RFR: 8257848: -XX:CompileCommand=blackhole, * should be diagnostic [v4]

[Aleksey Shipilev]

On Tue, 8 Dec 2020 06:43:36 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/share/compiler/compilerOracle.cpp line 426:
>> 
>>> 424:     return false;
>>> 425:   }
>>> 426:   guarantee(UnlockDiagnosticVMOptions, "Checked during initial parsing");
>> 
>> You can move it up right after `check_predicate`: `check_predicate(CompileCommand::Blackhole, method)` is allowed to return `true` iff `UnlockDiagnosticVMOptions` is set. 
>> 
>> Not sure `guarantee` is well-justified here, IMO `assert` would suffice.
>
> `UnlockDiagnosticVMOptions` is `trueInDebug`, so `assert` is useless. We really care about "release" mode here.

Moved the `guarantee` closer to `check_predicate`.

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

PR: https://git.openjdk.java.net/jdk/pull/1674