RFR: 8287393: AArch64: Remove trampoline_call1 [v2]

[Evgeny Astigeevich]

On Tue, 26 Jul 2022 14:44:01 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Hi @theRealAph,
>> I am sorry I did not get your comment. Could you please explain it?
>> 
>> Thanks,
>> Evgeny
>
> The addition is
> 'PhaseOutput* phase_output = Compile::current()->output();'
> then
> 'phase_output != NULL && phase_output->in_scratch_emit_size()'
> 
> so AFAICS `Compile::current()->output()` is now checked for null, where it was not before.

Now I get it. Thank you.

I agree this looks suspicious. I could not recall why I added it.
Debugging helped me to find out.
During the parsing phase of C2 compilation `ciTypeFlow::StateVector::do_invoke` causes `LinkResolver::resolve_static_call` which now has the following code:

  if (resolved_method->is_continuation_enter_intrinsic()
      && resolved_method->from_interpreted_entry() == NULL) { // does a load_acquire
    methodHandle mh(THREAD, resolved_method);
    // Generate a compiled form of the enterSpecial intrinsic.
    AdapterHandlerLibrary::create_native_wrapper(mh);
  }

We generate a wrapper which is `nmethod` with trampoline calls.
As we are in the parsing phase the output is not created.
I can move `Compile::current()->output() != NULL` into the preceding IF and update the comment to the following:

Make sure this is code generation of a C2 compilation when Compile::current()->output() is not NULL.
C2 can generate native wrappers for the continuation enter intrinsic before code generation.
C1 allocates space only for trampoline stubs generated by Call LIR ops.

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

PR: https://git.openjdk.org/jdk/pull/9592