RFR: 8360561: PhaseIdealLoop::create_new_if_for_predicate hits "must be a uct if pattern" assert

[Christian Hagedorn]

On Thu, 14 Aug 2025 07:59:11 GMT, Marc Chevalier <mchevalier at openjdk.org> wrote:

>> Good to know. Thank you for clearing that up for me.
>
> Indeed. I use it here to prevent profiling from removing an actually impossible path with a trap, because bad things happen in a dead path. It's not the first time I use `Xcomp` for that, and there are other ways (like setting a maximum on the number of traps per method, or disabling the warmup (and so profiling) in IR framework execution). That was discussed in some other PR without strong opinions or consensus on what would be the preferred way.

Ideally you use `@Warmup(0)` without `-Xcomp` + `CompileOnly` to not stress the test VM unnecessarily. But depending on your use case/profiling requirements, it might not be enough, so `-Xcomp` + `CompileOnly` seems like a good option.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26504#discussion_r2276333491