Mercurial > cpython-lru_cache-weakref
diff Objects/floatobject.c @ 13141:cca84745da3e legacy-trunk
This patch addresses two main issues: (1) There exist some non-fatal
errors in some of the hash algorithms. For exmaple, in float_hash and
complex_hash a certain part of the value is not included in the hash
calculation. See Tim's, Guido's, and my discussion of this on
python-dev in May under the title "fix float_hash and complex_hash for
64-bit *nix"
(2) The hash algorithms that use pointers (e.g. func_hash, code_hash)
are universally not correct on Win64 (they assume that sizeof(long) ==
sizeof(void*))
As well, this patch significantly cleans up the hash code. It adds the
two function _Py_HashDouble and _PyHash_VoidPtr that the various
hashing routine are changed to use.
These help maintain the hash function invariant: (a==b) =>
(hash(a)==hash(b))) I have added Lib/test/test_hash.py and
Lib/test/output/test_hash to test this for some cases.
| author | Fred Drake <fdrake@acm.org> |
|---|---|
| date | Thu, 29 Jun 2000 19:17:04 +0000 |
| parents | 1c7c2dd1beb1 |
| children | ff243b0f16ee |
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--- a/Objects/floatobject.c Thu Jun 29 18:50:59 2000 +0000 +++ b/Objects/floatobject.c Thu Jun 29 19:17:04 2000 +0000 @@ -59,7 +59,13 @@ #endif #ifndef LONG_MAX +#if SIZEOF_LONG == 4 #define LONG_MAX 0X7FFFFFFFL +#elif SIZEOF_LONG == 8 +#define LONG_MAX 0X7FFFFFFFFFFFFFFFL +#else +#error "could not set LONG_MAX" +#endif #endif #ifndef LONG_MIN @@ -357,12 +363,12 @@ return (i < j) ? -1 : (i > j) ? 1 : 0; } + static long float_hash(v) PyFloatObject *v; { double intpart, fractpart; - int expo; long x; /* This is designed so that Python numbers with the same value hash to the same value, otherwise comparisons @@ -379,7 +385,7 @@ #endif if (fractpart == 0.0) { - if (intpart > 0x7fffffffL || -intpart > 0x7fffffffL) { + if (intpart > LONG_MAX || -intpart > LONG_MAX) { /* Convert to long int and use its hash... */ PyObject *w = PyLong_FromDouble(v->ob_fval); if (w == NULL) @@ -393,14 +399,9 @@ else { /* Note -- if you change this code, also change the copy in complexobject.c */ - long hipart; - fractpart = frexp(fractpart, &expo); - fractpart = fractpart * 2147483648.0; /* 2**31 */ - hipart = (long)fractpart; /* Take the top 32 bits */ - fractpart = (fractpart - (double)hipart) * 2147483648.0; - /* Get the next 32 bits */ - x = hipart + (long)fractpart + (long)intpart + (expo << 15); - /* Combine everything */ + x = _Py_HashDouble(v->ob_fval); + if (x == -1) + return -1; } if (x == -1) x = -2;