jsemit.h

java script test programing source code

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sw=4 et tw=78:
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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 * ***** END LICENSE BLOCK ***** */

#ifndef jsemit_h___
#define jsemit_h___
/*
 * JS bytecode generation.
 */

#include "jsstddef.h"
#include "jstypes.h"
#include "jsatom.h"
#include "jsopcode.h"
#include "jsprvtd.h"
#include "jspubtd.h"

JS_BEGIN_EXTERN_C

/*
 * NB: If you add enumerators for scope statements, add them between STMT_WITH
 * and STMT_CATCH, or you will break the STMT_TYPE_IS_SCOPE macro.  If you add
 * non-looping statement enumerators, add them before STMT_DO_LOOP or you will
 * break the STMT_TYPE_IS_LOOP macro.
 *
 * Also remember to keep the statementName array in jsemit.c in sync.
 */
typedef enum JSStmtType {
    STMT_LABEL,                 /* labeled statement:  L: s */
    STMT_IF,                    /* if (then) statement */
    STMT_ELSE,                  /* else clause of if statement */
    STMT_BODY,                  /* synthetic body of function with
                                   destructuring formal parameters */
    STMT_BLOCK,                 /* compound statement: { s1[;... sN] } */
    STMT_SWITCH,                /* switch statement */
    STMT_WITH,                  /* with statement */
    STMT_CATCH,                 /* catch block */
    STMT_TRY,                   /* try block */
    STMT_FINALLY,               /* finally block */
    STMT_SUBROUTINE,            /* gosub-target subroutine body */
    STMT_DO_LOOP,               /* do/while loop statement */
    STMT_FOR_LOOP,              /* for loop statement */
    STMT_FOR_IN_LOOP,           /* for/in loop statement */
    STMT_WHILE_LOOP             /* while loop statement */
} JSStmtType;

#define STMT_TYPE_IN_RANGE(t,b,e) ((uint)((t) - (b)) <= (uintN)((e) - (b)))

/*
 * A comment on the encoding of the JSStmtType enum and type-testing macros:
 *
 * STMT_TYPE_MAYBE_SCOPE tells whether a statement type is always, or may
 * become, a lexical scope.  It therefore includes block and switch (the two
 * low-numbered "maybe" scope types) and excludes with (with has dynamic scope
 * pending the "reformed with" in ES4/JS2).  It includes all try-catch-finally
 * types, which are high-numbered maybe-scope types.
 *
 * STMT_TYPE_LINKS_SCOPE tells whether a JSStmtInfo of the given type eagerly
 * links to other scoping statement info records.  It excludes the two early
 * "maybe" types, block and switch, as well as the try and both finally types,
 * since try and the other trailing maybe-scope types don't need block scope
 * unless they contain let declarations.
 *
 * We treat with as a static scope because it prevents lexical binding from
 * continuing further up the static scope chain.  With the "reformed with"
 * proposal for JS2, we'll be able to model it statically, too.
 */
#define STMT_TYPE_MAYBE_SCOPE(type)                                           \
    (type != STMT_WITH &&                                                     \
     STMT_TYPE_IN_RANGE(type, STMT_BLOCK, STMT_SUBROUTINE))

#define STMT_TYPE_LINKS_SCOPE(type)                                           \
    STMT_TYPE_IN_RANGE(type, STMT_WITH, STMT_CATCH)

#define STMT_TYPE_IS_TRYING(type)                                             \
    STMT_TYPE_IN_RANGE(type, STMT_TRY, STMT_SUBROUTINE)

#define STMT_TYPE_IS_LOOP(type) ((type) >= STMT_DO_LOOP)

#define STMT_MAYBE_SCOPE(stmt)  STMT_TYPE_MAYBE_SCOPE((stmt)->type)
#define STMT_LINKS_SCOPE(stmt)  (STMT_TYPE_LINKS_SCOPE((stmt)->type) ||       \
                                 ((stmt)->flags & SIF_SCOPE))
#define STMT_IS_TRYING(stmt)    STMT_TYPE_IS_TRYING((stmt)->type)
#define STMT_IS_LOOP(stmt)      STMT_TYPE_IS_LOOP((stmt)->type)

typedef struct JSStmtInfo JSStmtInfo;

struct JSStmtInfo {
    uint16          type;           /* statement type */
    uint16          flags;          /* flags, see below */
    ptrdiff_t       update;         /* loop update offset (top if none) */
    ptrdiff_t       breaks;         /* offset of last break in loop */
    ptrdiff_t       continues;      /* offset of last continue in loop */
    JSAtom          *atom;          /* name of LABEL, or block scope object */
    JSStmtInfo      *down;          /* info for enclosing statement */
    JSStmtInfo      *downScope;     /* next enclosing lexical scope */
};

#define SIF_SCOPE        0x0001     /* statement has its own lexical scope */
#define SIF_BODY_BLOCK   0x0002     /* STMT_BLOCK type is a function body */

/*
 * To reuse space in JSStmtInfo, rename breaks and continues for use during
 * try/catch/finally code generation and backpatching.  To match most common
 * use cases, the macro argument is a struct, not a struct pointer.  Only a
 * loop, switch, or label statement info record can have breaks and continues,
 * and only a for loop has an update backpatch chain, so it's safe to overlay
 * these for the "trying" JSStmtTypes.
 */
#define CATCHNOTE(stmt)  ((stmt).update)
#define GOSUBS(stmt)     ((stmt).breaks)
#define GUARDJUMP(stmt)  ((stmt).continues)

#define AT_TOP_LEVEL(tc)                                                      \
    (!(tc)->topStmt || ((tc)->topStmt->flags & SIF_BODY_BLOCK))

