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runtime: no need to protect key/value increments against end of bucket

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After the key and value arrays, we have an overflow pointer.
So there's no way a past-the-end key or value pointer could point
past the end of the containing bucket.

So we don't need this additional protection.

Update #21459

Change-Id: I7726140033b06b187f7a7d566b3af8cdcaeab0b0
Reviewed-on: https://go-review.googlesource.com/56772
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Avelino <t@avelino.xxx>
This commit is contained in:
Keith Randall 2017-08-17 23:13:57 -07:00
parent a93753401d
commit 77871cc664
1 changed files with 6 additions and 6 deletions
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12
src/runtime/hashmap.go
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@ -1119,12 +1119,12 @@ func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
typedmemmove(t.elem, dst.v, v)
}
dst.i++
// If we're at the end of the bucket, don't update k/v,
// to avoid pointers pointing past the end of the bucket.
if dst.i < bucketCnt {
dst.k = add(dst.k, uintptr(t.keysize))
dst.v = add(dst.v, uintptr(t.valuesize))
}
// These updates might push these pointers past the end of the
// key or value arrays. That's ok, as we have the overflow pointer
// at the end of the bucket to protect against pointing past the
// end of the bucket.
dst.k = add(dst.k, uintptr(t.keysize))
dst.v = add(dst.v, uintptr(t.valuesize))
}
}
// Unlink the overflow buckets & clear key/value to help GC.