lcode.c
(4.0.1)
/*
** $Id: lcode.c,v 1.51 2000/09/29 12:42:13 roberto Exp $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
#include "stdlib.h"
#include "lua.h"
#include "lcode.h"
#include "ldo.h"
#include "llex.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
void luaK_error (LexState *ls, const char *msg) {
luaX_error(ls, msg, ls->t.token);
}
/*
** Returns the the previous instruction, for optimizations.
** If there is a jump target between this and the current instruction,
** returns a dummy instruction to avoid wrong optimizations.
*/
static Instruction previous_instruction (FuncState *fs) {
if (fs->pc > fs->lasttarget) /* no jumps to current position? */
return fs->f->code[fs->pc-1]; /* returns previous instruction */
else
return CREATE_0(OP_END); /* no optimizations after an `END' */
}
int luaK_jump (FuncState *fs) {
int j = luaK_code1(fs, OP_JMP, NO_JUMP);
if (j == fs->lasttarget) { /* possible jumps to this jump? */
luaK_concat(fs, &j, fs->jlt); /* keep them on hold */
fs->jlt = NO_JUMP;
}
return j;
}
static void luaK_fixjump (FuncState *fs, int pc, int dest) {
Instruction *jmp = &fs->f->code[pc];
if (dest == NO_JUMP)
SETARG_S(*jmp, NO_JUMP); /* point to itself to represent end of list */
else { /* jump is relative to position following jump instruction */
int offset = dest-(pc+1);
if (abs(offset) > MAXARG_S)
luaK_error(fs->ls, "control structure too long");
SETARG_S(*jmp, offset);
}
}
static int luaK_getjump (FuncState *fs, int pc) {
int offset = GETARG_S(fs->f->code[pc]);
if (offset == NO_JUMP) /* point to itself represents end of list */
return NO_JUMP; /* end of list */
else
return (pc+1)+offset; /* turn offset into absolute position */
}
/*
** returns current `pc' and marks it as a jump target (to avoid wrong
** optimizations with consecutive instructions not in the same basic block).
** discharge list of jumps to last target.
*/
int luaK_getlabel (FuncState *fs) {
if (fs->pc != fs->lasttarget) {
int lasttarget = fs->lasttarget;
fs->lasttarget = fs->pc;
luaK_patchlist(fs, fs->jlt, lasttarget); /* discharge old list `jlt' */
fs->jlt = NO_JUMP; /* nobody jumps to this new label (yet) */
}
return fs->pc;
}
void luaK_deltastack (FuncState *fs, int delta) {
fs->stacklevel += delta;
if (fs->stacklevel > fs->f->maxstacksize) {
if (fs->stacklevel > MAXSTACK)
luaK_error(fs->ls, "function or expression too complex");
fs->f->maxstacksize = fs->stacklevel;
}
}
void luaK_kstr (LexState *ls, int c) {
luaK_code1(ls->fs, OP_PUSHSTRING, c);
}
static int number_constant (FuncState *fs, Number r) {
/* check whether `r' has appeared within the last LOOKBACKNUMS entries */
Proto *f = fs->f;
int c = f->nknum;
int lim = c < LOOKBACKNUMS ? 0 : c-LOOKBACKNUMS;
while (--c >= lim)
if (f->knum[c] == r) return c;
/* not found; create a new entry */
