RFR: 8255719: Zero: on return path, check for pending exception before attempting to clear it

[Severin Gehwolf]

On Sun, 1 Nov 2020 17:33:04 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Profiling shows we spend a lot of time trying to clear the pending exception at _return path, whereas it seldom is pending. 
> 
> The additional problem with calling into `clear_pending_exception` is that inlining budget is depleted completely at that point in the compilation unit, and so we do the full outbound call.
> 
> There are other places where we clear pending exception unconditionally, but those places do seem to expect the exceptions to be there.

Seems reasonable.

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Marked as reviewed by sgehwolf (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/986