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no need to ensure any stack space for panic function + some changes

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in 'tryfuncTM' (small simplification)
This commit is contained in:
Roberto Ierusalimschy
2014-11-11 15:13:39 -02:00
parent be87789a6c
commit 9a38c08011
1 changed files with 12 additions and 16 deletions
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28
ldo.c
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@@ -1,5 +1,5 @@
/* /*
** $Id: ldo.c,v 2.133 2014/11/02 19:33:33 roberto Exp roberto $ ** $Id: ldo.c,v 2.134 2014/11/10 17:42:04 roberto Exp roberto $
** Stack and Call structure of Lua ** Stack and Call structure of Lua
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -123,9 +123,9 @@ l_noret luaD_throw (lua_State *L, int errcode) {
if (g->panic) { /* panic function? */ if (g->panic) { /* panic function? */
seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */ seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */
if (L->ci->top < L->top) if (L->ci->top < L->top)
L->ci->top = L->top + 2; L->ci->top = L->top; /* pushing msg. can break this invariant */
lua_unlock(L); lua_unlock(L);
g->panic(L); /* call it (last chance to jump out) */ g->panic(L); /* call panic function (last chance to jump out) */
} }
abort(); abort();
} }
@@ -289,24 +289,18 @@ static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
/* /*
** Check whether __call metafield of 'func' is a function. If so, put ** Check whether __call metafield of 'func' is a function. If so, put
** it in stack below original 'func' so that 'luaD_precall' can call ** it in stack below original 'func' so that 'luaD_precall' can call
** it. Raise an error if __call metafield is not a function. (The ** it. Raise an error if __call metafield is not a function.
** check 'luaD_checkstack' avoids problems of errors in tag methods,
** because both tag methods and error messages may need EXTRA_STACK.)
*/ */
static StkId tryfuncTM (lua_State *L, StkId func) { static void tryfuncTM (lua_State *L, StkId func) {
const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
StkId p; StkId p;
ptrdiff_t funcr = savestack(L, func); if (!ttisfunction(tm))
if (!ttisfunction(tm)) {
luaD_checkstack(L, 1);
luaG_typeerror(L, func, "call"); luaG_typeerror(L, func, "call");
}
/* Open a hole inside the stack at 'func' */ /* Open a hole inside the stack at 'func' */
for (p = L->top; p > func; p--) setobjs2s(L, p, p-1); for (p = L->top; p > func; p--)
incr_top(L); setobjs2s(L, p, p-1);
func = restorestack(L, funcr); /* previous call may change stack */ L->top++; /* slot ensured by caller */
setobj2s(L, func, tm); /* tag method is the new function to be called */ setobj2s(L, func, tm); /* tag method is the new function to be called */
return func;
} }
@@ -376,7 +370,9 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
return 0; return 0;
} }
default: { /* not a function */ default: { /* not a function */
func = tryfuncTM(L, func); /* retry with 'function' tag method */ luaD_checkstack(L, 1); /* ensure space for metamethod */
func = restorestack(L, funcr); /* previous call may change stack */
tryfuncTM(L, func); /* try to get '__call' metamethod */
return luaD_precall(L, func, nresults); /* now it must be a function */ return luaD_precall(L, func, nresults); /* now it must be a function */
} }
} }