luaM_growvector(fs->L, f->knum, f->nknum, 1, Number,
"constant table overflow", MAXARG_U);
c = f->nknum++;
f->knum[c] = r;
return c;
}
void luaK_number (FuncState *fs, Number f) {
if (f <= (Number)MAXARG_S && (Number)(int)f == f)
luaK_code1(fs, OP_PUSHINT, (int)f); /* f has a short integer value */
else
luaK_code1(fs, OP_PUSHNUM, number_constant(fs, f));
}
void luaK_adjuststack (FuncState *fs, int n) {
if (n > 0)
luaK_code1(fs, OP_POP, n);
else
luaK_code1(fs, OP_PUSHNIL, -n);
}
int luaK_lastisopen (FuncState *fs) {
/* check whether last instruction is an open function call */
Instruction i = previous_instruction(fs);
if (GET_OPCODE(i) == OP_CALL && GETARG_B(i) == MULT_RET)
return 1;
else return 0;
}
void luaK_setcallreturns (FuncState *fs, int nresults) {
if (luaK_lastisopen(fs)) { /* expression is an open function call? */
SETARG_B(fs->f->code[fs->pc-1], nresults); /* set number of results */
luaK_deltastack(fs, nresults); /* push results */
}
}
static int discharge (FuncState *fs, expdesc *var) {
switch (var->k) {
case VLOCAL:
luaK_code1(fs, OP_GETLOCAL, var->u.index);
break;
case VGLOBAL:
luaK_code1(fs, OP_GETGLOBAL, var->u.index);
break;
case VINDEXED:
luaK_code0(fs, OP_GETTABLE);
break;
case VEXP:
return 0; /* nothing to do */
}
var->k = VEXP;
var->u.l.t = var->u.l.f = NO_JUMP;
return 1;
}
static void discharge1 (FuncState *fs, expdesc *var) {
discharge(fs, var);
/* if it has jumps then it is already discharged */
if (var->u.l.t == NO_JUMP && var->u.l.f == NO_JUMP)
luaK_setcallreturns(fs, 1); /* call must return 1 value */
}
void luaK_storevar (LexState *ls, const expdesc *var) {
FuncState *fs = ls->fs;
switch (var->k) {
case VLOCAL:
luaK_code1(fs, OP_SETLOCAL, var->u.index);
break;
case VGLOBAL:
luaK_code1(fs, OP_SETGLOBAL, var->u.index);
break;
case VINDEXED: /* table is at top-3; pop 3 elements after operation */
luaK_code2(fs, OP_SETTABLE, 3, 3);
break;
default:
LUA_INTERNALERROR("invalid var kind to store");
}
}
static OpCode invertjump (OpCode op) {
switch (op) {
case OP_JMPNE: return OP_JMPEQ;
case OP_JMPEQ: return OP_JMPNE;
case OP_JMPLT: return OP_JMPGE;
case OP_JMPLE: return OP_JMPGT;
case OP_JMPGT: return OP_JMPLE;
case OP_JMPGE: return OP_JMPLT;
case OP_JMPT: case OP_JMPONT: return OP_JMPF;
case OP_JMPF: case OP_JMPONF: return OP_JMPT;
default:
LUA_INTERNALERROR("invalid jump instruction");
return OP_END; /* to avoid warnings */
}
}
static void luaK_patchlistaux (FuncState *fs, int list, int target,
OpCode special, int special_target) {
Instruction *code = fs->f->code;
while (list != NO_JUMP) {
int next = luaK_getjump(fs, list);
Instruction *i = &code[list];
OpCode op = GET_OPCODE(*i);
if (op == special) /* this `op' already has a value */
luaK_fixjump(fs, list, special_target);
else {
