; /* offset - 1 within opcode of jump operand */
479 ptrdiff_t before; /* original offset - 1 of jump operand */
480 JSJumpTarget *target; /* tagged target pointer or backpatch delta */
484 * Jump targets are stored in an AVL tree, for O(log(n)) lookup with targets
485 * sorted by offset from left to right, so that targets after a span-dependent
486 * instruction whose jump offset operand must be extended can be found quickly
487 * and adjusted upward (toward higher offsets).
489 struct JSJumpTarget {
490 ptrdiff_t offset; /* offset of span-dependent jump target */
491 int balance; /* AVL tree balance number */
492 JSJumpTarget *kids[2]; /* left and right AVL tree child pointers */
497 #define JT_OTHER_DIR(dir) (1 - (dir))
498 #define JT_IMBALANCE(dir) (((dir) << 1) - 1)
499 #define JT_DIR(imbalance) (((imbalance) + 1) >> 1)
502 * Backpatch deltas are encoded in JSSpanDep.target if JT_TAG_BIT is clear,
503 * so we can maintain backpatch chains when using span dependency records to
504 * hold jump offsets that overflow 16 bits.
506 #define JT_TAG_BIT ((jsword) 1)
507 #define JT_UNTAG_SHIFT 1
508 #define JT_SET_TAG(jt) ((JSJumpTarget *)((jsword)(jt) | JT_TAG_BIT))
509 #define JT_CLR_TAG(jt) ((JSJumpTarget *)((jsword)(jt) & ~JT_TAG_BIT))
510 #define JT_HAS_TAG(jt) ((jsword)(jt) & JT_TAG_BIT)
512 #define BITS_PER_PTRDIFF (sizeof(ptrdiff_t) * JS_BITS_PER_BYTE)
513 #define BITS_PER_BPDELTA (BITS_PER_PTRDIFF - 1 - JT_UNTAG_SHIFT)
514 #define BPDELTA_MAX (((ptrdiff_t)1 << BITS_PER_BPDELTA) - 1)
515 #define BPDELTA_TO_JT(bp) ((JSJumpTarget *)((bp) << JT_UNTAG_SHIFT))
516 #define JT_TO_BPDELTA(jt) ((ptrdiff_t)((jsword)(jt) >> JT_UNTAG_SHIFT))
518 #define SD_SET_TARGET(sd,jt) ((sd)->target = JT_SET_TAG(jt))
519 #define SD_GET_TARGET(sd) (JS_ASSERT(JT_HAS_TAG((sd)->target)), \
520 JT_CLR_TAG((sd)->target))
521 #define SD_SET_BPDELTA(sd,bp) ((sd)->target = BPDELTA_TO_JT(bp))
522 #define SD_GET_BPDELTA(sd) (JS_ASSERT(!JT_HAS_TAG((sd)->target)), \
523 JT_TO_BPDELTA((sd)->target))
525 /* Avoid asserting twice by expanding SD_GET_TARGET in the "then" clause. */
526 #define SD_SPAN(sd,pivot) (SD_GET_TARGET(sd) \
527 ? JT_CLR_TAG((sd)->target)->offset - (pivot) \
530 typedef struct JSTryNode JSTryNode;
537 struct JSCGObjectList {
538 uint32 length; /* number of emitted so far objects */
539 JSObjectBox *lastbox; /* last emitted object */
541 JSCGObjectList() : length(0), lastbox(NULL) {}
543 uintN index(JSObjectBox *objbox);
544 void finish(JSObjectArray *array);
547 class JSGCConstList {
548 js::Vector<js::Value> list;
550 JSGCConstList(JSContext *cx) : list(cx) {}
551 bool append(js::Value v) { return list.append(v); }
552 size_t length() const { return list.length(); }
553 void finish(JSConstArray *array);
557 struct JSCodeGenerator : public JSTreeContext
559 JSArenaPool *codePool; /* pointer to thread code arena pool */
560 JSArenaPool *notePool; /* pointer to thread srcnote arena pool */
561 void *codeMark; /* low watermark in cg->codePool */
562 void *noteMark; /* low watermark in cg->notePool */
565 jsbytecode *base; /* base of JS bytecode vector */
566 jsbytecode *limit; /* one byte beyond end of bytecode */
567 jsbytecode *next; /* pointer to next free bytecode */
568 jssrcnote *notes; /* source notes, see below */
569 uintN noteCount; /* number of source notes so far */
570 uintN noteMask; /* growth increment for notes */
571 ptrdiff_t lastNoteOffset; /* code offset for last source note */
572 uintN currentLine; /* line number for tree-based srcnote gen */
573 } prolog, main, *current;
575 JSAtomList atomList; /* literals indexed for mapping */
576 uintN firstLine; /* first line, for js_NewScriptFromCG */
578 intN stackDepth; /* current stack depth in script frame */
579 uintN maxStackDepth; /* maximum stack depth so far */
581 uintN ntrynotes; /* number of allocated so far try notes */
582 JSTryNode *lastTryNode; /* the last allocated try node */
584 JSSpanDep *spanDeps; /* span dependent instruction records */
585 JSJumpTarget *jumpTargets; /* AVL tree of jump target offsets */
586 JSJumpTarget *jtFreeList; /* JT_LEFT-linked list of free structs */
587 uintN numSpanDeps; /* number of span dependencies */
588 uintN numJumpTargets; /* number of jump targets */
589 ptrdiff_t spanDepTodo; /* offset from main.base of potentially
590 unoptimized spandeps */
592 uintN arrayCompDepth; /* stack depth of array in comprehension */
594 uintN emitLevel; /* js_EmitTree recursion level */
596 typedef js::HashMap<JSAtom *, js::Value> ConstMap;
597 ConstMap constMap; /* compile time constants */
599 JSGCConstList constList; /* constants to be included with the script */
601 JSCGObjectList objectList; /* list of emitted objects */
602 JSCGObjectList regexpList; /* list of emitted regexp that will be
603 cloned during execution */
605 JSAtomList upvarList; /* map of atoms to upvar indexes */
606 JSUpvarArray upvarMap; /* indexed upvar pairs (JS_realloc'ed) */
608 typedef js::Vector<js::GlobalSlotArray::Entry, 16, js::ContextAllocPolicy> GlobalUseVector;
610 GlobalUseVector globalUses; /* per-script global uses */
611 JSAtomList globalMap; /* per-script map of global name to globalUses vector */
613 /* Vectors of pn_cookie slot values. */
614 typedef js::Vector<uint32, 8, js::ContextAllocPolicy> SlotVector;
615 SlotVector closedArgs;
616 SlotVector closedVars;
618 uint16 traceIndex; /* index for the next JSOP_TRACE instruction */
621 * Initialize cg to allocate bytecode space from codePool, source note
622 * space from notePool, and all other arena-allocated temporaries from
623 * parser->context->tempPool.
625 JSCodeGenerator(js::Parser *parser,
626 JSArenaPool *codePool, JSArenaPool *notePool,
631 * Release cg->codePool, cg->notePool, and parser->context->tempPool to
632 * marks set by JSCodeGenerator's ctor. Note that cgs are magic: they own
633 * the arena pool "tops-of-stack" space above their codeMark, noteMark, and
634 * tempMark points. This means you cannot alloc from tempPool and save the
635 * pointer beyond the next JSCodeGenerator destructor call.
640 * Adds a use of a variable that is statically known to exist on the
643 * The actual slot of the variable on the global object is not known
644 * until after compilation. Properties must be resolved before being
645 * added, to avoid aliasing properties that should be resolved. This makes
646 * slot prediction based on the global object's free slot impossible. So,
647 * we use the slot to index into cg->globalScope->defs, and perform a
648 * fixup of the script at the very end of compilation.
650 * If the global use can be cached, |cookie| will be set to |slot|.
