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correct way to avoid compile-time errors in integer divisions

This commit is contained in:
Roberto Ierusalimschy 2013-05-06 14:22:16 -03:00
parent f2043b7a58
commit 1f2b82bf25
1 changed files with 7 additions and 4 deletions
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11
lcode.c
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@ -1,5 +1,5 @@
/*
** $Id: lcode.c,v 2.67 2013/04/29 16:57:48 roberto Exp roberto $
** $Id: lcode.c,v 2.68 2013/05/02 12:37:24 roberto Exp roberto $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
@ -741,11 +741,14 @@ void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
static int constfolding (OpCode op, expdesc *e1, expdesc *e2) {
TValue v1, v2, res;
lua_Integer i2;
lua_Integer i;
if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2))
return 0;
if ((op == OP_IDIV || op == OP_MOD) && tointeger(&v2, &i2) && i2 == 0)
return 0; /* avoid division by 0 at compile time */
if (op == OP_IDIV &&
(!tointeger(&v1, &i) || !tointeger(&v2, &i) || i == 0))
return 0; /* avoid division by 0 and conversion errors */
if (op == OP_MOD && ttisinteger(&v1) && ttisinteger(&v2) && ivalue(&v2) == 0)
return 0; /* avoid module by 0 at compile time */
luaO_arith(NULL, op - OP_ADD + LUA_OPADD, &v1, &v2, &res);
if (ttisinteger(&res)) {
e1->k = VKINT;