luaK_fixjump(fs, list, target); /* do the patch */
if (op == OP_JMPONT) /* remove eventual values */
SET_OPCODE(*i, OP_JMPT);
else if (op == OP_JMPONF)
SET_OPCODE(*i, OP_JMPF);
}
list = next;
}
}
void luaK_patchlist (FuncState *fs, int list, int target) {
if (target == fs->lasttarget) /* same target that list `jlt'? */
luaK_concat(fs, &fs->jlt, list); /* delay fixing */
else
luaK_patchlistaux(fs, list, target, OP_END, 0);
}
static int need_value (FuncState *fs, int list, OpCode hasvalue) {
/* check whether list has a jump without a value */
for (; list != NO_JUMP; list = luaK_getjump(fs, list))
if (GET_OPCODE(fs->f->code[list]) != hasvalue) return 1;
return 0; /* not found */
}
void luaK_concat (FuncState *fs, int *l1, int l2) {
if (*l1 == NO_JUMP)
*l1 = l2;
else {
int list = *l1;
for (;;) { /* traverse `l1' */
int next = luaK_getjump(fs, list);
if (next == NO_JUMP) { /* end of list? */
luaK_fixjump(fs, list, l2);
return;
}
list = next;
}
}
}
static void luaK_testgo (FuncState *fs, expdesc *v, int invert, OpCode jump) {
int prevpos; /* position of last instruction */
Instruction *previous;
int *golist, *exitlist;
if (!invert) {
golist = &v->u.l.f; /* go if false */
exitlist = &v->u.l.t; /* exit if true */
}
else {
golist = &v->u.l.t; /* go if true */
exitlist = &v->u.l.f; /* exit if false */
}
discharge1(fs, v);
prevpos = fs->pc-1;
previous = &fs->f->code[prevpos];
LUA_ASSERT(*previous==previous_instruction(fs), "no jump allowed here");
if (!ISJUMP(GET_OPCODE(*previous)))
prevpos = luaK_code1(fs, jump, NO_JUMP);
else { /* last instruction is already a jump */
if (invert)
SET_OPCODE(*previous, invertjump(GET_OPCODE(*previous)));
}
luaK_concat(fs, exitlist, prevpos); /* insert last jump in `exitlist' */
luaK_patchlist(fs, *golist, luaK_getlabel(fs));
*golist = NO_JUMP;
}
void luaK_goiftrue (FuncState *fs, expdesc *v, int keepvalue) {
luaK_testgo(fs, v, 1, keepvalue ? OP_JMPONF : OP_JMPF);
}
static void luaK_goiffalse (FuncState *fs, expdesc *v, int keepvalue) {
luaK_testgo(fs, v, 0, keepvalue ? OP_JMPONT : OP_JMPT);
}
static int code_label (FuncState *fs, OpCode op, int arg) {
luaK_getlabel(fs); /* those instructions may be jump targets */
return luaK_code1(fs, op, arg);
}
void luaK_tostack (LexState *ls, expdesc *v, int onlyone) {
FuncState *fs = ls->fs;
if (!discharge(fs, v)) { /* `v' is an expression? */
OpCode previous = GET_OPCODE(fs->f->code[fs->pc-1]);
if (!ISJUMP(previous) && v->u.l.f == NO_JUMP && v->u.l.t == NO_JUMP) {
/* expression has no jumps */
if (onlyone)
luaK_setcallreturns(fs, 1); /* call must return 1 value */
}
else { /* expression has jumps */
int final; /* position after whole expression */
int j = NO_JUMP; /* eventual jump over values */
int p_nil = NO_JUMP; /* position of an eventual PUSHNIL */
int p_1 = NO_JUMP; /* position of an eventual PUSHINT */
