path: root/generic/tclCompile.h

/*
 * 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 1.61 2005/11/30 14:59:40 dkf Exp $
 */

#ifndef _TCLCOMPILATION
#define _TCLCOMPILATION 1

#include "tclInt.h"

/*
 *------------------------------------------------------------------------
 * 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".
 */

MODULE_SCOPE int 	tclTraceCompile;

/*
 * 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".
 */

MODULE_SCOPE 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)  (ClientData clientData);
typedef void       (AuxDataFreeProc) (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

/*
 * When a bytecode is compiled, interp or namespace resolvers have not been
 * applied yet: this is indicated by the TCL_BYTECODE_RESOLVE_VARS flag.
 */

#define TCL_BYTECODE_RESOLVE_VARS		0x0002

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. If -127 <=
				 * delta <= 127, it is encoded as 1 byte,
				 * otherwise 0xFF (128) appears and the delta
				 * is encoded by the next 4 bytes. Code deltas
				 * are always positive. This sequence is just
				 * after the last entry in the AuxData
				 * array. */
    unsigned char *codeLengthStart;
				/* Points to the first of a sequence of bytes
				 * that encode the length of each command's
				 * code. The encoding is the same as for code
				 * deltas. Code lengths are always positive.
				 * This sequence is just after the last entry
				 * in the code delta sequence. */
    unsigned char *srcDeltaStart;
				/* Points to the first of a sequence of bytes
				 * that encode the change in the starting
				 * offset of each command's source. The
				 * encoding is the same as for code deltas.
				 * Source deltas can be negative. This
				 * sequence is just after the last byte in the
				 * code length sequence. */
    unsigned char *srcLengthStart;
				/* Points to the first of a sequence of bytes
				 * that encode the length of each command's
				 * source. The encoding is the same as for
				 * code deltas. Source lengths are always
				 * positive. This sequence is just after the
				 * last byte in the source delta sequence. */
#ifdef TCL_COMPILE_STATS
    Tcl_Time createTime;	/* Absolute time when the ByteCode was
				 * created. */
#endif /* TCL_COMPILE_STATS */
} ByteCode;

/*
 * Opcodes for the Tcl bytecode instructions. These must correspond to the
 * entries in the table of instruction descriptions, tclInstructionTable, in
 * tclCompile.c. Also, the order and number of the expression opcodes (e.g.,
 * INST_LOR) must match the entries in the array operatorStrings in
 * tclExecute.c.
 */

/* Opcodes 0 to 9 */
#define INST_DONE			0
#define INST_PUSH1			1
#define INST_PUSH4			2
#define INST_POP			3
#define INST_DUP			4
#define INST_CONCAT1			5
#define INST_INVOKE_STK1		6
#define INST_INVOKE_STK4		7
#define INST_EVAL_STK			8
#define INST_EXPR_STK			9

/* Opcodes 10 to 23 */
#define INST_LOAD_SCALAR1		10
#define INST_LOAD_SCALAR4		11
#define INST_LOAD_SCALAR_STK		12
#define INST_LOAD_ARRAY1		13
#define INST_LOAD_ARRAY4		14
#define INST_LOAD_ARRAY_STK		15
#define INST_LOAD_STK			16
#define INST_STORE_SCALAR1		17
#define INST_STORE_SCALAR4		18
#define INST_STORE_SCALAR_STK		19
#define INST_STORE_ARRAY1		20
#define INST_STORE_ARRAY4		21
#define INST_STORE_ARRAY_STK		22
#define INST_STORE_STK			23

/* Opcodes 24 to 33 */
#define INST_INCR_SCALAR1		24
#define INST_INCR_SCALAR_STK		25
#define INST_INCR_ARRAY1		26
#define INST_INCR_ARRAY_STK		27
#define INST_INCR_STK			28
#define INST_INCR_SCALAR1_IMM		29
#define INST_INCR_SCALAR_STK_IMM	30
#define INST_INCR_ARRAY1_IMM		31
#define INST_INCR_ARRAY_STK_IMM		32
#define INST_INCR_STK_IMM		33

