/*
** Lua parser (source code -> bytecode).
** Copyright (C) 2005-2009 Mike Pall. See Copyright Notice in luajit.h
**
** Major portions taken verbatim or adapted from the Lua interpreter.
** Copyright (C) 1994-2008 Lua.org, PUC-Rio. See Copyright Notice in lua.h
*/
#define lj_parse_c
#define LUA_CORE
#include "lj_obj.h"
#include "lj_gc.h"
#include "lj_err.h"
#include "lj_str.h"
#include "lj_tab.h"
#include "lj_func.h"
#include "lj_state.h"
#include "lj_bc.h"
#include "lj_lex.h"
#include "lj_parse.h"
#include "lj_vm.h"
#include "lj_vmevent.h"
/* -- Parser structures and definitions ----------------------------------- */
/* Expression kinds. */
typedef enum {
/* Constant expressions must be first and in this order: */
VKNIL,
VKFALSE,
VKTRUE,
VKSTR, /* sval = string value */
VKNUM, /* nval = numerical value */
VKLAST = VKNUM,
/* Non-constant expressions follow: */
VLOCAL, /* info = local register */
VUPVAL, /* info = upvalue index */
VGLOBAL, /* sval = string value */
VINDEXED, /* info = table register, aux = index reg/byte/string const */
VJMP, /* info = instruction PC */
VRELOCABLE, /* info = instruction PC */
VNONRELOC, /* info = result register */
VCALL, /* info = instruction PC, aux = base */
VVOID
} ExpKind;
/* Expression descriptor. */
typedef struct ExpDesc {
union {
struct { uint32_t info, aux; } s;
TValue nval;
GCstr *sval;
} u;
ExpKind k;
BCPos t; /* true condition exit list */
BCPos f; /* false condition exit list */
} ExpDesc;
/* Tests for expression types */
#define isK(e) ((uint32_t)((e)->k) <= VKLAST)
#define isnumK(e) ((e)->k == VKNUM)
#define isstrK(e) ((e)->k == VKSTR)
#define expnumV(e) check_exp(isnumK((e)), numV(&(e)->u.nval))
#define hasjumps(e) ((e)->t != (e)->f)
#define isKexp(e) (isK(e) && !hasjumps(e))
#define isnumKexp(e) (isnumK(e) && !hasjumps(e))
#define priKk(k) check_exp((k) <= VKTRUE, (k) - VKNIL)
#define priK(e) priKk((e)->k)
/* Per-function linked list of blocks. */
typedef struct FuncBlock {
struct FuncBlock *previous; /* chain */
BCPos breaklist; /* list of jumps out of this loop */
uint8_t nactvar; /* # active locals outside the breakable structure */
uint8_t upval; /* true if some variable in the block is an upvalue */
uint8_t isbreakable; /* true if `block' is a loop */
} FuncBlock;
typedef struct UpValDesc {
uint8_t k;
uint8_t info;
} UpValDesc;
/* Per-function state. */
typedef struct FuncState {
GCproto *pt; /* current function header */
GCtab *kt; /* table to find (and reuse) elements in `k' */
struct FuncState *prev; /* enclosing function */
struct LexState *ls; /* lexical state */
struct lua_State *L; /* copy of the Lua state */
struct FuncBlock *bl; /* chain of current blocks */
BCPos pc; /* next bytecode position */
BCPos lasttarget; /* PC of last jump target */
BCPos jpc; /* list of pending jumps to PC */
BCReg freereg; /* first free register */
BCReg nkn, nkgc; /* number of lua_Number/GCobj constants */
uint16_t nlocvars; /* number of elements in `locvars' */
uint8_t nactvar; /* number of active local variables */
uint8_t nuv; /* number of upvalues */
UpValDesc upvalues[LJ_MAX_UPVAL]; /* upvalues */
uint16_t actvar[LJ_MAX_LOCVAR]; /* declared-variable stack */
} FuncState;
/* Binary and unary operators. ORDER OPR */
typedef enum BinOpr {
OPR_ADD, OPR_SUB, OPR_MUL, OPR_DIV, OPR_MOD, OPR_POW, /* ORDER ARITH */
OPR_CONCAT,
OPR_NE, OPR_EQ,
OPR_LT, OPR_GE, OPR_LE, OPR_GT,
OPR_AND, OPR_OR,
OPR_NOBINOPR
} BinOpr;
LJ_STATIC_ASSERT((int)BC_ISGE-(int)BC_ISLT == (int)OPR_GE-(int)OPR_LT);
LJ_STATIC_ASSERT((int)BC_ISLE-(int)BC_ISLT == (int)OPR_LE-(int)OPR_LT);
LJ_STATIC_ASSERT((int)BC_ISGT-(int)BC_ISLT == (int)OPR_GT-(int)OPR_LT);
LJ_STATIC_ASSERT((int)BC_SUBVV-(int)BC_ADDVV == (int)OPR_SUB-(int)OPR_ADD);
LJ_STATIC_ASSERT((int)BC_MULVV-(int)BC_ADDVV == (int)OPR_MUL-(int)OPR_ADD);
LJ_STATIC_ASSERT((int)BC_DIVVV-(int)BC_ADDVV == (int)OPR_DIV-(int)OPR_ADD);
LJ_STATIC_ASSERT((int)BC_MODVV-(int)BC_ADDVV == (int)OPR_MOD-(int)OPR_ADD);
typedef enum UnOpr { OPR_MINUS, OPR_NOT, OPR_LEN, OPR_NOUNOPR } UnOpr;
/* -- Error handling ------------------------------------------------------ */
LJ_NORET LJ_NOINLINE static void err_syntax(LexState *ls, ErrMsg em)
{
lj_lex_error(ls, ls->token, em);
}
LJ_NORET LJ_NOINLINE static void err_token(LexState *ls, LexToken token)
{
lj_lex_error(ls, ls->token, LJ_ERR_XTOKEN, lj_lex_token2str(ls, token));
}
LJ_NORET static void err_limit(FuncState *fs, uint32_t limit, const char *what)
{
if (fs->pt->linedefined == 0)
lj_lex_error(fs->ls, 0, LJ_ERR_XLIMM, limit, what);
else
lj_lex_error(fs->ls, 0, LJ_ERR_XLIMF, fs->pt->linedefined, limit, what);
}
#define checklimit(fs, v, l, m) if ((v) >= (l)) err_limit(fs, l, m)
#define checklimitgt(fs, v, l, m) if ((v) > (l)) err_limit(fs, l, m)
#define checkcond(ls, c, em) { if (!(c)) err_syntax(ls, em); }
/* -- Code emitter: branches ---------------------------------------------- */
static BCPos getjump(FuncState *fs, BCPos pc)
{
ptrdiff_t delta = bc_j(fs->pt->bc[pc]);
if ((BCPos)delta == NO_JMP)
return NO_JMP;
else
return (BCPos)(((ptrdiff_t)pc+1)+delta);
}
static int need_value(FuncState *fs, BCPos list)
{
for (; list != NO_JMP; list = getjump(fs, list)) {
BCOp op = bc_op(fs->pt->bc[list >= 1 ? list-1 : list]);
if (!(op == BC_ISTC || op == BC_ISFC)) return 1;
}
return 0; /* Not found. */
}
static int patchtestreg(FuncState *fs, BCPos pc, BCReg reg)
{
BCIns *i = &fs->pt->bc[pc >= 1 ? pc-1 : pc];
BCOp op = bc_op(*i);
if (!(op == BC_ISTC || op == BC_ISFC))
return 0; /* cannot patch other instructions */
if (reg != NO_REG && reg != bc_d(*i)) {
setbc_a(i, reg);
} else { /* no register to put value or register already has the value */
setbc_op(i, op+(BC_IST-BC_ISTC));
setbc_a(i, 0);
}
return 1;
}
static void removevalues(FuncState *fs, BCPos list)
{
for (; list != NO_JMP; list = getjump(fs, list))
patchtestreg(fs, list, NO_REG);
}
static void fixjump(FuncState *fs, BCPos pc, BCPos dest)
{
BCIns *jmp = &fs->pt->bc[pc];
BCPos offset = dest-(pc+1)+BCBIAS_J;
lua_assert(dest != NO_JMP);
if (offset > BCMAX_D)
err_syntax(fs->ls, LJ_ERR_XJUMP);
setbc_d(jmp, offset);
}
static void concatjumps(FuncState *fs, BCPos *l1, BCPos l2)
{
if (l2 == NO_JMP) return;
else if (*l1 == NO_JMP) {
*l1 = l2;
} else {
BCPos list = *l1;
BCPos next;
while ((next = getjump(fs, list)) != NO_JMP) /* find last element */
list = next;
fixjump(fs, list, l2);
}
}
static void patchlistaux(FuncState *fs, BCPos list, BCPos vtarget,
BCReg reg, BCPos dtarget)
{
while (list != NO_JMP) {
BCPos next = getjump(fs, list);
if (patchtestreg(fs, list, reg))
fixjump(fs, list, vtarget);
else
fixjump(fs, list, dtarget); /* jump to default target */
list = next;
}
}
static void patchtohere(FuncState *fs, BCPos list)
{
fs->lasttarget = fs->pc;
concatjumps(fs, &fs->jpc, list);
}
static void patchlist(FuncState *fs, BCPos list, BCPos target)
{
if (target == fs->pc) {
patchtohere(fs, list);
} else {
lua_assert(target < fs->pc);
patchlistaux(fs, list, target, NO_REG, target);
}
}
/* -- Code emitter: instructions ------------------------------------------ */
static BCPos emitINS(FuncState *fs, BCIns i)
{
GCproto *pt;
patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
fs->jpc = NO_JMP;
pt = fs->pt;
if (LJ_UNLIKELY(fs->pc >= pt->sizebc)) {
checklimit(fs, fs->pc, LJ_MAX_BCINS, "bytecode instructions");
lj_mem_growvec(fs->L, pt->bc, pt->sizebc, LJ_MAX_BCINS, BCIns);
lj_mem_growvec(fs->L, pt->lineinfo, pt->sizelineinfo, LJ_MAX_BCINS, BCLine);
}
pt->bc[fs->pc] = i;
pt->lineinfo[fs->pc] = fs->ls->lastline;
return fs->pc++;
}
#define emitABC(fs, o, a, b, c) emitINS(fs, BCINS_ABC(o, a, b, c))
#define emitAD(fs, o, a, d) emitINS(fs, BCINS_AD(o, a, d))
#define emitAJ(fs, o, a, j) emitINS(fs, BCINS_AJ(o, a, j))
#define bcptr(fs, e) (&(fs)->pt->bc[(e)->u.s.info])
static BCPos emit_jump(FuncState *fs)
{
BCPos jpc = fs->jpc; /* save list of jumps to here */
BCPos j = fs->pc - 1;
fs->jpc = NO_JMP;
if ((int32_t)j >= (int32_t)fs->lasttarget && bc_op(fs->pt->bc[j]) == BC_UCLO)
setbc_j(&fs->pt->bc[j], NO_JMP);
else
j = emitAJ(fs, BC_JMP, fs->freereg, NO_JMP);
concatjumps(fs, &j, jpc); /* keep them on hold */
return j;
}
/* -- Code emitter: constants --------------------------------------------- */
static BCReg numK(FuncState *fs, ExpDesc *e)
{
lua_State *L = fs->L;
TValue *val;
lua_assert(isnumK(e));
val = lj_tab_set(L, fs->kt, &e->u.nval);
if (tvisnum(val))
return val->u32.lo;
val->u64 = fs->nkn;
return fs->nkn++;
}
static BCReg gcK(FuncState *fs, GCobj *gc, int itype)
{
lua_State *L = fs->L;
TValue o, *val;
setgcV(L, &o, &gc->gch, itype);
val = lj_tab_set(L, fs->kt, &o);
if (tvisnum(val))
return val->u32.lo;
val->u64 = fs->nkgc;
return fs->nkgc++;
}
static BCReg strK(FuncState *fs, ExpDesc *e)
{
lua_assert(isstrK(e) || e->k == VGLOBAL);
return gcK(fs, obj2gco(e->u.sval), LJ_TSTR);
}
GCstr *lj_parse_keepstr(LexState *ls, const char *str, size_t len)
{
lua_State *L = ls->L;
GCstr *s = lj_str_new(L, str, len);
TValue *tv = lj_tab_setstr(L, ls->fs->kt, s);
if (tvisnil(tv)) setboolV(tv, 1); /* Anchor string to avoid GC. */
lj_gc_check(L);
return s;
}
static void keep_token(LexState *ls)
{
if (ls->token == TK_name || ls->token == TK_string) {
TValue *tv = lj_tab_setstr(ls->L, ls->fs->kt, strV(&ls->tokenval));
if (tvisnil(tv)) setboolV(tv, 1); /* Anchor string to avoid GC. */
}
}
static void nilK(FuncState *fs, BCReg from, BCReg n)
{
BCIns *pr;
if (fs->pc > fs->lasttarget) { /* no jumps to current position? */
BCReg pfrom, pto;
pr = &fs->pt->bc[fs->pc-1];
pfrom = bc_a(*pr);
switch (bc_op(*pr)) {
case BC_KPRI:
if (bc_d(*pr) != ~LJ_TNIL) break;
if (from == pfrom) {
if (n == 1) return;
} else if (from == pfrom+1) {
from = pfrom;
n++;
} else {
break;
}
fs->pc--;
break;
case BC_KNIL:
pto = bc_d(*pr);
if (pfrom <= from && from <= pto+1) { /* can connect both? */
if (from+n-1 > pto)
setbc_d(pr, from+n-1);
return;
}
break;
default:
break;
}
}
emitINS(fs, n == 1 ? BCINS_AD(BC_KPRI, from, priKk(VKNIL))
: BCINS_AD(BC_KNIL, from, from+n-1));
}
/* -- Code emitter: registers --------------------------------------------- */
static void checkframe(FuncState *fs, BCReg n)
{
BCReg sz = fs->freereg + n;
if (sz > fs->pt->framesize) {
if (sz >= LJ_MAX_SLOTS)
err_syntax(fs->ls, LJ_ERR_XSLOTS);
fs->pt->framesize = cast_byte(sz);
}
}
static void reserveregs(FuncState *fs, BCReg n)
{
checkframe(fs, n);
fs->freereg += n;
}
static void freereg(FuncState *fs, BCReg reg)
{
if (reg >= fs->nactvar) {
fs->freereg--;
lua_assert(reg == fs->freereg);
}
}
static void freeexp(FuncState *fs, ExpDesc *e)
{
if (e->k == VNONRELOC)
freereg(fs, e->u.s.info);
}
/* -- Code emitter: expressions ------------------------------------------- */
static void dischargevars(FuncState *fs, ExpDesc *e)
{
BCIns ins;
switch (e->k) {
case VUPVAL:
ins = BCINS_AD(BC_UGET, 0, e->u.s.info);
break;
case VGLOBAL:
ins = BCINS_AD(BC_GGET, 0, strK(fs, e));
break;
case VINDEXED: {
/* TGET[VSB] key = reg, string const or byte const */
BCReg rc = e->u.s.aux;
if ((int32_t)rc < 0) {
ins = BCINS_ABC(BC_TGETS, 0, e->u.s.info, ~rc);
} else if (rc > BCMAX_C) {
ins = BCINS_ABC(BC_TGETB, 0, e->u.s.info, rc-(BCMAX_C+1));
} else {
freereg(fs, rc);
ins = BCINS_ABC(BC_TGETV, 0, e->u.s.info, rc);
}
freereg(fs, e->u.s.info);
break;
}
case VCALL:
e->u.s.info = e->u.s.aux;
/* fallthrough */
case VLOCAL:
e->k = VNONRELOC;
/* fallthrough */
default:
return;
}
e->u.s.info = emitINS(fs, ins);
e->k = VRELOCABLE;
}
static void discharge2reg(FuncState *fs, ExpDesc *e, BCReg reg)
{
BCIns ins;
dischargevars(fs, e);
switch (e->k) {
case VKNIL: case VKFALSE: case VKTRUE:
ins = BCINS_AD(BC_KPRI, reg, priK(e));
break;
case VKSTR:
ins = BCINS_AD(BC_KSTR, reg, strK(fs, e));
break;
case VKNUM: {
lua_Number n = expnumV(e);
int32_t k = lj_num2int(n);
if (checki16(k) && n == cast_num(k))
ins = BCINS_AD(BC_KSHORT, reg, (BCReg)(uint16_t)k);
else
ins = BCINS_AD(BC_KNUM, reg, numK(fs, e));
break;
}
case VRELOCABLE:
setbc_a(bcptr(fs, e), reg);
goto noins;
case VNONRELOC:
if (reg == e->u.s.info)
goto noins;
ins = BCINS_AD(BC_MOV, reg, e->u.s.info);
break;
default:
lua_assert(e->k == VVOID || e->k == VJMP);
return; /* nothing to do... */
}
emitINS(fs, ins);
noins:
e->u.s.info = reg;
e->k = VNONRELOC;
}
static void exp2reg(FuncState *fs, ExpDesc *e, BCReg reg)
{
discharge2reg(fs, e, reg);
if (e->k == VJMP)
concatjumps(fs, &e->t, e->u.s.info); /* put this jump in `t' list */
if (hasjumps(e)) {
BCPos final; /* position after whole expression */
BCPos p_f = NO_JMP; /* position of an eventual LOAD false */
BCPos p_t = NO_JMP; /* position of an eventual LOAD true */
if (need_value(fs, e->t) || need_value(fs, e->f)) {
BCPos fj = (e->k == VJMP) ? NO_JMP : emit_jump(fs);
p_f = emitAD(fs, BC_KPRI, reg, priKk(VKFALSE));
emitAJ(fs, BC_JMP, fs->freereg, 1);
p_t = emitAD(fs, BC_KPRI, reg, priKk(VKTRUE));
patchtohere(fs, fj);
}
final = fs->pc;
fs->lasttarget = final;
patchlistaux(fs, e->f, final, reg, p_f);
patchlistaux(fs, e->t, final, reg, p_t);
}
e->f = e->t = NO_JMP;
e->u.s.info = reg;
e->k = VNONRELOC;
}
static void exp2nextreg(FuncState *fs, ExpDesc *e)
{
dischargevars(fs, e);
freeexp(fs, e);
reserveregs(fs, 1);
exp2reg(fs, e, fs->freereg - 1);
}
static BCReg exp2anyreg(FuncState *fs, ExpDesc *e)
{
dischargevars(fs, e);
if (e->k == VNONRELOC) {
if (!hasjumps(e)) return e->u.s.info; /* exp is already in a register */
if (e->u.s.info >= fs->nactvar) { /* reg. is not a local? */
exp2reg(fs, e, e->u.s.info); /* put value on it */
return e->u.s.info;
}
}
exp2nextreg(fs, e); /* default */
return e->u.s.info;
}
static void exp2val(FuncState *fs, ExpDesc *e)
{
if (hasjumps(e))