#define SET_STATEMENT_TOP(stmt, top)                                          \
    ((stmt)->update = (top), (stmt)->breaks = (stmt)->continues = (-1))

struct JSTreeContext {              /* tree context for semantic checks */
    uint16          flags;          /* statement state flags, see below */
    uint16          numGlobalVars;  /* max. no. of global variables/regexps */
    uint32          tryCount;       /* total count of try statements parsed */
    uint32          globalUses;     /* optimizable global var uses in total */
    uint32          loopyGlobalUses;/* optimizable global var uses in loops */
    JSStmtInfo      *topStmt;       /* top of statement info stack */
    JSStmtInfo      *topScopeStmt;  /* top lexical scope statement */
    JSObject        *blockChain;    /* compile time block scope chain (NB: one
                                       deeper than the topScopeStmt/downScope
                                       chain when in head of let block/expr) */
    JSParseNode     *blockNode;     /* parse node for a lexical scope.
                                       XXX combine with blockChain? */
    JSAtomList      decls;          /* function, const, and var declarations */
    JSParseNode     *nodeList;      /* list of recyclable parse-node structs */
};

#define TCF_COMPILING          0x01 /* generating bytecode; this tc is a cg */
#define TCF_IN_FUNCTION        0x02 /* parsing inside function body */
#define TCF_RETURN_EXPR        0x04 /* function has 'return expr;' */
#define TCF_RETURN_VOID        0x08 /* function has 'return;' */
#define TCF_RETURN_FLAGS       0x0C /* propagate these out of blocks */
#define TCF_IN_FOR_INIT        0x10 /* parsing init expr of for; exclude 'in' */
#define TCF_FUN_CLOSURE_VS_VAR 0x20 /* function and var with same name */
#define TCF_FUN_USES_NONLOCALS 0x40 /* function refers to non-local names */
#define TCF_FUN_HEAVYWEIGHT    0x80 /* function needs Call object per call */
#define TCF_FUN_IS_GENERATOR  0x100 /* parsed yield statement in function */
#define TCF_FUN_FLAGS         0x1E0 /* flags to propagate from FunctionBody */
#define TCF_HAS_DEFXMLNS      0x200 /* default xml namespace = ...; parsed */
#define TCF_HAS_FUNCTION_STMT 0x400 /* block contains a function statement */

#define TREE_CONTEXT_INIT(tc)                                                 \
    ((tc)->flags = (tc)->numGlobalVars = 0,                                   \
     (tc)->tryCount = (tc)->globalUses = (tc)->loopyGlobalUses = 0,           \
     (tc)->topStmt = (tc)->topScopeStmt = NULL,                               \
     (tc)->blockChain = NULL,                                                 \
     ATOM_LIST_INIT(&(tc)->decls),                                            \
     (tc)->nodeList = NULL, (tc)->blockNode = NULL)

#define TREE_CONTEXT_FINISH(tc)                                               \
    ((void)0)

/*
 * Span-dependent instructions are jumps whose span (from the jump bytecode to
 * the jump target) may require 2 or 4 bytes of immediate operand.
 */
typedef struct JSSpanDep    JSSpanDep;
typedef struct JSJumpTarget JSJumpTarget;

struct JSSpanDep {
    ptrdiff_t       top;        /* offset of first bytecode in an opcode */
    ptrdiff_t       offset;     /* offset - 1 within opcode of jump operand */
    ptrdiff_t       before;     /* original offset - 1 of jump operand */
    JSJumpTarget    *target;    /* tagged target pointer or backpatch delta */
};

/*
 * Jump targets are stored in an AVL tree, for O(log(n)) lookup with targets
 * sorted by offset from left to right, so that targets after a span-dependent
 * instruction whose jump offset operand must be extended can be found quickly
 * and adjusted upward (toward higher offsets).
 */
struct JSJumpTarget {
    ptrdiff_t       offset;     /* offset of span-dependent jump target */
    int             balance;    /* AVL tree balance number */
    JSJumpTarget    *kids[2];   /* left and right AVL tree child pointers */
};

#define JT_LEFT                 0
#define JT_RIGHT                1
#define JT_OTHER_DIR(dir)       (1 - (dir))
#define JT_IMBALANCE(dir)       (((dir) << 1) - 1)
#define JT_DIR(imbalance)       (((imbalance) + 1) >> 1)

/*
 * Backpatch deltas are encoded in JSSpanDep.target if JT_TAG_BIT is clear,
 * so we can maintain backpatch chains when using span dependency records to
 * hold jump offsets that overflow 16 bits.
 */
#define JT_TAG_BIT              ((jsword) 1)
#define JT_UNTAG_SHIFT          1
#define JT_SET_TAG(jt)          ((JSJumpTarget *)((jsword)(jt) | JT_TAG_BIT))
#define JT_CLR_TAG(jt)          ((JSJumpTarget *)((jsword)(jt) & ~JT_TAG_BIT))
#define JT_HAS_TAG(jt)          ((jsword)(jt) & JT_TAG_BIT)

#define BITS_PER_PTRDIFF        (sizeof(ptrdiff_t) * JS_BITS_PER_BYTE)
#define BITS_PER_BPDELTA        (BITS_PER_PTRDIFF - 1 - JT_UNTAG_SHIFT)
#define BPDELTA_MAX             (((ptrdiff_t)1 << BITS_PER_BPDELTA) - 1)
#define BPDELTA_TO_JT(bp)       ((JSJumpTarget *)((bp) << JT_UNTAG_SHIFT))
#define JT_TO_BPDELTA(jt)       ((ptrdiff_t)((jsword)(jt) >> JT_UNTAG_SHIFT))

#define SD_SET_TARGET(sd,jt)    ((sd)->target = JT_SET_TAG(jt))
#define SD_GET_TARGET(sd)       (JS_ASSERT(JT_HAS_TAG((sd)->target)),         \