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[patch 1/2] Accelerate iter_match_first_hashed 1.8x
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 20 Oct 2014 23:44:38 +0200
- Subject: [patch 1/2] Accelerate iter_match_first_hashed 1.8x
- Authentication-results: sourceware.org; auth=none
Hi,
very simple caching. dict_hash() is being called again and again for the same
string.
#0 in skip_spaces_const (chp=0x7fffb10f9bb6 "ts<char>, std::allocator<char> >::npos") at ./cli/cli-utils.c:244
#1 in msymbol_hash_iw (string=0x7fffb10f9bb6 "ts<char>, std::allocator<char> >::npos") at minsyms.c:89
#2 in dict_hash ( string0=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos") at dictionary.c:840
#3 in iter_match_first_hashed (dict=0x105a7840, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", compare=0x8b82f8 <strcmp_iw>, iterator=0x7fffb10f9970) at dictionary.c:659
#4 in dict_iter_match_first (dict=0x105a7840, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", compare=0x8b82f8 <strcmp_iw>, iterator=0x7fffb10f9970) at dictionary.c:555
#5 in dict_iter_name_first (dict=0x105a7840, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", iterator=0x7fffb10f9970) at dictionary.c:541
#6 in block_iter_name_step (iterator=0x7fffb10f9960, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", first=1) at block.c:580
#7 in block_iter_name_first (block=0x10593e10, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", iterator=0x7fffb10f9960) at block.c:609
#8 in lookup_block_symbol (block=0x10593e10, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", domain=VAR_DOMAIN) at symtab.c:2062
#9 in lookup_symbol_aux_objfile (objfile=0x466f870, block_index=0, name=0x7fffb10f9b90 "std::basic_string<char, std::char_traits<char>, std::allocator<char> >::npos", domain=VAR_DOMAIN) at symtab.c:1664
#10 in lookup_symbol_global_iterator_cb (objfile=0x466f870, cb_data=0x7fffb10f9ad0) at symtab.c:1868
Maybe it could get cached at the caller but:
* We would need to pass the hash value along the whole {dict,block}_iter_*
call chain.
* The DICT_VECTOR virtualization would get violated as dict_linear*_vector do
not use any hash values.
Jan
gdb/
2014-10-20 Jan Kratochvil <jan.kratochvil@redhat.com>
* dictionary.c (iter_match_first_hashed): Provide state cache for
hash_index from NAME.
diff --git a/gdb/dictionary.c b/gdb/dictionary.c
index 055c87e..90bcd6d 100644
--- a/gdb/dictionary.c
+++ b/gdb/dictionary.c
@@ -656,9 +656,26 @@ iter_match_first_hashed (const struct dictionary *dict, const char *name,
symbol_compare_ftype *compare,
struct dict_iterator *iterator)
{
- unsigned int hash_index = dict_hash (name) % DICT_HASHED_NBUCKETS (dict);
+ unsigned int hash_index;
struct symbol *sym;
+ /* Cache HASH_INDEX. */
+ {
+ static const char *name_ptr_cached;
+ static char *name_content_cached;
+ static unsigned int dict_hash_cached;
+
+ if (name_ptr_cached != name || strcmp (name_content_cached, name) != 0)
+ {
+ dict_hash_cached = dict_hash (name);
+ name_ptr_cached = name;
+ xfree (name_content_cached);
+ name_content_cached = xstrdup (name);
+ }
+ hash_index = dict_hash_cached;
+ }
+ hash_index %= DICT_HASHED_NBUCKETS (dict);
+
DICT_ITERATOR_DICT (iterator) = dict;
/* Loop through the symbols in the given bucket, breaking when SYM