diff options
| author | Paul Eggert <eggert@cs.ucla.edu> | 2019-07-22 21:27:33 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2019-07-22 21:28:18 -0700 |
| commit | f378ed1a0b1ca2ceed5afabcf5f303ae339039ba (patch) | |
| tree | 767e994477690e2681cb7fe027af7d708efd6cc6 /src/fns.c | |
| parent | 97477edaf2044e51696f46b166b43801893156a3 (diff) | |
| download | emacs-f378ed1a0b1ca2ceed5afabcf5f303ae339039ba.tar.gz | |
Avoid overexposing fixnums for hash codes
Following a suggestion by Stefan Monnier in:
https://lists.gnu.org/r/emacs-devel/2019-07/msg00530.html
* doc/lispref/hash.texi (Creating Hash, Defining Hash):
* src/fns.c (Fsxhash_eq, Fsxhash_eql, Fsxhash_equal, Fmake_hash_table):
Don’t insist that hash codes be fixnums, reverting
the recent doc changes to the contrary.
* src/bytecode.c (exec_byte_code): Special-case only the eq case,
as the others aren’t worth tuning now that we treat bignum hashes
like fixnums.
* src/fns.c (hashfn_user_defined): If the hash code is a bignum,
reduce its hash down to a fixnum.
Diffstat (limited to 'src/fns.c')
| -rw-r--r-- | src/fns.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/src/fns.c b/src/fns.c index 734a2e253c7..d28d437df9c 100644 --- a/src/fns.c +++ b/src/fns.c @@ -47,6 +47,7 @@ static void sort_vector_copy (Lisp_Object, ptrdiff_t, enum equal_kind { EQUAL_NO_QUIT, EQUAL_PLAIN, EQUAL_INCLUDING_PROPERTIES }; static bool internal_equal (Lisp_Object, Lisp_Object, enum equal_kind, int, Lisp_Object); +static EMACS_UINT sxhash_bignum (struct Lisp_Bignum *); DEFUN ("identity", Fidentity, Sidentity, 1, 1, 0, doc: /* Return the argument unchanged. */ @@ -4021,7 +4022,8 @@ Lisp_Object hashfn_user_defined (Lisp_Object key, struct Lisp_Hash_Table *h) { Lisp_Object args[] = { h->test.user_hash_function, key }; - return hash_table_user_defined_call (ARRAYELTS (args), args, h); + Lisp_Object hash = hash_table_user_defined_call (ARRAYELTS (args), args, h); + return BIGNUMP (hash) ? make_fixnum (sxhash_bignum (XBIGNUM (hash))) : hash; } struct hash_table_test const @@ -4707,7 +4709,7 @@ sxhash (Lisp_Object obj, int depth) ***********************************************************************/ DEFUN ("sxhash-eq", Fsxhash_eq, Ssxhash_eq, 1, 1, 0, - doc: /* Return a fixnum hash code for OBJ suitable for `eq'. + doc: /* Return an integer hash code for OBJ suitable for `eq'. If (eq A B), then (= (sxhash-eq A) (sxhash-eq B)). Hash codes are not guaranteed to be preserved across Emacs sessions. */) @@ -4717,7 +4719,7 @@ Hash codes are not guaranteed to be preserved across Emacs sessions. */) } DEFUN ("sxhash-eql", Fsxhash_eql, Ssxhash_eql, 1, 1, 0, - doc: /* Return a fixnum hash code for OBJ suitable for `eql'. + doc: /* Return an integer hash code for OBJ suitable for `eql'. If (eql A B), then (= (sxhash-eql A) (sxhash-eql B)). Hash codes are not guaranteed to be preserved across Emacs sessions. */) @@ -4727,7 +4729,7 @@ Hash codes are not guaranteed to be preserved across Emacs sessions. */) } DEFUN ("sxhash-equal", Fsxhash_equal, Ssxhash_equal, 1, 1, 0, - doc: /* Return a fixnum hash code for OBJ suitable for `equal'. + doc: /* Return an integer hash code for OBJ suitable for `equal'. If (equal A B), then (= (sxhash-equal A) (sxhash-equal B)). Hash codes are not guaranteed to be preserved across Emacs sessions. */) @@ -4751,7 +4753,7 @@ keys. Default is `eql'. Predefined are the tests `eq', `eql', and Default is 65. :rehash-size REHASH-SIZE - Indicates how to expand the table when it -fills up. If REHASH-SIZE is a fixnum, increase the size by that +fills up. If REHASH-SIZE is an integer, increase the size by that amount. If it is a float, it must be > 1.0, and the new size is the old size multiplied by that factor. Default is 1.5. |