if (ISJUMP(previous) || need_value(fs, v->u.l.f, OP_JMPONF)
|| need_value(fs, v->u.l.t, OP_JMPONT)) {
/* expression needs values */
if (ISJUMP(previous))
luaK_concat(fs, &v->u.l.t, fs->pc-1); /* put `previous' in t. list */
else {
j = code_label(fs, OP_JMP, NO_JUMP); /* to jump over both pushes */
/* correct stack for compiler and symbolic execution */
luaK_adjuststack(fs, 1);
}
p_nil = code_label(fs, OP_PUSHNILJMP, 0);
p_1 = code_label(fs, OP_PUSHINT, 1);
luaK_patchlist(fs, j, luaK_getlabel(fs));
}
final = luaK_getlabel(fs);
luaK_patchlistaux(fs, v->u.l.f, p_nil, OP_JMPONF, final);
luaK_patchlistaux(fs, v->u.l.t, p_1, OP_JMPONT, final);
v->u.l.f = v->u.l.t = NO_JUMP;
}
}
}
void luaK_prefix (LexState *ls, UnOpr op, expdesc *v) {
FuncState *fs = ls->fs;
if (op == OPR_MINUS) {
luaK_tostack(ls, v, 1);
luaK_code0(fs, OP_MINUS);
}
else { /* op == NOT */
Instruction *previous;
discharge1(fs, v);
previous = &fs->f->code[fs->pc-1];
if (ISJUMP(GET_OPCODE(*previous)))
SET_OPCODE(*previous, invertjump(GET_OPCODE(*previous)));
else
luaK_code0(fs, OP_NOT);
/* interchange true and false lists */
{ int temp = v->u.l.f; v->u.l.f = v->u.l.t; v->u.l.t = temp; }
}
}
void luaK_infix (LexState *ls, BinOpr op, expdesc *v) {
FuncState *fs = ls->fs;
switch (op) {
case OPR_AND:
luaK_goiftrue(fs, v, 1);
break;
case OPR_OR:
luaK_goiffalse(fs, v, 1);
break;
default:
luaK_tostack(ls, v, 1); /* all other binary operators need a value */
}
}
static const struct {
OpCode opcode; /* opcode for each binary operator */
int arg; /* default argument for the opcode */
} codes[] = { /* ORDER OPR */
{OP_ADD, 0}, {OP_SUB, 0}, {OP_MULT, 0}, {OP_DIV, 0},
{OP_POW, 0}, {OP_CONCAT, 2},
{OP_JMPNE, NO_JUMP}, {OP_JMPEQ, NO_JUMP},
{OP_JMPLT, NO_JUMP}, {OP_JMPLE, NO_JUMP},
{OP_JMPGT, NO_JUMP}, {OP_JMPGE, NO_JUMP}
};
void luaK_posfix (LexState *ls, BinOpr op, expdesc *v1, expdesc *v2) {
FuncState *fs = ls->fs;
switch (op) {
case OPR_AND: {
LUA_ASSERT(v1->u.l.t == NO_JUMP, "list must be closed");
discharge1(fs, v2);
v1->u.l.t = v2->u.l.t;
luaK_concat(fs, &v1->u.l.f, v2->u.l.f);
break;
}
case OPR_OR: {
LUA_ASSERT(v1->u.l.f == NO_JUMP, "list must be closed");
discharge1(fs, v2);
v1->u.l.f = v2->u.l.f;
luaK_concat(fs, &v1->u.l.t, v2->u.l.t);
break;
}
default: {
luaK_tostack(ls, v2, 1); /* `v2' must be a value */
luaK_code1(fs, codes[op].opcode, codes[op].arg);
}
}
}
static void codelineinfo (FuncState *fs) {
Proto *f = fs->f;
LexState *ls = fs->ls;
if (ls->lastline > fs->lastline) {
luaM_growvector(fs->L, f->lineinfo, f->nlineinfo, 2, int,
"line info overflow", MAX_INT);
if (ls->lastline > fs->lastline+1)
f->lineinfo[f->nlineinfo++] = -(ls->lastline - (fs->lastline+1));
f->lineinfo[f->nlineinfo++] = fs->pc;
fs->lastline = ls->lastline;
}
}
int luaK_code0 (FuncState *fs, OpCode o) {
