RFR: 8275638: GraphKit::combine_exception_states fails with "matching stack sizes" assert [v2]

[Dean Long]

On Thu, 2 Dec 2021 15:38:06 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> So you agree that if there's no handler then there's no need to preserve the stack?

Yes, if we are blowing away the frame and there's no chance the state will be used by an uncommon trap.  As far as I can tell from SCCS comments for JDK-4432078 and related duplicate bugs, the original problem was re-executing the trapping bytecode with an uncommon trap.  And one way that could have happened was removed between jdk5 and jdk6 with this change:

http://hg.openjdk.java.net/jdk6/jdk6/hotspot/rev/fdd57634910e

If that was the only uncommon trap causing a problem, then there's a good chance that preserving the stack is no longer needed at all.

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PR: https://git.openjdk.java.net/jdk/pull/6572