RFR: 8250876: Build system preparation to macos on aarch64

[David Holmes]

Thanks Bernhard. General cross-compilation improvement are a good thing.

Cheers,
David
-----

On 5/08/2020 12:02 am, Bernhard Urban-Forster wrote:
> Good observation David, the change in adlc is just fixing a symptom. The difference to a regular macOS build is that technically, despite running on the same machine, it's actually cross compiling due to Rosetta being the --build=x86_64 system.
> 
> Being a cross-compile, we therefore hit this case:
> https://github.com/openjdk/jdk/blob/b0ceab23dd4176329cbf3a95f21e8e9ac2d8723f/make/autoconf/toolchain.m4#L905-L921
> 
> And thus infers `/usr/bin/CC` for CXX.
> 
> I guess cross compiling hasn't been a thing on macOS yet. I tried the following and it passes the adlc build:
> 
> --- a/make/autoconf/toolchain.m4
> +++ b/make/autoconf/toolchain.m4
> @@ -917,7 +917,7 @@ AC_DEFUN_ONCE([TOOLCHAIN_SETUP_BUILD_COMPILERS],
>       # find the build compilers in the tools dir, if needed.
>       UTIL_REQUIRE_PROGS(BUILD_CC, [cl cc gcc])
>       UTIL_FIXUP_EXECUTABLE(BUILD_CC)
> -    UTIL_REQUIRE_PROGS(BUILD_CXX, [cl CC g++])
> +    UTIL_REQUIRE_PROGS(BUILD_CXX, [clang++ cl CC g++])
>       UTIL_FIXUP_EXECUTABLE(BUILD_CXX)
>       UTIL_PATH_PROGS(BUILD_NM, nm gcc-nm)
>       UTIL_FIXUP_EXECUTABLE(BUILD_NM)
> 
> Although I'm not sure about its cleanliness :-)
> 
> -Bernhard
> 
> ________________________________________
> From: build-dev <build-dev-retn at openjdk.java.net> on behalf of David Holmes <david.holmes at oracle.com>
> Sent: Tuesday, August 4, 2020 00:46
> To: Erik Joelsson; Vladimir Kempik; build-dev
> Cc: Anton Kozlov; Alexander Ioffe; Andrew Brygin; Andrey Petushkov
> Subject: Re: RFR: 8250876: Build system preparation to macos on aarch64
> 
> On 3/08/2020 10:57 pm, Erik Joelsson wrote:
>> Hello Vladimir,
>>
>> These changes look innocent enough to me. They aren't actually adding
>> macosx-aarch64 support, they are just removing two minor (and more
>> likely OS version related) hurdles from the build. You still have to
>> provide the actual configuration on the configure command line as is
>> shown in your example. Before we can call build system support, we would
>> need configure to automatically setup those flags and add a separate
>> parameter for the JNF framework. So, given that, I don't think this
>> change warrants a JEP in itself.
> 
> Of course this change doesn't warrant a JEP in itself :) My point is
> that until we have a JEP for the platform that is being targeted then we
> shouldn't be making changes to provide support for that platform.
> 
> That said I didn't actually look at the changes but focused on the
> larger stated aim, so apologies for that.
> 
> The actual changes here are small and not obviously related to
> supporting macOS-Aarch64. But I'm unclear on this change as it affects
> all macOS builds:
> 
>     42   else ifeq ($(call isBuildOs, macosx), true)
>     43     ADLC_LDFLAGS := -lc++
> 
> if this was fixing a bug as indicated, why do we not see this bug in
> regular builds?
> 
> Thanks,
> David
> -----
> 
> 
>> My only complaint is that you revert jib-profiles.js. That file is only
>> used internally at Oracle. If/when we need it to support macosx-aarch64,
>> we will provide those changes.
>>
>> I must say I'm happy to see you managed to get a working build
>> configuration with just this though!
>>
>> /Erik
>>
>> On 2020-08-01 00:24, Vladimir Kempik 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: https://nam06.safelinks.protection.outlook.com/?url=http:%2F%2Fcr.openjdk.java.net%2F~vkempik%2F8250876%2Fwebrev.00%2F&data=02%7C01%7Cbeurba%40microsoft.com%7C0c8d58d5eb9144e8717f08d837ff3736%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637320916565796801&sdata=HpXJmHXbuawTdExWESK9ssesYTuPTj7N6inXjaHfVaM%3D&reserved=0
>>> The bug: https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.openjdk.java.net%2Fbrowse%2FJDK-8250876&data=02%7C01%7Cbeurba%40microsoft.com%7C0c8d58d5eb9144e8717f08d837ff3736%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637320916565796801&sdata=9z2Nw8d0pa5huxUKOYorMOVy6SBo7o%2FhDT1EmgOhxQ8%3D&reserved=0
>>>
>>> Testing: jdk/submit.
>>>
>>> Thanks, Vladimir.