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e0ab13c62f
lua/lopcodes.h
Roberto Ierusalimschy 490ecfcaa1 Better comments about the use of 'k' in opcodes
2019-12-05 12:59:42 -03:00

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/*
** $Id: lopcodes.h $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/
#ifndef lopcodes_h
#define lopcodes_h
#include "llimits.h"
/*===========================================================================
We assume that instructions are unsigned 32-bit integers.
All instructions have an opcode in the first 7 bits.
Instructions can have the following formats:
3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0
1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
iABC C(8) | B(8) |k| A(8) | Op(7) |
iABx Bx(17) | A(8) | Op(7) |
iAsBx sBx (signed)(17) | A(8) | Op(7) |
iAx Ax(25) | Op(7) |
isJ sJ(25) | Op(7) |
A signed argument is represented in excess K: the represented value is
the written unsigned value minus K, where K is half the maximum for the
corresponding unsigned argument.
===========================================================================*/
enum OpMode {iABC, iABx, iAsBx, iAx, isJ}; /* basic instruction formats */
/*
** size and position of opcode arguments.
*/
#define SIZE_C 8
#define SIZE_B 8
#define SIZE_Bx (SIZE_C + SIZE_B + 1)
#define SIZE_A 8
#define SIZE_Ax (SIZE_Bx + SIZE_A)
#define SIZE_sJ (SIZE_Bx + SIZE_A)
#define SIZE_OP 7
#define POS_OP 0
#define POS_A (POS_OP + SIZE_OP)
#define POS_k (POS_A + SIZE_A)
#define POS_B (POS_k + 1)
#define POS_C (POS_B + SIZE_B)
#define POS_Bx POS_k
#define POS_Ax POS_A
#define POS_sJ POS_A
/*
** limits for opcode arguments.
** we use (signed) 'int' to manipulate most arguments,
** so they must fit in ints.
*/
/* Check whether type 'int' has at least 'b' bits ('b' < 32) */
#define L_INTHASBITS(b) ((UINT_MAX >> ((b) - 1)) >= 1)
#if L_INTHASBITS(SIZE_Bx)
#define MAXARG_Bx ((1<<SIZE_Bx)-1)
#else
#define MAXARG_Bx MAX_INT
#endif
#define OFFSET_sBx (MAXARG_Bx>>1) /* 'sBx' is signed */
#if L_INTHASBITS(SIZE_Ax)
#define MAXARG_Ax ((1<<SIZE_Ax)-1)
#else
#define MAXARG_Ax MAX_INT
#endif
#if L_INTHASBITS(SIZE_sJ)
#define MAXARG_sJ ((1 << SIZE_sJ) - 1)
#else
#define MAXARG_sJ MAX_INT
#endif
#define OFFSET_sJ (MAXARG_sJ >> 1)
#define MAXARG_A ((1<<SIZE_A)-1)
#define MAXARG_B ((1<<SIZE_B)-1)
#define MAXARG_C ((1<<SIZE_C)-1)
#define OFFSET_sC (MAXARG_C >> 1)
#define int2sC(i) ((i) + OFFSET_sC)
#define sC2int(i) ((i) - OFFSET_sC)
/* 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 checkopm(i,m) (getOpMode(GET_OPCODE(i)) == m)
#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) check_exp(checkopm(i, iABC), getarg(i, POS_B, SIZE_B))
#define GETARG_sB(i) sC2int(GETARG_B(i))
#define SETARG_B(i,v) setarg(i, v, POS_B, SIZE_B)
#define GETARG_C(i) check_exp(checkopm(i, iABC), getarg(i, POS_C, SIZE_C))
#define GETARG_sC(i) sC2int(GETARG_C(i))
#define SETARG_C(i,v) setarg(i, v, POS_C, SIZE_C)
#define TESTARG_k(i) check_exp(checkopm(i, iABC), (cast_int(((i) & (1u << POS_k)))))
#define GETARG_k(i) check_exp(checkopm(i, iABC), getarg(i, POS_k, 1))
#define SETARG_k(i,v) setarg(i, v, POS_k, 1)
#define GETARG_Bx(i) check_exp(checkopm(i, iABx), getarg(i, POS_Bx, SIZE_Bx))
#define SETARG_Bx(i,v) setarg(i, v, POS_Bx, SIZE_Bx)
#define GETARG_Ax(i) check_exp(checkopm(i, iAx), getarg(i, POS_Ax, SIZE_Ax))
#define SETARG_Ax(i,v) setarg(i, v, POS_Ax, SIZE_Ax)
#define GETARG_sBx(i) \
check_exp(checkopm(i, iAsBx), getarg(i, POS_Bx, SIZE_Bx) - OFFSET_sBx)
#define SETARG_sBx(i,b) SETARG_Bx((i),cast_uint((b)+OFFSET_sBx))
