Lua 5.3.4 里的 lopcodes.c
我们先来看看 lopcodes.h。
/*===========================================================================
We assume that instructions are unsigned numbers.
All instructions have an opcode in the first 6 bits.
Instructions can have the following fields:
'A' : 8 bits
'B' : 9 bits
'C' : 9 bits
'Ax' : 26 bits ('A', 'B', and 'C' together)
'Bx' : 18 bits ('B' and 'C' together)
'sBx' : signed Bx
A signed argument is represented in excess K; that is, the number
value is the unsigned value minus K. K is exactly the maximum value
for that argument (so that -max is represented by 0, and +max is
represented by 2*max), which is half the maximum for the corresponding
unsigned argument.
===========================================================================*/
enum OpMode {iABC, iABx, iAsBx, iAx}; /* basic instruction format */
/*
** size and position of opcode arguments.
*/
#define SIZE_C 9
#define SIZE_B 9
#define SIZE_Bx (SIZE_C + SIZE_B)
#define SIZE_A 8
#define SIZE_Ax (SIZE_C + SIZE_B + SIZE_A)
#define SIZE_OP 6
#define POS_OP 0
#define POS_A (POS_OP + SIZE_OP)
#define POS_C (POS_A + SIZE_A)
#define POS_B (POS_C + SIZE_C)
#define POS_Bx POS_C
#define POS_Ax POS_A
/*
** limits for opcode arguments.
** we use (signed) int to manipulate most arguments,
** so they must fit in LUAI_BITSINT-1 bits (-1 for sign)
*/
#if SIZE_Bx < LUAI_BITSINT-1
#define MAXARG_Bx ((1<<SIZE_Bx)-1)
#define MAXARG_sBx (MAXARG_Bx>>1) /* 'sBx' is signed */
#else
#define MAXARG_Bx MAX_INT
#define MAXARG_sBx MAX_INT
#endif
#if SIZE_Ax < LUAI_BITSINT-1
#define MAXARG_Ax ((1<<SIZE_Ax)-1)
#else
#define MAXARG_Ax MAX_INT
#endif
#define MAXARG_A ((1<<SIZE_A)-1)
#define MAXARG_B ((1<<SIZE_B)-1)
#define MAXARG_C ((1<<SIZE_C)-1)
/* creates a mask with 'n' 1 bits at position 'p' */
#define MASK1(n,p) ((~((~(Instruction)0)<<(n)))<<(p))
/* creates a mask with 'n' 0 bits at position 'p' */
#define MASK0(n,p) (~MASK1(n,p))
/*
** the following macros help to manipulate instructions
*/
#define GET_OPCODE(i) (cast(OpCode, ((i)>>POS_OP) & MASK1(SIZE_OP,0)))
#define SET_OPCODE(i,o) ((i) = (((i)&MASK0(SIZE_OP,POS_OP)) | \
((cast(Instruction, o)<<POS_OP)&MASK1(SIZE_OP,POS_OP))))
#define getarg(i,pos,size) (cast(int, ((i)>>pos) & MASK1(size,0)))
#define setarg(i,v,pos,size) ((i) = (((i)&MASK0(size,pos)) | \
((cast(Instruction, v)<<pos)&MASK1(size,pos))))
#define GETARG_A(i) getarg(i, POS_A, SIZE_A)
#define SETARG_A(i,v) setarg(i, v, POS_A, SIZE_A)
#define GETARG_B(i) getarg(i, POS_B, SIZE_B)
#define SETARG_B(i,v) setarg(i, v, POS_B, SIZE_B)
#define GETARG_C(i) getarg(i, POS_C, SIZE_C)
#define SETARG_C(i,v) setarg(i, v, POS_C, SIZE_C)
#define GETARG_Bx(i) getarg(i, POS_Bx, SIZE_Bx)
#define SETARG_Bx(i,v) setarg(i, v, POS_Bx, SIZE_Bx)
#define GETARG_Ax(i) getarg(i, POS_Ax, SIZE_Ax)
#define SETARG_Ax(i,v) setarg(i, v, POS_Ax, SIZE_Ax)
#define GETARG_sBx(i) (GETARG_Bx(i)-MAXARG_sBx)
#define SETARG_sBx(i,b) SETARG_Bx((i),cast(unsigned int, (b)+MAXARG_sBx))
#define CREATE_ABC(o,a,b,c) ((cast(Instruction, o)<<POS_OP) \
