RFR: 8250876: Build system preparation to macos on aarch64

[Magnus Ihse Bursie]

On 2020-08-13 09:15, Kim Barrett wrote:
>> On Aug 1, 2020, at 3:24 AM, Vladimir Kempik <vkempik at azul.com> wrote:
>>
>> Hello
>>
>> Please review this change for JDK-8250876
>>
>> This changeset adds support for macos/aarch64 into build system.
>> It will allow to crosscompile for macos/aarch64 using intel mac as well.
>>
>> This changeset does NOT address some arm specific issues in the macos related code, we plan to do that in s separate commit.
>>
>> An example of configure to cross-compile for macos/arm64:
>>
>> --with-boot-jdk=/path/to/java/ --with-build-jdk=/path/to/same/java/as/compiled  --disable-warnings-as-errors --with-jvm-variants=zero --openjdk-target=aarch64-apple-darwin --with-extra-cflags='-arch arm64' --with-extra-ldflags='-arch arm64 -F/Path/To/Folder/Containing/JNF_framework/' —with-extra-cxxflags='-arch arm64’
>>
>> JNF.framework is missing arm64 part as of next macos release, but Apple has opensourced it.
>>
>> Fix to adlc were needed due to it using symbols from stdc++ and not linking to it, so it fails when doing make images.
>>
>> The webrev: http://cr.openjdk.java.net/~vkempik/8250876/webrev.00/
>> The bug: https://bugs.openjdk.java.net/browse/JDK-8250876
>>
>> Testing: jdk/submit.
>>
>> Thanks, Vladimir.
> Coming late to the party, as I see this has already been pushed.  But
> one thing caught my eye.
>
> ------------------------------------------------------------------------------
>    42   else ifeq ($(call isBuildOs, macosx), true)
>    43     ADLC_LDFLAGS := -lc++
>
> I'm surprised this is needed. I expected the C++ toolchain to
> implicitly include that, the way g++ does.
>
> If something like this really is needed, then it seems like it should
> be ADLC_LIBS that should be modified, rather than ADLC_LDFLAGS.
> Though I noticed there are currently no assignments to ADLC_LIBS.
>
> I'm similarly surprised by this pre-existing bit in CoreLibraries.gmk:
>
> $(eval $(call SetupJdkLibrary, BUILD_LIBJIMAGE, \
> ...
>      LIBS_unix := -ljvm -ldl $(LIBCXX), \
>      LIBS_macosx := -lc++, \
>
> And that suggests a better place for all this (assuming its needed at
> all) is in lib-std.m4, setting LIBCXX for macosx and using it where
> needed.
Yes, that looks weird. Probably some left-over from the initial 
integration of libjimage. I can build fine locally without it; I'm just 
verifying that it also works in the CI. Thank you for noticing this!

/Magnus

>
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