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avoid using raw representation of numbers for hashing, as number may

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not use all its space (e.g., long double can have sizeof=12 but
use only 10 bytes)
This commit is contained in:
Roberto Ierusalimschy 2013-06-25 15:57:18 -03:00
parent 982aa7058f
commit 483c2ccd0f
1 changed files with 25 additions and 15 deletions
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40
lcode.c
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@ -1,10 +1,11 @@
/*
** $Id: lcode.c,v 2.69 2013/05/06 17:22:16 roberto Exp roberto $
** $Id: lcode.c,v 2.70 2013/06/20 17:37:31 roberto Exp roberto $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
#include <math.h>
#include <stdlib.h>
#define lcode_c
@ -26,6 +27,14 @@
#include "lvm.h"
/* test for x == -0 */
#if defined(signbit)
#define isminuszero(x) ((x) == 0.0 && signbit(x))
#else
#define isminuszero(x) ((x) == 0.0 && 1.0/(x) < 0.0)
#endif
#define hasjumps(e) ((e)->t != (e)->f)
@ -332,30 +341,28 @@ int luaK_stringK (FuncState *fs, TString *s) {
}
/*
** use userdata as key to avoid collision with float with same value;
** conversion to 'void*' used only for hash, no "precision" problems
*/
int luaK_intK (FuncState *fs, lua_Integer n) {
TValue k, o;
/* use userdata as key to avoid collision with float with same value;
conversion to 'void*' used only for hash, no "precision" problems */
setpvalue(&k, cast(void*, cast(size_t, n)));
setivalue(&o, n);
return addk(fs, &k, &o);
}
/*
** Both NaN and -0.0 should not go to the constant table, as they have
** problems with the hashing. (NaN is not ** a valid key,
** -0.0 collides with +0.0.)
*/
static int luaK_numberK (FuncState *fs, lua_Number r) {
int n;
lua_State *L = fs->ls->L;
TValue o;
lua_assert(!luai_numisnan(NULL, r) && !isminuszero(r));
setnvalue(&o, r);
if (r != 0 && !luai_numisnan(NULL, r)) /* avoid -0 and NaN */
n = addk(fs, &o, &o); /* regular case */
else { /* handle -0 and NaN */
/* use raw representation as key to avoid numeric problems */
setsvalue(L, L->top++, luaS_newlstr(L, (char *)&r, sizeof(r)));
n = addk(fs, L->top - 1, &o);
L->top--;
}
return n;
return addk(fs, &o, &o);
}
@ -755,8 +762,11 @@ static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
e1->u.ival = ivalue(&res);
}
else {
lua_Number n = fltvalue(&res);
if (luai_numisnan(NULL, n) || isminuszero(n))
return 0; /* folds neither NaN nor -0 */
e1->k = VKFLT;
e1->u.nval = fltvalue(&res);
e1->u.nval = n;
}
return 1;
}