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'for' loop tries to convert limit to integer when initial value and 

step are integers
This commit is contained in:
Roberto Ierusalimschy 2014-04-29 15:11:57 -03:00
parent a0d4f0fc8a
commit 9c4398de8f
1 changed files with 23 additions and 2 deletions
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25
lvm.c
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@ -1,5 +1,5 @@
/*
** $Id: lvm.c,v 2.198 2014/04/15 16:32:49 roberto Exp roberto $
** $Id: lvm.c,v 2.199 2014/04/27 14:41:11 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
@ -110,6 +110,24 @@ int luaV_tointeger_ (const TValue *obj, lua_Integer *p) {
}
/*
** Check whether the limit of a 'for' loop can be safely converted
** to an integer (rounding down or up depending on the signal of 'step')
*/
static int limittointeger (const TValue *n, lua_Integer *p, lua_Integer step) {
if (ttisinteger(n)) {
*p = ivalue(n);
return 1;
}
else if (!ttisfloat(n)) return 0;
else {
lua_Number f = fltvalue(n);
f = (step >= 0) ? l_floor(f) : -l_floor(-f);
return luaV_numtointeger(f, p);
}
}
void luaV_gettable (lua_State *L, const TValue *t, TValue *key, StkId val) {
int loop;
for (loop = 0; loop < MAXTAGLOOP; loop++) {
@ -946,9 +964,12 @@ void luaV_execute (lua_State *L) {
TValue *init = ra;
TValue *plimit = ra + 1;
TValue *pstep = ra + 2;
if (ttisinteger(init) && ttisinteger(plimit) && ttisinteger(pstep)) {
lua_Integer ilimit;
if (ttisinteger(init) && ttisinteger(pstep) &&
limittointeger(plimit, &ilimit, ivalue(pstep))) {
/* all values are integer */
setivalue(init, ivalue(init) - ivalue(pstep));
setivalue(plimit, ilimit);
}
else { /* try making all values floats */
lua_Number ninit; lua_Number nlimit; lua_Number nstep;