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

[Aleksey Shipilev]

On Tue, 1 Dec 2020 12:30:12 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/c1/c1_GraphBuilder.cpp line 2032:
> 
>> 2030:   if (target->is_loaded() && target->return_type()->basic_type() == T_VOID &&
>> 2031:       compilation()->directive()->should_blackhole(target)) {
>> 2032:     if (try_blackhole(target)) {
> 
> Since `try_blackhole` can't fail, why do the check at all?

Right. This used to be modeled after `try_inline`, which could bail. `try_blackhole` cannot bail, so there is no reason to assert it. Fixed.

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