Running jaotc with an external Graal

[Mandy Chung]

> On Feb 16, 2017, at 1:33 AM, Doug Simon <doug.simon at oracle.com> wrote:
> 
> With the current bits in jdk9/hs and graal-core, the following bootstrapping command works in terms of replacing Graal in the JDK:
> 
> java -server -XX:+UnlockExperimentalVMOptions --module-path=/Users/dsimon/hs/truffle/mxbuild/modules/com.oracle.truffle.truffle_api.jar --upgrade-module-path=/Users/dsimon/hs/graal-core/mxbuild/modules/jdk.vm.compiler.jar --patch-module=jdk.vm.compiler=.jar -XX:+UseJVMCICompiler -XX:+BootstrapJVMCI -version
> 
> However, the --patch-module + --upgrade-module-path trick[1] we’re using to replace the version of Graal in the JDK apparently only works due to a bug that will be fixed at some point. From Mandy Chung:
> 
> "-—patch-module is to patch a module to replace or add content of that module and yes it disables the hash checking on the patched module. However, it’s not intended to allow it to combine with —-upgrade-module-path as you did, to change the module dependences.”
> 

It’s a bug that --patch-module + --upgrade-module-path work as described above.  I have a patch to fix —-patch-module that no longer has to disable the hash checking but allow patching the content of the mdoule.

I think we will need to look into the alternatives how Graal can be upgraded to a different version of module-info.class.

Mandy

> Given all the continuing flux around jigsaw, we cannot be sure that developing and using GitHub Graal on JDK 9 is stable until jigsaw is stable.
> 
> -Doug
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8171448?focusedCommentId=14046154&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14046154
> 
>> On 16 Feb 2017, at 10:17, Andrew Haley <aph at redhat.com> wrote:
>> 
>> On 15/02/17 21:56, Christian Thalinger wrote:
>>> 
>>>> On Feb 14, 2017, at 4:38 AM, Andrew Haley <aph at redhat.com> wrote:
>>>> 
>>>> On 14/02/17 14:37, Alan Bateman wrote:
>>>>> --patch-module can be used to patch any module in the boot layer. So if 
>>>>> you are looking to override or add classes then --patch-module should work.
>>>> 
>>>> Aha!  Thanks,
>>> 
>>> Does it?
>> 
>> Not quite.  The problem is that the service loader finds classes in
>> the Hotspot copy of Graal which don't exist in the external copy, and
>> chaos ensues.
>> 
>> I suppose the only way to make it work is to replace the copy of Graal
>> in HotSpot, but I don't think that's a trivial thing to do.
>> 
>> Andrew.
>> 
>