/* Opcodes 34 to 39 */
#define INST_JUMP1			34
#define INST_JUMP4			35
#define INST_JUMP_TRUE1			36
#define INST_JUMP_TRUE4			37
#define INST_JUMP_FALSE1		38
#define INST_JUMP_FALSE4		39

/* Opcodes 40 to 64 */
#define INST_LOR			40
#define INST_LAND			41
#define INST_BITOR			42
#define INST_BITXOR			43
#define INST_BITAND			44
#define INST_EQ				45
#define INST_NEQ			46
#define INST_LT				47
#define INST_GT				48
#define INST_LE				49
#define INST_GE				50
#define INST_LSHIFT			51
#define INST_RSHIFT			52
#define INST_ADD			53
#define INST_SUB			54
#define INST_MULT			55
#define INST_DIV			56
#define INST_MOD			57
#define INST_UPLUS			58
#define INST_UMINUS			59
#define INST_BITNOT			60
#define INST_LNOT			61
#define INST_CALL_BUILTIN_FUNC1		62
#define INST_CALL_FUNC1			63
#define INST_TRY_CVT_TO_NUMERIC		64

/* Opcodes 65 to 66 */
#define INST_BREAK			65
#define INST_CONTINUE			66

/* Opcodes 67 to 68 */
#define INST_FOREACH_START4		67
#define INST_FOREACH_STEP4		68

/* Opcodes 69 to 72 */
#define INST_BEGIN_CATCH4		69
#define INST_END_CATCH			70
#define INST_PUSH_RESULT		71
#define INST_PUSH_RETURN_CODE		72

/* Opcodes 73 to 78 */
#define INST_STR_EQ			73
#define INST_STR_NEQ			74
#define INST_STR_CMP			75
#define INST_STR_LEN			76
#define INST_STR_INDEX			77
#define INST_STR_MATCH			78

/* Opcodes 78 to 81 */
#define INST_LIST			79
#define INST_LIST_INDEX			80
#define INST_LIST_LENGTH		81

/* Opcodes 82 to 87 */
#define INST_APPEND_SCALAR1		82
#define INST_APPEND_SCALAR4		83
#define INST_APPEND_ARRAY1		84
#define INST_APPEND_ARRAY4		85
#define INST_APPEND_ARRAY_STK		86
#define INST_APPEND_STK			87

/* Opcodes 88 to 93 */
#define INST_LAPPEND_SCALAR1		88
#define INST_LAPPEND_SCALAR4		89
#define INST_LAPPEND_ARRAY1		90
#define INST_LAPPEND_ARRAY4		91
#define INST_LAPPEND_ARRAY_STK		92
#define INST_LAPPEND_STK		93

/* TIP #22 - LINDEX operator with flat arg list */

#define INST_LIST_INDEX_MULTI		94

/*
 * TIP #33 - 'lset' command. Code gen also required a Forth-like
 *	     OVER operation.
 */

#define INST_OVER			95
#define INST_LSET_LIST			96
#define INST_LSET_FLAT			97

/* TIP#90 - 'return' command. */

#define INST_RETURN_IMM			98

/* TIP#123 - exponentiation operator. */

#define INST_EXPON			99

/* TIP #157 - {expand}... language syntax support. */

#define INST_EXPAND_START		100
#define INST_EXPAND_STKTOP		101
#define INST_INVOKE_EXPANDED		102

/*
 * TIP #57 - 'lassign' command. Code generation requires immediate
 *	     LINDEX and LRANGE operators.
 */

