RFR: 8252505: C1/C2 compiler support for blackholes [v11]

[Aleksey Shipilev]

On Tue, 1 Dec 2020 12:26:58 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Cleanup BlackholeCallGenerator
>
> src/hotspot/share/opto/doCall.cpp line 115:
> 
>> 113: 
>> 114:   // Try blackholing a method
>> 115:   if (callee->is_loaded() &&
> 
> The check can be turned into a property on `ciMethod` and the result cached there.

Yes, but only partially, because C1 and C2 check their own directive sets, and C2 also checks for matching rule. But it does skip unloaded methods more cleanly if we move the first two checks to `ciMethod`. Fixed.

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PR: https://git.openjdk.java.net/jdk/pull/1203