RFR: 8267118: OutOfMemoryError cannot be caught as a Throwable

[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

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Commit messages:
 - 8267118: OutOfMemoryError cannot be caught as a Throwable

Changes: https://git.openjdk.java.net/jdk/pull/4266/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4266&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267118
  Stats: 112 lines in 3 files changed: 111 ins; 0 del; 1 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