RFR: 8284848: C2: Compiler blackhole arguments should be treated as globally escaping [v4]

[Aleksey Shipilev]

On Fri, 22 Apr 2022 17:53:27 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Blackholes should make the arguments to be treated as globally escaping, to match the expected behavior of legacy JMH blackholes. See more discussion in the bug.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 fastdebug `tier1`
>>  - [x] Linux x86_64 fastdebug `tier2`
>>  - [x] OpenJDK microbenchmark corpus sanity run
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains ten additional commits since the last revision:
> 
>  - Copyrights
>  - Merge branch 'master' into JDK-8284848-blackhole-ea-args
>  - Cherry pick JDK-8285394
>  - Merge branch 'master' into JDK-8284848-blackhole-ea-args
>  - Merge branch 'master' into JDK-8284848-blackhole-ea-args
>  - Fix failures found by microbenchmark corpus run 1
>  - IR tests
>  - Handle only pointer arguments
>  - Fix

Thanks for reviews! It seems to work as expected in the benchmarks.

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

PR: https://git.openjdk.java.net/jdk/pull/8228