[lworld] RFR: 8372824: [lworld] C2 hits "Unexpected argument type" assertion with --enable-preview [v2]

[Tobias Hartmann]

On Tue, 20 Jan 2026 19:01:14 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> src/hotspot/share/opto/graphKit.cpp line 1960:
>> 
>>> 1958:           // scalarized receiver instead.
>>> 1959:           assert(arg_idx == 0 && !call->method()->is_static(), "must be the receiver");
>>> 1960:           arg = InlineTypeNode::make_from_oop(this, arg, t->inline_klass());
>> 
>> So this is post-parse call-devirtualization, i.e. [JDK-8257211](https://bugs.openjdk.org/browse/JDK-8257211), right? Could we assert `call->generator()->is_virtual_late_inline()` here?
>
> Unfortunately, the `CallNode` here does not have a generator, because it is created just above. Checking `is_late_inline` does not work either, because we are too deep handling now. `LateInlineVirtualCallGenerator::do_late_inline_check` calls into `Compile::call_generator` to find the replacement. This method, after deciding that it does not want to inline the callee, will create a  `PredictedCallGenerator` with the fast path being a `DirectCallGenerator`. And this `DirectCallGenerator` is the one calling the method we are in, and this subclass of `CallGenerator` does not return `true` for `is_late_inline()`.

Ah, too bad. What about `Compile::strength_reduction` that @dafedafe introduced with https://github.com/openjdk/valhalla/pull/1768? I think it would just be nice to have a strong assert here because these kind of asserts helped in the past to catch cases where we failed to scalarize early.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1935#discussion_r2712152107