From 060d8b9ced04715030eef33ce40ab64b34a0a349 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Mon, 11 Nov 2019 16:09:32 +0100 Subject: WIP mul64 dlsym optimization Change-Id: I4caf4f14deb7a106c17e3ca89bdff5cd89f9541b --- elf/dl-lookup.c | 18 ++++++++---------- include/link.h | 3 +-- 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; -- cgit v1.1