exp2anyreg(fs, e);
else
dischargevars(fs, e);
}
static void storevar(FuncState *fs, ExpDesc *var, ExpDesc *e)
{
BCIns ins;
switch (var->k) {
case VLOCAL:
freeexp(fs, e);
exp2reg(fs, e, var->u.s.info);
return;
case VUPVAL:
exp2val(fs, e);
switch (e->k) {
case VKNIL: case VKFALSE: case VKTRUE:
ins = BCINS_AD(BC_USETP, var->u.s.info, priK(e));
break;
case VKSTR:
ins = BCINS_AD(BC_USETS, var->u.s.info, strK(fs, e));
break;
case VKNUM:
ins = BCINS_AD(BC_USETN, var->u.s.info, numK(fs, e));
break;
default:
ins = BCINS_AD(BC_USETV, var->u.s.info, exp2anyreg(fs, e));
break;
}
break;
case VGLOBAL: {
BCReg ra = exp2anyreg(fs, e);
ins = BCINS_AD(BC_GSET, ra, strK(fs, var));
break;
}
case VINDEXED: {
/* TSET[VSB] key = reg, string const or byte const */
BCReg ra = exp2anyreg(fs, e);
BCReg rc = var->u.s.aux;
if ((int32_t)rc < 0) {
ins = BCINS_ABC(BC_TSETS, ra, var->u.s.info, ~rc);
} else if (rc > BCMAX_C) {
ins = BCINS_ABC(BC_TSETB, ra, var->u.s.info, rc-(BCMAX_C+1));
} else {
/* Free late alloced key reg to avoid assert on free of value reg. */
/* This can only happen when called from constructor(). */
lua_assert(e->k != VNONRELOC || ra < fs->nactvar ||
rc < ra || (freereg(fs, rc),1));
ins = BCINS_ABC(BC_TSETV, ra, var->u.s.info, rc);
}
break;
}
default:
lua_assert(0); /* invalid var kind to store */
return;
}
emitINS(fs, ins);
freeexp(fs, e);
}
static void indexexp(FuncState *fs, ExpDesc *t, ExpDesc *e)
{
/* already called: exp2val(fs, e) */
t->k = VINDEXED;
if (isnumK(e)) {
lua_Number n = expnumV(e);
int32_t k = lj_num2int(n);
if (checku8(k) && n == cast_num(k)) {
t->u.s.aux = BCMAX_C+1+(uint32_t)k; /* 256..511: const byte key */
return;
}
} else if (isstrK(e)) {
BCReg idx = strK(fs, e);
if (idx <= BCMAX_C) {
t->u.s.aux = ~idx; /* -256..-1: const string key */
return;
}
}
t->u.s.aux = exp2anyreg(fs, e); /* 0..255: register */
}
static void methodexp(FuncState *fs, ExpDesc *e, ExpDesc *key)
{
BCReg idx, func, tab = exp2anyreg(fs, e);
freeexp(fs, e);
func = fs->freereg;
emitAD(fs, BC_MOV, func+1, tab);
lua_assert(isstrK(key));
idx = strK(fs, key);
if (idx <= BCMAX_C) {
reserveregs(fs, 2);
emitABC(fs, BC_TGETS, func, tab, idx);
} else {
reserveregs(fs, 3);
emitAD(fs, BC_KSTR, func+2, idx);
emitABC(fs, BC_TGETV, func, tab, func+2);
fs->freereg--;
}
e->u.s.info = func;
e->k = VNONRELOC;
}
/* -- Code emitter: conditionals ------------------------------------------ */
static void invertjump(FuncState *fs, ExpDesc *e)
{
BCIns *i = bcptr(fs, e) - 1;
setbc_op(i, bc_op(*i)^1);
}
static BCPos jumponcond(FuncState *fs, ExpDesc *e, int cond)
{
BCPos pc;
if (e->k == VRELOCABLE) {
BCIns *i = bcptr(fs, e);
if (bc_op(*i) == BC_NOT) {
*i = BCINS_AD(cond ? BC_ISF : BC_IST, 0, bc_d(*i));
return emit_jump(fs);
}
/* else go through */
}
if (e->k != VNONRELOC) {
reserveregs(fs, 1);
discharge2reg(fs, e, fs->freereg-1);
}
emitAD(fs, cond ? BC_ISTC : BC_ISFC, NO_REG, e->u.s.info);
pc = emit_jump(fs);
freeexp(fs, e);
return pc;
}
static void goiftrue(FuncState *fs, ExpDesc *e)
{
BCPos pc; /* PC of last jump. */
dischargevars(fs, e);
switch (e->k) {
case VKSTR: case VKNUM: case VKTRUE:
pc = NO_JMP; /* always true; do nothing */
break;
case VJMP:
invertjump(fs, e);
pc = e->u.s.info;
break;
case VKFALSE:
if (!hasjumps(e)) {
pc = emit_jump(fs); /* always jump */
break;
}
/* fallthrough */
default:
pc = jumponcond(fs, e, 0);
break;
}
concatjumps(fs, &e->f, pc); /* insert last jump in `f' list */
patchtohere(fs, e->t);
e->t = NO_JMP;
}
static void goiffalse(FuncState *fs, ExpDesc *e)
{
BCPos pc; /* PC of last jump. */
dischargevars(fs, e);
switch (e->k) {
case VKNIL: case VKFALSE:
pc = NO_JMP; /* always false; do nothing */
break;
case VJMP:
pc = e->u.s.info;
break;
case VKTRUE:
if (!hasjumps(e)) {
pc = emit_jump(fs); /* always jump */
break;
}
/* fallthrough */
default:
pc = jumponcond(fs, e, 1);
break;
}
concatjumps(fs, &e->t, pc); /* insert last jump in `t' list */
patchtohere(fs, e->f);
e->f = NO_JMP;
}
/* -- Code emitter: operators --------------------------------------------- */
static int foldarith(BinOpr opr, ExpDesc *e1, ExpDesc *e2)
{
TValue o;
if (!isnumKexp(e1) || !isnumKexp(e2)) return 0;
setnumV(&o, lj_vm_foldarith(expnumV(e1), expnumV(e2), (int)opr-OPR_ADD));
if (tvisnan(&o) || tvismzero(&o)) return 0; /* Avoid NaN and -0 as consts. */
setnumV(&e1->u.nval, numV(&o));
return 1;
}
static void codearith(FuncState *fs, BinOpr opr, ExpDesc *e1, ExpDesc *e2)
{
BCReg rb, rc, t;
uint32_t op;
if (foldarith(opr, e1, e2))
return;
if (opr == OPR_POW) {
op = BC_POW;
rc = exp2anyreg(fs, e2);
rb = exp2anyreg(fs, e1);
} else {
op = opr-OPR_ADD+BC_ADDVV;
/* must discharge 2nd operand first since VINDEXED might free regs */
exp2val(fs, e2);
if (isnumK(e2) && (rc = numK(fs, e2)) <= BCMAX_C)
op -= BC_ADDVV-BC_ADDVN;
else
rc = exp2anyreg(fs, e2);
/* emit_prebinop discharges 1st operand, but may need to use KNUM/KSHORT */
lua_assert(isnumK(e1) || e1->k == VNONRELOC);
exp2val(fs, e1);
/* avoid two consts to satisfy bytecode constraints */
if (isnumK(e1) && !isnumK(e2) && (t = numK(fs, e1)) <= BCMAX_B) {
rb = rc; rc = t; op -= BC_ADDVV-BC_ADDNV;
} else {
rb = exp2anyreg(fs, e1);
}
}
/* using freeexp might cause asserts if the order is wrong */
if (e1->k == VNONRELOC && e1->u.s.info >= fs->nactvar) fs->freereg--;
if (e2->k == VNONRELOC && e2->u.s.info >= fs->nactvar) fs->freereg--;
e1->u.s.info = emitABC(fs, op, 0, rb, rc);
e1->k = VRELOCABLE;
}
static void codecomp(FuncState *fs, BinOpr opr, ExpDesc *e1, ExpDesc *e2)
{
ExpDesc *eret = e1;
BCIns ins;
exp2val(fs, e1);
if (opr == OPR_EQ || opr == OPR_NE) {
BCOp op = opr == OPR_EQ ? BC_ISEQV : BC_ISNEV;
BCReg ra;
if (isK(e1)) { e1 = e2; e2 = eret; } /* need constant in 2nd arg */
ra = exp2anyreg(fs, e1); /* first arg must be in a reg */
exp2val(fs, e2);
switch (e2->k) {
case VKNIL: case VKFALSE: case VKTRUE:
ins = BCINS_AD(op+(BC_ISEQP-BC_ISEQV), ra, priK(e2));
break;
case VKSTR:
ins = BCINS_AD(op+(BC_ISEQS-BC_ISEQV), ra, strK(fs, e2));
break;
case VKNUM:
ins = BCINS_AD(op+(BC_ISEQN-BC_ISEQV), ra, numK(fs, e2));
break;
default:
ins = BCINS_AD(op, ra, exp2anyreg(fs, e2));
break;
}
} else {
uint32_t op = opr-OPR_LT+BC_ISLT;
BCReg ra;
if ((op-BC_ISLT) & 1) { /* GT -> LT, GE -> LE */
e1 = e2; e2 = eret; /* swap operands */
op = ((op-BC_ISLT)^3)+BC_ISLT;
}
ra = exp2anyreg(fs, e1);
ins = BCINS_AD(op, ra, exp2anyreg(fs, e2));
}
/* using freeexp might cause asserts if the order is wrong */
if (e1->k == VNONRELOC && e1->u.s.info >= fs->nactvar) fs->freereg--;
if (e2->k == VNONRELOC && e2->u.s.info >= fs->nactvar) fs->freereg--;
emitINS(fs, ins);
eret->u.s.info = emit_jump(fs);
eret->k = VJMP;
}
static void emit_unop(FuncState *fs, UnOpr uop, ExpDesc *e)
{
BCOp op = BC_LEN;
switch (uop) {
case OPR_MINUS:
if (isnumKexp(e) && expnumV(e) != 0) { /* Avoid const-folding to -0. */
setnumV(&e->u.nval, -expnumV(e));
return;
}
op = BC_UNM;
/* fallthrough */
case OPR_LEN:
exp2anyreg(fs, e);
break;
case OPR_NOT:
/* interchange true and false lists */
{ BCPos temp = e->f; e->f = e->t; e->t = temp; }
removevalues(fs, e->f);
removevalues(fs, e->t);
dischargevars(fs, e);
switch (e->k) {
case VKNIL: case VKFALSE:
e->k = VKTRUE;
return;
case VKSTR: case VKNUM: case VKTRUE:
e->k = VKFALSE;
return;
case VJMP:
invertjump(fs, e);
return;
case VRELOCABLE:
reserveregs(fs, 1);
setbc_a(bcptr(fs, e), fs->freereg-1);
e->u.s.info = fs->freereg-1;
e->k = VNONRELOC;
break;
case VNONRELOC:
break;
default: lua_assert(0); return;
}
op = BC_NOT;
break;
default: lua_assert(0); return;
}
freeexp(fs, e);
e->u.s.info = emitAD(fs, op, 0, e->u.s.info);
e->k = VRELOCABLE;
}
static void prepare_binop(FuncState *fs, BinOpr op, ExpDesc *e)
{
switch (op) {
case OPR_AND:
goiftrue(fs, e);
break;
case OPR_OR:
goiffalse(fs, e);
break;
case OPR_CONCAT:
exp2nextreg(fs, e); /* operand must be on the `stack' */
break;
case OPR_EQ: case OPR_NE:
if (!isKexp(e)) exp2anyreg(fs, e);
break;
default:
if (!isnumKexp(e)) exp2anyreg(fs, e);
break;
}
}
static void emit_binop(FuncState *fs, BinOpr op, ExpDesc *e1, ExpDesc *e2)
{
switch (op) {
case OPR_AND:
lua_assert(e1->t == NO_JMP); /* list must be closed */
dischargevars(fs, e2);
concatjumps(fs, &e2->f, e1->f);
*e1 = *e2;
break;
case OPR_OR:
lua_assert(e1->f == NO_JMP); /* list must be closed */
dischargevars(fs, e2);
concatjumps(fs, &e2->t, e1->t);
*e1 = *e2;
break;
case OPR_CONCAT:
exp2val(fs, e2);
if (e2->k == VRELOCABLE && bc_op(*bcptr(fs, e2)) == BC_CAT) {
lua_assert(e1->u.s.info == bc_b(*bcptr(fs, e2))-1);
freeexp(fs, e1);
setbc_b(bcptr(fs, e2), e1->u.s.info);
e1->u.s.info = e2->u.s.info;
} else {
exp2nextreg(fs, e2);
freeexp(fs, e2);
freeexp(fs, e1);
e1->u.s.info = emitABC(fs, BC_CAT, 0, e1->u.s.info, e2->u.s.info);
}
e1->k = VRELOCABLE;
break;
case OPR_ADD: case OPR_SUB: case OPR_MUL:
case OPR_DIV: case OPR_MOD: case OPR_POW:
codearith(fs, op, e1, e2);
break;
case OPR_EQ: case OPR_NE:
case OPR_LT: case OPR_LE: case OPR_GT: case OPR_GE:
codecomp(fs, op, e1, e2);
break;
default: lua_assert(0); break;
}
}
/* -- Lexer support ------------------------------------------------------- */
static int testnext(LexState *ls, LexToken tok)
{
if (ls->token == tok) {
lj_lex_next(ls);
return 1;
}
return 0;
}
static void checknext(LexState *ls, LexToken tok)
{
if (ls->token != tok)
err_token(ls, tok);
lj_lex_next(ls);
}
static void checkmatch(LexState *ls, LexToken what, LexToken who, BCLine line)
{
if (!testnext(ls, what)) {
if (line == ls->linenumber) {
err_token(ls, what);
} else {
const char *swhat = lj_lex_token2str(ls, what);
const char *swho = lj_lex_token2str(ls, who);
lj_lex_error(ls, ls->token, LJ_ERR_XMATCH, swhat, swho, line);
}
}
}
static GCstr *str_checkname(LexState *ls)
{
GCstr *s;
if (ls->token != TK_name)
err_token(ls, TK_name);
s = strV(&ls->tokenval);
lj_lex_next(ls);
return s;
}
static void init_exp(ExpDesc *e, ExpKind k, uint32_t info)
{
e->k = k;
e->u.s.info = info;
e->f = e->t = NO_JMP;
}
static void checkname(LexState *ls, ExpDesc *e)
{
init_exp(e, VKSTR, 0);
e->u.sval = str_checkname(ls);
}
/* -- Variable handling --------------------------------------------------- */
#define getlocvar(fs, i) ((fs)->pt->varinfo[(fs)->actvar[(i)]])
static BCReg registerlocalvar(LexState *ls, GCstr *name)
{
FuncState *fs = ls->fs;
GCproto *pt = fs->pt;
if (LJ_UNLIKELY(fs->nlocvars >= pt->sizevarinfo)) {
MSize oldsize = pt->sizevarinfo;
checklimit(fs, fs->nlocvars, 32767, "local variables");
lj_mem_growvec(fs->L, pt->varinfo, pt->sizevarinfo, 32767, VarInfo);
while (oldsize < pt->sizevarinfo) pt->varinfo[oldsize++].name = NULL;
}
pt->varinfo[fs->nlocvars].name = name;
lj_gc_objbarrier(ls->L, pt, name);
return fs->nlocvars++;
}
static void new_localvar(LexState *ls, GCstr *name, BCReg n)
{
FuncState *fs = ls->fs;
checklimit(fs, fs->nactvar+n, LJ_MAX_LOCVAR, "local variables");
fs->actvar[fs->nactvar+n] = cast(uint16_t, registerlocalvar(ls, name));
}
#define new_localvarliteral(ls,v,n) \
new_localvar(ls, lj_parse_keepstr(ls, "" v, sizeof(v)-1), n)
static void adjustlocalvars(LexState *ls, BCReg nvars)
{
FuncState *fs = ls->fs;
fs->nactvar = cast_byte(fs->nactvar + nvars);
for (; nvars; nvars--)
getlocvar(fs, fs->nactvar - nvars).startpc = fs->pc;
}
static void removevars(LexState *ls, BCReg tolevel)
{
FuncState *fs = ls->fs;
while (fs->nactvar > tolevel)
getlocvar(fs, --fs->nactvar).endpc = fs->pc;
}
static uint32_t indexupvalue(FuncState *fs, GCstr *name, ExpDesc *v)
{
uint32_t i;
GCproto *pt = fs->pt;
for (i = 0; i < fs->nuv; i++) {
if (fs->upvalues[i].k == v->k && fs->upvalues[i].info == v->u.s.info) {
lua_assert(pt->uvname[i] == name);
return i;
}
}
/* Not found, create a new upvalue for this name. */
if (LJ_UNLIKELY(fs->nuv >= pt->sizeuvname)) {
MSize oldsize = pt->sizeuvname;
checklimit(fs, fs->nuv, LJ_MAX_UPVAL, "upvalues");
lj_mem_growvec(fs->L, pt->uvname, pt->sizeuvname, LJ_MAX_UPVAL, GCstr *);
while (oldsize < pt->sizeuvname) pt->uvname[oldsize++] = NULL;
}
pt->uvname[fs->nuv] = name;
lj_gc_objbarrier(fs->L, pt, name);
lua_assert(v->k == VLOCAL || v->k == VUPVAL);
fs->upvalues[fs->nuv].k = cast_byte(v->k);
fs->upvalues[fs->nuv].info = cast_byte(v->u.s.info);
return fs->nuv++;
}
static BCReg searchvar(FuncState *fs, GCstr *n)
{
int i;
for (i = fs->nactvar-1; i >= 0; i--) {
if (n == getlocvar(fs, i).name)
return (BCReg)i;
}
return (BCReg)-1; /* Not found. */
}
static void markupval(FuncState *fs, BCReg level)
{
FuncBlock *bl = fs->bl;
while (bl && bl->nactvar > level) bl = bl->previous;
if (bl) bl->upval = 1;
}
static int singlevaraux(FuncState *fs, GCstr *name, ExpDesc *e, int first)
{
if (fs == NULL) { /* no more levels? */
init_exp(e, VGLOBAL, 0); /* default is global variable */
e->u.sval = name;
return 1;
} else {
BCReg reg = searchvar(fs, name); /* look up at current level */
if ((int32_t)reg >= 0) {
init_exp(e, VLOCAL, reg);
if (!first)
markupval(fs, reg); /* local will be used as an upval */
return 0;
} else { /* not found at current level; try upper one */
if (singlevaraux(fs->prev, name, e, 0)) /* global? */
return 1;
e->u.s.info = indexupvalue(fs, name, e); /* else was local or upvalue */
e->k = VUPVAL; /* upvalue in this level */
return 0;
}
}
}
#define singlevar(ls, e) singlevaraux((ls)->fs, str_checkname(ls), (e), 1)
static void adjust_assign(LexState *ls, BCReg nvars, BCReg nexps, ExpDesc *e)
{
FuncState *fs = ls->fs;
int32_t extra = (int32_t)nvars - (int32_t)nexps;
if (e->k == VCALL) {
extra++; /* includes call itself */
if (extra < 0) extra = 0;
setbc_b(bcptr(fs, e), extra+1);
if (extra > 1) reserveregs(fs, (BCReg)extra-1);
} else {
if (e->k != VVOID) exp2nextreg(fs, e); /* close last expression */
if (extra > 0) {
BCReg reg = fs->freereg;
reserveregs(fs, (BCReg)extra);
nilK(fs, reg, (BCReg)extra);
}
}
}
/* -- Function handling --------------------------------------------------- */
/* Forward declaration. */
static void chunk(LexState *ls);
static void open_func(LexState *ls, FuncState *fs)
{
lua_State *L = ls->L;
GCproto *pt = lj_func_newproto(L);
fs->pt = pt;
fs->prev = ls->fs; /* linked list of funcstates */
fs->ls = ls;
fs->L = L;
ls->fs = fs;
fs->pc = 0;
fs->lasttarget = 0;
fs->jpc = NO_JMP;
fs->freereg = 0;
fs->nkgc = 0;
fs->nkn = 0;
fs->nlocvars = 0;
fs->nactvar = 0;
fs->nuv = 0;
fs->bl = NULL;
pt->chunkname = ls->chunkname;
pt->framesize = 2; /* registers 0/1 are always valid */
fs->kt = lj_tab_new(L, 0, 0);
/* anchor table of constants and prototype (to avoid being collected) */
settabV(L, L->top, fs->kt);
incr_top(L);
setprotoV(L, L->top, pt);
incr_top(L);
}
static void collectk(FuncState *fs, GCproto *pt)
{
GCtab *kt;
TValue *array;
Node *node;
BCReg nkgc;
MSize i, hmask, sizek;
GCRef *kstart;
checklimitgt(fs, fs->nkn, BCMAX_D+1, "constants");
checklimitgt(fs, fs->nkgc, BCMAX_D+1, "constants");
nkgc = round_nkgc(fs->nkgc);
sizek = (MSize)(nkgc*sizeof(MRef) + fs->nkn*sizeof(lua_Number));
kstart = lj_mem_newt(fs->L, sizek, GCRef);
if (nkgc) setgcrefnull(kstart[0]); /* May be uninitialized otherwise. */
pt->k.gc = kstart + nkgc;
pt->sizekn = fs->nkn;
pt->sizekgc = fs->nkgc;
kt = fs->kt;
array = tvref(kt->array);
for (i = 0; i < kt->asize; i++)
if (tvisnum(&array[i]))
pt->k.n[array[i].u32.lo] = cast_num(i);
node = noderef(kt->node);
hmask = kt->hmask;
for (i = 0; i <= hmask; i++) {
Node *n = &node[i];
if (tvisnum(&n->val)) {
ptrdiff_t kidx = (ptrdiff_t)n->val.u32.lo;
if (tvisnum(&n->key)) {
pt->k.n[kidx] = numV(&n->key);
} else {
GCobj *o = gcV(&n->key);
setgcref(pt->k.gc[~kidx], o);
lj_gc_objbarrier(fs->L, pt, o);
}
}
}
}
static void collectuv(FuncState *fs, GCproto *pt)
{
uint32_t i;
pt->uv = lj_mem_newvec(fs->L, fs->nuv, int16_t);
pt->sizeuv = fs->nuv;
for (i = 0; i < pt->sizeuv; i++) {
uint32_t v = fs->upvalues[i].info;
if (fs->upvalues[i].k == VUPVAL) v = ~v;
pt->uv[i] = (int16_t)v;
}
}
static void finalret(FuncState *fs, GCproto *pt)
{
BCPos lastpc = fs->pc;
if (lastpc > fs->lasttarget) {
switch (bc_op(pt->bc[lastpc-1])) {
case BC_CALLMT: case BC_CALLT:
case BC_RETM: case BC_RET: case BC_RET0: case BC_RET1:
goto suppress_return; /* already got a return */
default: break;
}
}
if (fs->pt->flags & PROTO_HAS_FNEW)
emitAJ(fs, BC_UCLO, 0, 0);
emitAD(fs, BC_RET0, 0, 1); /* final return */
suppress_return:
/* may need to fixup returns encoded before first function was created */
if (fs->pt->flags & PROTO_FIXUP_RETURN) {
BCPos pc;
for (pc = 0; pc < lastpc; pc++) {
BCIns i = pt->bc[pc];
BCPos offset;
switch (bc_op(i)) {
case BC_CALLMT: case BC_CALLT:
case BC_RETM: case BC_RET: case BC_RET0: case BC_RET1:
offset = emitINS(fs, i)-(pc+1)+BCBIAS_J; /* copy return ins */
if (offset > BCMAX_D)
err_syntax(fs->ls, LJ_ERR_XFIXUP);
pt->bc[pc] = BCINS_AD(BC_UCLO, 0, offset); /* replace w/ UCLO+branch */
break;
case BC_UCLO: return; /* we're done */
default: break;
}
}
}
}
static void close_func(LexState *ls)
{
lua_State *L = ls->L;
FuncState *fs = ls->fs;
GCproto *pt = fs->pt;
removevars(ls, 0);
finalret(fs, pt);
lj_mem_reallocvec(L, pt->bc, pt->sizebc, fs->pc, BCIns);
pt->sizebc = fs->pc;
collectk(fs, pt);
collectuv(fs, pt);
lj_mem_reallocvec(L, pt->lineinfo, pt->sizelineinfo, fs->pc, BCLine);
pt->sizelineinfo = fs->pc;
lj_mem_reallocvec(L, pt->varinfo, pt->sizevarinfo, fs->nlocvars, VarInfo);
pt->sizevarinfo = fs->nlocvars;
lj_mem_reallocvec(L, pt->uvname, pt->sizeuvname, fs->nuv, GCstr *);
pt->sizeuvname = fs->nuv;
lua_assert(fs->bl == NULL);
lj_vmevent_send(L, BC,
setprotoV(L, L->top++, pt);
);
ls->fs = fs->prev;
L->top -= 2; /* Remove table and prototype from the stack. */
lua_assert(ls->fs != NULL || ls->token == TK_eof);
keep_token(ls); /* Re-anchor last token. */
}
GCproto *lj_parse(LexState *ls)
{
struct FuncState fs;
ls->level = 0;
open_func(ls, &fs);
fs.pt->flags |= PROTO_IS_VARARG; /* Main chunk is always a vararg func. */
lj_lex_next(ls); /* Read-ahead first token. */
chunk(ls);
if (ls->token != TK_eof)
err_token(ls, TK_eof);
fs.pt->lastlinedefined = ls->linenumber;
close_func(ls);
lua_assert(fs.prev == NULL);
lua_assert(fs.pt->sizeuv == 0);
lua_assert(ls->fs == NULL);
return fs.pt;
}
/* -- Expressions --------------------------------------------------------- */
/* forward declaration */
static void expr(LexState *ls, ExpDesc *v);
static void field(LexState *ls, ExpDesc *v)
{
/* field -> ['.' | ':'] NAME */
FuncState *fs = ls->fs;
ExpDesc key;
exp2anyreg(fs, v);
lj_lex_next(ls); /* skip the dot or colon */
checkname(ls, &key);
indexexp(fs, v, &key);
}
static void yindex(LexState *ls, ExpDesc *v)
{
/* index -> '[' expr ']' */
lj_lex_next(ls); /* skip the '[' */
expr(ls, v);
exp2val(ls->fs, v);
checknext(ls, ']');
}
static void kexp2tv(TValue *v, ExpDesc *e)
{
switch (e->k) {
case VKNIL: case VKFALSE: case VKTRUE: v->it = ~(int32_t)e->k; break;
case VKSTR:
setgcref(v->gcr, obj2gco(e->u.sval)); v->it = LJ_TSTR; break;
case VKNUM: setnumV(v, expnumV(e)); break;
default: lua_assert(0); break;
}
}
static void constructor(LexState *ls, ExpDesc *e)
{
FuncState *fs = ls->fs;
BCLine line = ls->linenumber;
GCtab *t = NULL;
int vcall = 0, needarr = 0;
int32_t narr = 1; /* first array index */
uint32_t nhash = 0; /* number of hash entries */
BCReg freg = fs->freereg;
BCPos pc = emitAD(fs, BC_TNEW, freg, 0);
init_exp(e, VNONRELOC, freg);
reserveregs(fs, 1);
freg++;
checknext(ls, '{');
while (ls->token != '}') {
ExpDesc key, val;
vcall = 0;
if (ls->token == '[') {
yindex(ls, &key); /* already calls exp2val */
if (!isK(&key)) indexexp(fs, e, &key);
if (isnumK(&key) && expnumV(&key) == 0) needarr = 1; else nhash++;
checknext(ls, '=');
} else if (ls->token == TK_name && lj_lex_lookahead(ls) == '=') {
checkname(ls, &key);
checknext(ls, '=');
nhash++;
} else {
init_exp(&key, VKNUM, 0);
setintV(&key.u.nval, narr);
narr++;
needarr = vcall = 1;
}
expr(ls, &val);
if (isKexp(&val) && isK(&key) && key.k != VKNIL) {
TValue k;
if (!t) { /* create template table on demand */
BCReg kidx;
t = lj_tab_new(fs->L, 0, 0);
kidx = gcK(fs, obj2gco(t), LJ_TTAB);
fs->pt->bc[pc] = BCINS_AD(BC_TDUP, freg-1, kidx);
}
vcall = 0;
kexp2tv(&k, &key);
kexp2tv(lj_tab_set(fs->L, t, &k), &val);
if (val.k == VKSTR)
lj_gc_objbarriert(fs->L, t, val.u.sval);
} else {
if (isK(&key)) indexexp(fs, e, &key);
if (val.k != VCALL) vcall = 0;
storevar(fs, e, &val);
}
fs->freereg = freg;
if (!testnext(ls, ',') && !testnext(ls, ';')) break;
}
checkmatch(ls, '}', '{', line);
if (vcall) {
BCIns *i = &fs->pt->bc[fs->pc-1];
ExpDesc en;
lua_assert(bc_a(*i)==freg && bc_op(*i) == (narr>256?BC_TSETV:BC_TSETB));
init_exp(&en, VKNUM, 0);
setintV(&en.u.nval, narr-1);
if (narr > 256) { fs->pc--; i--; }
*i = BCINS_AD(BC_TSETM, freg, numK(fs, &en));
setbc_b(i-1, 0);
}
if (pc == fs->pc-1) { /* make expr relocable if possible */
e->u.s.info = pc;
fs->freereg--;
e->k = VRELOCABLE;
} else {
e->k = VNONRELOC; /* indexexp may have changed it */
}
if (!t) { /* Construct TNEW RD: hhhhhaaaaaaaaaaa. */
if (!needarr) narr = 0;
else if (narr < 3) narr = 3;
else if (narr > 0x7ff) narr = 0x7ff;
setbc_d(&fs->pt->bc[pc], (uint32_t)narr | (hsize2hbits(nhash) << 11));
}
}
static void parlist(LexState *ls)
{
/* parlist -> [ param { `,' param } ] */
FuncState *fs = ls->fs;
GCproto *pt = fs->pt;
BCReg nparams = 0;
if (ls->token != ')') { /* is `parlist' not empty? */
do {
switch (ls->token) {
case TK_name: /* param -> NAME */
new_localvar(ls, str_checkname(ls), nparams++);
break;
case TK_dots: /* param -> `...' */
lj_lex_next(ls);
pt->flags |= PROTO_IS_VARARG;
break;
default:
err_syntax(ls, LJ_ERR_XPARAM);
break;
}
} while (!(pt->flags & PROTO_IS_VARARG) && testnext(ls, ','));
}
adjustlocalvars(ls, nparams);
pt->numparams = cast_byte(fs->nactvar);
reserveregs(fs, fs->nactvar); /* reserve register for parameters */
}
static void body(LexState *ls, ExpDesc *e, int needself, BCLine line)
{
/* body -> `(' parlist `)' chunk END */
FuncState *fs, new_fs;
BCReg kidx;
open_func(ls, &new_fs);
new_fs.pt->linedefined = line;
checknext(ls, '(');
if (needself) {
new_localvarliteral(ls, "self", 0);
adjustlocalvars(ls, 1);
}
parlist(ls);
checknext(ls, ')');
chunk(ls);
new_fs.pt->lastlinedefined = ls->linenumber;
checkmatch(ls, TK_end, TK_function, line);
close_func(ls);
fs = ls->fs;
kidx = gcK(fs, obj2gco(new_fs.pt), LJ_TPROTO);
init_exp(e, VRELOCABLE, emitAD(fs, BC_FNEW, 0, kidx));
if (!(fs->pt->flags & PROTO_HAS_FNEW)) {
if (fs->pt->flags & PROTO_HAS_RETURN)
fs->pt->flags |= PROTO_FIXUP_RETURN;
fs->pt->flags |= PROTO_HAS_FNEW;
}
}
static BCReg explist1(LexState *ls, ExpDesc *v)
{
/* explist1 -> expr { `,' expr } */
BCReg n = 1; /* at least one expression */
expr(ls, v);
while (testnext(ls, ',')) {
exp2nextreg(ls->fs, v);
expr(ls, v);
n++;
}
return n;
}
static void funcargs(LexState *ls, ExpDesc *e)
{
FuncState *fs = ls->fs;
ExpDesc args;
BCIns ins;
BCReg base;
BCLine line = ls->linenumber;
switch (ls->token) {
case '(': { /* funcargs -> `(' [ explist1 ] `)' */
if (line != ls->lastline)
err_syntax(ls, LJ_ERR_XAMBIG);
lj_lex_next(ls);
if (ls->token == ')') { /* arg list is empty? */
args.k = VVOID;
} else {
explist1(ls, &args);
if (args.k == VCALL)
setbc_b(bcptr(fs, &args), 0);
}
checkmatch(ls, ')', '(', line);
break;
}
case '{': { /* funcargs -> constructor */
constructor(ls, &args);
break;
}
case TK_string: { /* funcargs -> STRING */
init_exp(&args, VKSTR, 0);
args.u.sval = strV(&ls->tokenval);
lj_lex_next(ls); /* must use `seminfo' before `next' */
break;
}
default: {
err_syntax(ls, LJ_ERR_XFUNARG);
return;
}
}
lua_assert(e->k == VNONRELOC);
base = e->u.s.info; /* base register for call */
if (args.k == VCALL) {
ins = BCINS_ABC(BC_CALLM, base, 2, args.u.s.aux - base - 1);
} else {
if (args.k != VVOID)
exp2nextreg(fs, &args); /* close last argument */
ins = BCINS_ABC(BC_CALL, base, 2, fs->freereg - base);
}
init_exp(e, VCALL, emitINS(fs, ins));
e->u.s.aux = base;
fs->pt->lineinfo[fs->pc - 1] = line;
fs->freereg = base+1; /* call removes function and arguments and leaves
(unless changed) one result */
}
static void prefixexp(LexState *ls, ExpDesc *v)
{
/* prefixexp -> NAME | '(' expr ')' */
switch (ls->token) {
case '(': {
BCLine line = ls->linenumber;
lj_lex_next(ls);
expr(ls, v);
checkmatch(ls, ')', '(', line);
dischargevars(ls->fs, v);
return;
}
case TK_name: {
singlevar(ls, v);
return;
}
default: {
err_syntax(ls, LJ_ERR_XSYMBOL);
return;
}
}
}
static void primaryexp(LexState *ls, ExpDesc *v)
{
/* primaryexp ->
prefixexp { `.' NAME | `[' exp `]' | `:' NAME funcargs | funcargs } */
FuncState *fs = ls->fs;
prefixexp(ls, v);
for (;;) {
switch (ls->token) {
case '.': /* field */
field(ls, v);
break;
case '[': { /* `[' exp1 `]' */
ExpDesc key;
exp2anyreg(fs, v);
yindex(ls, &key);
indexexp(fs, v, &key);
break;
}
case ':': { /* `:' NAME funcargs */
ExpDesc key;
lj_lex_next(ls);
checkname(ls, &key);
methodexp(fs, v, &key);
funcargs(ls, v);
break;
}
case '(': case TK_string: case '{': /* funcargs */
exp2nextreg(fs, v);
funcargs(ls, v);
break;
default: return;
}
}
}
static void simpleexp(LexState *ls, ExpDesc *v)
{
/* simpleexp -> NUMBER | STRING | NIL | true | false | ... |
constructor | FUNCTION body | primaryexp */
switch (ls->token) {
case TK_number:
init_exp(v, VKNUM, 0);
setnumV(&v->u.nval, numV(&ls->tokenval));
break;
case TK_string:
init_exp(v, VKSTR, 0);
v->u.sval = strV(&ls->tokenval);
break;
case TK_nil:
init_exp(v, VKNIL, 0);
break;
case TK_true:
init_exp(v, VKTRUE, 0);
break;
case TK_false:
init_exp(v, VKFALSE, 0);
break;
case TK_dots: { /* vararg */
FuncState *fs = ls->fs;
BCReg base;
checkcond(ls, fs->pt->flags & PROTO_IS_VARARG, LJ_ERR_XDOTS);
reserveregs(fs, 1);
base = fs->freereg-1;
init_exp(v, VCALL, emitABC(fs, BC_VARG, base, 2, 1));
v->u.s.aux = base;
break;
}
case '{': /* constructor */
constructor(ls, v);
return;
case TK_function:
lj_lex_next(ls);
body(ls, v, 0, ls->linenumber);
return;
default:
primaryexp(ls, v);
return;
}
lj_lex_next(ls);
}
static void enterlevel(LexState *ls)
{
if (++ls->level >= LJ_MAX_XLEVEL)
lj_lex_error(ls, 0, LJ_ERR_XLEVELS);
}
#define leavelevel(ls) ((ls)->level--)
static UnOpr getunopr(LexToken tok)
{
switch (tok) {
case TK_not: return OPR_NOT;
case '-': return OPR_MINUS;
case '#': return OPR_LEN;
default: return OPR_NOUNOPR;
}
}
static BinOpr getbinopr(LexToken tok)
{
switch (tok) {
case '+': return OPR_ADD;
case '-': return OPR_SUB;
case '*': return OPR_MUL;
case '/': return OPR_DIV;
case '%': return OPR_MOD;
case '^': return OPR_POW;
case TK_concat: return OPR_CONCAT;
case TK_ne: return OPR_NE;
case TK_eq: return OPR_EQ;
case '<': return OPR_LT;
case TK_le: return OPR_LE;
case '>': return OPR_GT;
case TK_ge: return OPR_GE;
case TK_and: return OPR_AND;
case TK_or: return OPR_OR;
default: return OPR_NOBINOPR;
}
}
static const struct {
uint8_t left; /* left priority for each binary operator */
uint8_t right; /* right priority */
} priority[] = { /* ORDER OPR */
{6,6}, {6,6}, {7,7}, {7,7}, {7,7}, /* ADD SUB MUL DIV MOD */
{10,9}, {5,4}, /* POW CONCAT (right associative) */
{3,3}, {3,3}, /* EQ NE */
{3,3}, {3,3}, {3,3}, {3,3}, /* LT GE GT LE */
{2,2}, {1,1} /* AND OR */
};
#define UNARY_PRIORITY 8 /* priority for unary operators */
/*
** subexpr -> (simpleexp | unop subexpr) { binop subexpr }
** where `binop' is any binary operator with a priority higher than `limit'
*/
static BinOpr subexpr(LexState *ls, ExpDesc *v, uint32_t limit)
{
BinOpr op;
UnOpr uop;
enterlevel(ls);
uop = getunopr(ls->token);
if (uop != OPR_NOUNOPR) {
lj_lex_next(ls);
subexpr(ls, v, UNARY_PRIORITY);
emit_unop(ls->fs, uop, v);
} else {
simpleexp(ls, v);
}
/* expand while operators have priorities higher than `limit' */
op = getbinopr(ls->token);
while (op != OPR_NOBINOPR && priority[op].left > limit) {
ExpDesc v2;
BinOpr nextop;
lj_lex_next(ls);
prepare_binop(ls->fs, op, v);
/* read sub-expression with higher priority */
nextop = subexpr(ls, &v2, priority[op].right);
emit_binop(ls->fs, op, v, &v2);
op = nextop;
}
leavelevel(ls);
return op; /* return first untreated operator */
}
static void expr(LexState *ls, ExpDesc *v)
{
subexpr(ls, v, 0);
}
static BCPos condexpr(LexState *ls)
{
/* cond -> exp */
ExpDesc v;
expr(ls, &v); /* read condition */
if (v.k == VKNIL) v.k = VKFALSE; /* `falses' are all equal here */
goiftrue(ls->fs, &v);
return v.f;
}
/* -- Scope handling ------------------------------------------------------ */
static void enterblock(FuncState *fs, FuncBlock *bl, int isbreakable)
{
bl->breaklist = NO_JMP;
bl->isbreakable = (uint8_t)isbreakable;
bl->nactvar = fs->nactvar;
bl->upval = 0;
bl->previous = fs->bl;
fs->bl = bl;
lua_assert(fs->freereg == fs->nactvar);
}
static void leaveblock(FuncState *fs)
{
FuncBlock *bl = fs->bl;
fs->bl = bl->previous;
removevars(fs->ls, bl->nactvar);
fs->freereg = fs->nactvar; /* free registers */
lua_assert(bl->nactvar == fs->nactvar);
/* a block either controls scope or breaks (never both) */
lua_assert(!bl->isbreakable || !bl->upval);
if (bl->upval)
emitAJ(fs, BC_UCLO, bl->nactvar, 0);
else /* avoid in upval case, it clears lasttarget and kills UCLO+JMP join */
patchtohere(fs, bl->breaklist);
}
static void block(LexState *ls)
{
/* block -> chunk */
FuncState *fs = ls->fs;
FuncBlock bl;
enterblock(fs, &bl, 0);
chunk(ls);
lua_assert(bl.breaklist == NO_JMP);
leaveblock(fs);
}
/* -- Statements ---------------------------------------------------------- */
/*
** structure to chain all variables in the left-hand side of an
** assignment
*/
struct LHS_assign {
ExpDesc v; /* variable (global, local, upvalue, or indexed) */
struct LHS_assign *prev;
};
/*
** check whether, in an assignment to a local variable, the local variable
** is needed in a previous assignment (to a table). If so, save original
** local value in a safe place and use this safe copy in the previous
** assignment.
*/
static void check_conflict(LexState *ls, struct LHS_assign *lh,
const ExpDesc *v)
{
FuncState *fs = ls->fs;
BCReg reg = fs->freereg; /* eventual position to save local variable */
int conflict = 0;
for (; lh; lh = lh->prev) {
if (lh->v.k == VINDEXED) {
if (lh->v.u.s.info == v->u.s.info) { /* conflict? */
conflict = 1;
lh->v.u.s.info = reg; /* previous assignment will use safe copy */
}
if (lh->v.u.s.aux == v->u.s.info) { /* conflict? */
conflict = 1;
lh->v.u.s.aux = reg; /* previous assignment will use safe copy */
}
}
}
if (conflict) {
emitAD(fs, BC_MOV, reg, v->u.s.info); /* make copy */
reserveregs(fs, 1);
}
}
static void assignment(LexState *ls, struct LHS_assign *lh, BCReg nvars)
{
ExpDesc e;
checkcond(ls, VLOCAL <= lh->v.k && lh->v.k <= VINDEXED, LJ_ERR_XSYNTAX);
if (testnext(ls, ',')) { /* assignment -> `,' primaryexp assignment */
struct LHS_assign nv;
nv.prev = lh;
primaryexp(ls, &nv.v);
if (nv.v.k == VLOCAL)
check_conflict(ls, lh, &nv.v);
checklimit(ls->fs, ls->level + nvars, LJ_MAX_XLEVEL, "variable names");
assignment(ls, &nv, nvars+1);
} else { /* assignment -> `=' explist1 */
BCReg nexps;
checknext(ls, '=');
nexps = explist1(ls, &e);
if (nexps == nvars) {
if (e.k == VCALL) {
if (bc_op(*bcptr(ls->fs, &e)) == BC_VARG) {
ls->fs->freereg--;
e.k = VRELOCABLE;
} else {
e.u.s.info = e.u.s.aux;
e.k = VNONRELOC;
}
}
storevar(ls->fs, &lh->v, &e);
return;
}
adjust_assign(ls, nvars, nexps, &e);
if (nexps > nvars)
ls->fs->freereg -= nexps - nvars; /* remove extra values */
}
init_exp(&e, VNONRELOC, ls->fs->freereg-1); /* default assignment */
storevar(ls->fs, &lh->v, &e);
}
static void breakstat(LexState *ls)
{
FuncState *fs = ls->fs;
FuncBlock *bl = fs->bl;
int upval = 0;
while (bl && !bl->isbreakable) {
upval |= bl->upval;
bl = bl->previous;
}
if (!bl)
err_syntax(ls, LJ_ERR_XBREAK);
if (upval)
emitAJ(fs, BC_UCLO, bl->nactvar, 0);
concatjumps(fs, &bl->breaklist, emit_jump(fs));
}
static void whilestat(LexState *ls, BCLine line)
{
/* whilestat -> WHILE cond DO block END */
FuncState *fs = ls->fs;
BCPos start, loop, condexit;
FuncBlock bl;
lj_lex_next(ls); /* skip WHILE */
start = fs->lasttarget = fs->pc;
condexit = condexpr(ls);
enterblock(fs, &bl, 1);
checknext(ls, TK_do);
loop = emitAD(fs, BC_LOOP, fs->nactvar, 0);
block(ls);
patchlist(fs, emit_jump(fs), start);
checkmatch(ls, TK_end, TK_while, line);
leaveblock(fs);
patchtohere(fs, condexit); /* false conditions finish the loop */
fixjump(fs, loop, fs->pc);
}
static void repeatstat(LexState *ls, BCLine line)
{
/* repeatstat -> REPEAT block UNTIL cond */
FuncState *fs = ls->fs;
BCPos loop = fs->lasttarget = fs->pc;
BCPos condexit;
FuncBlock bl1, bl2;
enterblock(fs, &bl1, 1); /* loop block */
enterblock(fs, &bl2, 0); /* scope block */
lj_lex_next(ls); /* skip REPEAT */
emitAD(fs, BC_LOOP, fs->nactvar, 0);
chunk(ls);
checkmatch(ls, TK_until, TK_repeat, line);
condexit = condexpr(ls); /* read condition (inside scope block) */
if (!bl2.upval) { /* no upvalues? */
leaveblock(fs); /* finish scope */
} else { /* complete semantics when there are upvalues */
breakstat(ls); /* if condition then break */
patchtohere(fs, condexit); /* else... */
leaveblock(fs); /* finish scope... */
condexit = emit_jump(fs); /* and repeat */
}
patchlist(fs, condexit, loop); /* close the loop */
fixjump(fs, loop, fs->pc);
leaveblock(fs); /* finish loop */
}
static void exp1(LexState *ls)
{
ExpDesc e;
expr(ls, &e);
exp2nextreg(ls->fs, &e);
}
static void forbody(LexState *ls, BCReg base, BCLine line, BCReg nvars,
int isnum)
{
/* forbody -> DO block */
FuncBlock bl;
FuncState *fs = ls->fs;
BCPos loop, loopend;
adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_do);
loop = isnum ? emitAJ(fs, BC_FORI, base, NO_JMP) :
emitAJ(fs, BC_JMP, fs->freereg, NO_JMP);
enterblock(fs, &bl, 0); /* scope for declared variables */
adjustlocalvars(ls, nvars);
reserveregs(fs, nvars);
block(ls);
leaveblock(fs); /* end of scope for declared variables */
if (isnum) {
loopend = emitAJ(fs, BC_FORL, base, NO_JMP);
fixjump(fs, loop, fs->pc);
} else {
fixjump(fs, loop, fs->pc);
emitABC(fs, BC_ITERC, base+3, nvars+1, 2+1);
loopend = emitAJ(fs, BC_ITERL, base+3, NO_JMP);
fs->pt->lineinfo[loopend-1] = line;
}
fs->pt->lineinfo[loopend] = line; /* pretend last op starts the loop */
fixjump(fs, loopend, loop+1);
}
static void fornum(LexState *ls, GCstr *varname, BCLine line)
{
/* fornum -> NAME = exp1,exp1[,exp1] forbody */
FuncState *fs = ls->fs;
BCReg base = fs->freereg;
new_localvarliteral(ls, "(for index)", FORL_IDX);
new_localvarliteral(ls, "(for limit)", FORL_STOP);
new_localvarliteral(ls, "(for step)", FORL_STEP);
new_localvar(ls, varname, FORL_EXT);
checknext(ls, '=');
exp1(ls); /* initial value */
checknext(ls, ',');
exp1(ls); /* limit */
if (testnext(ls, ',')) {
exp1(ls); /* optional step */
} else { /* default step = 1 */
emitAD(fs, BC_KSHORT, fs->freereg, 1);
reserveregs(fs, 1);
}
forbody(ls, base, line, 1, 1);
}
static void forlist(LexState *ls, GCstr *indexname)
{
/* forlist -> NAME {,NAME} IN explist1 forbody */
FuncState *fs = ls->fs;
ExpDesc e;
BCReg nvars = 0;
BCLine line;
BCReg base = fs->freereg;
/* create control variables */
new_localvarliteral(ls, "(for generator)", nvars++);
new_localvarliteral(ls, "(for state)", nvars++);
new_localvarliteral(ls, "(for control)", nvars++);
/* create declared variables */
new_localvar(ls, indexname, nvars++);
while (testnext(ls, ','))
new_localvar(ls, str_checkname(ls), nvars++);
checknext(ls, TK_in);
line = ls->linenumber;
adjust_assign(ls, 3, explist1(ls, &e), &e);
checkframe(fs, 3); /* extra space to call generator */
forbody(ls, base, line, nvars - 3, 0);
}
static void forstat(LexState *ls, BCLine line)
{
/* forstat -> FOR (fornum | forlist) END */
FuncState *fs = ls->fs;
GCstr *varname;
FuncBlock bl;
enterblock(fs, &bl, 1); /* scope for loop and control variables */
lj_lex_next(ls); /* skip `for' */
varname = str_checkname(ls); /* first variable name */
switch (ls->token) {
case '=': fornum(ls, varname, line); break;
case ',': case TK_in: forlist(ls, varname); break;
default: err_syntax(ls, LJ_ERR_XFOR);
}
checkmatch(ls, TK_end, TK_for, line);
leaveblock(fs); /* loop scope (`break' jumps to this point) */
}
static BCPos test_then_block(LexState *ls)
{
/* test_then_block -> [IF | ELSEIF] cond THEN block */
BCPos condexit;
lj_lex_next(ls); /* skip IF or ELSEIF */
condexit = condexpr(ls);
checknext(ls, TK_then);
block(ls); /* `then' part */
return condexit;
}
static void ifstat(LexState *ls, BCLine line)
{
/* ifstat -> IF cond THEN block {ELSEIF cond THEN block} [ELSE block] END */
FuncState *fs = ls->fs;
BCPos flist;
BCPos escapelist = NO_JMP;
flist = test_then_block(ls); /* IF cond THEN block */
while (ls->token == TK_elseif) {
concatjumps(fs, &escapelist, emit_jump(fs));
patchtohere(fs, flist);
flist = test_then_block(ls); /* ELSEIF cond THEN block */
}
if (ls->token == TK_else) {
concatjumps(fs, &escapelist, emit_jump(fs));
patchtohere(fs, flist);
lj_lex_next(ls); /* skip ELSE (after patch, for correct line info) */
block(ls); /* `else' part */
} else {
concatjumps(fs, &escapelist, flist);
}
patchtohere(fs, escapelist);
checkmatch(ls, TK_end, TK_if, line);
}
static void localfunc(LexState *ls)
{
ExpDesc v, b;
FuncState *fs = ls->fs;
new_localvar(ls, str_checkname(ls), 0);
init_exp(&v, VLOCAL, fs->freereg);
reserveregs(fs, 1);
adjustlocalvars(ls, 1);
body(ls, &b, 0, ls->linenumber);
storevar(fs, &v, &b);
/* debug information will only see the variable after this point! */
getlocvar(fs, fs->nactvar - 1).startpc = fs->pc;
}
static void localstat(LexState *ls)
{
/* stat -> LOCAL NAME {`,' NAME} [`=' explist1] */
BCReg nvars = 0;
BCReg nexps;
ExpDesc e;
do {
new_localvar(ls, str_checkname(ls), nvars++);
} while (testnext(ls, ','));
if (testnext(ls, '=')) {
nexps = explist1(ls, &e);
} else {
e.k = VVOID;
nexps = 0;
}
adjust_assign(ls, nvars, nexps, &e);
adjustlocalvars(ls, nvars);
}
static int func_name(LexState *ls, ExpDesc *v)
{
/* func_name -> NAME {field} [`:' NAME] */
int needself = 0;
singlevar(ls, v);
while (ls->token == '.')
field(ls, v);
if (ls->token == ':') {
needself = 1;
field(ls, v);
}
return needself;
}
static void funcstat(LexState *ls, BCLine line)
{
/* funcstat -> FUNCTION func_name body */
FuncState *fs;
int needself;
ExpDesc v, b;
lj_lex_next(ls); /* skip FUNCTION */
needself = func_name(ls, &v);
body(ls, &b, needself, line);
fs = ls->fs;
storevar(fs, &v, &b);
fs->pt->lineinfo[fs->pc - 1] = line;
}
static void exprstat(LexState *ls)
{
/* stat -> func | assignment */
FuncState *fs = ls->fs;
struct LHS_assign v;
primaryexp(ls, &v.v);
if (v.v.k == VCALL) { /* stat -> func */
setbc_b(bcptr(fs, &v.v), 1); /* call statement uses no results */
} else { /* stat -> assignment */
v.prev = NULL;
assignment(ls, &v, 1);
}
}
static int block_follow(LexToken token)
{
switch (token) {
case TK_else: case TK_elseif: case TK_end: case TK_until: case TK_eof:
return 1;
default:
return 0;
}
}
static void retstat(LexState *ls)
{
/* stat -> RETURN explist */
BCIns ins;
FuncState *fs = ls->fs;
lj_lex_next(ls); /* skip RETURN */
fs->pt->flags |= PROTO_HAS_RETURN;
if (block_follow(ls->token) || ls->token == ';') {
ins = BCINS_AD(BC_RET0, 0, 1); /* return no values */
} else {
ExpDesc e;
BCReg nret = explist1(ls, &e); /* optional return values */
if (nret == 1) {
if (e.k == VCALL) {
BCIns *i = bcptr(fs, &e);
/* It doesn't pay off to add BC_VARGT just for 'return ...'. */
if (bc_op(*i) == BC_VARG) goto notailcall;
fs->pc--;
ins = BCINS_AD(bc_op(*i)-BC_CALL+BC_CALLT, bc_a(*i), bc_c(*i));
} else {
ins = BCINS_AD(BC_RET1, exp2anyreg(fs, &e), 2);
}
} else {
if (e.k == VCALL) {
notailcall:
setbc_b(bcptr(fs, &e), 0);
ins = BCINS_AD(BC_RETM, fs->nactvar, e.u.s.aux - fs->nactvar);
} else {
exp2nextreg(fs, &e); /* values must go to the `stack' */
ins = BCINS_AD(BC_RET, fs->nactvar, nret+1);
}
}
}
if (fs->pt->flags & PROTO_HAS_FNEW)
emitAJ(fs, BC_UCLO, 0, 0);
emitINS(fs, ins);
}
static int statement(LexState *ls)
{
BCLine line = ls->linenumber; /* may be needed for error messages */
switch (ls->token) {
case TK_if:
ifstat(ls, line);
return 0;
case TK_while:
whilestat(ls, line);
return 0;
case TK_do:
lj_lex_next(ls); /* skip DO */
block(ls);
checkmatch(ls, TK_end, TK_do, line);
return 0;
case TK_for:
forstat(ls, line);
return 0;
case TK_repeat:
repeatstat(ls, line);
return 0;
case TK_function:
funcstat(ls, line);
return 0;
case TK_local:
lj_lex_next(ls); /* skip LOCAL */
if (testnext(ls, TK_function)) /* local function? */
localfunc(ls);
else
localstat(ls);
return 0;
case TK_return:
retstat(ls);
return 1; /* must be last statement */
case TK_break:
lj_lex_next(ls); /* skip BREAK */
breakstat(ls);
return 1; /* must be last statement */
default:
exprstat(ls);
return 0;
}
}
static void chunk(LexState *ls)
{
/* chunk -> { stat [`;'] } */
int islast = 0;
enterlevel(ls);
while (!islast && !block_follow(ls->token)) {
islast = statement(ls);
testnext(ls, ';');
lua_assert(ls->fs->pt->framesize >= ls->fs->freereg &&
ls->fs->freereg >= ls->fs->nactvar);
ls->fs->freereg = ls->fs->nactvar; /* free registers */
}
leavelevel(ls);
}