RFR: 8352064: AIX: now also able to build static-jdk image with a statically linked launcher [v4]

[Martin Doerr]

On Fri, 21 Mar 2025 11:44:49 GMT, Joachim Kern <jkern at openjdk.org> wrote:

>> After "JDK-8339480: Build static-jdk image with a statically linked launcher" AIX was not able to build the new target. Therefore with "JDK-8345590 AIX 'make all' fails after JDK-8339480" the new target was disabled again.
>> 
>> Now with this change we can enable the statically linked launcher target again.
>> There are 3 things to do.
>> 1.	Modify `dladdr()`. Because this API does not exist on AIX it is implemented based on the `loadquery()` API. Unfortunately, this API does only return the name of the executable, but not its path. Beforehand this was no problem, because we asked for a loaded library, for which the API provides the path. But now we are asking for the executable itself.
>> 2.	`dladdr()` is differently implemented three times in the openjdk code. In the static case I supressed now the usage of the additional modules containing version two and three. I know this shouldn't be the final version. Magnus mentioned that they have discussed from time to time to have a "basic JDK utility lib" that can be shared between hotspot and the JDK libraries. I think this is a good idea for the future, but far beyond the scope of this PR. The second best thing Magnus proposed is to only have the `dladdr()` functionality in Hotspot and then export it. Let's see how the community decides.
>> 3.	Because we lack a linker flag like `whole-archive`, I had to force the export of all symbols by creating export files containing all symbols of the static libs. I introduced the new rule for the export file generation as "raw" make recipes. Magnus claimed to use the `SetupExecute`. Unfortunately I was not able to make it function. So I still have my "raw" solution in place, but my last try with `SetupExecute` as comment beneath. Help is welcome.
>
> Joachim Kern has updated the pull request incrementally with one additional commit since the last revision:
> 
>   follow Magnus

I'm not really familiar with it, but I have some code style requests.

src/hotspot/os/aix/loadlib_aix.cpp line 218:

> 216:     procentry64 PInfo;
> 217:     PInfo.pi_pid = ::getpid();
> 218:     if ( 0 == ::getargs(&PInfo, sizeof(PInfo), (char*)pgmpath,PATH_MAX) && *pgmpath ) {

Coding style: spaces after `(` and before `)` are uncommon, but we should have one before `PATH_MAX`.
I think hotspot style guide compliant would be:
`if (0 == ::getargs(&PInfo, sizeof(PInfo), (char*)pgmpath, PATH_MAX) && *pgmpath != 0)`

src/hotspot/os/aix/loadlib_aix.cpp line 221:

> 219:       pgmpath[PATH_MAX] = '\0';
> 220:       pgmbase = strrchr(pgmpath, '/');
> 221:       if (pgmbase) {

Better: `if (pgmbase != nullptr)`

src/hotspot/os/aix/loadlib_aix.cpp line 222:

> 220:       pgmbase = strrchr(pgmpath, '/');
> 221:       if (pgmbase) {
> 222:         pgmbase +=1;

Maybe add a space: "+= 1"?

src/hotspot/os/aix/loadlib_aix.cpp line 245:

> 243:     lm->data_len = ldi->ldinfo_datasize;
> 244: 
> 245:     if (pgmbase && 0 == strcmp(pgmbase, ldi->ldinfo_filename)) {

`pmgbase != nullptr`

-------------

PR Review: https://git.openjdk.org/jdk/pull/24062#pullrequestreview-2706439265
PR Review Comment: https://git.openjdk.org/jdk/pull/24062#discussion_r2007864471
PR Review Comment: https://git.openjdk.org/jdk/pull/24062#discussion_r2007869385
PR Review Comment: https://git.openjdk.org/jdk/pull/24062#discussion_r2007866684
PR Review Comment: https://git.openjdk.org/jdk/pull/24062#discussion_r2007870732