#define INST_LIST_INDEX_IMM		103
#define INST_LIST_RANGE_IMM		104

#define INST_START_CMD			105

#define INST_LIST_IN			106
#define INST_LIST_NOT_IN		107

#define INST_PUSH_RETURN_OPTIONS	108
#define INST_RETURN_STK			109

/*
 * Dictionary (TIP#111) related commands.
 */

#define INST_DICT_GET			110
#define INST_DICT_SET			111
#define INST_DICT_UNSET			112
#define INST_DICT_INCR_IMM		113
#define INST_DICT_APPEND		114
#define INST_DICT_LAPPEND		115
#define INST_DICT_FIRST			116
#define INST_DICT_NEXT			117
#define INST_DICT_DONE			118
#define INST_DICT_UPDATE_START		119
#define INST_DICT_UPDATE_END		120

/*
 * Instruction to support jumps defined by tables (instead of the classic
 * [switch] technique of chained comparisons).
 */

#define INST_JUMP_TABLE			121

/* The last opcode */
#define LAST_INST_OPCODE		121

/*
 * Table describing the Tcl bytecode instructions: their name (for displaying
 * code), total number of code bytes required (including operand bytes), and a
 * description of the type of each operand. These operand types include signed
 * and unsigned integers of length one and four bytes. The unsigned integers
 * are used for indexes or for, e.g., the count of objects to push in a "push"
 * instruction.
 */

#define MAX_INSTRUCTION_OPERANDS 2

typedef enum InstOperandType {
    OPERAND_NONE,
    OPERAND_INT1,		/* One byte signed integer. */
    OPERAND_INT4,		/* Four byte signed integer. */
    OPERAND_UINT1,		/* One byte unsigned integer. */
    OPERAND_UINT4,		/* Four byte unsigned integer. */
    OPERAND_IDX4,		/* Four byte signed index (actually an
				 * integer, but displayed differently.) */
    OPERAND_LVT1,		/* One byte unsigned index into the local
				 * variable table. */
    OPERAND_LVT4		/* Four byte unsigned index into the local
				 * variable table. */
} InstOperandType;

typedef struct InstructionDesc {
    char *name;			/* Name of instruction. */
    int numBytes;		/* Total number of bytes for instruction. */
    int stackEffect;		/* The worst-case balance stack effect of the
				 * instruction, used for stack requirements
				 * computations. The value INT_MIN signals
				 * that the instruction's worst case effect is
				 * (1-opnd1).
				 */
    int numOperands;		/* Number of operands. */
    InstOperandType opTypes[MAX_INSTRUCTION_OPERANDS];
				/* The type of each operand. */
} InstructionDesc;

MODULE_SCOPE InstructionDesc tclInstructionTable[];

/*
 * Compilation of some Tcl constructs such as if commands and the logical or
 * (||) and logical and (&&) operators in expressions requires the generation
 * of forward jumps. Since the PC target of these jumps isn't known when the
 * jumps are emitted, we record the offset of each jump in an array of
 * JumpFixup structures. There is one array for each sequence of jumps to one
 * target PC. When we learn the target PC, we update the jumps with the
 * correct distance. Also, if the distance is too great (> 127 bytes), we
 * replace the single-byte jump with a four byte jump instruction, move the
 * instructions after the jump down, and update the code offsets for any
 * commands between the jump and the target.
 */

typedef enum {
    TCL_UNCONDITIONAL_JUMP,
    TCL_TRUE_JUMP,
    TCL_FALSE_JUMP
} TclJumpType;

typedef struct JumpFixup {
    TclJumpType jumpType;	/* Indicates the kind of jump. */
    int codeOffset;		/* Offset of the first byte of the one-byte
				 * forward jump's code. */
    int cmdIndex;		/* Index of the first command after the one
				 * for which the jump was emitted. Used to
				 * update the code offsets for subsequent
				 * commands if the two-byte jump at jumpPc
				 * must be replaced with a five-byte one. */
    int exceptIndex;		/* Index of the first range entry in the
				 * ExceptionRange array after the current one.
				 * This field is used to adjust the code
				 * offsets in subsequent ExceptionRange
				 * records when a jump is grown from 2 bytes
				 * to 5 bytes. */
} JumpFixup;

