tclcompile.h

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/*
 * tclCompile.h --
 *
 * Copyright (c) 1996-1998 Sun Microsystems, Inc.
 * Copyright (c) 1998-2000 by Scriptics Corporation.
 * Copyright (c) 2001 by Kevin B. Kenny.  All rights reserved.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclCompile.h,v 1.33 2002/10/09 11:54:05 das Exp $
 */

#ifndef _TCLCOMPILATION
#define _TCLCOMPILATION 1

#ifndef _TCLINT
#include "tclInt.h"
#endif /* _TCLINT */

#ifdef BUILD_tcl
# undef TCL_STORAGE_CLASS
# define TCL_STORAGE_CLASS DLLEXPORT
#endif

/*
 *------------------------------------------------------------------------
 * Variables related to compilation. These are used in tclCompile.c,
 * tclExecute.c, tclBasic.c, and their clients.
 *------------------------------------------------------------------------
 */

#ifdef TCL_COMPILE_DEBUG
/*
 * Variable that controls whether compilation tracing is enabled and, if so,
 * what level of tracing is desired:
 *    0: no compilation tracing
 *    1: summarize compilation of top level cmds and proc bodies
 *    2: display all instructions of each ByteCode compiled
 * This variable is linked to the Tcl variable "tcl_traceCompile".
 */

extern int 		tclTraceCompile;
#endif

#ifdef TCL_COMPILE_DEBUG
/*
 * Variable that controls whether execution tracing is enabled and, if so,
 * what level of tracing is desired:
 *    0: no execution tracing
 *    1: trace invocations of Tcl procs only
 *    2: trace invocations of all (not compiled away) commands
 *    3: display each instruction executed
 * This variable is linked to the Tcl variable "tcl_traceExec".
 */

extern int 		tclTraceExec;
#endif

/*
 *------------------------------------------------------------------------
 * Data structures related to compilation.
 *------------------------------------------------------------------------
 */

/*
 * The structure used to implement Tcl "exceptions" (exceptional returns):
 * for example, those generated in loops by the break and continue commands,
 * and those generated by scripts and caught by the catch command. This
 * ExceptionRange structure describes a range of code (e.g., a loop body),
 * the kind of exceptions (e.g., a break or continue) that might occur, and
 * the PC offsets to jump to if a matching exception does occur. Exception
 * ranges can nest so this structure includes a nesting level that is used
 * at runtime to find the closest exception range surrounding a PC. For
 * example, when a break command is executed, the ExceptionRange structure
 * for the most deeply nested loop, if any, is found and used. These
 * structures are also generated for the "next" subcommands of for loops
 * since a break there terminates the for command. This means a for command
 * actually generates two LoopInfo structures.
 */

typedef enum {
    LOOP_EXCEPTION_RANGE,	/* Exception's range is part of a loop.
				 * Break and continue "exceptions" cause
				 * jumps to appropriate PC offsets. */
    CATCH_EXCEPTION_RANGE	/* Exception's range is controlled by a
				 * catch command. Errors in the range cause
				 * a jump to a catch PC offset. */
} ExceptionRangeType;

typedef struct ExceptionRange {
    ExceptionRangeType type;	/* The kind of ExceptionRange. */
    int nestingLevel;		/* Static depth of the exception range.
				 * Used to find the most deeply-nested
				 * range surrounding a PC at runtime. */
    int codeOffset;		/* Offset of the first instruction byte of
				 * the code range. */
    int numCodeBytes;		/* Number of bytes in the code range. */
    int breakOffset;		/* If LOOP_EXCEPTION_RANGE, the target PC
				 * offset for a break command in the range. */
    int continueOffset;		/* If LOOP_EXCEPTION_RANGE and not -1, the
				 * target PC offset for a continue command in
				 * the code range. Otherwise, ignore this range
				 * when processing a continue command. */
    int catchOffset;		/* If a CATCH_EXCEPTION_RANGE, the target PC
				 * offset for any "exception" in range. */
} ExceptionRange;

/*
 * Structure used to map between instruction pc and source locations. It
 * defines for each compiled Tcl command its code's starting offset and 
 * its source's starting offset and length. Note that the code offset
 * increases monotonically: that is, the table is sorted in code offset
 * order. The source offset is not monotonic.
 */

typedef struct CmdLocation {
    int codeOffset;		/* Offset of first byte of command code. */
    int numCodeBytes;		/* Number of bytes for command's code. */
    int srcOffset;		/* Offset of first char of the command. */
    int numSrcBytes;		/* Number of command source chars. */
} CmdLocation;

/*
 * CompileProcs need the ability to record information during compilation
 * that can be used by bytecode instructions during execution. The AuxData
 * structure provides this "auxiliary data" mechanism. An arbitrary number
 * of these structures can be stored in the ByteCode record (during
 * compilation they are stored in a CompileEnv structure). Each AuxData
 * record holds one word of client-specified data (often a pointer) and is
 * given an index that instructions can later use to look up the structure
 * and its data.
 *
 * The following definitions declare the types of procedures that are called
 * to duplicate or free this auxiliary data when the containing ByteCode
 * objects are duplicated and freed. Pointers to these procedures are kept
 * in the AuxData structure.
 */

typedef ClientData (AuxDataDupProc)  _ANSI_ARGS_((ClientData clientData));
typedef void       (AuxDataFreeProc) _ANSI_ARGS_((ClientData clientData));