651 * Otherwise, |cookie| is set to the free cookie value.
653 bool addGlobalUse(JSAtom *atom, uint32 slot, js::UpvarCookie *cookie);
655 bool hasSharps() const {
656 bool rv = !!(flags & TCF_HAS_SHARPS);
657 JS_ASSERT((sharpSlotBase >= 0) == rv);
661 uintN sharpSlots() const {
662 return hasSharps() ? SHARP_NSLOTS : 0;
665 bool compilingForEval() const { return !!(flags & TCF_COMPILE_FOR_EVAL); }
666 JSVersion version() const { return parser->versionWithFlags(); }
668 bool shouldNoteClosedName(JSParseNode *pn);
670 bool checkSingletonContext() {
671 if (!compileAndGo() || inFunction())
673 for (JSStmtInfo *stmt = topStmt; stmt; stmt = stmt->down) {
674 if (STMT_IS_LOOP(stmt))
677 flags |= TCF_HAS_SINGLETONS;
682 #define CG_TS(cg) TS((cg)->parser)
684 #define CG_BASE(cg) ((cg)->current->base)
685 #define CG_LIMIT(cg) ((cg)->current->limit)
686 #define CG_NEXT(cg) ((cg)->current->next)
687 #define CG_CODE(cg,offset) (CG_BASE(cg) + (offset))
688 #define CG_OFFSET(cg) (CG_NEXT(cg) - CG_BASE(cg))
690 #define CG_NOTES(cg) ((cg)->current->notes)
691 #define CG_NOTE_COUNT(cg) ((cg)->current->noteCount)
692 #define CG_NOTE_MASK(cg) ((cg)->current->noteMask)
693 #define CG_LAST_NOTE_OFFSET(cg) ((cg)->current->lastNoteOffset)
694 #define CG_CURRENT_LINE(cg) ((cg)->current->currentLine)
696 #define CG_PROLOG_BASE(cg) ((cg)->prolog.base)
697 #define CG_PROLOG_LIMIT(cg) ((cg)->prolog.limit)
698 #define CG_PROLOG_NEXT(cg) ((cg)->prolog.next)
699 #define CG_PROLOG_CODE(cg,poff) (CG_PROLOG_BASE(cg) + (poff))
700 #define CG_PROLOG_OFFSET(cg) (CG_PROLOG_NEXT(cg) - CG_PROLOG_BASE(cg))
702 #define CG_SWITCH_TO_MAIN(cg) ((cg)->current = &(cg)->main)
703 #define CG_SWITCH_TO_PROLOG(cg) ((cg)->current = &(cg)->prolog)
705 inline JSCodeGenerator *
706 JSTreeContext::asCodeGenerator()
708 JS_ASSERT(compiling());
709 return static_cast<JSCodeGenerator *>(this);
716 js_Emit1(JSContext *cx, JSCodeGenerator *cg, JSOp op);
719 * Emit two bytecodes, an opcode (op) with a byte of immediate operand (op1).
722 js_Emit2(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1);
725 * Emit three bytecodes, an opcode with two bytes of immediate operands.
728 js_Emit3(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1,
732 * Emit five bytecodes, an opcode with two 16-bit immediates.
735 js_Emit5(JSContext *cx, JSCodeGenerator *cg, JSOp op, uint16 op1,
739 * Emit (1 + extra) bytecodes, for N bytes of op and its immediate operand.
742 js_EmitN(JSContext *cx, JSCodeGenerator *cg, JSOp op, size_t extra);
745 * Unsafe macro to call js_SetJumpOffset and return false if it does.