#define JUMPFIXUP_INIT_ENTRIES	10

typedef struct JumpFixupArray {
    JumpFixup *fixup;		/* Points to start of jump fixup array. */
    int next;			/* Index of next free array entry. */
    int end;			/* Index of last usable entry in array. */
    int mallocedArray;		/* 1 if array was expanded and fixups points
				 * into the heap, else 0. */
    JumpFixup staticFixupSpace[JUMPFIXUP_INIT_ENTRIES];
				/* Initial storage for jump fixup array. */
} JumpFixupArray;

/*
 * The structure describing one variable list of a foreach command. Note that
 * only foreach commands inside procedure bodies are compiled inline so a
 * ForeachVarList structure always describes local variables. Furthermore,
 * only scalar variables are supported for inline-compiled foreach loops.
 */

typedef struct ForeachVarList {
    int numVars;		/* The number of variables in the list. */
    int varIndexes[1];		/* An array of the indexes ("slot numbers")
				 * for each variable in the procedure's array
				 * of local variables. Only scalar variables
				 * are supported. The actual size of this
				 * field will be large enough to numVars
				 * indexes. THIS MUST BE THE LAST FIELD IN THE
				 * STRUCTURE! */
} ForeachVarList;

/*
 * Structure used to hold information about a foreach command that is needed
 * during program execution. These structures are stored in CompileEnv and
 * ByteCode structures as auxiliary data.
 */

typedef struct ForeachInfo {
    int numLists;		/* The number of both the variable and value
				 * lists of the foreach command. */
    int firstValueTemp;		/* Index of the first temp var in a proc frame
				 * used to point to a value list. */
    int loopCtTemp;		/* Index of temp var in a proc frame holding
				 * the loop's iteration count. Used to
				 * determine next value list element to assign
				 * each loop var. */
    ForeachVarList *varLists[1];/* An array of pointers to ForeachVarList
				 * structures describing each var list. The
				 * actual size of this field will be large
				 * enough to numVars indexes. THIS MUST BE THE
				 * LAST FIELD IN THE STRUCTURE! */
} ForeachInfo;

MODULE_SCOPE AuxDataType	tclForeachInfoType;

/*
 * Structure used to hold information about a switch command that is needed
 * during program execution. These structures are stored in CompileEnv and
 * ByteCode structures as auxiliary data.
 */

typedef struct JumptableInfo {
    Tcl_HashTable hashTable;	/* Hash that maps strings to signed ints (PC
				 * offsets). */
} JumptableInfo;

MODULE_SCOPE AuxDataType	tclJumptableInfoType;

/*
 *----------------------------------------------------------------
 * Procedures exported by tclBasic.c to be used within the engine.
 *----------------------------------------------------------------
 */

MODULE_SCOPE int	TclEvalObjvInternal(Tcl_Interp *interp,
			    int objc, Tcl_Obj *CONST objv[],
			    CONST char *command, int length, int flags);

/*
 *----------------------------------------------------------------
 * Procedures exported by the engine to be used by tclBasic.c
 *----------------------------------------------------------------
 */

/*
 * Declaration moved to the internal stubs table
 *
MODULE_SCOPE int	TclCompEvalObj(Tcl_Interp *interp, Tcl_Obj *objPtr);
 */

/*
 *----------------------------------------------------------------
 * Procedures shared among Tcl bytecode compilation and execution
 * modules but not used outside:
 *----------------------------------------------------------------
 */

