RFR: 8354083: Support --add-reads with -XX:+AOTClassLinking

[Ioi Lam]

On Thu, 8 May 2025 00:19:17 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

> This fix adds the `--add-reads` support for CDS and AOTClassLinking.
> Before the fix, if the `--add-reads` is specified during CDS archive dumping, the user will see the following log if `-Xlog:cds=info` is enabled:
> `[0.000s][info][cds] optimized module handling: disabled due to incompatible property: jdk.module.addreads=com.norequires=org.astro`
> During runtime, the archived full module graph will be disabled:
> `[0.021s][info][cds       ] full module graph: disabled`
> 
> With the fix, the optimized module handling won't be disabled during dump time and the full module graph will be enabled during runtime provided the same --add-reads option is specified during dump time and runtime.
> 
> Testing: tiers 1 - 4.

I think we need a test to validate that the `--add-reads` flag actually works. I wrote such a test when I implemented `--add-exports`: see [runtime/cds/appcds/jigsaw/modulepath/AddExports.java](https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/runtime/cds/appcds/jigsaw/modulepath/AddExports.java)

I think we need a similar test for `--add-opens` as well.

Since the main reason for supporting `--add-{expors,opens,reads}` is for user of AOT class linking, I would suggest moving the above AddExports.java test to 

- runtime/cds/appcds/aotClassLinking/modules/AddExports.java

And then add AddReads.java and AddOpens.java there as well.

The reason for putting the tests inside aotClassLinking is that they will be excluded from the `hotspot_appcds_dynamic` and `hotspot_aot_classlinking` test groups, so you don't need to add special case code to handle those two test groups.

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

PR Comment: https://git.openjdk.org/jdk/pull/25109#issuecomment-2861575003