747 #define CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx,cg,pc,off,BAD_EXIT) \
749 if (!js_SetJumpOffset(cx, cg, pc, off)) { \
754 #define CHECK_AND_SET_JUMP_OFFSET(cx,cg,pc,off) \
755 CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx,cg,pc,off,return JS_FALSE)
757 #define CHECK_AND_SET_JUMP_OFFSET_AT_CUSTOM(cx,cg,off,BAD_EXIT) \
758 CHECK_AND_SET_JUMP_OFFSET_CUSTOM(cx, cg, CG_CODE(cg,off), \
759 CG_OFFSET(cg) - (off), BAD_EXIT)
761 #define CHECK_AND_SET_JUMP_OFFSET_AT(cx,cg,off) \
762 CHECK_AND_SET_JUMP_OFFSET_AT_CUSTOM(cx, cg, off, return JS_FALSE)
765 js_SetJumpOffset(JSContext *cx, JSCodeGenerator *cg, jsbytecode *pc,
769 * Push the C-stack-allocated struct at stmt onto the stmtInfo stack.
772 js_PushStatement(JSTreeContext *tc, JSStmtInfo *stmt, JSStmtType type,
776 * Push a block scope statement and link blockObj into tc->blockChain. To pop
777 * this statement info record, use js_PopStatement as usual, or if appropriate
778 * (if generating code), js_PopStatementCG.
781 js_PushBlockScope(JSTreeContext *tc, JSStmtInfo *stmt, JSObjectBox *blockBox,
785 * Pop tc->topStmt. If the top JSStmtInfo struct is not stack-allocated, it
786 * is up to the caller to free it.
789 js_PopStatement(JSTreeContext *tc);
792 * Like js_PopStatement(cg), also patch breaks and continues unless the top
793 * statement info record represents a try-catch-finally suite. May fail if a
794 * jump offset overflows.
797 js_PopStatementCG(JSContext *cx, JSCodeGenerator *cg);
800 * Define and lookup a primitive jsval associated with the const named by atom.
801 * js_DefineCompileTimeConstant analyzes the constant-folded initializer at pn
802 * and saves the const's value in cg->constList, if it can be used at compile
803 * time. It returns true unless an error occurred.
805 * If the initializer's value could not be saved, js_DefineCompileTimeConstant
806 * calls will return the undefined value. js_DefineCompileTimeConstant tries
807 * to find a const value memorized for atom, returning true with *vp set to a
808 * value other than undefined if the constant was found, true with *vp set to
809 * JSVAL_VOID if not found, and false on error.
812 js_DefineCompileTimeConstant(JSContext *cx, JSCodeGenerator *cg, JSAtom *atom,
816 * Find a lexically scoped variable (one declared by let, catch, or an array
817 * comprehension) named by atom, looking in tc's compile-time scopes.
819 * If a WITH statement is reached along the scope stack, return its statement
820 * info record, so callers can tell that atom is ambiguous. If slotp is not
821 * null, then if atom is found, set *slotp to its stack slot, otherwise to -1.
822 * This means that if slotp is not null, all the block objects on the lexical
823 * scope chain must have had their depth slots computed by the code generator,
824 * so the caller must be under js_EmitTree.
826 * In any event, directly return the statement info record in which atom was
827 * found. Otherwise return null.
830 js_LexicalLookup(JSTreeContext *tc, JSAtom *atom, jsint *slotp,
831 JSStmtInfo *stmt = NULL);
834 * Emit code into cg for the tree rooted at pn.
837 js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn);
840 * Emit function code using cg for the tree rooted at body.
843 js_EmitFunctionScript(JSContext *cx, JSCodeGenerator *cg, JSParseNode *body);
846 * Source notes generated along with bytecode for decompiling and debugging.
847 * A source note is a uint8 with 5 bits of type and 3 of offset from the pc of
848 * the previous note. If 3 bits of offset aren't enough, extended delta notes
849 * (SRC_XDELTA) consisting of 2 set high order bits followed by 6 offset bits
850 * are emitted before the next note. Some notes have operand offsets encoded
851 * immediately after them, in note bytes or byte-triples.