| (cast(Instruction, a)<<POS_A) \
| (cast(Instruction, b)<<POS_B) \
| (cast(Instruction, c)<<POS_C))
#define CREATE_ABx(o,a,bc) ((cast(Instruction, o)<<POS_OP) \
| (cast(Instruction, a)<<POS_A) \
| (cast(Instruction, bc)<<POS_Bx))
#define CREATE_Ax(o,a) ((cast(Instruction, o)<<POS_OP) \
| (cast(Instruction, a)<<POS_Ax))
/*
** Macros to operate RK indices
*/
/* this bit 1 means constant (0 means register) */
#define BITRK (1 << (SIZE_B - 1))
/* test whether value is a constant */
#define ISK(x) ((x) & BITRK)
/* gets the index of the constant */
#define INDEXK(r) ((int)(r) & ~BITRK)
#if !defined(MAXINDEXRK) /* (for debugging only) */
#define MAXINDEXRK (BITRK - 1)
#endif
/* code a constant index as a RK value */
#define RKASK(x) ((x) | BITRK)
/*
** invalid register that fits in 8 bits
*/
#define NO_REG MAXARG_A
/*
** R(x) - register
** Kst(x) - constant (in constant table)
** RK(x) == if ISK(x) then Kst(INDEXK(x)) else R(x)
*/
/*
** grep "ORDER OP" if you change these enums
*/
typedef enum {
/*----------------------------------------------------------------------
name args description
------------------------------------------------------------------------*/
OP_MOVE,/* A B R(A) := R(B) */
OP_LOADK,/* A Bx R(A) := Kst(Bx) */
OP_LOADKX,/* A R(A) := Kst(extra arg) */
OP_LOADBOOL,/* A B C R(A) := (Bool)B; if (C) pc++ */
OP_LOADNIL,/* A B R(A), R(A+1), ..., R(A+B) := nil */
OP_GETUPVAL,/* A B R(A) := UpValue[B] */
OP_GETTABUP,/* A B C R(A) := UpValue[B][RK(C)] */
OP_GETTABLE,/* A B C R(A) := R(B)[RK(C)] */
OP_SETTABUP,/* A B C UpValue[A][RK(B)] := RK(C) */
OP_SETUPVAL,/* A B UpValue[B] := R(A) */
OP_SETTABLE,/* A B C R(A)[RK(B)] := RK(C) */
OP_NEWTABLE,/* A B C R(A) := {} (size = B,C) */
OP_SELF,/* A B C R(A+1) := R(B); R(A) := R(B)[RK(C)] */
OP_ADD,/* A B C R(A) := RK(B) + RK(C) */
OP_SUB,/* A B C R(A) := RK(B) - RK(C) */
OP_MUL,/* A B C R(A) := RK(B) * RK(C) */
OP_MOD,/* A B C R(A) := RK(B) % RK(C) */
OP_POW,/* A B C R(A) := RK(B) ^ RK(C) */
OP_DIV,/* A B C R(A) := RK(B) / RK(C) */
OP_IDIV,/* A B C R(A) := RK(B) // RK(C) */
OP_BAND,/* A B C R(A) := RK(B) & RK(C) */
OP_BOR,/* A B C R(A) := RK(B) | RK(C) */
OP_BXOR,/* A B C R(A) := RK(B) ~ RK(C) */
OP_SHL,/* A B C R(A) := RK(B) << RK(C) */
OP_SHR,/* A B C R(A) := RK(B) >> RK(C) */
OP_UNM,/* A B R(A) := -R(B) */
OP_BNOT,/* A B R(A) := ~R(B) */
OP_NOT,/* A B R(A) := not R(B) */
OP_LEN,/* A B R(A) := length of R(B) */
OP_CONCAT,/* A B C R(A) := R(B).. ... ..R(C) */
OP_JMP,/* A sBx pc+=sBx; if (A) close all upvalues >= R(A - 1) */
OP_EQ,/* A B C if ((RK(B) == RK(C)) ~= A) then pc++ */
OP_LT,/* A B C if ((RK(B) < RK(C)) ~= A) then pc++ */
OP_LE,/* A B C if ((RK(B) <= RK(C)) ~= A) then pc++ */
OP_TEST,/* A C if not (R(A) <=> C) then pc++ */
OP_TESTSET,/* A B C if (R(B) <=> C) then R(A) := R(B) else pc++ */
OP_CALL,/* A B C R(A), ... ,R(A+C-2) := R(A)(R(A+1), ... ,R(A+B-1)) */
OP_TAILCALL,/* A B C return R(A)(R(A+1), ... ,R(A+B-1)) */
OP_RETURN,/* A B return R(A), ... ,R(A+B-2) (see note) */
OP_FORLOOP,/* A sBx R(A)+=R(A+2);
