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

[Joachim Kern]

On Fri, 14 Mar 2025 17:35:02 GMT, Erik Joelsson <erikj 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.
>
> make/StaticLibs.gmk line 116:
> 
>> 114: #    DEPS :=  $(STATIC_LIB_FILE), \
>> 115: #    OUTPUT_FILE := $(STATIC_LIB_EXPORT_FILES), \
>> 116: #    COMMAND := $(AR) $(ARFLAGS) -w $(patsubst %.exp, %, $@) | $(GREP) -v '^\.' | $(AWK) '{print $$1}' | sort -u >$@, \
> 
> The problem with using SetupExecute here is using `$@` variables in the command line. To get this to work you need to delay resolving such variables. It may work by adding an adequate number of extra `$`, but I'm not sure how many would be needed or if it would actually work. You could try this, but it's probably trickier to get right than just doubling:
> 
> Suggestion:
> 
> #    COMMAND := $(AR) $(ARFLAGS) -w $$(patsubst %.exp, %, $$@) | $(GREP) -v '^.' | $(AWK) '{print $$$$1}' | sort -u >$$@, \
> 
> 
> You are probably better off using the explicit output file variable `$(STATIC_LIB_EXPORT_FILES)`.

Thanks Eric, this might help with the command, but my problem is the dependency. The rules to generate the export files is not called, because in the build output I cannot find any line 'Generating export list for static libs'. Can you help out here too?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24062#discussion_r1998375442