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.

2 files changed, 3 insertions, 3 deletions

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)
 {