jsemit.h

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** 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
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 * http://www.mozilla.org/MPL/
 *
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 * 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.
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 *
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 * 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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#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 non-loop STMT_* enumerators, do so before STMT_DO_LOOP or
 * you will break the STMT_IS_LOOP macro, just below this enum.
 */
typedef enum JSStmtType {
    STMT_BLOCK        = 0,      /* compound statement: { s1[;... sN] } */
    STMT_LABEL        = 1,      /* labeled statement:  L: s */
    STMT_IF           = 2,      /* if (then) statement */
    STMT_ELSE         = 3,      /* else clause of if statement */
    STMT_SWITCH       = 4,      /* switch statement */
    STMT_WITH         = 5,      /* with statement */
    STMT_TRY          = 6,      /* try statement */
    STMT_CATCH        = 7,      /* catch block */
    STMT_FINALLY      = 8,      /* finally statement */
    STMT_SUBROUTINE   = 9,      /* gosub-target subroutine body */
    STMT_DO_LOOP      = 10,     /* do/while loop statement */
    STMT_FOR_LOOP     = 11,     /* for loop statement */
    STMT_FOR_IN_LOOP  = 12,     /* for/in loop statement */
    STMT_WHILE_LOOP   = 13      /* while loop statement */
} JSStmtType;

#define STMT_IS_LOOP(stmt)      ((stmt)->type >= STMT_DO_LOOP)

typedef struct JSStmtInfo JSStmtInfo;

struct JSStmtInfo {
    JSStmtType      type;           /* statement type */
    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 */
    ptrdiff_t       gosub;          /* offset of last GOSUB for this finally */
    ptrdiff_t       catchJump;      /* offset of last end-of-catch jump */
    JSAtom          *label;         /* name of LABEL or CATCH var */
    JSStmtInfo      *down;          /* info for enclosing statement */
};

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

struct JSTreeContext {              /* tree context for semantic checks */
    uint32          flags;          /* statement state flags, see below */
    uint32          tryCount;       /* total count of try statements parsed */
    JSStmtInfo      *topStmt;       /* top of statement info stack */
    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_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_FLAGS          0xE0 /* flags to propagate from FunctionBody */

#define TREE_CONTEXT_INIT(tc)                                                 \
    ((tc)->flags = 0, (tc)->tryCount = 0, (tc)->topStmt = NULL,               \
     ATOM_LIST_INIT(&(tc)->decls), (tc)->nodeList = 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_SET_BPDELTA(sd,bp)   ((sd)->target = BPDELTA_TO_JT(bp))
#define SD_GET_BPDELTA(sd)      (JS_ASSERT(!JT_HAS_TAG((sd)->target)),        \
                                 JT_TO_BPDELTA((sd)->target))
#define SD_TARGET_OFFSET(sd)    (JS_ASSERT(JT_HAS_TAG((sd)->target)),         \
                                 JT_CLR_TAG((sd)->target)->offset)

struct JSCodeGenerator {
    JSTreeContext   treeContext;    /* base state: statement info stack, etc. */
    JSArenaPool     *codePool;      /* pointer to thread code arena pool */
    JSArenaPool     *notePool;      /* pointer to thread srcnote arena pool */
    void            *codeMark;      /* low watermark in cg->codePool */
    void            *noteMark;      /* low watermark in cg->notePool */
    void            *tempMark;      /* low watermark in cx->tempPool */
    struct {
        jsbytecode  *base;          /* base of JS bytecode vector */
        jsbytecode  *limit;         /* one byte beyond end of bytecode */
        jsbytecode  *next;          /* pointer to next free bytecode */
        jssrcnote   *notes;         /* source notes, see below */
        uintN       noteCount;      /* number of source notes so far */
        uintN       noteMask;       /* growth increment for notes */
        ptrdiff_t   lastNoteOffset; /* code offset for last source note */
        uintN       currentLine;    /* line number for tree-based srcnote gen */
    } prolog, main, *current;
    const char      *filename;      /* null or weak link to source filename */
    uintN           firstLine;      /* first line, for js_NewScriptFromCG */
    JSPrincipals    *principals;    /* principals for constant folding eval */
    JSAtomList      atomList;       /* literals indexed for mapping */
    intN            stackDepth;     /* current stack depth in script frame */
    uintN           maxStackDepth;  /* maximum stack depth so far */
    JSTryNote       *tryBase;       /* first exception handling note */
    JSTryNote       *tryNext;       /* next available note */
    size_t          tryNoteSpace;   /* # of bytes allocated at tryBase */
    JSSpanDep       *spanDeps;      /* span dependent instruction records */
    JSJumpTarget    *jumpTargets;   /* AVL tree of jump target offsets */
    JSJumpTarget    *jtFreeList;    /* JT_LEFT-linked list of free structs */
    uintN           numSpanDeps;    /* number of span dependencies */
    uintN           numJumpTargets; /* number of jump targets */
    uintN           emitLevel;      /* js_EmitTree recursion level */
    JSAtomList      constList;      /* compile time constants */
    JSCodeGenerator *parent;        /* Enclosing function or global context */
};

