From 50447f0bfa84046961cdc7693f7c374f5b81d461 Mon Sep 17 00:00:00 2001 From: Sverker Eriksson Date: Thu, 26 May 2016 12:13:19 +0200 Subject: erts: Improve some bad hash functions Multiplying two atoms will always yield the same low 6 bits. The most important tabke 'export' was saved by the prime number table size which seemed to yield a decent uniform distribution anyway. --- erts/emulator/beam/export.c | 2 +- erts/emulator/hipe/hipe_bif0.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'erts/emulator') diff --git a/erts/emulator/beam/export.c b/erts/emulator/beam/export.c index 02c24557c1..cfe7c06823 100644 --- a/erts/emulator/beam/export.c +++ b/erts/emulator/beam/export.c @@ -31,7 +31,7 @@ #define EXPORT_INITIAL_SIZE 4000 #define EXPORT_LIMIT (512*1024) -#define EXPORT_HASH(m,f,a) ((m)*(f)+(a)) +#define EXPORT_HASH(m,f,a) ((atom_val(m) * atom_val(f)) ^ (a)) #ifdef DEBUG # define IF_DEBUG(x) x diff --git a/erts/emulator/hipe/hipe_bif0.c b/erts/emulator/hipe/hipe_bif0.c index 4063cbf306..307d2424ce 100644 --- a/erts/emulator/hipe/hipe_bif0.c +++ b/erts/emulator/hipe/hipe_bif0.c @@ -693,7 +693,7 @@ static struct nbif nbifs[BIF_SIZE] = { #undef BIF_LIST }; -#define NBIF_HASH(m,f,a) ((m)*(f)+(a)) +#define NBIF_HASH(m,f,a) (atom_val(m) ^ atom_val(f) ^ (a)) static Hash nbif_table; static HashValue nbif_hash(struct nbif *x) @@ -1059,7 +1059,7 @@ static inline void hipe_mfa_info_table_rwunlock(void) erts_smp_rwmtx_rwunlock(&hipe_mfa_info_table.lock); } -#define HIPE_MFA_HASH(M,F,A) ((M) * (F) + (A)) +#define HIPE_MFA_HASH(M,F,A) (atom_val(M) ^ atom_val(F) ^ (A)) static struct hipe_mfa_info **hipe_mfa_info_table_alloc_bucket(unsigned int size) { -- cgit v1.2.3