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author | Alexander Monakov <amonakov@ispras.ru> | 2015-06-28 02:48:31 +0300 |
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committer | Rich Felker <dalias@aerifal.cx> | 2015-06-28 01:49:53 +0000 |
commit | 84389c64562e2b2ba43225b5b7a9df7d974479b1 (patch) | |
tree | eef353570514b58e5aa4e91a6e76b9d6b7a31dfd /src | |
parent | 66d45787c865a1807ae397a89a14699394ed4fa4 (diff) | |
download | musl-84389c64562e2b2ba43225b5b7a9df7d974479b1.tar.gz musl-84389c64562e2b2ba43225b5b7a9df7d974479b1.tar.xz musl-84389c64562e2b2ba43225b5b7a9df7d974479b1.zip |
dynlink.c: use bloom filter in gnu hash lookup
Introduce gnu_lookup_filtered and use it to speed up symbol lookups in find_sym (do_dlsym is left as is, based on an expectation that frequently dlsym queries will use a dlopen handle rather than RTLD_NEXT or RTLD_DEFAULT, and will not need to look at more than one DSO).
Diffstat (limited to 'src')
-rw-r--r-- | src/ldso/dynlink.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c index ec96be16..4e6a5c83 100644 --- a/src/ldso/dynlink.c +++ b/src/ldso/dynlink.c @@ -200,6 +200,19 @@ static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso) return 0; } +static Sym *gnu_lookup_filtered(const char *s, uint32_t h1, struct dso *dso, uint32_t fofs, size_t fmask) +{ + uint32_t *hashtab = dso->ghashtab; + const size_t *bloomwords = (const void *)(hashtab+4); + size_t f = bloomwords[fofs & (hashtab[2]-1)]; + if (!(f & fmask)) return 0; + + f >>= (h1 >> hashtab[3]) % (8 * sizeof f); + if (!(f & 1)) return 0; + + return gnu_lookup(s, h1, dso); +} + #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS) #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE) @@ -209,14 +222,20 @@ static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso) static struct symdef find_sym(struct dso *dso, const char *s, int need_def) { - uint32_t h = 0, gh = 0; + uint32_t h = 0, gh, gho; + size_t ghm = 0; struct symdef def = {0}; for (; dso; dso=dso->next) { Sym *sym; if (!dso->global) continue; if (dso->ghashtab) { - if (!gh) gh = gnu_hash(s); - sym = gnu_lookup(s, gh, dso); + if (!ghm) { + gh = gnu_hash(s); + int maskbits = 8 * sizeof ghm; + gho = gh / maskbits; + ghm = 1ul << gh % maskbits; + } + sym = gnu_lookup_filtered(s, gh, dso, gho, ghm); } else { if (!h) h = sysv_hash(s); sym = sysv_lookup(s, h, dso); |