luaJIT指令集介绍[通俗易懂]

/* -- Common type definitions --------------------------------------------- */

/* Types for handling bytecodes. Need this here, details in lj_bc.h. */
typedef uint32_t BCIns;  //BC指令
typedef uint32_t BCPos;  //BC位置
typedef uint32_t BCReg;  //BC参数
typedef int32_t BCLine;  //BC行数

	#define BCMAX_A		0xff A的最大范围	
	#define BCMAX_B		0xff B的最大范围
	#define BCMAX_C		0xff C的最大范围
	#define BCMAX_D		0xffff D的最大范围
	#define BCBIAS_J	0x8000 跳转指令标记码
	#define NO_REG		BCMAX_A 没有参数定义
	#define NO_JMP		(~(BCPos)0) 没有跳转定义

 /* Macros to get instruction fields. */
 #define bc_op(i)	((BCOp)((i)&0xff))
 #define bc_a(i)		((BCReg)(((i)>>8)&0xff))
 #define bc_b(i)		((BCReg)((i)>>24))
 #define bc_c(i)		((BCReg)(((i)>>16)&0xff))
 #define bc_d(i)		((BCReg)((i)>>16))
 #define bc_j(i)		((ptrdiff_t)bc_d(i)-BCBIAS_J)

 #define setbc_byte(p, x, ofs) \
   ((uint8_t *)(p))[LJ_ENDIAN_SELECT(ofs, 3-ofs)] = (uint8_t)(x) 这就是一种贼骚的操作，先把32位转换成8位指针，强行分成4组后做处理
 #define setbc_op(p, x)	setbc_byte(p, (x), 0) 
 #define setbc_a(p, x)	setbc_byte(p, (x), 1)
 #define setbc_b(p, x)	setbc_byte(p, (x), 3)
 #define setbc_c(p, x)	setbc_byte(p, (x), 2)
 #define setbc_d(p, x) \
   ((uint16_t *)(p))[LJ_ENDIAN_SELECT(1, 0)] = (uint16_t)(x) 这里一样，强行拆成两组然后做骚操作
 #define setbc_j(p, x)	setbc_d(p, (BCPos)((int32_t)(x)+BCBIAS_J)) 设置跳转，用BCBIAS_J做标记

 /* Macros to compose instructions. */
 #define BCINS_ABC(o, a, b, c) \
   (((BCIns)(o))|((BCIns)(a)<<8)|((BCIns)(b)<<24)|((BCIns)(c)<<16)) 这一部分实现合成操作码指令
 #define BCINS_AD(o, a, d) \
   (((BCIns)(o))|((BCIns)(a)<<8)|((BCIns)(d)<<16))
 #define BCINS_AJ(o, a, j)	BCINS_AD(o, a, (BCPos)((int32_t)(j)+BCBIAS_J)) 这一部分合成跳转指令

 EQ 就是 EQUAL等于
 NQ 就是 NOT EQUAL不等于
 GT 就是 GREATER THAN大于　
 LT 就是 LESS THAN小于
 GE 就是 GREATER THAN OR EQUAL 大于等于
 LE 就是 LESS THAN OR EQUAL 小于等于
	/* Bytecode instruction definition. Order matters, see below.
**
** (name, filler, Amode, Bmode, Cmode or Dmode, metamethod)还有相对应的元操作
**
** The opcode name suffixes specify the type for RB/RC or RD:
** V = variable slot局部变量表
** S = string const
** N = number const
** P = primitive type (~itype) 私有变量
** B = unsigned byte literal 原义字符
** M = multiple args/results 多参数和返回
后缀命名指定 说明不同的后缀存有不同的意义*/
#define BCDEF(_) \
/* Comparison ops. ORDER OPR. */ \
_(ISLT,		var,	___,	var,	lt) \
_(ISGE,		var,	___,	var,	lt) \
_(ISLE,		var,	___,	var,	le) \
_(ISGT,		var,	___,	var,	le) \
\
_(ISEQV,	var,	___,	var,	eq) \
_(ISNEV,	var,	___,	var,	eq) \
_(ISEQS,	var,	___,	str,	eq) \
_(ISNES,	var,	___,	str,	eq) \
_(ISEQN,	var,	___,	num,	eq) \
_(ISNEN,	var,	___,	num,	eq) \
_(ISEQP,	var,	___,	pri,	eq) \
_(ISNEP,	var,	___,	pri,	eq) \
\
/* Unary test and copy ops. */ \
_(ISTC,		dst,	___,	var,	___) \
_(ISFC,		dst,	___,	var,	___) \
_(IST,		___,	___,	var,	___) \
_(ISF,		___,	___,	var,	___) \
\
/* Unary ops. */ \
_(MOV,		dst,	___,	var,	___) \
_(NOT,		dst,	___,	var,	___) \
_(UNM,		dst,	___,	var,	unm) \
_(LEN,		dst,	___,	var,	len) \
\
/* Binary ops. ORDER OPR. VV last, POW must be next. */ \
_(ADDVN,	dst,	var,	num,	add) \
_(SUBVN,	dst,	var,	num,	sub) \
_(MULVN,	dst,	var,	num,	mul) \
_(DIVVN,	dst,	var,	num,	div) \
_(MODVN,	dst,	var,	num,	mod) \
\
_(ADDNV,	dst,	var,	num,	add) \
_(SUBNV,	dst,	var,	num,	sub) \
_(MULNV,	dst,	var,	num,	mul) \
_(DIVNV,	dst,	var,	num,	div) \
_(MODNV,	dst,	var,	num,	mod) \
\
_(ADDVV,	dst,	var,	var,	add) \
_(SUBVV,	dst,	var,	var,	sub) \
_(MULVV,	dst,	var,	var,	mul) \
_(DIVVV,	dst,	var,	var,	div) \
_(MODVV,	dst,	var,	var,	mod) \
\
_(POW,		dst,	var,	var,	pow) \
_(CAT,		dst,	rbase,	rbase,	concat) \
\
/* Constant ops. */ \
_(KSTR,		dst,	___,	str,	___) \
_(KCDATA,	dst,	___,	cdata,	___) \
_(KSHORT,	dst,	___,	lits,	___) \
_(KNUM,		dst,	___,	num,	___) \
_(KPRI,		dst,	___,	pri,	___) \
_(KNIL,		base,	___,	base,	___) \
\
/* Upvalue and function ops. */ \
_(UGET,		dst,	___,	uv,	___) \
_(USETV,	uv,	___,	var,	___) \
_(USETS,	uv,	___,	str,	___) \
_(USETN,	uv,	___,	num,	___) \
_(USETP,	uv,	___,	pri,	___) \
_(UCLO,		rbase,	___,	jump,	___) \
_(FNEW,		dst,	___,	func,	gc) \
\
/* Table ops. */ \
_(TNEW,	dst,	___,	lit,	gc) \
_(TDUP,	dst,	___,	tab,	gc) \
_(GGET,	dst,	___,	str,	index) \
_(GSET,	var,	___,	str,	newindex) \
_(TGETV,	dst,	var,	var,	index) \
_(TGETS,	dst,	var,	str,	index) \
_(TGETB,	dst,	var,	lit,	index) \
_(TSETV,	var,	var,	var,	newindex) \
_(TSETS,	var,	var,	str,	newindex) \
_(TSETB,	var,	var,	lit,	newindex) \
_(TSETM,	base,	___,	num,	newindex) \
\
/* Calls and vararg handling. T = tail call. */ \
_(CALLM,	base,	lit,	lit,	call) \
_(CALL,	base,	lit,	lit,	call) \
_(CALLMT,	base,	___,	lit,	call) \
_(CALLT,	base,	___,	lit,	call) \
_(ITERC,	base,	lit,	lit,	call) \
_(ITERN,	base,	lit,	lit,	call) \
_(VARG,	base,	lit,	lit,	___) \
_(ISNEXT,	base,	___,	jump,	___) \
\
/* Returns. */ \
_(RETM,		base,	___,	lit,	___) \
_(RET,		rbase,	___,	lit,	___) \
_(RET0,		rbase,	___,	lit,	___) \
_(RET1,		rbase,	___,	lit,	___) \
\
/* Loops and branches. I/J = interp/JIT, I/C/L = init/call/loop. */ \
_(FORI,		base,	___,	jump,	___) \
_(JFORI,	base,	___,	jump,	___) \
\
_(FORL,		base,	___,	jump,	___) \
_(IFORL,	base,	___,	jump,	___) \
_(JFORL,	base,	___,	lit,	___) \
\
_(ITERL,	base,	___,	jump,	___) \
_(IITERL,	base,	___,	jump,	___) \
_(JITERL,	base,	___,	lit,	___) \
\
_(LOOP,		rbase,	___,	jump,	___) \
_(ILOOP,	rbase,	___,	jump,	___) \
_(JLOOP,	rbase,	___,	lit,	___) \
\
_(JMP,		rbase,	___,	jump,	___) \
\
/* Function headers. I/J = interp/JIT, F/V/C = fixarg/vararg/C func. */ \
_(FUNCF,	rbase,	___,	___,	___) \
_(IFUNCF,	rbase,	___,	___,	___) \
_(JFUNCF,	rbase,	___,	lit,	___) \
_(FUNCV,	rbase,	___,	___,	___) \
_(IFUNCV,	rbase,	___,	___,	___) \
_(JFUNCV,	rbase,	___,	lit,	___) \
_(FUNCC,	rbase,	___,	___,	___) \
_(FUNCCW,	rbase,	___,	___,	___)
在这之后以下两行代码处理了这部分的定义
 
/* Bytecode opcode numbers. */
typedef enum {
     
#define BCENUM(name, ma, mb, mc, mt) BC_##name,
BCDEF(BCENUM)
#undef BCENUM
  BC__MAX
} BCOp;
 
 
 
这里对之前定义过得BENUM完全undef了，这也就表明这里的枚举，仅仅是枚举用，命名为BC_操作名
 
 
/* This solves a circular dependency problem, change as needed. */
#define FF_next_N 4
 
 
这里说FF_next_N是用来解决循环依赖问题的，之后可以关注下
 
(7)BCMode定义
 
typedef enum {
     
  BCMnone, BCMdst, BCMbase, BCMvar, BCMrbase, BCMuv,  /* Mode A must be <= 7 */
  BCMlit, BCMlits, BCMpri, BCMnum, BCMstr, BCMtab, BCMfunc, BCMjump, BCMcdata,
  BCM_max
} BCMode;
 
 
 
 
这里定义了BCMode的类型，这里主要是定义参数类型，因为扩展了很多操作指令，所以参数类型的也变得更丰富
 
(8)参数类型校验
这里的参数校验定义为
a 0~2 位
b 3~6位
c 7~10位
d 与c相同，但是有hasd这个校验步骤，就是检验b是不是modeNone
mm 11位以后
到这里全部的指令集定义已经完全介绍完毕，接下来将介绍read和write来进一步讲解
 







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