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lua/lcode.c

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/*
** $Id: lcode.c,v 1.28 2000/04/19 13:41:37 roberto Exp roberto $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
#include "stdlib.h"
#define LUA_REENTRANT
#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->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_code0(fs, OP_JMP);
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 */
}
/*
** discharge list of jumps to last target.
** returns current `pc' and marks it as a jump target (to avoid wrong
** optimizations with consecutive instructions not in the same basic block).
*/
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 (till now) */
}
return fs->pc;
}
void luaK_deltastack (FuncState *fs, int delta) {
fs->stacklevel += delta;
if (delta > 0 && 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 real_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, constantEM, MAXARG_U);
c = f->nknum++;
f->knum[c] = r;
return c;
}
void luaK_number (FuncState *fs, Number f) {
if (f <= (Number)MAXARG_S && (int)f == f)
luaK_code1(fs, OP_PUSHINT, (int)f); /* f has a short integer value */
else
luaK_code1(fs, OP_PUSHNUM, real_constant(fs, f));
}
void luaK_adjuststack (FuncState *fs, int n) {
if (n > 0)
luaK_code1(fs, OP_POP, n);
else if (n < 0)
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 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(ls->L, "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(NULL, "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) {
Instruction *previous;
int *golist = &v->u.l.f;
int *exitlist = &v->u.l.t;
if (invert) { /* interchange `golist' and `exitlist' */
int *temp = golist; golist = exitlist; exitlist = temp;
}
discharge1(fs, v);
previous = &fs->f->code[fs->pc-1];
LUA_ASSERT(L, GET_OPCODE(*previous) != OP_SETLINE, "bad place to set line");
if (ISJUMP(GET_OPCODE(*previous))) {
if (invert)
SET_OPCODE(*previous, invertjump(GET_OPCODE(*previous)));
}
else
luaK_code0(fs, jump);
luaK_concat(fs, exitlist, fs->pc-1); /* 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);
}
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) {
int j = luaK_getlabel(fs);
luaK_code1(fs, op, arg);
return j;
}
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]);
LUA_ASSERT(L, previous != OP_SETLINE, "bad place to set line");
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, 0); /* to jump over both pushes */
luaK_deltastack(fs, -1); /* next PUSHes may be skipped */
}
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, int op, expdesc *v) {
FuncState *fs = ls->fs;
if (op == '-') {
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, int op, expdesc *v) {
FuncState *fs = ls->fs;
if (op == TK_AND)
luaK_goiftrue(fs, v, 1);
else if (op == TK_OR)
luaK_goiffalse(fs, v, 1);
else
luaK_tostack(ls, v, 1); /* all other binary operators need a value */
}
void luaK_posfix (LexState *ls, int op, expdesc *v1, expdesc *v2) {
FuncState *fs = ls->fs;
if (op == TK_AND) {
LUA_ASSERT(ls->L, 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);
}
else if (op == TK_OR) {
LUA_ASSERT(ls->L, 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);
}
else {
luaK_tostack(ls, v2, 1); /* `v2' must be a value */
switch (op) {
case '+': luaK_code0(fs, OP_ADD); break;
case '-': luaK_code0(fs, OP_SUB); break;
case '*': luaK_code0(fs, OP_MULT); break;
case '/': luaK_code0(fs, OP_DIV); break;
case '^': luaK_code0(fs, OP_POW); break;
case TK_CONCAT: luaK_code1(fs, OP_CONCAT, 2); break;
case TK_EQ: luaK_code0(fs, OP_JMPEQ); break;
case TK_NE: luaK_code0(fs, OP_JMPNE); break;
case '>': luaK_code0(fs, OP_JMPGT); break;
case '<': luaK_code0(fs, OP_JMPLT); break;
case TK_GE: luaK_code0(fs, OP_JMPGE); break;
case TK_LE: luaK_code0(fs, OP_JMPLE); break;
}
}
}
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 = 0;
enum {iO, iU, iS, iAB, iP} mode; /* instruction format (or iP to optimize) */
mode = iP;
switch (o) {
case OP_CLOSURE:
delta = -arg2+1;
mode = iAB;
break;
case OP_SETLINE:
mode = iU;
break;
case OP_CALL:
mode = iAB;
break;
case OP_PUSHINT:
delta = 1;
mode = iS;
break;
case OP_SETTABLE:
delta = -arg2;
mode = iAB;
break;
case OP_SETLIST:
delta = -(arg2+1);
mode = iAB;
break;
case OP_SETMAP:
delta = -2*(arg1+1);
mode = iU;
break;
case OP_FORLOOP:
delta = -3;
arg1 = NO_JUMP;
mode = iS;
break;
case OP_SETLOCAL:
case OP_SETGLOBAL:
delta = -1;
mode = iU;
break;
case OP_FORPREP:
case OP_JMP:
arg1 = NO_JUMP;
mode = iS;
break;
case OP_END:
case OP_PUSHNILJMP:
case OP_NOT:
mode = iO;
break;
case OP_PUSHSTRING:
case OP_PUSHNUM:
case OP_PUSHNEGNUM:
case OP_PUSHUPVALUE:
case OP_GETLOCAL:
case OP_GETGLOBAL:
case OP_PUSHSELF:
case OP_CREATETABLE:
delta = 1;
mode = iU;
break;
case OP_JMPLT:
case OP_JMPLE:
case OP_JMPGT:
case OP_JMPGE:
delta = -2;
arg1 = NO_JUMP;
mode = iS;
break;
case OP_MULT:
case OP_DIV:
case OP_POW:
delta = -1;
mode = iO;
break;
case OP_RETURN:
if (GET_OPCODE(i) == OP_CALL && GETARG_B(i) == MULT_RET) {
SET_OPCODE(i, OP_TAILCALL);
SETARG_B(i, arg1);
}
else mode = iU;
break;
case OP_PUSHNIL:
delta = arg1;
switch(GET_OPCODE(i)) {
case OP_PUSHNIL: SETARG_U(i, GETARG_U(i)+arg1); break;
default: mode = iU; break;
}
break;
case OP_POP:
delta = -arg1;
switch(GET_OPCODE(i)) {
case OP_SETTABLE: SETARG_B(i, GETARG_B(i)+arg1); break;
default: mode = iU; break;
}
break;
case OP_GETTABLE:
delta = -1;
switch(GET_OPCODE(i)) {
case OP_PUSHSTRING: SET_OPCODE(i, OP_GETDOTTED); break; /* `t.x' */
case OP_GETLOCAL: SET_OPCODE(i, OP_GETINDEXED); break; /* `t[i]' */
default: mode = iO; break;
}
break;
case OP_ADD:
delta = -1;
switch(GET_OPCODE(i)) {
case OP_PUSHINT: SET_OPCODE(i, OP_ADDI); break; /* `a+k' */
default: mode = iO; break;
}
break;
case OP_SUB:
delta = -1;
switch(GET_OPCODE(i)) {
case OP_PUSHINT: i = CREATE_S(OP_ADDI, -GETARG_S(i)); break; /* `a-k' */
default: mode = iO; break;
}
break;
case OP_CONCAT:
delta = -arg1+1;
switch(GET_OPCODE(i)) {
case OP_CONCAT: SETARG_U(i, GETARG_U(i)+1); break; /* `a..b..c' */
default: mode = iU; break;
}
break;
case OP_MINUS:
switch(GET_OPCODE(i)) {
case OP_PUSHINT: SETARG_S(i, -GETARG_S(i)); break; /* `-k' */
case OP_PUSHNUM: SET_OPCODE(i, OP_PUSHNEGNUM); break; /* `-k' */
default: mode = iO; break;
}
break;
case OP_JMPNE:
delta = -2;
if (i == CREATE_U(OP_PUSHNIL, 1)) /* `a~=nil' */
i = CREATE_S(OP_JMPT, NO_JUMP);
else {
arg1 = NO_JUMP;
mode = iS;
}
break;
case OP_JMPEQ:
delta = -2;
if (i == CREATE_U(OP_PUSHNIL, 1)) { /* `a==nil' */
i = CREATE_0(OP_NOT);
delta = -1; /* just undo effect of previous PUSHNIL */
}
else {
arg1 = NO_JUMP;
mode = iS;
}
break;
case OP_JMPT:
case OP_JMPF:
case OP_JMPONT:
case OP_JMPONF:
delta = -1;
arg1 = NO_JUMP;
switch (GET_OPCODE(i)) {
case OP_NOT: i = CREATE_S(invertjump(o), NO_JUMP); break;
default: mode = iS; break;
}
break;
case OP_GETDOTTED:
case OP_GETINDEXED:
case OP_TAILCALL:
case OP_ADDI:
LUA_INTERNALERROR(L, "instruction used only for optimizations");
return 0; /* to avoid warnings */
}
luaK_deltastack(fs, delta);
switch (mode) { /* handle instruction formats */
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;
case iP: { /* optimize: put instruction in place of last one */
fs->f->code[fs->pc-1] = i; /* change previous instruction */
return fs->pc-1;
}
}
/* actually create the new instruction */
luaM_growvector(fs->L, fs->f->code, fs->pc, 1, Instruction, codeEM, MAX_INT);
fs->f->code[fs->pc] = i;
return fs->pc++;
}
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