RFR: 8252233: Enable debug-image target to support producing a pure debug image package

[Erik Joelsson]

On 2020-08-28 00:51, Magnus Ihse Bursie wrote:
> On 2020-08-27 23:26, Erik Joelsson wrote:
>> Hello Andrew,
>>
>> We certainly appreciate contributions, but this patch as it currently 
>> looks does not fit well with our current build system model. I'm 
>> however not against adding a target for your usecase.
>>
>> On a high level, just as Severin pointed out, the term "debug" is 
>> used for the type configuration we are building (release vs debug). 
>> For debug information we have instead chosen the term "symbols", so 
>> the target should rather be called symbols-image. Now I realize we 
>> already have that target, for something slightly different. I 
>> introduced that a long time ago for gcov symbols, with the intention 
>> of eventually move the main debug symbols into it too, but that never 
>> happened. I think we can just make that change now and let the 
>> symbols-image be what you are asking for (in addition to the gcov 
>> files if those are enabled). This will be one step in the direction 
>> of a bigger overhaul of the images that I want to do anyway.
>>
>> On a lower level, in Main.gmk, all targets should be declared as 
>> calls to the macro SetupTarget and in the correct section of the 
>> file. In this case it would be around line 418 where the current 
>> symbols-image is declared.
>>
>> The new file DebugImage.gmk contains a lot of duplication of logic 
>> already implemented in Images.gmk, which can quite easily be extended 
>> to cover your usecase.
>>
>> So all that said, this is how I would suggest to solve it:
>>
>> http://cr.openjdk.java.net/~erikj/8252233/webrev.01/index.html
> Erik,
>
> I fully agree with you in your analysis on the proper way to solve 
> this. However, I have a hard time figuring out how the patch you 
> supplied will achieve that. :-) Maybe you can help me understand how 
> this would actually make the debug symbols be added to the symbol image?

Sure! In the already present "Debug symbols" section of Images.gmk, we 
have a bunch of convoluted logic for finding all debugsymbols in the 
respective modules_libs and modules_cmds dirs and generate rules for 
copying them to the relevant images. This logic is already parameterized 
to do the same job for the JRE and JDK images, so at the bottom, there 
were already two calls to SetupCopyDebuginfo, one for JDK and one for 
JRE. For these calls to work, there needs to be 2 variables defined 
specific to the image we are copying to. The list of modules relevant 
for this image and the target directory, ALL_$1_MODULES and $_IMAGE_DIR 
respectively. The patch adds the first variable and the second was 
already defined as we already have symbols image.

In Bundles.gmk, we generate the main JDK bundle by filtering out the 
debugsymbols from the jdk image, then we generate the symbols image by 
filtering just the debugsymbols from the jdk image, as well as adding 
everything from the symbols image. The last part is basically only done 
in case we built with gcov. Now with this patch, the symbols image 
always contains the full set of debug symbols, so we would end up with 
duplicate rules as the same files would be copied from two different 
places. To fix this, I simply removed the JDK image as a source of files 
for the symbols bundle.

The logic in Bundles.gmk is still unreasonably complex, and I hope to 
fix this at some point, but I think it's out of scope for this change. 
What I would like to do is change Images.gmk to generate a pure symbols 
image (basically done with this patch) and a pure JDK image containing 
exactly what should go into the bundle, then also (optionally) a 3rd 
image that looks like our current JDK image with the former two combined 
which is convenient for development use in local builds.

/Erik

>
> /Magnus
>>
>> With this change, building the symbols image is part of the top level 
>> product-images target (but separate from the more specific jdk-image 
>> target). In Bundles.gmk, building the jdk bundles tar.gz gets 
>> slightly simpler as the files can be found directly in the symbols 
>> image.
>>
>> I still need to test this properly on all platforms.
>>
>> /Erik
>>
>> On 2020-08-27 08:55, Andrew Leonard wrote:
>>> Hi,
>>> Please may I request a sponsor and review for this build enhancement to
>>> provide a pure debug "image", for those developers that want to 
>>> accompany
>>> a straight jdk image with a debug-image when needed:
>>>      https://bugs.openjdk.java.net/browse/JDK-8252233
>>>      webrev: http://cr.openjdk.java.net/~aleonard/8252233/webrev.00/
>>> We have been providing this as part of the openj9 builds at 
>>> AdoptOpenJDK
>>> for a while now, and would like to contribute it upstream to openjdk.
>>>
>>> Thanks
>>> Andrew
>>>
>>> Andrew Leonard
>>> Java Runtimes Development
>>> IBM Hursley
>>> IBM United Kingdom Ltd
>>> internet email: andrew_m_leonard at uk.ibm.com
>>>
>>> Unless stated otherwise above:
>>> IBM United Kingdom Limited - Registered in England and Wales with 
>>> number
>>> 741598.
>>> Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire 
>>> PO6 3AU
>>>
>