mirror of https://github.com/sbt/sbt.git
5005abfef2
The compiler interface subclasses `scala.tools.nsc.Global`, and loading this new subclass before each `compile` task forces HotSpot JIT to deoptimize larges swathes of compiled code. It's a bit like SBT has rigged the dice to always descend the longest ladder in a game of Snakes and Ladders. The slowdown seems to be larger with Scala 2.12. There are a number of variables at play, but I think the main factor here is that we now rely on JIT to devirtualize calls to final methods in traits whereas we used to emit static calls. JIT does a good job at this, so long as classloading doesn't undo that good work. This commit extends the existing `ClassLoaderCache` to encompass the classloader that includes the compiler interface JAR. I've resorted to adding a var to `AnalyzingCompiler` to inject the dependency to get the cache to the spot I need it without binary incompatible changes to the intervening method signatures. |
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| .. | ||
| classpath | ||
| ModuleUtilities.scala | ||
| ReflectUtilities.scala | ||
| ScalaInstance.scala | ||