/*
 * We define a separate AuxDataType struct to hold type-related information
 * for the AuxData structure. This separation makes it possible for clients
 * outside of the TCL core to manipulate (in a limited fashion!) AuxData;
 * for example, it makes it possible to pickle and unpickle AuxData structs.
 */

typedef struct AuxDataType {
    char *name;					/* the name of the type. Types can be
                                 * registered and found by name */
    AuxDataDupProc *dupProc;	/* Callback procedure to invoke when the
                                 * aux data is duplicated (e.g., when the
                                 * ByteCode structure containing the aux
                                 * data is duplicated). NULL means just
                                 * copy the source clientData bits; no
                                 * proc need be called. */
    AuxDataFreeProc *freeProc;	/* Callback procedure to invoke when the
                                 * aux data is freed. NULL means no
                                 * proc need be called. */
} AuxDataType;

/*
 * The definition of the AuxData structure that holds information created
 * during compilation by CompileProcs and used by instructions during
 * execution.
 */

typedef struct AuxData {
    AuxDataType *type;		/* pointer to the AuxData type associated with
                             * this ClientData. */
    ClientData clientData;	/* The compilation data itself. */
} AuxData;

/*
 * Structure defining the compilation environment. After compilation, fields
 * describing bytecode instructions are copied out into the more compact
 * ByteCode structure defined below.
 */

#define COMPILEENV_INIT_CODE_BYTES    250
#define COMPILEENV_INIT_NUM_OBJECTS    60
#define COMPILEENV_INIT_EXCEPT_RANGES   5
#define COMPILEENV_INIT_CMD_MAP_SIZE   40
#define COMPILEENV_INIT_AUX_DATA_SIZE   5

typedef struct CompileEnv {
    Interp *iPtr;		/* Interpreter containing the code being
				 * compiled. Commands and their compile
				 * procs are specific to an interpreter so
				 * the code emitted will depend on the
				 * interpreter. */
    char *source;		/* The source string being compiled by
				 * SetByteCodeFromAny. This pointer is not
				 * owned by the CompileEnv and must not be
				 * freed or changed by it. */
    int numSrcBytes;		/* Number of bytes in source. */
    Proc *procPtr;		/* If a procedure is being compiled, a
				 * pointer to its Proc structure; otherwise
				 * NULL. Used to compile local variables.
				 * Set from information provided by
				 * ObjInterpProc in tclProc.c. */
    int numCommands;		/* Number of commands compiled. */
    int exceptDepth;		/* Current exception range nesting level;
				 * -1 if not in any range currently. */
    int maxExceptDepth;		/* Max nesting level of exception ranges;
				 * -1 if no ranges have been compiled. */
    int maxStackDepth;		/* Maximum number of stack elements needed
				 * to execute the code. Set by compilation
				 * procedures before returning. */
    int currStackDepth;         /* Current stack depth. */
    LiteralTable localLitTable;	/* Contains LiteralEntry's describing
				 * all Tcl objects referenced by this
				 * compiled code. Indexed by the string
				 * representations of the literals. Used to
				 * avoid creating duplicate objects. */
    unsigned char *codeStart;	/* Points to the first byte of the code. */
    unsigned char *codeNext;	/* Points to next code array byte to use. */
    unsigned char *codeEnd;	/* Points just after the last allocated
				 * code array byte. */
    int mallocedCodeArray;      /* Set 1 if code array was expanded 
				 * and codeStart points into the heap.*/
    LiteralEntry *literalArrayPtr;
    				/* Points to start of LiteralEntry array. */
    int literalArrayNext;	/* Index of next free object array entry. */
    int literalArrayEnd;	/* Index just after last obj array entry. */
    int mallocedLiteralArray;   /* 1 if object array was expanded and
                                 * objArray points into the heap, else 0. */
    ExceptionRange *exceptArrayPtr;
    				/* Points to start of the ExceptionRange
				 * array. */
    int exceptArrayNext;	/* Next free ExceptionRange array index.
				 * exceptArrayNext is the number of ranges
				 * and (exceptArrayNext-1) is the index of
				 * the current range's array entry. */
    int exceptArrayEnd;		/* Index after the last ExceptionRange
				 * array entry. */
    int mallocedExceptArray;	/* 1 if ExceptionRange array was expanded
				 * and exceptArrayPtr points in heap,
				 * else 0. */
    CmdLocation *cmdMapPtr;	/* Points to start of CmdLocation array.
				 * numCommands is the index of the next
				 * entry to use; (numCommands-1) is the
				 * entry index for the last command. */
    int cmdMapEnd;		/* Index after last CmdLocation entry. */
    int mallocedCmdMap;		/* 1 if command map array was expanded and
				 * cmdMapPtr points in the heap, else 0. */
    AuxData *auxDataArrayPtr;   /* Points to auxiliary data array start. */
    int auxDataArrayNext;	/* Next free compile aux data array index.
				 * auxDataArrayNext is the number of aux
				 * data items and (auxDataArrayNext-1) is
				 * index of current aux data array entry. */
    int auxDataArrayEnd;	/* Index after last aux data array entry. */
    int mallocedAuxDataArray;	/* 1 if aux data array was expanded and
				 * auxDataArrayPtr points in heap else 0. */
    unsigned char staticCodeSpace[COMPILEENV_INIT_CODE_BYTES];
                                /* Initial storage for code. */
    LiteralEntry staticLiteralSpace[COMPILEENV_INIT_NUM_OBJECTS];
                                /* Initial storage of LiteralEntry array. */
    ExceptionRange staticExceptArraySpace[COMPILEENV_INIT_EXCEPT_RANGES];
                                /* Initial ExceptionRange array storage. */
    CmdLocation staticCmdMapSpace[COMPILEENV_INIT_CMD_MAP_SIZE];
                                /* Initial storage for cmd location map. */
    AuxData staticAuxDataArraySpace[COMPILEENV_INIT_AUX_DATA_SIZE];
                                /* Initial storage for aux data array. */
} CompileEnv;

