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new way to GC stacks: the entire stack must be correct all the times;

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the 'dead' part of a stack (after the top) must have only nil's, so
that 'top' may go up without cleaning the stack.
This commit is contained in:
Roberto Ierusalimschy
2009-04-28 16:04:36 -03:00
parent 58c3aa8b5f
commit e091a254df
4 changed files with 63 additions and 47 deletions
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26
ldo.c
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@@ -1,5 +1,5 @@
/*
** $Id: ldo.c,v 2.61 2009/04/17 22:00:01 roberto Exp roberto $
** $Id: ldo.c,v 2.62 2009/04/26 21:55:35 roberto Exp roberto $
** Stack and Call structure of Lua
** See Copyright Notice in lua.h
*/
@@ -131,9 +131,12 @@ static void correctstack (lua_State *L, TValue *oldstack) {
void luaD_reallocstack (lua_State *L, int newsize) {
TValue *oldstack = L->stack;
int lim = L->stacksize;
int realsize = newsize + 1 + EXTRA_STACK;
lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK - 1);
luaM_reallocvector(L, L->stack, L->stacksize, realsize, TValue);
for (; lim < realsize; lim++)
setnilvalue(L->stack + lim); /* erase new segment */
L->stacksize = realsize;
L->stack_last = L->stack+newsize;
correctstack(L, oldstack);
@@ -182,14 +185,13 @@ static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
int i;
int nfixargs = p->numparams;
StkId base, fixed;
for (; actual < nfixargs; ++actual)
setnilvalue(L->top++);
lua_assert(actual >= nfixargs);
/* move fixed parameters to final position */
fixed = L->top - actual; /* first fixed argument */
base = L->top; /* final position of first argument */
for (i=0; i<nfixargs; i++) {
setobjs2s(L, L->top++, fixed+i);
setnilvalue(fixed+i);
setobjs2s(L, L->top++, fixed + i);
setnilvalue(fixed + i);
}
return base;
}
@@ -227,17 +229,19 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
L->ci->nresults = nresults;
if (!cl->isC) { /* Lua function? prepare its call */
CallInfo *ci;
StkId st, base;
int nparams, nargs;
StkId base;
Proto *p = cl->p;
luaD_checkstack(L, p->maxstacksize);
func = restorestack(L, funcr);
nargs = cast_int(L->top - func) - 1; /* number of real arguments */
nparams = p->numparams; /* number of expected parameters */
for (; nargs < nparams; nargs++)
setnilvalue(L->top++); /* complete missing arguments */
if (!p->is_vararg) /* no varargs? */
base = func + 1;
else { /* vararg function */
int nargs = cast_int(L->top - func) - 1;
else /* vararg function */
base = adjust_varargs(L, p, nargs);
func = restorestack(L, funcr); /* previous call may change the stack */
}
ci = next_ci(L); /* now 'enter' new function */
ci->func = func;
L->base = ci->base = base;
@@ -246,8 +250,6 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
ci->u.l.savedpc = p->code; /* starting point */
ci->u.l.tailcalls = 0;
ci->callstatus = CIST_LUA;
for (st = L->top; st < ci->top; st++)
setnilvalue(st);
L->top = ci->top;
if (L->hookmask & LUA_MASKCALL) {
ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */