[jdk8u-dev] RFR: 8281096: Flags introduced by configure script are not passed to ADLC build [v7]

[Andrew John Hughes]

On Mon, 24 Jun 2024 13:58:48 GMT, Andrew John Hughes <andrew at openjdk.org> wrote:

>> The 8u configure script defines compiler flags in `EXTRA_CFLAGS`, `EXTRA_LDFLAGS` and `EXTRA_ASFLAGS`. Some are added by configure tests, while others are taken directly from corresponding options passed by the user.
>> 
>> 8u still use the legacy HotSpot build system which is not fully integrated with the autoconf system. Variables defined by configure thus have to be explicitly passed down to the separate HotSpot build.
>> 
>> ADLC is a tool used at build-time and so the flags it uses don't impact on the end product. So, for a long time, it has been ignoring these flags defined by configure and using just its own minimal set.
>> 
>> However, with newer compilers, this means that the code is compiled to a newer version of the C++ standard, as the default has changed in GCC 6 and later (see [JDK-8151841](https://bugs.openjdk.org/browse/JDK-8151841)). With the latest versions of GCC (11 and 12), this actually leads to build failures due to the use of 'register' (GCC 11) and the way comments are used (GCC 12) in the code.
>> 
>> We should fix the ADLC build to use the same flags as the rest of the build. The impact should be negligible, given the same flags are already used in the code that is actually shipped.
>> 
>> This does not affect 9+ where HotSpot's build system has been replaced with full integration in the autoconf system.
>> 
>> With this change, 8u can be built with GCC 11 on GNU/Linux. I'd appreciate testing on other platforms, particularly those not covered by GHA (Solaris, AIX - @adamfarley, @sxa & @deepa181 who have provided previous fixes for these platforms)
>> 
>> During testing, we found we could not use the `EXTRA_` prefixed variables as they include flags for the target compiler on cross-compilation builds. To fix this, we split out new `HOST_` prefixed variables which include all the flags of the `EXTRA_` prefixed variables, bar the `--sysroot` options.
>
> Andrew John Hughes has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains ten additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'dev/master' into JDK-8281096
>  - Separate host and target compiler flags
>  - Merge remote-tracking branch 'dev/master' into JDK-8281096
>  - Print spec files in right workflow and use path to build directory
>  - Fix whitespace in yaml file
>  - Merge remote-tracking branch 'dev/master' into JDK-8281096
>  - Print the spec.gmk and hotspot-spec.gmk files
>  - Temporarily enable debug logging for cross-compile build
>  - 8281096: Flags introduced by configure script are not passed to ADLC build

> I have done some additional testing:
> 
>     * I  [tested](https://github.com/zzambers/jdk8u-dev/actions/runs/9664993178)  this, with GHA workflows updated to ubuntu-22.04 on top (+ [fix for jdi test](https://github.com/openjdk/jdk8u-dev/pull/497)). This is because, I have recently seen build failures on some archs, when I [tried to update GHA testing to ubuntu-22.04](https://github.com/openjdk/jdk8u-dev/pull/491#issue-2281128235), while looking at another issue. There are no build failures with this changeset (1 test failure/error on linux x86 seems unrelated).
> 
>     * I have also tried to do build in rhel-9 VM (gcc-11.4.1). It passed ADLC build (unlike unpatched version). Build later failed on another (separate) error in `hotspot/src/share/vm/opto/type.cpp` (see [8329826: GCC 12 reports some compiler error when building jdk8 #479 (comment)](https://github.com/openjdk/jdk8u-dev/pull/479#issuecomment-2058078166)). If I also modified `type.cpp` (based on that PR), build passed.
> 
> 
> Change looks good. (works for me)

Thanks for testing. Can you give me more details on what kind of build failed in `type.cpp` (e.g. release/slowdebug/fastdebug)?  With just this patch, it builds for me on GCC 13.

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PR Comment: https://git.openjdk.org/jdk8u-dev/pull/357#issuecomment-2289157265