853 * Source Note Extended Delta
854 * +7-6-5-4-3+2-1-0+ +7-6-5+4-3-2-1-0+
855 * |note-type|delta| |1 1| ext-delta |
856 * +---------+-----+ +---+-----------+
858 * At most one "gettable" note (i.e., a note of type other than SRC_NEWLINE,
859 * SRC_SETLINE, and SRC_XDELTA) applies to a given bytecode.
861 * NB: the js_SrcNoteSpec array in jsemit.c is indexed by this enum, so its
862 * initializers need to match the order here.
864 * Note on adding new source notes: every pair of bytecodes (A, B) where A and
865 * B have disjoint sets of source notes that could apply to each bytecode may
866 * reuse the same note type value for two notes (snA, snB) that have the same
867 * arity, offsetBias, and isSpanDep initializers in js_SrcNoteSpec. This is
868 * why SRC_IF and SRC_INITPROP have the same value below. For bad historical
869 * reasons, some bytecodes below that could be overlayed have not been, but
870 * before using SRC_EXTENDED, consider compressing the existing note types.
872 * Don't forget to update JSXDR_BYTECODE_VERSION in jsxdrapi.h for all such
873 * incompatible source note or other bytecode changes.
875 typedef enum JSSrcNoteType {
876 SRC_NULL = 0, /* terminates a note vector */
877 SRC_IF = 1, /* JSOP_IFEQ bytecode is from an if-then */
878 SRC_BREAK = 1, /* JSOP_GOTO is a break */
879 SRC_INITPROP = 1, /* disjoint meaning applied to JSOP_INITELEM or
880 to an index label in a regular (structuring)
881 or a destructuring object initialiser */
882 SRC_GENEXP = 1, /* JSOP_LAMBDA from generator expression */
883 SRC_IF_ELSE = 2, /* JSOP_IFEQ bytecode is from an if-then-else */
884 SRC_FOR_IN = 2, /* JSOP_GOTO to for-in loop condition from
885 before loop (same arity as SRC_IF_ELSE) */
886 SRC_FOR = 3, /* JSOP_NOP or JSOP_POP in for(;;) loop head */
887 SRC_WHILE = 4, /* JSOP_GOTO to for or while loop condition
888 from before loop, else JSOP_NOP at top of
890 SRC_TRACE = 4, /* For JSOP_TRACE; includes distance to loop end */
891 SRC_CONTINUE = 5, /* JSOP_GOTO is a continue, not a break;
892 also used on JSOP_ENDINIT if extra comma
893 at end of array literal: [1,2,,];
894 JSOP_DUP continuing destructuring pattern */
895 SRC_DECL = 6, /* type of a declaration (var, const, let*) */
896 SRC_DESTRUCT = 6, /* JSOP_DUP starting a destructuring assignment
897 operation, with SRC_DECL_* offset operand */
898 SRC_PCDELTA = 7, /* distance forward from comma-operator to
899 next POP, or from CONDSWITCH to first CASE
900 opcode, etc. -- always a forward delta */
901 SRC_GROUPASSIGN = 7, /* SRC_DESTRUCT variant for [a, b] = [c, d] */
902 SRC_ASSIGNOP = 8, /* += or another assign-op follows */
903 SRC_COND = 9, /* JSOP_IFEQ is from conditional ?: operator */
904 SRC_BRACE = 10, /* mandatory brace, for scope or to avoid
906 SRC_HIDDEN = 11, /* opcode shouldn't be decompiled */
907 SRC_PCBASE = 12, /* distance back from annotated getprop or
908 setprop op to left-most obj.prop.subprop
909 bytecode -- always a backward delta */
910 SRC_LABEL = 13, /* JSOP_NOP for label: with atomid immediate */
911 SRC_LABELBRACE = 14, /* JSOP_NOP for label: {...} begin brace */
912 SRC_ENDBRACE = 15, /* JSOP_NOP for label: {...} end brace */
913 SRC_BREAK2LABEL = 16, /* JSOP_GOTO for 'break label' with atomid */
914 SRC_CONT2LABEL = 17, /* JSOP_GOTO for 'continue label' with atomid */
915 SRC_SWITCH = 18, /* JSOP_*SWITCH with offset to end of switch,
916 2nd off to first JSOP_CASE if condswitch */
917 SRC_FUNCDEF = 19, /* JSOP_NOP for function f() with atomid */
918 SRC_CATCH = 20, /* catch block has guard */
919 SRC_EXTENDED = 21, /* extended source note, 32-159, in next byte */
920 SRC_NEWLINE = 22, /* bytecode follows a source newline */
921 SRC_SETLINE = 23, /* a file-absolute source line number note */
922 SRC_XDELTA = 24 /* 24-31 are for extended delta notes */
926 * Constants for the SRC_DECL source note. Note that span-dependent bytecode
927 * selection means that any SRC_DECL offset greater than SRC_DECL_LET may need
928 * to be adjusted, but these "offsets" are too small to span a span-dependent
929 * instruction, so can be used to denote distinct declaration syntaxes to the
932 * NB: the var_prefix array in jsopcode.c depends on these dense indexes from
933 * SRC_DECL_VAR through SRC_DECL_LET.
