Here's the scoop. I changed a field in Chronoscope from RangeAxis[] to List<RangeAxis> and suffered ~50% performance regression. An Axis is a class responsible for mapping values in the range [low, high] to [0,1], among other things, so it is a hot class/method in Chronoscope. After profiling, I noticed the method was no longer being inlined, and a huge number of calls to dynamicCast/canCastUnsafe appeared. This brings to mind two optimizations:
1) if a method's return type is covariant in a generic type, do not insert a cast or cast check. Assume that the method *will* return objects of this type at the callsite. 2) eliminate dynamicCast/canCastUnsafe altogether. These methods only exist to throw class cast exceptions. I can't believe that there's any code that actually expects these exceptions and depends on them being thrown except perhaps unit tests. Anyone running unit tests or UI tests in hosted mode will get these exceptions during development, so it seems the only use case might be web-mode unit tests. But for production deployed code, dynamicCast/canCaseUnsafe/setCheck/et al seem to just be bloat and a performance hit to boot. Can we get a compile mode that removes them? Maybe an -XX method, or some other mechanism which says "I want potentially unsafe, but super fast code"? -Ray --~--~---------~--~----~------------~-------~--~----~ http://groups.google.com/group/Google-Web-Toolkit-Contributors -~----------~----~----~----~------~----~------~--~---