MODULE_SCOPE void	TclCleanupByteCode(ByteCode *codePtr);
MODULE_SCOPE void	TclCompileCmdWord(Tcl_Interp *interp,
			    Tcl_Token *tokenPtr, int count,
			    CompileEnv *envPtr);
MODULE_SCOPE int	TclCompileExpr(Tcl_Interp *interp, CONST char *script,
			    int numBytes, CompileEnv *envPtr);
MODULE_SCOPE void	TclCompileExprWords(Tcl_Interp *interp,
			    Tcl_Token *tokenPtr, int numWords,
			    CompileEnv *envPtr);
MODULE_SCOPE void	TclCompileScript(Tcl_Interp *interp,
			    CONST char *script, int numBytes,
			    CompileEnv *envPtr);
MODULE_SCOPE void	TclCompileTokens(Tcl_Interp *interp,
			    Tcl_Token *tokenPtr, int count,
			    CompileEnv *envPtr);
MODULE_SCOPE int	TclCreateAuxData(ClientData clientData,
			    AuxDataType *typePtr, CompileEnv *envPtr);
MODULE_SCOPE int	TclCreateExceptRange(ExceptionRangeType type,
			    CompileEnv *envPtr);
MODULE_SCOPE ExecEnv *	TclCreateExecEnv(Tcl_Interp *interp);
MODULE_SCOPE void	TclDeleteExecEnv(ExecEnv *eePtr);
MODULE_SCOPE void	TclDeleteLiteralTable(Tcl_Interp *interp,
			    LiteralTable *tablePtr);
MODULE_SCOPE void	TclEmitForwardJump(CompileEnv *envPtr,
			    TclJumpType jumpType, JumpFixup *jumpFixupPtr);
MODULE_SCOPE ExceptionRange * TclGetExceptionRangeForPc(unsigned char *pc,
			    int catchOnly, ByteCode* codePtr);
MODULE_SCOPE void	TclExpandJumpFixupArray(JumpFixupArray *fixupArrayPtr);
MODULE_SCOPE void	TclFinalizeAuxDataTypeTable(void);
MODULE_SCOPE int	TclFindCompiledLocal(CONST char *name, int nameChars,
			    int create, int flags, Proc *procPtr);
MODULE_SCOPE LiteralEntry * TclLookupLiteralEntry(Tcl_Interp *interp,
			    Tcl_Obj *objPtr);
MODULE_SCOPE int	TclFixupForwardJump(CompileEnv *envPtr,
			    JumpFixup *jumpFixupPtr, int jumpDist,
			    int distThreshold);
MODULE_SCOPE void	TclFreeCompileEnv(CompileEnv *envPtr);
MODULE_SCOPE void	TclFreeJumpFixupArray(JumpFixupArray *fixupArrayPtr);
MODULE_SCOPE void	TclInitAuxDataTypeTable(void);
MODULE_SCOPE void	TclInitByteCodeObj(Tcl_Obj *objPtr,
			    CompileEnv *envPtr);
MODULE_SCOPE void	TclInitCompilation(void);
MODULE_SCOPE void	TclInitCompileEnv(Tcl_Interp *interp,
			    CompileEnv *envPtr, char *string, int numBytes);
MODULE_SCOPE void	TclInitJumpFixupArray(JumpFixupArray *fixupArrayPtr);
MODULE_SCOPE void	TclInitLiteralTable(LiteralTable *tablePtr);
#ifdef TCL_COMPILE_STATS
MODULE_SCOPE char *	TclLiteralStats(LiteralTable *tablePtr);
MODULE_SCOPE int	TclLog2(int value);
#endif
#ifdef TCL_COMPILE_DEBUG
MODULE_SCOPE void	TclPrintByteCodeObj(Tcl_Interp *interp,
			    Tcl_Obj *objPtr);
#endif
MODULE_SCOPE int	TclPrintInstruction(ByteCode* codePtr,
			    unsigned char *pc);
MODULE_SCOPE void	TclPrintObject(FILE *outFile,
			    Tcl_Obj *objPtr, int maxChars);
MODULE_SCOPE void	TclPrintSource(FILE *outFile,
			    CONST char *string, int maxChars);
MODULE_SCOPE void	TclRegisterAuxDataType(AuxDataType *typePtr);
MODULE_SCOPE int	TclRegisterLiteral(CompileEnv *envPtr,
			    char *bytes, int length, int flags);
MODULE_SCOPE void	TclReleaseLiteral(Tcl_Interp *interp, Tcl_Obj *objPtr);
MODULE_SCOPE void	TclSetCmdNameObj(Tcl_Interp *interp, Tcl_Obj *objPtr,
			    Command *cmdPtr);
#ifdef TCL_COMPILE_DEBUG
MODULE_SCOPE void	TclVerifyGlobalLiteralTable(Interp *iPtr);
MODULE_SCOPE void	TclVerifyLocalLiteralTable(CompileEnv *envPtr);
#endif
MODULE_SCOPE int	TclCompileVariableCmd(Tcl_Interp *interp,
			    Tcl_Parse *parsePtr, CompileEnv *envPtr);
MODULE_SCOPE int	TclWordKnownAtCompileTime(Tcl_Token *tokenPtr,
			    Tcl_Obj *valuePtr);

