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[buddy] Reduce the size of bddNode to improve cache efficiency.

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The unicity table was mixed with the bddNode table for now
apparent reason.  After the hash of some node is computed,
bddnodes[hash] did only contain some random node (not the one
looked for) whose .hash member would point to the actual node with
this hash.  So that's a two step lookup.  With this patch, we sill
have a two step lookup, but the .hash member have been moved to a
separate array.  A consequence is that bddNode is now 16-byte long
(instead of 20) so it will never span across two cache lines.

* src/kernel.h (bddNode): Remove the hash member, and move it...
(bddhash): ... as this new separate table.
* src/kernel.c, src/reorder.c: Adjust all code.
This commit is contained in:
Alexandre Duret-Lutz 2012-06-08 11:28:48 +02:00
parent 96c436e0e2
commit e7a46e10e2
4 changed files with 75 additions and 43 deletions
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43
buddy/src/kernel.c
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@ -90,6 +90,7 @@ int bddnodesize; /* Number of allocated nodes */
int bddmaxnodesize; /* Maximum allowed number of nodes */
int bddmaxnodeincrease; /* Max. # of nodes used to inc. table */
BddNode* bddnodes; /* All of the bdd nodes */
int* bddhash; /* Unicity hash table */
int bddfreepos; /* First free node */
int bddfreenum; /* Number of free nodes */
long int bddproduced; /* Number of new nodes ever produced */
@ -183,13 +184,18 @@ int bdd_init(int initnodesize, int cs)
if ((bddnodes=(BddNode*)malloc(sizeof(BddNode)*bddnodesize)) == NULL)
return bdd_error(BDD_MEMORY);
if ((bddhash=(int*)calloc(bddnodesize, sizeof(*bddhash))) == NULL)
{
free(bddnodes);
return bdd_error(BDD_MEMORY);
}
bddresized = 0;
for (n=0 ; n<bddnodesize ; n++)
{
bddnodes[n].refcou = 0;
LOW(n) = -1;
bddnodes[n].hash = 0;
LEVEL(n) = 0;
bddnodes[n].next = n+1;
}
@ -1018,8 +1024,8 @@ static void bdd_gbc_rehash(void)
register unsigned int hash;
hash = NODEHASH(LEVELp(node), LOWp(node), HIGHp(node));
node->next = bddnodes[hash].hash;
bddnodes[hash].hash = n;
node->next = bddhash[hash];
bddhash[hash] = n;
}
else
{
@ -1055,9 +1061,10 @@ void bdd_gbc(void)
{
if (bddnodes[n].refcou > 0)
bdd_mark(n);
bddnodes[n].hash = 0;
}
memset(bddhash, 0, bddnodesize*sizeof(*bddhash));
bddfreepos = 0;
bddfreenum = 0;
@ -1071,8 +1078,8 @@ void bdd_gbc(void)
LEVELp(node) &= MARKOFF;
hash = NODEHASH(LEVELp(node), LOWp(node), HIGHp(node));
node->next = bddnodes[hash].hash;
bddnodes[hash].hash = n;
node->next = bddhash[hash];
bddhash[hash] = n;
}
else
{
@ -1313,7 +1320,7 @@ int bdd_makenode(unsigned int level, int low, int high)
/* Try to find an existing node of this kind */
hash = NODEHASH(level, low, high);
res = bddnodes[hash].hash;
res = bddhash[hash];
while(res != 0)
{
@ -1378,8 +1385,8 @@ int bdd_makenode(unsigned int level, int low, int high)
HIGHp(node) = high;
/* Insert node */
node->next = bddnodes[hash].hash;
bddnodes[hash].hash = res;
node->next = bddhash[hash];
bddhash[hash] = res;
return res;
}
@ -1412,14 +1419,26 @@ int bdd_noderesize(int doRehash)
return bdd_error(BDD_MEMORY);
bddnodes = newnodes;
/* An error while reallocating bddhash is very unlikely, because
the new bddhash should fit easily in the area freed by the old
bddnode. */
if (doRehash)
for (n=0 ; n<oldsize ; n++)
bddnodes[n].hash = 0;
{
free(bddhash);
if ((bddhash=(int*)calloc(bddnodesize, sizeof(*bddhash))) == NULL)
return bdd_error(BDD_MEMORY);
}
else
{
bddhash = (int*)realloc(bddhash, sizeof(*bddhash)*bddnodesize);
if (bddhash == NULL)
return bdd_error(BDD_MEMORY);
memset(bddhash + oldsize, 0, (bddnodesize-oldsize)*sizeof(*bddhash));
}
for (n=oldsize ; n<bddnodesize ; n++)
{
bddnodes[n].refcou = 0;
bddnodes[n].hash = 0;
LEVEL(n) = 0;
LOW(n) = -1;
bddnodes[n].next = n+1;