935 #define SRC_DECL_VAR 0
936 #define SRC_DECL_CONST 1
937 #define SRC_DECL_LET 2
938 #define SRC_DECL_NONE 3
940 #define SN_TYPE_BITS 5
941 #define SN_DELTA_BITS 3
942 #define SN_XDELTA_BITS 6
943 #define SN_TYPE_MASK (JS_BITMASK(SN_TYPE_BITS) << SN_DELTA_BITS)
944 #define SN_DELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_DELTA_BITS))
945 #define SN_XDELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_XDELTA_BITS))
947 #define SN_MAKE_NOTE(sn,t,d) (*(sn) = (jssrcnote) \
948 (((t) << SN_DELTA_BITS) \
949 | ((d) & SN_DELTA_MASK)))
950 #define SN_MAKE_XDELTA(sn,d) (*(sn) = (jssrcnote) \
951 ((SRC_XDELTA << SN_DELTA_BITS) \
952 | ((d) & SN_XDELTA_MASK)))
954 #define SN_IS_XDELTA(sn) ((*(sn) >> SN_DELTA_BITS) >= SRC_XDELTA)
955 #define SN_TYPE(sn) ((JSSrcNoteType)(SN_IS_XDELTA(sn) \
957 : *(sn) >> SN_DELTA_BITS))
958 #define SN_SET_TYPE(sn,type) SN_MAKE_NOTE(sn, type, SN_DELTA(sn))
959 #define SN_IS_GETTABLE(sn) (SN_TYPE(sn) < SRC_NEWLINE)
961 #define SN_DELTA(sn) ((ptrdiff_t)(SN_IS_XDELTA(sn) \
962 ? *(sn) & SN_XDELTA_MASK \
963 : *(sn) & SN_DELTA_MASK))
964 #define SN_SET_DELTA(sn,delta) (SN_IS_XDELTA(sn) \
965 ? SN_MAKE_XDELTA(sn, delta) \
966 : SN_MAKE_NOTE(sn, SN_TYPE(sn), delta))
968 #define SN_DELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_DELTA_BITS))
969 #define SN_XDELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_XDELTA_BITS))
972 * Offset fields follow certain notes and are frequency-encoded: an offset in
973 * [0,0x7f] consumes one byte, an offset in [0x80,0x7fffff] takes three, and
974 * the high bit of the first byte is set.