#define CG_BASE(cg)             ((cg)->current->base)
#define CG_LIMIT(cg)            ((cg)->current->limit)
#define CG_NEXT(cg)             ((cg)->current->next)
#define CG_CODE(cg,offset)      (CG_BASE(cg) + (offset))
#define CG_OFFSET(cg)           PTRDIFF(CG_NEXT(cg), CG_BASE(cg), jsbytecode)

#define CG_NOTES(cg)            ((cg)->current->notes)
#define CG_NOTE_COUNT(cg)       ((cg)->current->noteCount)
#define CG_NOTE_MASK(cg)        ((cg)->current->noteMask)
#define CG_LAST_NOTE_OFFSET(cg) ((cg)->current->lastNoteOffset)
#define CG_CURRENT_LINE(cg)     ((cg)->current->currentLine)

#define CG_PROLOG_BASE(cg)      ((cg)->prolog.base)
#define CG_PROLOG_LIMIT(cg)     ((cg)->prolog.limit)
#define CG_PROLOG_NEXT(cg)      ((cg)->prolog.next)
#define CG_PROLOG_CODE(cg,poff) (CG_PROLOG_BASE(cg) + (poff))
#define CG_PROLOG_OFFSET(cg)    PTRDIFF(CG_PROLOG_NEXT(cg), CG_PROLOG_BASE(cg),\
                                        jsbytecode)

#define CG_SWITCH_TO_MAIN(cg)   ((cg)->current = &(cg)->main)
#define CG_SWITCH_TO_PROLOG(cg) ((cg)->current = &(cg)->prolog)

/*
 * Initialize cg to allocate bytecode space from codePool, source note space
 * from notePool, and all other arena-allocated temporaries from cx->tempPool.
 * Return true on success.  Report an error and return false if the initial
 * code segment can't be allocated.
 */
extern JS_FRIEND_API(JSBool)
js_InitCodeGenerator(JSContext *cx, JSCodeGenerator *cg,
                     JSArenaPool *codePool, JSArenaPool *notePool,
                     const char *filename, uintN lineno,
                     JSPrincipals *principals);

/*
 * Release cg->codePool, cg->notePool, and cx->tempPool to marks set by
 * js_InitCodeGenerator.  Note that cgs are magic: they own the arena pool
 * "tops-of-stack" space above their codeMark, noteMark, and tempMark points.
 * This means you cannot alloc from tempPool and save the pointer beyond the
 * next JS_FinishCodeGenerator.
 */
extern JS_FRIEND_API(void)
js_FinishCodeGenerator(JSContext *cx, JSCodeGenerator *cg);

/*
 * Emit one bytecode.
 */
extern ptrdiff_t
js_Emit1(JSContext *cx, JSCodeGenerator *cg, JSOp op);

/*
 * Emit two bytecodes, an opcode (op) with a byte of immediate operand (op1).
 */
extern ptrdiff_t
js_Emit2(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1);

/*
 * Emit three bytecodes, an opcode with two bytes of immediate operands.
 */
extern ptrdiff_t
js_Emit3(JSContext *cx, JSCodeGenerator *cg, JSOp op, jsbytecode op1,
         jsbytecode op2);

/*
 * Emit (1 + extra) bytecodes, for N bytes of op and its immediate operand.
 */
extern ptrdiff_t
js_EmitN(JSContext *cx, JSCodeGenerator *cg, JSOp op, size_t extra);

/*
 * Unsafe macro to call js_SetJumpOffset and return false if it does.
 */
#define CHECK_AND_SET_JUMP_OFFSET(cx,cg,pc,off)                               \
    JS_BEGIN_MACRO                                                            \