/*
 * The structure defining the bytecode instructions resulting from compiling
 * a Tcl script. Note that this structure is variable length: a single heap
 * object is allocated to hold the ByteCode structure immediately followed
 * by the code bytes, the literal object array, the ExceptionRange array,
 * the CmdLocation map, and the compilation AuxData array.
 */

/*
 * A PRECOMPILED bytecode struct is one that was generated from a compiled
 * image rather than implicitly compiled from source
 */
#define TCL_BYTECODE_PRECOMPILED		0x0001

typedef struct ByteCode {
    TclHandle interpHandle;	/* Handle for interpreter containing the
				 * compiled code.  Commands and their compile
				 * procs are specific to an interpreter so the
				 * code emitted will depend on the
				 * interpreter. */
    int compileEpoch;		/* Value of iPtr->compileEpoch when this
				 * ByteCode was compiled. Used to invalidate
				 * code when, e.g., commands with compile
				 * procs are redefined. */
    Namespace *nsPtr;		/* Namespace context in which this code
				 * was compiled. If the code is executed
				 * if a different namespace, it must be
				 * recompiled. */
    int nsEpoch;		/* Value of nsPtr->resolverEpoch when this
				 * ByteCode was compiled. Used to invalidate
				 * code when new namespace resolution rules
				 * are put into effect. */
    int refCount;		/* Reference count: set 1 when created
				 * plus 1 for each execution of the code
				 * currently active. This structure can be
				 * freed when refCount becomes zero. */
    unsigned int flags;		/* flags describing state for the codebyte.
                                 * this variable holds ORed values from the
                                 * TCL_BYTECODE_ masks defined above */
    char *source;		/* The source string from which this
				 * ByteCode was compiled. Note that this
				 * pointer is not owned by the ByteCode and
				 * must not be freed or modified by it. */
    Proc *procPtr;		/* If the ByteCode was compiled from a
				 * procedure body, this is a pointer to its
				 * Proc structure; otherwise NULL. This
				 * pointer is also not owned by the ByteCode
				 * and must not be freed by it. */
    size_t structureSize;	/* Number of bytes in the ByteCode structure
				 * itself. Does not include heap space for
				 * literal Tcl objects or storage referenced
				 * by AuxData entries. */
    int numCommands;		/* Number of commands compiled. */
    int numSrcBytes;		/* Number of source bytes compiled. */
    int numCodeBytes;		/* Number of code bytes. */
    int numLitObjects;		/* Number of objects in literal array. */
    int numExceptRanges;	/* Number of ExceptionRange array elems. */
    int numAuxDataItems;	/* Number of AuxData items. */
    int numCmdLocBytes;		/* Number of bytes needed for encoded
				 * command location information. */
    int maxExceptDepth;		/* Maximum nesting level of ExceptionRanges;
				 * -1 if no ranges were compiled. */
    int maxStackDepth;		/* Maximum number of stack elements needed
				 * to execute the code. */
    unsigned char *codeStart;	/* Points to the first byte of the code.
				 * This is just after the final ByteCode
				 * member cmdMapPtr. */
    Tcl_Obj **objArrayPtr;	/* Points to the start of the literal
				 * object array. This is just after the
				 * last code byte. */
    ExceptionRange *exceptArrayPtr;
    				/* Points to the start of the ExceptionRange
				 * array. This is just after the last
				 * object in the object array. */
    AuxData *auxDataArrayPtr;   /* Points to the start of the auxiliary data
				 * array. This is just after the last entry
				 * in the ExceptionRange array. */
    unsigned char *codeDeltaStart;
				/* Points to the first of a sequence of
				 * bytes that encode the change in the
				 * starting offset of each command's code.