JDK-8350637 : C2: verify that main_loop finds pre_loop and that multiversion loops find the multiversion_if
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 25
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2025-02-25
  • Updated: 2025-02-25
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Other
tbdUnresolved
Related Reports
Blocks :  
JDK-8323582 - C2 SuperWord AlignVector: misaligned vector memory access with unaligned native memory
Blocks :  
JDK-8350579 - Remove Template Assertion Predicates belonging to a loop once it is folded away during IGVN
Description
As discussed here:
https://github.com/openjdk/jdk/pull/22016#issuecomment-2678602660 / JDK-8323582

It seems that there are some issues with traversing the predicates, such that the pre_loop can be temporarily invisible because there are predicates that are not (yet) properly skipped. [~chagedorn] thinks this should be fixed with JDK-8350579, but of course there may be other blockers we can discover once that one is fixed.

This does not seem to be a huge issue at as far as we know, since eventually those predicates that are in the way die and then we can traverse again, but it is unfortunate for verification, and maybe it also limits optimizations.