Primitive boolean array packing
aph at redhat.com
Mon Oct 8 08:53:17 UTC 2018
On 10/07/2018 08:54 PM, Aleksey Shipilev wrote:
> You need to specify what do you mean by "it". Current prototype sure
> does break the provisions of JLS 17.6 "Word Tearing":
Oh, sure, of course.
> My comment was about generic thing: we cannot break the Java spec
> even if we have the JVM flag that makes it right again. I thought
> that what B. was suggesting as the escape hatch.
And I thought it was a switch between bit arrays and byte arrays.
> Of course, if you do packed boolean with locked/CAS-ed writes or
> otherwise guarantee the absence of word tearing, it does not break
> the spec.
Exactly. it's an interesting idea for large bit vectors, and it could
well generate good code. However, it probably makes more sense to
implement it as a bit vector class with suitable helper intrinsics.
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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