Small lookmapping nits:
- remove bogus initialization using uninitialized i
- derive initial incr from hash
- copy mp->ma_table into a local variable
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index bcd615d..8f3d3a6 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -169,14 +169,15 @@
register unsigned long sum = (unsigned long) hash;
register mappingentry *freeslot = NULL;
register int mask = mp->ma_size-1;
- register mappingentry *ep = &mp->ma_table[i];
+ mappingentry *ep0 = mp->ma_table;
+ register mappingentry *ep;
/* We must come up with (i, incr) such that 0 <= i < ma_size
and 0 < incr < ma_size and both are a function of hash */
i = (~sum) & mask;
/* We use ~sum instead if sum, as degenerate hash functions, such
as for ints <sigh>, can have lots of leading zeros. It's not
really a performance risk, but better safe than sorry. */
- ep = &mp->ma_table[i];
+ ep = &ep0[i];
if (ep->me_key == NULL)
return ep;
if (ep->me_key == dummy)
@@ -185,16 +186,16 @@
(ep->me_hash == hash && cmpobject(ep->me_key, key) == 0)) {
return ep;
}
- /* Derive incr from i, just to make it more arbitrary. Note that
+ /* Derive incr from sum, just to make it more arbitrary. Note that
incr must not be 0, or we will get into an infinite loop.*/
- incr = i << 1;
+ incr = (sum ^ (sum >> 3)) & mask;
if (!incr)
incr = mask;
if (incr > mask) /* Cycle through GF(2^n)-{0} */
incr ^= mp->ma_poly; /* This will implicitly clear the
highest bit */
for (;;) {
- ep = &mp->ma_table[(i+incr)&mask];
+ ep = &ep0[(i+incr)&mask];
if (ep->me_key == NULL) {
if (freeslot != NULL)
return freeslot;