C1 GraphBuilder::profile_call assert failing when inlining static interface method through MethodHandle

[Jorn Vernee]

Hi,

We were seeing an assert being hit in C1 when running the project Panama 
test suite. After some debugging I have narrowed the failure down to the 
following reproducer:

public class Test { static final MethodHandle MH_m; static { try { MH_m 
= lookup().findStatic(MyInterface.class, "m", 
MethodType.methodType(void.class)); } catch 
(ReflectiveOperationException e) { throw new BootstrapMethodError(e); } 
} public static void main(String[] args) throws Throwable { for (int i = 
0; i < 20_000; i++) { payload(); } } static void payload() throws 
Throwable { MH_m.invokeExact(); } } interface MyInterface { static void 
m() {} }

Run with `-Xbatch -XX:TieredStopAtLevel=3`.

The problem is the following assert in GraphBuild::profile_call:

   assert(known_holder == NULL || (known_holder->is_instance_klass() &&
                                   (!known_holder->is_interface() ||
                                    ((ciInstanceKlass*)known_holder)->has_nonstatic_concrete_methods())), "should be non-static concrete method");

In this particular case, we are inlining a static method in a known 
holder which is also an interface, but doesn't have any other non-static 
concrete methods, so the assert fails.

The MethodHandle seems to be significant since known_holder is NULL when 
simply calling MyInterface.m(). Looking at the a assert and it's 
history, I'm not really sure what it's supposed to guard against. It 
seems to want to check that the callee is non-abstract when we have a 
known holder, but in that case I'm not sure why it doesn't just use 
`!callee->is_abstract()`.

Not sure what should be done here? I tried changing the assert to 
`assert(known_holder == NULL || !callee->is_abstract())` but that seems 
to fail in other cases. Maybe we can just remove it?

Thanks,
Jorn