#define GETARG_sJ(i) \
check_exp(checkopm(i, isJ), getarg(i, POS_sJ, SIZE_sJ) - OFFSET_sJ)
#define SETARG_sJ(i,j) \
setarg(i, cast_uint((j)+OFFSET_sJ), POS_sJ, SIZE_sJ)
#define CREATE_ABCk(o,a,b,c,k) ((cast(Instruction, o)<<POS_OP) \
| (cast(Instruction, a)<<POS_A) \
| (cast(Instruction, b)<<POS_B) \
| (cast(Instruction, c)<<POS_C) \
| (cast(Instruction, k)<<POS_k))
#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))
#define CREATE_sJ(o,j,k) ((cast(Instruction, o) << POS_OP) \
| (cast(Instruction, j) << POS_sJ) \
| (cast(Instruction, k) << POS_k))
#if !defined(MAXINDEXRK) /* (for debugging only) */
#define MAXINDEXRK MAXARG_B
#endif
/*
** invalid register that fits in 8 bits
*/
#define NO_REG MAXARG_A
/*
** R[x] - register
** K[x] - constant (in constant table)
** RK(x) == if k(i) then K[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_LOADI,/* A sBx R[A] := sBx */
OP_LOADF,/* A sBx R[A] := (lua_Number)sBx */
OP_LOADK,/* A Bx R[A] := K[Bx] */
OP_LOADKX,/* A R[A] := K[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_SETUPVAL,/* A B UpValue[B] := R[A] */
OP_GETTABUP,/* A B C R[A] := UpValue[B][K[C]:string] */
OP_GETTABLE,/* A B C R[A] := R[B][R[C]] */
OP_GETI,/* A B C R[A] := R[B][C] */
OP_GETFIELD,/* A B C R[A] := R[B][K[C]:string] */
OP_SETTABUP,/* A B C UpValue[A][K[B]:string] := RK(C) */
OP_SETTABLE,/* A B C R[A][R[B]] := RK(C) */
OP_SETI,/* A B C R[A][B] := RK(C) */
OP_SETFIELD,/* A B C R[A][K[B]:string] := RK(C) */
OP_NEWTABLE,/* A B C k R[A] := {} */
OP_SELF,/* A B C R[A+1] := R[B]; R[A] := R[B][RK(C):string] */
OP_ADDI,/* A B sC R[A] := R[B] + sC */
OP_ADDK,/* A B C R[A] := R[B] + K[C] */
OP_SUBK,/* A B C R[A] := R[B] - K[C] */
OP_MULK,/* A B C R[A] := R[B] * K[C] */
OP_MODK,/* A B C R[A] := R[B] % K[C] */
OP_POWK,/* A B C R[A] := R[B] ^ K[C] */
OP_DIVK,/* A B C R[A] := R[B] / K[C] */
OP_IDIVK,/* A B C R[A] := R[B] // K[C] */
OP_BANDK,/* A B C R[A] := R[B] & K[C]:integer */
OP_BORK,/* A B C R[A] := R[B] | K[C]:integer */
OP_BXORK,/* A B C R[A] := R[B] ~ K[C]:integer */
OP_SHRI,/* A B sC R[A] := R[B] >> sC */
OP_SHLI,/* A B sC R[A] := sC << R[B] */
OP_ADD,/* A B C R[A] := R[B] + R[C] */
OP_SUB,/* A B C R[A] := R[B] - R[C] */
OP_MUL,/* A B C R[A] := R[B] * R[C] */
OP_MOD,/* A B C R[A] := R[B] % R[C] */
OP_POW,/* A B C R[A] := R[B] ^ R[C] */
OP_DIV,/* A B C R[A] := R[B] / R[C] */
OP_IDIV,/* A B C R[A] := R[B] // R[C] */
OP_BAND,/* A B C R[A] := R[B] & R[C] */
OP_BOR,/* A B C R[A] := R[B] | R[C] */
OP_BXOR,/* A B C R[A] := R[B] ~ R[C] */
OP_SHL,/* A B C R[A] := R[B] << R[C] */
OP_SHR,/* A B C R[A] := R[B] >> R[C] */
OP_MMBIN,/* A B C call C metamethod over R[A] and R[B] */
OP_MMBINI,/* A sB C k call C metamethod over R[A] and sB */
OP_MMBINK,/* A B C k call C metamethod over R[A] and K[B] */
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 R[A] := R[A].. ... ..R[A + B - 1] */
OP_CLOSE,/* A close all upvalues >= R[A] */
OP_TBC,/* A mark variable A "to be closed" */
OP_JMP,/* sJ pc += sJ */
OP_EQ,/* A B k if ((R[A] == R[B]) ~= k) then pc++ */
OP_LT,/* A B k if ((R[A] < R[B]) ~= k) then pc++ */
OP_LE,/* A B k if ((R[A] <= R[B]) ~= k) then pc++ */
OP_EQK,/* A B k if ((R[A] == K[B]) ~= k) then pc++ */
OP_EQI,/* A sB k if ((R[A] == sB) ~= k) then pc++ */
OP_LTI,/* A sB k if ((R[A] < sB) ~= k) then pc++ */
OP_LEI,/* A sB k if ((R[A] <= sB) ~= k) then pc++ */
OP_GTI,/* A sB k if ((R[A] > sB) ~= k) then pc++ */
OP_GEI,/* A sB k if ((R[A] >= sB) ~= k) then pc++ */
OP_TEST,/* A k if (not R[A] == k) then pc++ */
OP_TESTSET,/* A B k if (not R[B] == k) then pc++ else R[A] := R[B] */