return luaK_code2(fs, o, 0, 0);
}
int luaK_code1 (FuncState *fs, OpCode o, int arg1) {
return luaK_code2(fs, o, arg1, 0);
}
int luaK_code2 (FuncState *fs, OpCode o, int arg1, int arg2) {
Instruction i = previous_instruction(fs);
int delta = luaK_opproperties[o].push - luaK_opproperties[o].pop;
int optm = 0; /* 1 when there is an optimization */
switch (o) {
case OP_CLOSURE: {
delta = -arg2+1;
break;
}
case OP_SETTABLE: {
delta = -arg2;
break;
}
case OP_SETLIST: {
if (arg2 == 0) return NO_JUMP; /* nothing to do */
delta = -arg2;
break;
}
case OP_SETMAP: {
if (arg1 == 0) return NO_JUMP; /* nothing to do */
delta = -2*arg1;
break;
}
case OP_RETURN: {
if (GET_OPCODE(i) == OP_CALL && GETARG_B(i) == MULT_RET) {
SET_OPCODE(i, OP_TAILCALL);
SETARG_B(i, arg1);
optm = 1;
}
break;
}
case OP_PUSHNIL: {
if (arg1 == 0) return NO_JUMP; /* nothing to do */
delta = arg1;
switch(GET_OPCODE(i)) {
case OP_PUSHNIL: SETARG_U(i, GETARG_U(i)+arg1); optm = 1; break;
default: break;
}
break;
}
case OP_POP: {
if (arg1 == 0) return NO_JUMP; /* nothing to do */
delta = -arg1;
switch(GET_OPCODE(i)) {
case OP_SETTABLE: SETARG_B(i, GETARG_B(i)+arg1); optm = 1; break;
default: break;
}
break;
}
case OP_GETTABLE: {
switch(GET_OPCODE(i)) {
case OP_PUSHSTRING: /* `t.x' */
SET_OPCODE(i, OP_GETDOTTED);
optm = 1;
break;
case OP_GETLOCAL: /* `t[i]' */
SET_OPCODE(i, OP_GETINDEXED);
optm = 1;
break;
default: break;
}
break;
}
case OP_ADD: {
switch(GET_OPCODE(i)) {
case OP_PUSHINT: SET_OPCODE(i, OP_ADDI); optm = 1; break; /* `a+k' */
default: break;
}
break;
}
case OP_SUB: {
switch(GET_OPCODE(i)) {
case OP_PUSHINT: /* `a-k' */
i = CREATE_S(OP_ADDI, -GETARG_S(i));
optm = 1;
break;
default: break;
}
break;
}
case OP_CONCAT: {
delta = -arg1+1;
switch(GET_OPCODE(i)) {
case OP_CONCAT: /* `a..b..c' */
SETARG_U(i, GETARG_U(i)+1);
optm = 1;
break;
default: break;
}
break;
}
case OP_MINUS: {
switch(GET_OPCODE(i)) {
case OP_PUSHINT: /* `-k' */
SETARG_S(i, -GETARG_S(i));
optm = 1;
break;
case OP_PUSHNUM: /* `-k' */
SET_OPCODE(i, OP_PUSHNEGNUM);
optm = 1;
break;
default: break;
}
break;
}
case OP_JMPNE: {
if (i == CREATE_U(OP_PUSHNIL, 1)) { /* `a~=nil' */
i = CREATE_S(OP_JMPT, NO_JUMP);
optm = 1;
}
break;
}
case OP_JMPEQ: {
if (i == CREATE_U(OP_PUSHNIL, 1)) { /* `a==nil' */
i = CREATE_0(OP_NOT);
delta = -1; /* just undo effect of previous PUSHNIL */
optm = 1;
}
break;
}
case OP_JMPT:
case OP_JMPONT: {
switch (GET_OPCODE(i)) {
case OP_NOT: {
i = CREATE_S(OP_JMPF, NO_JUMP);
optm = 1;
break;
}
case OP_PUSHINT: {
if (o == OP_JMPT) { /* JMPONT must keep original integer value */
i = CREATE_S(OP_JMP, NO_JUMP);
optm = 1;
}
break;
}
case OP_PUSHNIL: {
if (GETARG_U(i) == 1) {
fs->pc--; /* erase previous instruction */
luaK_deltastack(fs, -1); /* correct stack */
return NO_JUMP;