/*
 *----------------------------------------------------------------
 * Macros and flag values used by Tcl bytecode compilation and execution
 * modules inside the Tcl core but not used outside.
 *----------------------------------------------------------------
 */

#define LITERAL_ON_HEAP    0x01
#define LITERAL_NS_SCOPE   0x02

/*
 * Form of TclRegisterLiteral with onHeap == 0. In that case, it is safe to
 * cast away CONSTness, and it is cleanest to do that here, all in one place.
 *
 * int TclRegisterNewLiteral(CompileEnv *envPtr, const char *bytes,
 *			     int length);
 */

#define TclRegisterNewLiteral(envPtr, bytes, length) \
	TclRegisterLiteral(envPtr, (char *)(bytes), length, /*flags*/ 0)

/*
 * Form of TclRegisterNSLiteral with onHeap == 0. In that case, it is safe to
 * cast away CONSTness, and it is cleanest to do that here, all in one place.
 *
 * int TclRegisterNewNSLiteral(CompileEnv *envPtr, const char *bytes,
 *			       int length);
 */

#define TclRegisterNewNSLiteral(envPtr, bytes, length) \
	TclRegisterLiteral(envPtr, (char *)(bytes), length, \
		/*flags*/ LITERAL_NS_SCOPE)

/*
 * Macro used to manually adjust the stack requirements; used in cases where
 * the stack effect cannot be computed from the opcode and its operands, but
 * is still known at compile time.
 *
 * void TclAdjustStackDepth(int delta, CompileEnv *envPtr);
 */

#define TclAdjustStackDepth(delta, envPtr) \
    if ((delta) < 0) {\
	if((envPtr)->maxStackDepth < (envPtr)->currStackDepth) {\
	    (envPtr)->maxStackDepth = (envPtr)->currStackDepth;\
	}\
    }\
    (envPtr)->currStackDepth += (delta)

/*
 * Macro used to update the stack requirements. It is called by the macros
 * TclEmitOpCode, TclEmitInst1 and TclEmitInst4.
 * Remark that the very last instruction of a bytecode always reduces the
 * stack level: INST_DONE or INST_POP, so that the maxStackdepth is always
 * updated.
 *
 * void TclUpdateStackReqs(unsigned char op, int i, CompileEnv *envPtr);
 */

#define TclUpdateStackReqs(op, i, envPtr) \
    {\
	int delta = tclInstructionTable[(op)].stackEffect;\
	if (delta) {\
	    if (delta == INT_MIN) {\
		delta = 1 - (i);\
	    }\
	    TclAdjustStackDepth(delta, envPtr);\
	}\
    }

/*
 * Macro to emit an opcode byte into a CompileEnv's code array. The ANSI C
 * "prototype" for this macro is:
 *
 * void TclEmitOpcode(unsigned char op, CompileEnv *envPtr);
 */