if R(A) <?= R(A+1) then { pc+=sBx; R(A+3)=R(A) }*/
OP_FORPREP,/* A sBx R(A)-=R(A+2); pc+=sBx */
OP_TFORCALL,/* A C R(A+3), ... ,R(A+2+C) := R(A)(R(A+1), R(A+2)); */
OP_TFORLOOP,/* A sBx if R(A+1) ~= nil then { R(A)=R(A+1); pc += sBx }*/
OP_SETLIST,/* A B C R(A)[(C-1)*FPF+i] := R(A+i), 1 <= i <= B */
OP_CLOSURE,/* A Bx R(A) := closure(KPROTO[Bx]) */
OP_VARARG,/* A B R(A), R(A+1), ..., R(A+B-2) = vararg */
OP_EXTRAARG/* Ax extra (larger) argument for previous opcode */
} OpCode;
#define NUM_OPCODES (cast(int, OP_EXTRAARG) + 1)
/*===========================================================================
Notes:
(*) In OP_CALL, if (B == 0) then B = top. If (C == 0), then 'top' is
set to last_result+1, so next open instruction (OP_CALL, OP_RETURN,
OP_SETLIST) may use 'top'.
(*) In OP_VARARG, if (B == 0) then use actual number of varargs and
set top (like in OP_CALL with C == 0).
(*) In OP_RETURN, if (B == 0) then return up to 'top'.
(*) In OP_SETLIST, if (B == 0) then B = 'top'; if (C == 0) then next
'instruction' is EXTRAARG(real C).
(*) In OP_LOADKX, the next 'instruction' is always EXTRAARG.
(*) For comparisons, A specifies what condition the test should accept
(true or false).
(*) All 'skips' (pc++) assume that next instruction is a jump.
===========================================================================*/
/*
** masks for instruction properties. The format is:
** bits 0-1: op mode
** bits 2-3: C arg mode
** bits 4-5: B arg mode
** bit 6: instruction set register A
** bit 7: operator is a test (next instruction must be a jump)
*/
enum OpArgMask {
OpArgN, /* argument is not used */
OpArgU, /* argument is used */
OpArgR, /* argument is a register or a jump offset */
OpArgK /* argument is a constant or register/constant */
};
LUAI_DDEC const lu_byte luaP_opmodes[NUM_OPCODES];
#define getOpMode(m) (cast(enum OpMode, luaP_opmodes[m] & 3))
#define getBMode(m) (cast(enum OpArgMask, (luaP_opmodes[m] >> 4) & 3))
#define getCMode(m) (cast(enum OpArgMask, (luaP_opmodes[m] >> 2) & 3))
#define testAMode(m) (luaP_opmodes[m] & (1 << 6))
#define testTMode(m) (luaP_opmodes[m] & (1 << 7))
LUAI_DDEC const char *const luaP_opnames[NUM_OPCODES+1]; /* opcode names */
/* number of list items to accumulate before a SETLIST instruction */
#define LFIELDS_PER_FLUSH 50
#endif从 lopcodes.h 里面我们可以看出对于一个 Instruction 每个部分的意义。大概是这样的：
0.....6,7.......14,15.......23,24......31
[opcode][ A ] [ B ] [ C ]
[opcode][ AX ]
[opcode][ A ] [ BX ]其中 opcode 的定义在 OpCode enum 里面。
而在 lopcodes.c 里面，定义了 LUAI_DDEF const char *const luaP_opnames[NUM_OPCODES+1] 和 LUAI_DDEF const lu_byte luaP_opmodes[NUM_OPCODES]。
/*
** $Id: lopcodes.c,v 1.55 2015/01/05 13:48:33 roberto Exp $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/
#define lopcodes_c
#define LUA_CORE
#include "lprefix.h"
#include <stddef.h>
#include "lopcodes.h"
/* ORDER OP */
LUAI_DDEF const char *const luaP_opnames[NUM_OPCODES+1] = {
"MOVE",
"LOADK",
"LOADKX",
"LOADBOOL",
"LOADNIL",
"GETUPVAL",
"GETTABUP",
"GETTABLE",
"SETTABUP",
"SETUPVAL",