}
break;
}
default: break;
}
break;
}
case OP_JMPF:
case OP_JMPONF: {
switch (GET_OPCODE(i)) {
case OP_NOT: {
i = CREATE_S(OP_JMPT, NO_JUMP);
optm = 1;
break;
}
case OP_PUSHINT: { /* `while 1 do ...' */
fs->pc--; /* erase previous instruction */
luaK_deltastack(fs, -1); /* correct stack */
return NO_JUMP;
}
case OP_PUSHNIL: { /* `repeat ... until nil' */
if (GETARG_U(i) == 1) {
i = CREATE_S(OP_JMP, NO_JUMP);
optm = 1;
}
break;
}
default: break;
}
break;
}
case OP_GETDOTTED:
case OP_GETINDEXED:
case OP_TAILCALL:
case OP_ADDI: {
LUA_INTERNALERROR("instruction used only for optimizations");
break;
}
default: {
LUA_ASSERT(delta != VD, "invalid delta");
break;
}
}
luaK_deltastack(fs, delta);
if (optm) { /* optimize: put instruction in place of last one */
fs->f->code[fs->pc-1] = i; /* change previous instruction */
return fs->pc-1; /* do not generate new instruction */
}
/* else build new instruction */
switch ((enum Mode)luaK_opproperties[o].mode) {
case iO: i = CREATE_0(o); break;
case iU: i = CREATE_U(o, arg1); break;
case iS: i = CREATE_S(o, arg1); break;
case iAB: i = CREATE_AB(o, arg1, arg2); break;
}
codelineinfo(fs);
/* put new instruction in code array */
luaM_growvector(fs->L, fs->f->code, fs->pc, 1, Instruction,
"code size overflow", MAX_INT);
fs->f->code[fs->pc] = i;
return fs->pc++;
}
const struct OpProperties luaK_opproperties[NUM_OPCODES] = {
{iO, 0, 0}, /* OP_END */
{iU, 0, 0}, /* OP_RETURN */
{iAB, 0, 0}, /* OP_CALL */
{iAB, 0, 0}, /* OP_TAILCALL */
{iU, VD, 0}, /* OP_PUSHNIL */
{iU, VD, 0}, /* OP_POP */
{iS, 1, 0}, /* OP_PUSHINT */
{iU, 1, 0}, /* OP_PUSHSTRING */
{iU, 1, 0}, /* OP_PUSHNUM */
{iU, 1, 0}, /* OP_PUSHNEGNUM */
{iU, 1, 0}, /* OP_PUSHUPVALUE */
{iU, 1, 0}, /* OP_GETLOCAL */
{iU, 1, 0}, /* OP_GETGLOBAL */
{iO, 1, 2}, /* OP_GETTABLE */
{iU, 1, 1}, /* OP_GETDOTTED */
{iU, 1, 1}, /* OP_GETINDEXED */
{iU, 2, 1}, /* OP_PUSHSELF */
{iU, 1, 0}, /* OP_CREATETABLE */
{iU, 0, 1}, /* OP_SETLOCAL */
{iU, 0, 1}, /* OP_SETGLOBAL */
{iAB, VD, 0}, /* OP_SETTABLE */
{iAB, VD, 0}, /* OP_SETLIST */
{iU, VD, 0}, /* OP_SETMAP */
{iO, 1, 2}, /* OP_ADD */
{iS, 1, 1}, /* OP_ADDI */
{iO, 1, 2}, /* OP_SUB */
{iO, 1, 2}, /* OP_MULT */
{iO, 1, 2}, /* OP_DIV */
{iO, 1, 2}, /* OP_POW */
{iU, VD, 0}, /* OP_CONCAT */
{iO, 1, 1}, /* OP_MINUS */
{iO, 1, 1}, /* OP_NOT */
{iS, 0, 2}, /* OP_JMPNE */
{iS, 0, 2}, /* OP_JMPEQ */
{iS, 0, 2}, /* OP_JMPLT */
{iS, 0, 2}, /* OP_JMPLE */
{iS, 0, 2}, /* OP_JMPGT */
{iS, 0, 2}, /* OP_JMPGE */
{iS, 0, 1}, /* OP_JMPT */
{iS, 0, 1}, /* OP_JMPF */
{iS, 0, 1}, /* OP_JMPONT */
{iS, 0, 1}, /* OP_JMPONF */
{iS, 0, 0}, /* OP_JMP */
{iO, 0, 0}, /* OP_PUSHNILJMP */
{iS, 0, 0}, /* OP_FORPREP */
{iS, 0, 3}, /* OP_FORLOOP */
{iS, 2, 0}, /* OP_LFORPREP */
{iS, 0, 3}, /* OP_LFORLOOP */
{iAB, VD, 0} /* OP_CLOSURE */
};