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runtime: if key type is reflexive, don't call equal(k, k)

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Most types are reflexive (k == k for all k of type t), so don't
bother calling equal(k, k) when the key type is reflexive.

Change-Id: Ia716b4198b8b298687843b94b878dbc5e8fc2c65
Reviewed-on: https://go-review.googlesource.com/1480
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
Keith Randall 2014-12-12 13:45:19 -08:00
parent 324f38a222
commit df1739c77d
4 changed files with 81 additions and 3 deletions
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6
src/runtime/hashmap.go
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@ -652,7 +652,7 @@ next:
if t.indirectkey {
k2 = *((*unsafe.Pointer)(k2))
}
if alg.equal(k2, k2, uintptr(t.key.size)) {
if t.reflexivekey || alg.equal(k2, k2, uintptr(t.key.size)) {
// If the item in the oldbucket is not destined for
// the current new bucket in the iteration, skip it.
hash := alg.hash(k2, uintptr(t.key.size), uintptr(h.hash0))
@ -689,7 +689,7 @@ next:
if t.indirectkey {
k2 = *((*unsafe.Pointer)(k2))
}
if alg.equal(k2, k2, uintptr(t.key.size)) {
if t.reflexivekey || alg.equal(k2, k2, uintptr(t.key.size)) {
// Check the current hash table for the data.
// This code handles the case where the key
// has been deleted, updated, or deleted and reinserted.
@ -798,7 +798,7 @@ func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
// to send this key/value to bucket x or bucket y).
hash := alg.hash(k2, uintptr(t.key.size), uintptr(h.hash0))
if h.flags&iterator != 0 {
if !alg.equal(k2, k2, uintptr(t.key.size)) {
if !t.reflexivekey && !alg.equal(k2, k2, uintptr(t.key.size)) {
// If key != key (NaNs), then the hash could be (and probably
// will be) entirely different from the old hash. Moreover,
// it isn't reproducible. Reproducibility is required in the