diff options
Diffstat (limited to 'lcode.c')
| -rw-r--r-- | lcode.c | 34 |
1 files changed, 26 insertions, 8 deletions
@@ -10,6 +10,7 @@ #include "lprefix.h" +#include <float.h> #include <limits.h> #include <math.h> #include <stdlib.h> @@ -580,24 +581,41 @@ static int stringK (FuncState *fs, TString *s) { /* ** Add an integer to list of constants and return its index. -** Integers use userdata as keys to avoid collision with floats with -** same value; conversion to 'void*' is used only for hashing, so there -** are no "precision" problems. */ static int luaK_intK (FuncState *fs, lua_Integer n) { - TValue k, o; - setpvalue(&k, cast_voidp(cast_sizet(n))); + TValue o; setivalue(&o, n); - return addk(fs, &k, &o); + return addk(fs, &o, &o); /* use integer itself as key */ } /* -** Add a float to list of constants and return its index. +** Add a float to list of constants and return its index. Floats +** with integral values need a different key, to avoid collision +** with actual integers. To that, we add to the number its smaller +** power-of-two fraction that is still significant in its scale. +** For doubles, that would be 1/2^52. +** (This method is not bulletproof: there may be another float +** with that value, and for floats larger than 2^53 the result is +** still an integer. At worst, this only wastes an entry with +** a duplicate.) */ static int luaK_numberK (FuncState *fs, lua_Number r) { TValue o; + lua_Integer ik; setfltvalue(&o, r); - return addk(fs, &o, &o); /* use number itself as key */ + if (!luaV_flttointeger(r, &ik, F2Ieq)) /* not an integral value? */ + return addk(fs, &o, &o); /* use number itself as key */ + else { /* must build an alternative key */ + const int nbm = l_floatatt(MANT_DIG); + const lua_Number q = l_mathop(ldexp)(1.0, -nbm + 1); + const lua_Number k = (ik == 0) ? q : r + r*q; /* new key */ + TValue kv; + setfltvalue(&kv, k); + /* result is not an integral value, unless value is too large */ + lua_assert(!luaV_flttointeger(k, &ik, F2Ieq) || + l_mathop(fabs)(r) >= l_mathop(1e6)); + return addk(fs, &kv, &o); + } } |