RFR: 8287312: G1: Early return on first failure in VerifyRegionClosure

[Albert Mingkun Yang]

On Wed, 25 May 2022 11:18:23 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple restructuring to match the intent of the comment.
> 
> Test: hotspot_gc

Open/Closed-region verifiers use `guarantee` -- it crashes on failure. There is indeed some inconsistency: other regions verifers report the status back to the caller. Such inconsistency also exists at the top-level caller `G1HeapVerifier::verify`.

For unification, I believe using `guarantee` and discarding the "out parameter" would be cleaner, with the potential drawback of printing too little info on failure. However, when failure does occur during verification, some domain-specific knowledge is required to resolve it, so blindly printing all info is not always necessarily helpful.

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PR: https://git.openjdk.java.net/jdk/pull/8882