JDK-8159999 : Control flow in BasicMatcher::matches could be improved
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Priority: P4
  • Status: Resolved
  • Resolution: Cannot Reproduce
  • Submitted: 2016-06-21
  • Updated: 2016-08-09
  • Resolved: 2016-08-09
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JDK 9
9Resolved
Related Reports
Relates :  
JDK-8057169 - Improve CompilerOracle matchers search
Description
Noticed that when running various benchmarks, e.g., Octane gbemu, in the presence of many compiler control directives that BasicMatcher::matches may show up prominently in some profiles.

During experiments it appears that on some platforms, Windows in particular, small adjustments to the control flow in that method - specifically to avoid eager lookup of Symbol*'s that won't be used - can have a significant impact.

This issue is possibly part of JDK-8057169
Comments
Possibly false positive, timing sensitive. Closing as I can no longer reproduce the effect.
09-08-2016
FC Extension approved by Lead. Very low risk. Small code refactoring without changing logic.
27-06-2016
FC Extension Request This trivial optimization can have a significant impact on JIT compilation times, especially on Windows. The risk of including the enhancement is minimal to non-existent, as there is no behavioral change. Patch is ready, tested and only needs a review to integrate.
26-06-2016
ILW = performance improvement in product part; case of many compiler control directives; none = MLH = P4
23-06-2016