Add jit helper stub for acmp

[tajila]

Add jit helper stub for acmp

Related to eclipse-openj9/openj9#8600

Signed-off-by: Tobi Ajila atobia@ca.ibm.com

[andrewcraik]

What is this helper going to call when it is evaluated in a code generator? The JIT needs something to call in the VM.

I think we need that before we even start looking to add the symbol to any of the internal JIT infrastructure. When that addition happens I would hope the PR would add the symbol, the ilgen, the evaluation as well as as some kind of integration test showing it passes through the optimizer to the codegen successfully rather than trying to set the aliasing in isolation which is quite likely to result in bugs and unexpected behaviour once the other parts of the JIT implementation are added.

[tajila]

What is this helper going to call when it is evaluated in a code generator? The JIT needs something to call in the VM.

The actual JIT helper is in eclipse-openj9/openj9#8600

When that addition happens I would hope the PR would add the symbol, the ilgen, the evaluation as well as as some kind of integration test showing it passes through the optimizer to the codegen successfully rather than trying to set the aliasing in isolation which is quite likely to result in bugs and unexpected behaviour once the other parts of the JIT implementation are added.

I've attempted adding the jit helpers without the il/aliases changes in the past but that resulted in build failures on z/OS. Not sure if that is at all related to what you are describing.

Is there a better way to coordinate these changes? As it stands the openj9 changes will not compile without these omr changes.

[0xdaryl]

The helper references have to live in OMR because of the unfortunate way things are architected at the moment. But does the symbol reference creation need to live here?

[Leonardo2718]

As @0xdaryl pointed out, the name of the helper has to be defined in OMR. However, defining the alias sets and creation will require careful thinking and may be better placed in OpenJ9. So, for this PR, maybe we can just add the name definition and debug printing and leave the rest for later when more of the JIT implementation is ready? That way eclipse-openj9/openj9#8600 can get merged and we can start incrementally testing the rest of the code that is still under development.

I can help figure out some of the details that will be needed, since I'm already working on the OpenJ9 JIT part that will need this.

[tajila]

Thanks @Leonardo2718 @0xdaryl I've kept the debug and helper changes and removed the rest

[Leonardo2718]

LGTM 👍

[Leonardo2718]

@genie-omr build all

[Leonardo2718]

@andrewcraik @0xdaryl Are you ok with the proposed changed?