RFR: 8370939: C2: SIGSEGV in SafePointNode::verify_input when processing MH call from Compile::process_late_inline_calls_no_inline()

[Vladimir Ivanov]

On Fri, 31 Oct 2025 16:39:07 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> In test cases, `mh` is initially not constant so the method handle
> invoke can't be inlined. It is later found to be constant, so it can
> be turned into a direct call by
> `Compile::process_late_inline_calls_no_inline()`. In the meantime, the
> `CallNode` for the mh invoke is cloned (by loop switching). In the
> process, only a shallow copy of the `JVMState` for the call is
> made. The initial `CallNode` is the first to be processed by
> `Compile::process_late_inline_calls_no_inline()` and that causes that
> `CallNode` to become dead. The cloned `CallNode` is then
> processed. The `JVMState` for that one references the initial
> `CallNode` in its caller's `JVMState`. Because that node is dead, that
> causes a crash. The fix I propose is to make a deep copy of the
> `JVMState` when a `CallNode` is cloned, if a `CallGenerator` is
> assigned to the node.
> 
> The other failure I see with these tests is:
> 
> 
> #  Internal Error (/home/roland/jdk-jdk/src/hotspot/share/opto/compile.hpp:1091), pid=3319164, tid=3319186
> #  assert(_number_of_mh_late_inlines > 0) failed: _number_of_mh_late_inlines < 0 !
> 
> 
> because even though the `CallNode` is cloned, there's still only one
> late inline recorded. The fix here is to increment
> `_number_of_mh_late_inlines` when the node is cloned.
> 
> This was reported by the netty developers.

Overall, looks reasonable.

src/hotspot/share/opto/node.cpp line 567:

> 565:       n->as_Call()->set_generator(cloned_cg);
> 566:       if (cloned_cg->is_mh_late_inline()) {
> 567:         C->inc_number_of_mh_late_inlines();

Do you need to decrement the counter when a CallNode with `generator()->is_mh_late_inline()` goes dead?

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

PR Review: https://git.openjdk.org/jdk/pull/28088#pullrequestreview-3406244440
PR Review Comment: https://git.openjdk.org/jdk/pull/28088#discussion_r2482724020