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runtime: shorten hash lookup stack frames

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On amd64 the frames are very close to the limit for a
nosplit (textflag 7) function, in part because the C compiler
does not make any attempt to reclaim space allocated for
completely registerized variables. Avoid a few short-lived
variables to reclaim two words.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/10758043
This commit is contained in:
Russ Cox 2013-06-28 13:37:07 -07:00
parent 46161cd079
commit a3f842a4c1
1 changed files with 18 additions and 22 deletions
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40
src/pkg/runtime/hashmap_fast.c
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@ -16,10 +16,8 @@
void
HASH_LOOKUP1(MapType *t, Hmap *h, KEYTYPE key, byte *value)
{
uintptr hash;
uintptr bucket, oldbucket;
uintptr bucket, i;
Bucket *b;
uintptr i;
KEYTYPE *k;
byte *v;
uint8 top;
@ -80,21 +78,21 @@ HASH_LOOKUP1(MapType *t, Hmap *h, KEYTYPE key, byte *value)
}
} else {
dohash:
hash = h->hash0;
HASHFUNC(&hash, sizeof(KEYTYPE), &key);
bucket = hash & (((uintptr)1 << h->B) - 1);
bucket = h->hash0;
HASHFUNC(&bucket, sizeof(KEYTYPE), &key);
top = bucket >> (sizeof(uintptr)*8 - 8);
if(top == 0)
top = 1;
bucket &= (((uintptr)1 << h->B) - 1);
if(h->oldbuckets != nil) {
oldbucket = bucket & (((uintptr)1 << (h->B - 1)) - 1);
b = (Bucket*)(h->oldbuckets + oldbucket * h->bucketsize);
i = bucket & (((uintptr)1 << (h->B - 1)) - 1);
b = (Bucket*)(h->oldbuckets + i * h->bucketsize);
if(evacuated(b)) {
b = (Bucket*)(h->buckets + bucket * h->bucketsize);
}
} else {
b = (Bucket*)(h->buckets + bucket * h->bucketsize);
}
top = hash >> (sizeof(uintptr)*8 - 8);
if(top == 0)
top = 1;
do {
for(i = 0, k = (KEYTYPE*)b->data, v = (byte*)(k + BUCKETSIZE); i < BUCKETSIZE; i++, k++, v += h->valuesize) {
if(b->tophash[i] == top && EQFUNC(key, *k)) {
@ -114,10 +112,8 @@ dohash:
void
HASH_LOOKUP2(MapType *t, Hmap *h, KEYTYPE key, byte *value, bool res)
{
uintptr hash;
uintptr bucket, oldbucket;
uintptr bucket, i;
Bucket *b;
uintptr i;
KEYTYPE *k;
byte *v;
uint8 top;
@ -184,21 +180,21 @@ HASH_LOOKUP2(MapType *t, Hmap *h, KEYTYPE key, byte *value, bool res)
}
} else {
dohash:
hash = h->hash0;
HASHFUNC(&hash, sizeof(KEYTYPE), &key);
bucket = hash & (((uintptr)1 << h->B) - 1);
bucket = h->hash0;
HASHFUNC(&bucket, sizeof(KEYTYPE), &key);
top = bucket >> (sizeof(uintptr)*8 - 8);
if(top == 0)
top = 1;
bucket &= (((uintptr)1 << h->B) - 1);
if(h->oldbuckets != nil) {
oldbucket = bucket & (((uintptr)1 << (h->B - 1)) - 1);
b = (Bucket*)(h->oldbuckets + oldbucket * h->bucketsize);
i = bucket & (((uintptr)1 << (h->B - 1)) - 1);
b = (Bucket*)(h->oldbuckets + i * h->bucketsize);
if(evacuated(b)) {
b = (Bucket*)(h->buckets + bucket * h->bucketsize);
}
} else {
b = (Bucket*)(h->buckets + bucket * h->bucketsize);
}
top = hash >> (sizeof(uintptr)*8 - 8);
if(top == 0)
top = 1;
do {
for(i = 0, k = (KEYTYPE*)b->data, v = (byte*)(k + BUCKETSIZE); i < BUCKETSIZE; i++, k++, v += h->valuesize) {
if(b->tophash[i] == top && EQFUNC(key, *k)) {