"SETTABLE",
"NEWTABLE",
"SELF",
"ADD",
"SUB",
"MUL",
"MOD",
"POW",
"DIV",
"IDIV",
"BAND",
"BOR",
"BXOR",
"SHL",
"SHR",
"UNM",
"BNOT",
"NOT",
"LEN",
"CONCAT",
"JMP",
"EQ",
"LT",
"LE",
"TEST",
"TESTSET",
"CALL",
"TAILCALL",
"RETURN",
"FORLOOP",
"FORPREP",
"TFORCALL",
"TFORLOOP",
"SETLIST",
"CLOSURE",
"VARARG",
"EXTRAARG",
NULL
};
#define opmode(t,a,b,c,m) (((t)<<7) | ((a)<<6) | ((b)<<4) | ((c)<<2) | (m))
LUAI_DDEF const lu_byte luaP_opmodes[NUM_OPCODES] = {
/* T A B C mode opcode */
opmode(0, 1, OpArgR, OpArgN, iABC) /* OP_MOVE */
,opmode(0, 1, OpArgK, OpArgN, iABx) /* OP_LOADK */
,opmode(0, 1, OpArgN, OpArgN, iABx) /* OP_LOADKX */
,opmode(0, 1, OpArgU, OpArgU, iABC) /* OP_LOADBOOL */
,opmode(0, 1, OpArgU, OpArgN, iABC) /* OP_LOADNIL */
,opmode(0, 1, OpArgU, OpArgN, iABC) /* OP_GETUPVAL */
,opmode(0, 1, OpArgU, OpArgK, iABC) /* OP_GETTABUP */
,opmode(0, 1, OpArgR, OpArgK, iABC) /* OP_GETTABLE */
,opmode(0, 0, OpArgK, OpArgK, iABC) /* OP_SETTABUP */
,opmode(0, 0, OpArgU, OpArgN, iABC) /* OP_SETUPVAL */
,opmode(0, 0, OpArgK, OpArgK, iABC) /* OP_SETTABLE */
,opmode(0, 1, OpArgU, OpArgU, iABC) /* OP_NEWTABLE */
,opmode(0, 1, OpArgR, OpArgK, iABC) /* OP_SELF */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_ADD */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_SUB */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_MUL */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_MOD */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_POW */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_DIV */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_IDIV */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_BAND */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_BOR */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_BXOR */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_SHL */
,opmode(0, 1, OpArgK, OpArgK, iABC) /* OP_SHR */
,opmode(0, 1, OpArgR, OpArgN, iABC) /* OP_UNM */
,opmode(0, 1, OpArgR, OpArgN, iABC) /* OP_BNOT */
,opmode(0, 1, OpArgR, OpArgN, iABC) /* OP_NOT */
,opmode(0, 1, OpArgR, OpArgN, iABC) /* OP_LEN */
,opmode(0, 1, OpArgR, OpArgR, iABC) /* OP_CONCAT */
,opmode(0, 0, OpArgR, OpArgN, iAsBx) /* OP_JMP */
,opmode(1, 0, OpArgK, OpArgK, iABC) /* OP_EQ */
,opmode(1, 0, OpArgK, OpArgK, iABC) /* OP_LT */
,opmode(1, 0, OpArgK, OpArgK, iABC) /* OP_LE */
,opmode(1, 0, OpArgN, OpArgU, iABC) /* OP_TEST */
,opmode(1, 1, OpArgR, OpArgU, iABC) /* OP_TESTSET */
,opmode(0, 1, OpArgU, OpArgU, iABC) /* OP_CALL */
,opmode(0, 1, OpArgU, OpArgU, iABC) /* OP_TAILCALL */
,opmode(0, 0, OpArgU, OpArgN, iABC) /* OP_RETURN */
,opmode(0, 1, OpArgR, OpArgN, iAsBx) /* OP_FORLOOP */
,opmode(0, 1, OpArgR, OpArgN, iAsBx) /* OP_FORPREP */
,opmode(0, 0, OpArgN, OpArgU, iABC) /* OP_TFORCALL */
,opmode(0, 1, OpArgR, OpArgN, iAsBx) /* OP_TFORLOOP */
,opmode(0, 0, OpArgU, OpArgU, iABC) /* OP_SETLIST */
,opmode(0, 1, OpArgU, OpArgN, iABx) /* OP_CLOSURE */
,opmode(0, 1, OpArgU, OpArgN, iABC) /* OP_VARARG */
,opmode(0, 0, OpArgU, OpArgU, iAx) /* OP_EXTRAARG */
};