976 #define SN_3BYTE_OFFSET_FLAG 0x80
977 #define SN_3BYTE_OFFSET_MASK 0x7f
979 typedef struct JSSrcNoteSpec {
980 const char *name; /* name for disassembly/debugging output */
981 int8 arity; /* number of offset operands */
982 uint8 offsetBias; /* bias of offset(s) from annotated pc */
983 int8 isSpanDep; /* 1 or -1 if offsets could span extended ops,
984 0 otherwise; sign tells span direction */
987 extern JS_FRIEND_DATA(JSSrcNoteSpec) js_SrcNoteSpec[];
988 extern JS_FRIEND_API(uintN) js_SrcNoteLength(jssrcnote *sn);
990 #define SN_LENGTH(sn) ((js_SrcNoteSpec[SN_TYPE(sn)].arity == 0) ? 1 \
991 : js_SrcNoteLength(sn))
992 #define SN_NEXT(sn) ((sn) + SN_LENGTH(sn))
994 /* A source note array is terminated by an all-zero element. */
995 #define SN_MAKE_TERMINATOR(sn) (*(sn) = SRC_NULL)
996 #define SN_IS_TERMINATOR(sn) (*(sn) == SRC_NULL)
999 * Append a new source note of the given type (and therefore size) to cg's
1000 * notes dynamic array, updating cg->noteCount. Return the new note's index
1001 * within the array pointed at by cg->current->notes. Return -1 if out of
1005 js_NewSrcNote(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type);
1008 js_NewSrcNote2(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type,
1012 js_NewSrcNote3(JSContext *cx, JSCodeGenerator *cg, JSSrcNoteType type,
1013 ptrdiff_t offset1, ptrdiff_t offset2);
1016 * NB: this function can add at most one extra extended delta note.
1019 js_AddToSrcNoteDelta(JSContext *cx, JSCodeGenerator *cg, jssrcnote *sn,
1023 * Get and set the offset operand identified by which (0 for the first, etc.).
1025 extern JS_FRIEND_API(ptrdiff_t)
1026 js_GetSrcNoteOffset(jssrcnote *sn, uintN which);
1029 js_SetSrcNoteOffset(JSContext *cx, JSCodeGenerator *cg, uintN index,
1030 uintN which, ptrdiff_t offset);
1033 * Finish taking source notes in cx's notePool, copying final notes to the new
1034 * stable store allocated by the caller and passed in via notes. Return false
1035 * on malloc failure, which means this function reported an error.
1037 * To compute the number of jssrcnotes to allocate and pass in via notes, use
1038 * the CG_COUNT_FINAL_SRCNOTES macro. This macro knows a lot about details of
1039 * js_FinishTakingSrcNotes, SO DON'T CHANGE jsemit.c's js_FinishTakingSrcNotes
1040 * FUNCTION WITHOUT CHECKING WHETHER THIS MACRO NEEDS CORRESPONDING CHANGES!
1042 #define CG_COUNT_FINAL_SRCNOTES(cg, cnt) \
1044 ptrdiff_t diff_ = CG_PROLOG_OFFSET(cg) - (cg)->prolog.lastNoteOffset; \
1045 cnt = (cg)->prolog.noteCount + (cg)->main.noteCount + 1; \
1046 if ((cg)->prolog.noteCount && \
1047 (cg)->prolog.currentLine != (cg)->firstLine) { \
1048 if (diff_ > SN_DELTA_MASK) \
1049 cnt += JS_HOWMANY(diff_ - SN_DELTA_MASK, SN_XDELTA_MASK); \
1050 cnt += 2 + (((cg)->firstLine > SN_3BYTE_OFFSET_MASK) << 1); \
1051 } else if (diff_ > 0) { \
1052 if (cg->main.noteCount) { \
1053 jssrcnote *sn_ = (cg)->main.notes; \
1054 diff_ -= SN_IS_XDELTA(sn_) \
1055 ? SN_XDELTA_MASK - (*sn_ & SN_XDELTA_MASK) \
1056 : SN_DELTA_MASK - (*sn_ & SN_DELTA_MASK); \
1059 cnt += JS_HOWMANY(diff_, SN_XDELTA_MASK); \
1064 js_FinishTakingSrcNotes(JSContext *cx, JSCodeGenerator *cg, jssrcnote *notes);
1067 js_FinishTakingTryNotes(JSCodeGenerator *cg, JSTryNoteArray *array);
1071 #endif /* jsemit_h___ */