RFR: 8292329: Enable CDS shared heap for zero builds [v2]

[Ioi Lam]

On Tue, 23 Aug 2022 17:12:44 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

>> In that case, the loop you proposed make a lot of sense and I think you should add it.
>
> Oh, the loop is already there, it's jus the naming of the variable. I think we should adjust that so the check-jvm-feature macro can be used.

@erikj79 I couldn't get it to work. I believe the following is evaluated only once, so `$(JVM_VARIANT)` is bound to the value when HotspotCommon.gmk is loaded:


check-jvm-feature = \
  $(strip \
    $(if $(filter-out $(VALID_JVM_FEATURES), $1), \
      $(error Internal error: Invalid feature tested: $1)) \
    $(if $(filter $1, $(JVM_FEATURES_$(JVM_VARIANT))), true, false))


So I would need to run a submake in order to get this function to behave differently for each variant. That's going to be complicated in order to support multiple JVM variants per build.

I heard that we are going to remove multiple variant support (?), so maybe this is not worth it.

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PR: https://git.openjdk.org/jdk/pull/9984