RFR: 8267118: OutOfMemoryError cannot be caught as a Throwable [v3]

[David Holmes]

> This interesting little quirk was discovered by @iklam. During verification, the catch-type in a catch clause is normally resolved as part of being checked to see that it is a subclass of Throwable. At runtime when an exception is thrown, we also have to check if the exception being thrown is assignable to the catch-type and so handled by that catch block. For the case where the catch-type is Throwable itself, the verification subclass check trivially passes (due to a name match) without actually resolving the CP entry for the catch-type. So at runtime when the exception is thrown we have to perform the CP resolution of the catch-type. But the resolution process itself can trigger exceptions and in particular if we have thrown OutOfMemoryError, the resolution may throw a secondary OutOfMemoryError, which prevents the first from being caught by the catch block!
> 
> The fix is to force resolution of the catch-type at verification time, when it is Throwable.
> 
> To aid in debugging the original problem I've also added some new logging statements that show how we find a catch block and if we encounter further exceptions in trying to catch the exception - see example in the JBS issue.
> 
> Testing: tiers 1-3, plus the new test
> 
> Thanks,
> David

David Holmes has updated the pull request incrementally with one additional commit since the last revision:

  Reworked the new logging to seperate Info and Debug levels to reduce verbosity, per
  feedback from @coleenp @iklam

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4266/files
  - new: https://git.openjdk.java.net/jdk/pull/4266/files/f5718224..57561f1d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4266&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4266&range=01-02

  Stats: 34 lines in 1 file changed: 20 ins; 1 del; 13 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4266.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4266/head:pull/4266

PR: https://git.openjdk.java.net/jdk/pull/4266