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st.c: use power-of-two sizes to avoid slow modulo ops
* st.c (hash_pos): use bitwise AND to avoid slow modulo op (new_size): power-of-two sizes for hash_pos change (st_numhash): adjust for common keys due to lack of prime modulo [Feature #9425] * hash.c (rb_any_hash): right shift for symbols * benchmark/bm_hash_aref_miss.rb: added to show improvement * benchmark/bm_hash_aref_sym_long.rb: ditto * benchmark/bm_hash_aref_str.rb: ditto * benchmark/bm_hash_aref_sym.rb: ditto * benchmark/bm_hash_ident_num.rb: added to prevent regression * benchmark/bm_hash_ident_obj.rb: ditto * benchmark/bm_hash_ident_str.rb: ditto * benchmark/bm_hash_ident_sym.rb: ditto git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45384 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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12 changed files with 77 additions and 57 deletions
16
ChangeLog
16
ChangeLog
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@ -1,3 +1,19 @@
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Sun Mar 23 08:12:27 2014 Eric Wong <e@80x24.org>
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* st.c (hash_pos): use bitwise AND to avoid slow modulo op
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(new_size): power-of-two sizes for hash_pos change
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(st_numhash): adjust for common keys due to lack of prime modulo
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[Feature #9425]
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* hash.c (rb_any_hash): right shift for symbols
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* benchmark/bm_hash_aref_miss.rb: added to show improvement
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* benchmark/bm_hash_aref_sym_long.rb: ditto
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* benchmark/bm_hash_aref_str.rb: ditto
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* benchmark/bm_hash_aref_sym.rb: ditto
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* benchmark/bm_hash_ident_num.rb: added to prevent regression
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* benchmark/bm_hash_ident_obj.rb: ditto
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* benchmark/bm_hash_ident_str.rb: ditto
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* benchmark/bm_hash_ident_sym.rb: ditto
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Sat Mar 22 22:56:45 2014 NARUSE, Yui <naruse@ruby-lang.org>
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* addr2line.c (fill_lines): compare the file names of object in which
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6
NEWS
6
NEWS
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@ -84,3 +84,9 @@ with all sufficient information, see the ChangeLog file.
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* struct RBignum is hidden. [Feature #6083]
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Use rb_integer_pack and rb_integer_unpack instead.
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* st hash table uses power-of-two sizes for speed [Feature #9425].
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Lookups are 10-25% faster if using appropriate hash functions.
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However, weaknesses in hash distribution can no longer be masked
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by prime number-sized tables, so extensions may need to tweak
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hash functions to ensure good distribution.
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5
benchmark/bm_hash_aref_miss.rb
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5
benchmark/bm_hash_aref_miss.rb
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@ -0,0 +1,5 @@
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h = {}
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strs = ('a'..'z').to_a.map!(&:freeze)
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strs.each { |s| h[s] = s }
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strs = ('A'..'Z').to_a
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200_000.times { strs.each { |s| h[s] } }
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4
benchmark/bm_hash_aref_str.rb
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4
benchmark/bm_hash_aref_str.rb
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@ -0,0 +1,4 @@
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h = {}
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strs = ('a'..'z').to_a.map!(&:freeze)
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strs.each { |s| h[s] = s }
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200_000.times { strs.each { |s| h[s] } }
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4
benchmark/bm_hash_aref_sym.rb
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4
benchmark/bm_hash_aref_sym.rb
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@ -0,0 +1,4 @@
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h = {}
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syms = ('a'..'z').to_a.map(&:to_sym)
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syms.each { |s| h[s] = s }
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200_000.times { syms.each { |s| h[s] } }
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8
benchmark/bm_hash_aref_sym_long.rb
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8
benchmark/bm_hash_aref_sym_long.rb
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@ -0,0 +1,8 @@
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h = {}
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syms = %w[puts warn syswrite write stat bacon lettuce tomato
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some symbols in this array may already be interned others should not be
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hash browns make good breakfast but not cooked using prime numbers
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shift for division entries delete_if keys exist?
