Help analyzing output from COMPARE_BUILD

[Magnus Ihse Bursie]

On 2025-03-07 18:35, Magnus Ihse Bursie wrote:

> This question belongs on build-dev. I've cc:ed that list, please keep 
> future discussions there and not in jdk-dev. I'll repsond to your 
> question in build-dev.
>
> /Magnus
>
> On 2025-03-07 16:28, Harald Eilertsen wrote:
>> Hi,
>>
>> I've made a small patch to parameterize how support for pthreads is
>> enables in the makefiles. This should not make any difference to
>> existing builds, but running make with COMPARE_BUILD like this:
>>
>>      make jdk-image test-image COMPARE_BUILD=PATCH=pthread-diff.patch
>>
>> I get the following results indicating that there are differences in
>> libjvm.so:
>>
>> https://cryptpad.fr/code/#/2/code/view/t1NVNd5bPzuxVBfEgDKSrt2rLazJaFcFFRimYq6h1-0/ 
>>
>>
>> I could use some help analyzing this output.

You are seeing some minor variance in the special hotspot gtest library. 
This is known (at least to me :)) to be somewhat flaky, and does not 
always build without differences, even if the rest of the JDK does so. 
These changes are harmless, and are just some kind of offset changes in 
the ELF structure. I guess there is something in the gtest framework 
that triggers this, I just have not figured out what. I have intended to 
dig into it some day, but never gotten around to it.

/Magnus


>>
>>
>> The full patch is here:
>>
>> https://cryptpad.fr/code/#/2/code/view/2bB0IOCAyG+RZTUSiUQE3g5skfYr2TE7Vx+XYO5a8wY/ 
>>
>>
>> The only difference I can see in the generated configure and makefiles
>> is the added `LIBPTHREAD` variable in spec.gmk.
>>
>> Thanks in adcance,
>> Harald