#define TclEmitOpcode(op, envPtr) \
    if ((envPtr)->codeNext == (envPtr)->codeEnd) \
	TclExpandCodeArray(envPtr); \
    *(envPtr)->codeNext++ = (unsigned char) (op);\
    TclUpdateStackReqs(op, 0, envPtr)

/*
 * Macros to emit an integer operand. The ANSI C "prototype" for these macros
 * are:
 *
 * void TclEmitInt1(int i, CompileEnv *envPtr);
 * void TclEmitInt4(int i, CompileEnv *envPtr);
 */

#define TclEmitInt1(i, envPtr) \
    if ((envPtr)->codeNext == (envPtr)->codeEnd) \
	TclExpandCodeArray(envPtr); \
    *(envPtr)->codeNext++ = (unsigned char) ((unsigned int) (i))

#define TclEmitInt4(i, envPtr) \
    if (((envPtr)->codeNext + 4) > (envPtr)->codeEnd) { \
	TclExpandCodeArray(envPtr); \
    } \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i) >> 24); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i) >> 16); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i) >>  8); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i)      )

/*
 * Macros to emit an instruction with signed or unsigned integer operands.
 * Four byte integers are stored in "big-endian" order with the high order
 * byte stored at the lowest address. The ANSI C "prototypes" for these macros
 * are:
 *
 * void TclEmitInstInt1(unsigned char op, int i, CompileEnv *envPtr);
 * void TclEmitInstInt4(unsigned char op, int i, CompileEnv *envPtr);
 */

#define TclEmitInstInt1(op, i, envPtr) \
    if (((envPtr)->codeNext + 2) > (envPtr)->codeEnd) { \
	TclExpandCodeArray(envPtr); \
    } \
    *(envPtr)->codeNext++ = (unsigned char) (op); \
    *(envPtr)->codeNext++ = (unsigned char) ((unsigned int) (i));\
    TclUpdateStackReqs(op, i, envPtr)

#define TclEmitInstInt4(op, i, envPtr) \
    if (((envPtr)->codeNext + 5) > (envPtr)->codeEnd) { \
	TclExpandCodeArray(envPtr); \
    } \
    *(envPtr)->codeNext++ = (unsigned char) (op); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i) >> 24); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i) >> 16); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i) >>  8); \
    *(envPtr)->codeNext++ = \
	(unsigned char) ((unsigned int) (i)      );\
    TclUpdateStackReqs(op, i, envPtr)

/*
 * Macro to push a Tcl object onto the Tcl evaluation stack. It emits the
 * object's one or four byte array index into the CompileEnv's code array.
 * These support, respectively, a maximum of 256 (2**8) and 2**32 objects in a
 * CompileEnv. The ANSI C "prototype" for this macro is:
 *
 * void	TclEmitPush(int objIndex, CompileEnv *envPtr);
 */

#define TclEmitPush(objIndex, envPtr) \
    {\
	register int objIndexCopy = (objIndex);\
	if (objIndexCopy <= 255) { \
	    TclEmitInstInt1(INST_PUSH1, objIndexCopy, (envPtr)); \
	} else { \
	    TclEmitInstInt4(INST_PUSH4, objIndexCopy, (envPtr)); \
	}\
    }

/*
 * Macros to update a (signed or unsigned) integer starting at a pointer. The
 * two variants depend on the number of bytes. The ANSI C "prototypes" for
 * these macros are:
 *
 * void TclStoreInt1AtPtr(int i, unsigned char *p);
 * void TclStoreInt4AtPtr(int i, unsigned char *p);
 */

#define TclStoreInt1AtPtr(i, p) \
    *(p)   = (unsigned char) ((unsigned int) (i))

