On Wed, 25 Nov 2020 09:47:19 GMT, Erik Österlund <[email protected]> wrote:
>> src/hotspot/cpu/x86/gc/z/z_x86_64.ad line 123:
>>
>>> 121:
>>> 122: ins_encode %{
>>> 123: if (barrier_data() != 0) { // barrier could be elided by
>>> ZBarrierSetC2::analyze_dominating_barriers()
>>
>> Maybe keep a bit reserved for `ZLoadBarrierElided` to just map it to `0`?
>> The former is preferred because it keeps the info that there was a barrier
>> data attached in the first place.
>
> The information that there was a barrier attached, is implicit in the
> ins_encode block due to it being run at all. In other words, since we matched
> the mach node to our ZGC access instead of a normal access, we already know
> that there was barrier data attached, and that we no longer have such barrier
> data.
Ok, makes sense. What do you think about making `ZLoadBarrierElided = 0` then?
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PR: https://git.openjdk.java.net/jdk/pull/1425
