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authorFlorian Weimer <fweimer@redhat.com>2019-11-11 16:09:32 +0100
committerFlorian Weimer <fweimer@redhat.com>2019-11-11 16:09:32 +0100
commit060d8b9ced04715030eef33ce40ab64b34a0a349 (patch)
treeb4e649439054054a0afbf6352aa0ad8d5cc1dc25
parent0fa7402cbb4c88ab230eb4447f3fc2a182b17ae7 (diff)
downloadglibc-fw/dl-bind-performance.zip
glibc-fw/dl-bind-performance.tar.gz
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WIP mul64 dlsym optimizationfw/dl-bind-performance
Change-Id: I4caf4f14deb7a106c17e3ca89bdff5cd89f9541b
-rw-r--r--elf/dl-lookup.c18
-rw-r--r--include/link.h3
2 files changed, 9 insertions, 12 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 205d043..4d2f3b9 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -396,16 +396,15 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
& (bitmask_word >> hashbit2) & 1))
{
Elf32_Word bucket;
- if (map->l_nbuckets > 1)
+ if (powerof2 (map->l_nbuckets))
+ bucket = map->l_gnu_buckets[new_hash & (map->l_nbuckets - 1)];
+ else
{
uint32_t quotient
- = divopt_32 (new_hash, map->l_nbuckets_multiplier,
- map->l_nbuckets_multiplier_shift);
+ = ((unsigned __int128) map->l_nbuckets_multiplier * ((uint64_t) new_hash + 1)) >> 64;
uint32_t remainder = new_hash - map->l_nbuckets * quotient;
bucket = map->l_gnu_buckets[remainder];
}
- else
- bucket = map->l_gnu_buckets[0];
if (bucket != 0)
{
@@ -942,11 +941,10 @@ _dl_setup_hash (struct link_map *map)
/* Initialize MIPS xhash translation table. */
ELF_MACHINE_XHASH_SETUP (hash32, symbias, map);
- if (map->l_nbuckets >= 2)
- map->l_nbuckets_multiplier_shift
- = precompute_divopt_32 (map->l_nbuckets,
- &map->l_nbuckets_multiplier);
-
+ if (powerof2 (map->l_nbuckets))
+ map->l_nbuckets_multiplier = __builtin_ctz (map->l_nbuckets);
+ else
+ map->l_nbuckets_multiplier = ((unsigned __int128) 1 << 64) / map->l_nbuckets;
return;
}
diff --git a/include/link.h b/include/link.h
index b09aa81..eec4c9e 100644
--- a/include/link.h
+++ b/include/link.h
@@ -153,8 +153,7 @@ struct link_map
/* Symbol hash table. */
Elf_Symndx l_nbuckets;
- uint32_t l_nbuckets_multiplier;
- int l_nbuckets_multiplier_shift;
+ uint64_t l_nbuckets_multiplier;
Elf32_Word l_gnu_bitmask_idxbits;
Elf32_Word l_gnu_shift;
const ElfW(Addr) *l_gnu_bitmask;