RFR: 8252505: C1/C2 compiler support for blackholes [v16]

[Aleksey Shipilev]

On Thu, 3 Dec 2020 11:28:07 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Formatting touchups
>
> src/hotspot/share/ci/ciMethod.cpp line 161:
> 
>> 159:   if (CompilerOracle::should_blackhole(h_m) &&
>> 160:       _signature->return_type()->basic_type() == T_VOID &&
>> 161:       h_m->intrinsic_id() == vmIntrinsics::_none) {
> 
> Why not switch to blackhole unconditionally and override existing intrinsic if any?

I thought existing intrinsic should take precedence over blackhole. But maybe blackhole should really take a precedence here, as it comes from an explicit compile command. I'll drop `== none` check.

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