diff options
Diffstat (limited to 'hash.c')
| -rw-r--r-- | hash.c | 41 |
1 files changed, 27 insertions, 14 deletions
@@ -138,7 +138,8 @@ any_hash(VALUE a, st_index_t (*other_func)(VALUE)) if (SPECIAL_CONST_P(a)) { if (a == Qundef) return 0; if (STATIC_SYM_P(a)) { - a >>= (RUBY_SPECIAL_SHIFT + ID_SCOPE_SHIFT); + hnum = a >> (RUBY_SPECIAL_SHIFT + ID_SCOPE_SHIFT); + goto out; } else if (FLONUM_P(a)) { /* prevent pathological behavior: [Bug #10761] */ @@ -160,6 +161,7 @@ any_hash(VALUE a, st_index_t (*other_func)(VALUE)) else { hnum = other_func(a); } + out: hnum <<= 1; return (st_index_t)RSHIFT(hnum, 1); } @@ -177,10 +179,31 @@ rb_any_hash(VALUE a) return any_hash(a, obj_any_hash); } +static st_index_t +rb_num_hash_start(st_index_t n) +{ + /* + * This hash function is lightly-tuned for Ruby. Further tuning + * should be possible. Notes: + * + * - (n >> 3) alone is great for heap objects and OK for fixnum, + * however symbols perform poorly. + * - (n >> (RUBY_SPECIAL_SHIFT+3)) was added to make symbols hash well, + * n.b.: +3 to remove most ID scope, +1 worked well initially, too + * n.b.: +1 (instead of 3) worked well initially, too + * - (n << 3) was finally added to avoid losing bits for fixnums + * - avoid expensive modulo instructions, it is currently only + * shifts and bitmask operations. + */ + return (n >> (RUBY_SPECIAL_SHIFT + 3) | (n << 3)) ^ (n >> 3); +} + long rb_objid_hash(st_index_t index) { - st_index_t hnum = rb_hash_start(index); + st_index_t hnum = rb_num_hash_start(index); + + hnum = rb_hash_start(hnum); hnum = rb_hash_uint(hnum, (st_index_t)rb_any_hash); hnum = rb_hash_end(hnum); return hnum; @@ -215,28 +238,18 @@ static const struct st_hash_type objhash = { static st_index_t rb_ident_hash(st_data_t n) { +#ifdef USE_FLONUM /* RUBY */ /* - * This hash function is lightly-tuned for Ruby. Further tuning - * should be possible. Notes: - * - * - (n >> 3) alone is great for heap objects and OK for fixnum, - * however symbols perform poorly. - * - (n >> (RUBY_SPECIAL_SHIFT+3)) was added to make symbols hash well, - * n.b.: +3 to remove ID scope, +1 worked well initially, too - * - (n << 3) was finally added to avoid losing bits for fixnums - * - avoid expensive modulo instructions, it is currently only - * shifts and bitmask operations. * - flonum (on 64-bit) is pathologically bad, mix the actual * float value in, but do not use the float value as-is since * many integers get interpreted as 2.0 or -2.0 [Bug #10761] */ -#ifdef USE_FLONUM /* RUBY */ if (FLONUM_P(n)) { n ^= (st_data_t)rb_float_value(n); } #endif - return (st_index_t)((n>>(RUBY_SPECIAL_SHIFT+3)|(n<<3)) ^ (n>>3)); + return (st_index_t)rb_num_hash_start((st_index_t)n); } static const struct st_hash_type identhash = { |