RFR: 8284848: C2: Compiler blackhole arguments should be treated as globally escaping [v2]

[Vladimir Kozlov]

On Thu, 14 Apr 2022 09:08:08 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> WIP so far, but I would appreciate early review of someone savvy in C2 EA code. I'll try to whip up the test with IR Framework too.
>> 
>> 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 incrementally with two additional commits since the last revision:
> 
>  - IR tests
>  - Handle only pointer arguments

Yes, this looks good. And thank you for adding IR tests to verify it.

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