[patch] expanding tables for bfd/hash.c
Alan Modra
amodra@bigpond.net.au
Wed May 3 04:19:00 GMT 2006
On Tue, May 02, 2006 at 11:52:14PM -0400, DJ Delorie wrote:
>
> > A quicker alternative might be to leave the default unchanged. There
> > are a lot of tests that depend on symbol table order, and some only run
> > natively.
>
> I assume none (or few) tests have more than 4k symbols then?
Fortunately, that seems to be the case.
> > How about this?
> >
> > * hash.c (DEFAULT_SIZE): Revert last change.
> > (higher_prime_number): Correct test for no larger prime. Don't
> > abort on error, instead return 0. Depopulate primes[].
> > (bfd_hash_lookup): If we overflow size, refuse to grow table.
>
> That looks like a good change.
I'm committing a slightly different patch after realising that leaving
8191 in the table means the first table expansion is only doubling in
size.
Index: bfd/hash.c
===================================================================
RCS file: /cvs/src/src/bfd/hash.c,v
retrieving revision 1.21
diff -u -p -r1.21 hash.c
--- bfd/hash.c 1 May 2006 19:36:27 -0000 1.21
+++ bfd/hash.c 3 May 2006 04:13:05 -0000
@@ -298,10 +298,11 @@ SUBSUBSECTION
*/
/* The default number of entries to use when creating a hash table. */
-#define DEFAULT_SIZE (4093)
+#define DEFAULT_SIZE 4051
/* The following function returns a nearest prime number which is
- greater than N, and near a power of two. Copied from libiberty. */
+ greater than N, and near a power of two. Copied from libiberty.
+ Returns zero for ridiculously large N to signify an error. */
static unsigned long
higher_prime_number (unsigned long n)
@@ -309,18 +310,8 @@ higher_prime_number (unsigned long n)
/* These are primes that are near, but slightly smaller than, a
power of two. */
static const unsigned long primes[] = {
- (unsigned long) 7,
- (unsigned long) 13,
- (unsigned long) 31,
- (unsigned long) 61,
(unsigned long) 127,
- (unsigned long) 251,
- (unsigned long) 509,
- (unsigned long) 1021,
(unsigned long) 2039,
- (unsigned long) 4093,
- (unsigned long) 8191,
- (unsigned long) 16381,
(unsigned long) 32749,
(unsigned long) 65521,
(unsigned long) 131071,
@@ -343,7 +334,7 @@ higher_prime_number (unsigned long n)
};
const unsigned long *low = &primes[0];
- const unsigned long *high = &primes[sizeof(primes) / sizeof(primes[0])];
+ const unsigned long *high = &primes[sizeof (primes) / sizeof (primes[0])];
while (low != high)
{
@@ -354,12 +345,8 @@ higher_prime_number (unsigned long n)
high = mid;
}
- /* If we've run out of primes, abort. */
- if (n > *low)
- {
- fprintf (stderr, "Cannot find prime bigger than %lu\n", n);
- abort ();
- }
+ if (n >= *low)
+ return 0;
return *low;
}
@@ -486,12 +473,19 @@ bfd_hash_lookup (struct bfd_hash_table *
if (table->count > table->size * 3 / 4)
{
- int newsize = higher_prime_number (table->size);
+ unsigned long newsize = higher_prime_number (table->size);
struct bfd_hash_entry **newtable;
unsigned int hi;
- unsigned int alloc;
+ unsigned long alloc = newsize * sizeof (struct bfd_hash_entry *);
- alloc = newsize * sizeof (struct bfd_hash_entry *);
+ /* If we can't find a higher prime, or we can't possibly alloc
+ that much memory, don't try to grow the table. */
+ if (newsize == 0 || alloc / sizeof (struct bfd_hash_entry *) != newsize)
+ {
+ /* Lie. Stops us trying to grow again for a while. */
+ table->count = 0;
+ return hashp;
+ }
newtable = ((struct bfd_hash_entry **)
objalloc_alloc ((struct objalloc *) table->memory, alloc));
@@ -505,7 +499,7 @@ bfd_hash_lookup (struct bfd_hash_table *
int index;
while (chain_end->next && chain_end->next->hash == chain->hash)
- chain_end = chain_end->next;
+ chain_end = chain_end->next;
table->table[hi] = chain_end->next;
index = chain->hash % newsize;
--
Alan Modra
IBM OzLabs - Linux Technology Centre
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