RFR: 8240567: MethodTooLargeException thrown while creating a jlink image [v6]

[Mandy Chung]

On Sat, 1 Jul 2023 10:38:05 GMT, Oliver Kopp <duke at openjdk.org> wrote:

>> src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/SystemModulesPlugin.java line 691:
>> 
>>> 689:             }
>>> 690: 
>>> 691:             List<List<ModuleInfo>> splitModuleInfos = new ArrayList<>();
>> 
>> Please add the comments to describe what this does.   Pseudo code may also help.   It'd be helpful to explain the reason why the Sub method stores and restores what local variables.
>> 
>> I also wonder if you consider `moduleDescriptors` does this:
>> 
>>     ArrayList<Object> localVars = new ArrayList<>();
>>     moduleDescriptorsSub0(moduleInfos, localVars);
>>     .... // add new local variables to localVars
>>     moduleDescriptorsSub1(moduleInfos, localVars);
>>     .... // add new local variables to localVars
>>     :
>>     :
>> 
>> 
>> The same `localVars` array list is used and just add the new local variables defined from each batch (no need to create a new ArrayList and stores local variables every time)
>
> I assume the "old" comments were too detailed. I removed them at [JabRef/jdk@`23bbc0c` (#2)](https://github.com/JabRef/jdk/pull/2/commits/23bbc0ce0c8fd8a4cd689c0260c5fbcb91b20046) to have the code reviewable. I can readd some of them if that helps.
> 
> I also added a compressed description of the idea at [`edd85c9` (#14408)](https://github.com/openjdk/jdk/pull/14408/commits/edd85c996125ce0a2950b0cfb95d1e387c35d5ff). **Update** here, in the PR one simply needs to scroll up and sees the new comment.

Have you considered passing the same ArrayList for saving and restoring local variables?  Currently each method creates one new array list and save the local variables from `firstVariableForDedup` to `nextLocalVar`, but the local variables from `firstVariableForDedup`  are already added to the array list created by the previous method.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14408#discussion_r1251088902