Re: [rvm-research] Inserting Assembly into Jikes

Hi Claire,

> > We literally want a faster equivalent of using JNI to insert C, 
> > which inserts assembly. 
> See org.jikesrvm.runtime.SysCall.java and follow the pattern that is there for the other sysCalls.

Just to make this explicit, which might be helpful for future hackers [ http://xkcd.com/979/ ]

1) add your C function foo (possibly containing inline assembler) in tools/bootImageRunner/sys.C

extern "C" void
foo(void) {
  // your code here
}

2) add an Address field for the runtime entry point to your C function in
rvm/src/org/jikesrvm/runtime/BootRecord.java

public Address fooIP;  // IP on end is required for correct code rewriting

Does this field need an @EntryPoint annotation?

3) add a method signature for the Java wrapper to your C function in 
rvm/src/org/jikesrvm/runtime/SysCall.java

@SysCallTemplate
public abstract void foo();

4) Invoke your code from somewhere in Jikes RVM (or your user application running on Jikes RVM) with:

import org.jikesrvm.runtime.SysCall;

…
SysCall.sysCall.foo();


Things get slightly more complicated when you try to map Java types onto C types, but you should be able to pass Addresses  and ints fairly easily - follow the existing code in sys.C I guess.

Best regards,
Jeremy

---
http://www.dcs.gla.ac.uk/~jsinger



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