RFR: 8303415: Add VM_Version::is_intrinsic_supported(id) [v2]

[David Holmes]

On Thu, 9 Mar 2023 05:31:52 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Currently we check VM flags, directives and JIT compiler support when we generate intrinsics. 
>> We have *product* VM flags for most intrinsics and set them in VM based on HW support. 
>> But not all intrinsics have such flags and it is not scalable to add new *product* flag for each new intrinsic. 
>> Also we have `-XX:DisableIntrinsic=<id>` and `-XX:ControlIntrinsic=<id>` flags to control intrinsics from command line. We don't need specific flags for that. 
>> 
>> I propose to add new `VM_Version::is_intrinsic_supported(id)` method to check platform support for intrinsic without adding new flag. I used it for `_floatToFloat16` intrinsic for my work on [JDK-8302976](https://bugs.openjdk.org/browse/JDK-8302976).
>> 
>> Additional fixes:
>> Fixed Interpreter to skip intrinsics if they are disabled with flag.
>> Moved Interpreter's `InlineIntrinsics` flag check into one place in shared code.
>> Added separate interpreter id for `_dsqrt_strict` so it could be disabled separately from regular `_dsqrt`.
>> Added missing `native` mark to `_currentThread`.
>> Removed unused `AbstractInterpreter::in_native_entry()`.
>> Cleanup C2 intrinsic checks code.
>> 
>> Tested tier1-4,xcomp,stress. Also ran tier1-3,xcomp with `-XX:-InlineIntrinsics`.
>
> Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address comments

So are there plans to migrate to this new mechanism and remove those global flags?

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PR: https://git.openjdk.org/jdk/pull/12858