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].map!(&:to_sym)
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syms.each { |s| h[s] = s }
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200_000.times { syms.each { |s| h[s] } }
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4
benchmark/bm_hash_ident_num.rb
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4
benchmark/bm_hash_ident_num.rb
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@ -0,0 +1,4 @@
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h = {}.compare_by_identity
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nums = (1..26).to_a
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nums.each { |n| h[n] = n }
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200_000.times { nums.each { |n| h[n] } }
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4
benchmark/bm_hash_ident_obj.rb
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4
benchmark/bm_hash_ident_obj.rb
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h = {}.compare_by_identity
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objs = 26.times.map { Object.new }
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objs.each { |o| h[o] = o }
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200_000.times { objs.each { |o| h[o] } }
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4
benchmark/bm_hash_ident_str.rb
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4
benchmark/bm_hash_ident_str.rb
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@ -0,0 +1,4 @@
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h = {}.compare_by_identity
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strs = ('a'..'z').to_a
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strs.each { |s| h[s] = s }
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200_000.times { strs.each { |s| h[s] } }
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4
benchmark/bm_hash_ident_sym.rb
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4
benchmark/bm_hash_ident_sym.rb
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@ -0,0 +1,4 @@
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h = {}.compare_by_identity
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syms = ('a'..'z').to_a.map(&:to_sym)
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syms.each { |s| h[s] = s }
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200_000.times { syms.each { |s| h[s] } }
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1
hash.c
1
hash.c
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@ -132,6 +132,7 @@ rb_any_hash(VALUE a)
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if (SPECIAL_CONST_P(a)) {
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if (a == Qundef) return 0;
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if (SYMBOL_P(a)) a >>= (RUBY_SPECIAL_SHIFT + 3); /* 3=ID_SCOPE_SHIFT */
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hnum = rb_objid_hash((st_index_t)a);
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}
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else if (BUILTIN_TYPE(a) == T_STRING) {
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74
st.c
74
st.c
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@ -33,8 +33,7 @@ typedef struct st_packed_entry {
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#define STATIC_ASSERT(name, expr) typedef int static_assert_##name##_check[(expr) ? 1 : -1];
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#define ST_DEFAULT_MAX_DENSITY 5
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#define ST_DEFAULT_INIT_TABLE_SIZE 11
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#define ST_DEFAULT_SECOND_TABLE_SIZE 19
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#define ST_DEFAULT_INIT_TABLE_SIZE 16
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#define ST_DEFAULT_PACKED_TABLE_SIZE 18
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#define PACKED_UNIT (int)(sizeof(st_packed_entry) / sizeof(st_table_entry*))
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#define MAX_PACKED_HASH (int)(ST_DEFAULT_PACKED_TABLE_SIZE * sizeof(st_table_entry*) / sizeof(st_packed_entry))
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#define EQUAL(table,x,y) ((x)==(y) || (*(table)->type->compare)((x),(y)) == 0)
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#define do_hash(key,table) (st_index_t)(*(table)->type->hash)((key))
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#define hash_pos(h,n) ((h) % (n))
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#define hash_pos(h,n) ((h) & (n - 1))
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#define do_hash_bin(key,table) hash_pos(do_hash((key), (table)), (table)->num_bins)
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/* preparation for possible allocation improvements */
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@ -140,69 +139,18 @@ remove_safe_packed_entry(st_table *table, st_index_t i, st_data_t never)
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PHASH_SET(table, i, 0);
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}
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/*
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* MINSIZE is the minimum size of a dictionary.
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*/
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#define MINSIZE 8
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/*
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Table of prime numbers 2^n+a, 2<=n<=30.
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*/
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static const unsigned int primes[] = {
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ST_DEFAULT_INIT_TABLE_SIZE,
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ST_DEFAULT_SECOND_TABLE_SIZE,
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32 + 5,
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64 + 3,
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128 + 3,
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256 + 27,
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512 + 9,
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1024 + 9,
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2048 + 5,
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4096 + 3,
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8192 + 27,
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16384 + 43,
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32768 + 3,
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65536 + 45,
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131072 + 29,
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262144 + 3,
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524288 + 21,
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1048576 + 7,
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2097152 + 17,
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4194304 + 15,
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8388608 + 9,
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16777216 + 43,
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33554432 + 35,
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67108864 + 15,
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134217728 + 29,
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268435456 + 3,
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536870912 + 11,
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1073741824 + 85,
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0
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};
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static st_index_t
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new_size(st_index_t size)
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{
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int i;
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st_index_t i;
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#if 0
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for (i=3; i<31; i++) {
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if ((1<<i) > size) return 1<<i;
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if ((st_index_t)(1<<i) > size) return 1<<i;
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}
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return -1;
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#else
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st_index_t newsize;
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for (i = 0, newsize = MINSIZE; i < numberof(primes); i++, newsize <<= 1) {
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if (newsize > size) return primes[i];
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}
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/* Ran out of primes */
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#ifndef NOT_RUBY
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rb_raise(rb_eRuntimeError, "st_table too big");
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#endif
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return -1; /* should raise exception */
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#endif
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}
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#ifdef HASH_LOG
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st_index_t
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st_numhash(st_data_t n)
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{
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return (st_index_t)n;
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/*
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* This hash function is lightly-tuned for Ruby. Further tuning
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* should be possible. Notes:
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*
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* - (n >> 3) alone is great for heap objects and OK for fixnum,
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* however symbols perform poorly.
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* - (n >> (RUBY_SPECIAL_SHIFT+3)) was added to make symbols hash well,
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* n.b.: +3 to remove ID scope, +1 worked well initially, too
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* - (n << 3) was finally added to avoid losing bits for fixnums
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* - avoid expensive modulo instructions, it is currently only
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* shifts and bitmask operations.
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*/
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return (st_index_t)((n>>(RUBY_SPECIAL_SHIFT+3)|(n<<3)) ^ (n>>3));
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}
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