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 k return R[A](R[A+1], ... ,R[A+B-1]) */
OP_RETURN,/* A B C k return R[A], ... ,R[A+B-2] (see note) */
OP_RETURN0,/* return */
OP_RETURN1,/* A return R[A] */
OP_FORLOOP,/* A Bx update counters; if loop continues then pc-=Bx; */
OP_FORPREP,/* A Bx <check values and prepare counters>;
if not to run then pc+=Bx+1; */
OP_TFORPREP,/* A Bx create upvalue for R[A + 3]; pc+=Bx */
OP_TFORCALL,/* A C R[A+4], ... ,R[A+3+C] := R[A](R[A+1], R[A+2]); */
OP_TFORLOOP,/* A Bx if R[A+2] ~= nil then { R[A]=R[A+2]; pc -= Bx } */
OP_SETLIST,/* A B C k R[A][(C-1)*FPF+i] := R[A+i], 1 <= i <= B */
OP_CLOSURE,/* A Bx R[A] := closure(KPROTO[Bx]) */
OP_VARARG,/* A C R[A], R[A+1], ..., R[A+C-2] = vararg */
OP_VARARGPREP,/*A (adjust vararg parameters) */
OP_EXTRAARG/* Ax extra (larger) argument for previous opcode */
} OpCode;
#define NUM_OPCODES ((int)(OP_EXTRAARG) + 1)
/*===========================================================================
Notes:
(*) In OP_CALL, if (B == 0) then B = top - A. 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 (C == 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_LOADKX and OP_NEWTABLE, the next instruction is always
OP_EXTRAARG.
(*) In OP_SETLIST, if (B == 0) then real B = 'top'; if k, then
real C = EXTRAARG _ C (the bits of EXTRAARG concatenated with the
bits of C).
(*) In OP_NEWTABLE, B is log2 of the hash size (which is always a
power of 2) plus 1, or zero for size zero. If not k, the array size
is C. Otherwise, the array size is EXTRAARG _ C.
(*) For comparisons, k specifies what condition the test should accept
(true or false).
(*) In OP_MMBINI/OP_MMBINK, k means the arguments were flipped
(the constant is the first operand).
(*) All 'skips' (pc++) assume that next instruction is a jump.
(*) In instructions OP_RETURN/OP_TAILCALL, 'k' specifies that the
function builds upvalues, which may need to be closed. C > 0 means
the function is vararg, so that its 'func' must be corrected before
returning; in this case, (C - 1) is its number of fixed parameters.
(*) In comparisons with an immediate operand, C signals whether the
original operand was a float. (It must be corrected in case of
metamethods.)
===========================================================================*/
/*
** masks for instruction properties. The format is:
** bits 0-2: op mode
** bit 3: instruction set register A
** bit 4: operator is a test (next instruction must be a jump)
** bit 5: instruction uses 'L->top' set by previous instruction (when B == 0)
** bit 6: instruction sets 'L->top' for next instruction (when C == 0)
** bit 7: instruction is an MM instruction (call a metamethod)
*/
LUAI_DDEC(const lu_byte luaP_opmodes[NUM_OPCODES];)
#define getOpMode(m) (cast(enum OpMode, luaP_opmodes[m] & 7))
#define testAMode(m) (luaP_opmodes[m] & (1 << 3))
#define testTMode(m) (luaP_opmodes[m] & (1 << 4))
#define testITMode(m) (luaP_opmodes[m] & (1 << 5))
#define testOTMode(m) (luaP_opmodes[m] & (1 << 6))
#define testMMMode(m) (luaP_opmodes[m] & (1 << 7))
/* "out top" (set top for next instruction) */
#define isOT(i) \
((testOTMode(GET_OPCODE(i)) && GETARG_C(i) == 0) || \
GET_OPCODE(i) == OP_TAILCALL)
/* "in top" (uses top from previous instruction) */
#define isIT(i) (testITMode(GET_OPCODE(i)) && GETARG_B(i) == 0)
#define opmode(mm,ot,it,t,a,m) \
(((mm) << 7) | ((ot) << 6) | ((it) << 5) | ((t) << 4) | ((a) << 3) | (m))
/* number of list items to accumulate before a SETLIST instruction */
#define LFIELDS_PER_FLUSH 50
#endif
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