#define TclStoreInt4AtPtr(i, p) \
    *(p)   = (unsigned char) ((unsigned int) (i) >> 24); \
    *(p+1) = (unsigned char) ((unsigned int) (i) >> 16); \
    *(p+2) = (unsigned char) ((unsigned int) (i) >>  8); \
    *(p+3) = (unsigned char) ((unsigned int) (i)      )

/*
 * Macros to update instructions at a particular pc with a new op code and a
 * (signed or unsigned) int operand. The ANSI C "prototypes" for these macros
 * are:
 *
 * void TclUpdateInstInt1AtPc(unsigned char op, int i, unsigned char *pc);
 * void TclUpdateInstInt4AtPc(unsigned char op, int i, unsigned char *pc);
 */

#define TclUpdateInstInt1AtPc(op, i, pc) \
    *(pc) = (unsigned char) (op); \
    TclStoreInt1AtPtr((i), ((pc)+1))

#define TclUpdateInstInt4AtPc(op, i, pc) \
    *(pc) = (unsigned char) (op); \
    TclStoreInt4AtPtr((i), ((pc)+1))

/*
 * Macro to fix up a forward jump to point to the current code-generation
 * position in the bytecode being created (the most common case). The ANSI C
 * "prototypes" for this macro is:
 *
 * int TclFixupForwardJumpToHere(CompileEnv *envPtr, JumpFixup *fixupPtr,
 *				 int threshold);
 */

#define TclFixupForwardJumpToHere(envPtr, fixupPtr, threshold) \
    TclFixupForwardJump((envPtr), (fixupPtr), \
	    (envPtr)->codeNext-(envPtr)->codeStart-(fixupPtr)->codeOffset, \
	    (threshold))

/*
 * Macros to get a signed integer (GET_INT{1,2}) or an unsigned int
 * (GET_UINT{1,2}) from a pointer. There are two variants for each return type
 * that depend on the number of bytes fetched. The ANSI C "prototypes" for
 * these macros are:
 *
 * int TclGetInt1AtPtr(unsigned char *p);
 * int TclGetInt4AtPtr(unsigned char *p);
 * unsigned int TclGetUInt1AtPtr(unsigned char *p);
 * unsigned int TclGetUInt4AtPtr(unsigned char *p);
 */

/*
 * The TclGetInt1AtPtr macro is tricky because we want to do sign extension on
 * the 1-byte value. Unfortunately the "char" type isn't signed on all
 * platforms so sign-extension doesn't always happen automatically. Sometimes
 * we can explicitly declare the pointer to be signed, but other times we have
 * to explicitly sign-extend the value in software.
 */

#ifndef __CHAR_UNSIGNED__
#   define TclGetInt1AtPtr(p) ((int) *((char *) p))
#else
#   ifdef HAVE_SIGNED_CHAR
#	define TclGetInt1AtPtr(p) ((int) *((signed char *) p))
#   else
#	define TclGetInt1AtPtr(p) (((int) *((char *) p)) \
		| ((*(p) & 0200) ? (-256) : 0))
#   endif
#endif

#define TclGetInt4AtPtr(p) (((int) TclGetInt1AtPtr(p) << 24) | \
					    (*((p)+1) << 16) | \
				  	    (*((p)+2) <<  8) | \
				  	    (*((p)+3)))

#define TclGetUInt1AtPtr(p) ((unsigned int) *(p))
#define TclGetUInt4AtPtr(p) ((unsigned int) (*(p)     << 24) | \
					    (*((p)+1) << 16) | \
					    (*((p)+2) <<  8) | \
					    (*((p)+3)))

/*
 * Macros used to compute the minimum and maximum of two integers. The ANSI C
 * "prototypes" for these macros are:
 *
 * int TclMin(int i, int j);
 * int TclMax(int i, int j);
 */

#define TclMin(i, j)   ((((int) i) < ((int) j))? (i) : (j))
#define TclMax(i, j)   ((((int) i) > ((int) j))? (i) : (j))

#endif /* _TCLCOMPILATION */

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */