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New conceptual model for vararg

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Conceptually, all functions get their vararg arguments in a vararg
table. The storing of vararg arguments in the stack is always treated
as an optimization.
This commit is contained in:
Roberto I
2025-11-26 11:18:29 -03:00
parent d94f7ba304
commit f33cc4ddec
11 changed files with 155 additions and 70 deletions
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66
ltm.c
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@@ -242,6 +242,7 @@ static void createvarargtab (lua_State *L, StkId f, int n) {
luaH_set(L, t, &key, &value); /* t.n = n */
for (i = 0; i < n; i++)
luaH_setint(L, t, i + 1, s2v(f + i));
luaC_checkGC(L);
}
@@ -265,11 +266,11 @@ void luaT_adjustvarargs (lua_State *L, CallInfo *ci, const Proto *p) {
setobjs2s(L, L->top.p++, ci->func.p + i);
setnilvalue(s2v(ci->func.p + i)); /* erase original parameter (for GC) */
}
if (p->flag & PF_VAVAR) { /* is there a vararg parameter? */
if (p->flag & PF_VATAB) /* does it need a vararg table? */
createvarargtab(L, ci->func.p + nfixparams + 1, nextra);
else /* no table; set parameter to nil */
setnilvalue(s2v(L->top.p));
if (p->flag & PF_VATAB) /* does it need a vararg table? */
createvarargtab(L, ci->func.p + nfixparams + 1, nextra);
else { /* no table; set parameter to nil */
setnilvalue(s2v(L->top.p));
L->top.p++;
}
ci->func.p += totalargs + 1;
ci->top.p += totalargs + 1;
@@ -299,16 +300,53 @@ void luaT_getvararg (CallInfo *ci, StkId ra, TValue *rc) {
}
void luaT_getvarargs (lua_State *L, CallInfo *ci, StkId where, int wanted) {
int i;
int nextra = ci->u.l.nextraargs;
if (wanted < 0) {
wanted = nextra; /* get all extra arguments available */
checkstackp(L, nextra, where); /* ensure stack space */
L->top.p = where + nextra; /* next instruction will need top */
/*
** Get the number of extra arguments in a vararg function. If vararg
** table has been optimized away, that number is in the call info.
** Otherwise, get the field 'n' from the vararg table and check that it
** has a proper value (non-negative integer not larger than the stack
** limit).
*/
static int getnumargs (lua_State *L, CallInfo *ci, Table *h) {
if (h == NULL) /* no vararg table? */
return ci->u.l.nextraargs;
else {
TValue res;
if (luaH_getshortstr(h, luaS_new(L, "n"), &res) != LUA_VNUMINT ||
l_castS2U(ivalue(&res)) > cast_uint(INT_MAX/2))
luaG_runerror(L, "vararg table has no proper 'n'");
return cast_int(ivalue(&res));
}
}
/*
** Get 'wanted' vararg arguments and put them in 'where'. 'vatab' is
** the register of the vararg table or -1 if there is no vararg table.
*/
void luaT_getvarargs (lua_State *L, CallInfo *ci, StkId where, int wanted,
int vatab) {
Table *h = (vatab < 0) ? NULL : hvalue(s2v(ci->func.p + vatab + 1));
int nargs = getnumargs(L, ci, h); /* number of available vararg args. */
int i, touse; /* 'touse' is minimum between 'wanted' and 'nargs' */
if (wanted < 0) {
touse = wanted = nargs; /* get all extra arguments available */
checkstackp(L, nargs, where); /* ensure stack space */
L->top.p = where + nargs; /* next instruction will need top */
}
else
touse = (nargs > wanted) ? wanted : nargs;
if (h == NULL) { /* no vararg table? */
for (i = 0; i < touse; i++) /* get vararg values from the stack */
setobjs2s(L, where + i, ci->func.p - nargs + i);
}
else { /* get vararg values from vararg table */
for (i = 0; i < touse; i++) {
lu_byte tag = luaH_getint(h, i + 1, s2v(where + i));
if (tagisempty(tag))
setnilvalue(s2v(where + i));
}
}
for (i = 0; i < wanted && i < nextra; i++)
setobjs2s(L, where + i, ci->func.p - nextra + i);
for (; i < wanted; i++) /* complete required results with nil */
setnilvalue(s2v(where + i));
}