[15] RFR (M): 8238681: Make -XX:UseSSE flag x86-specific

[David Holmes]

On 11/02/2020 9:27 pm, Vladimir Ivanov wrote:
> Hi David,
> 
> Thanks for the feedback and for filing CSR request.
> 
>> open/test > vi 
>> ./hotspot/jtreg/compiler/cpuflags/TestAESIntrinsicsOnSupportedConfig.java
>>
>> it has
>>
>>   @requires vm.cpu.features ~= ".*aes.*"
>>
>> rather than a text for x86/x64. Is that a more specific runtime test 
>> for x86 capabilities?
> 
> AES intrinsics are available on other platforms as well (e.g., AARCH64 
> and SPARC have them) and CPU features are named uniformly [1] [2]. So, I 
> don't see an immediate problem to fix here.

But the test uses the UseSSE flag so that would mean it is limited to 
execution on x86 only - even if other platforms have AES. ??

David


> But while looking at the test, I noted that verification I added in 
> vm_version_x86.cpp requires some additional handling in CPUInfo [3] to 
> ignore trailing dot. So, here's updated webrev:
> 
>    http://cr.openjdk.java.net/~vlivanov/8238681/webrev.01/
> 
> Best regards,
> Vladimir Ivanov
> 
> [1] 
> http://hg.openjdk.java.net/jdk/jdk/file/8e6fa89397ca/src/hotspot/cpu/aarch64/vm_version_aarch64.cpp#l285 
> 
> 
> [2] 
> http://hg.openjdk.java.net/jdk/jdk/file/8e6fa89397ca/src/hotspot/cpu/sparc/vm_version_sparc.cpp#l233 
> 
> 
> [3] 
> http://hg.openjdk.java.net/jdk/jdk/file/8e6fa89397ca/test/lib/sun/hotspot/cpuinfo/CPUInfo.java 
> 
> 
>>
>> Thanks,
>> David
>>
>> On 11/02/2020 3:08 pm, David Holmes wrote:
>>> Hi Vladimir,
>>>
>>> On 11/02/2020 12:19 am, Vladimir Ivanov wrote:
>>>> http://cr.openjdk.java.net/~vlivanov/8238681/webrev.00/
>>>> https://bugs.openjdk.java.net/browse/JDK-8238681
>>>>
>>>> Turn UseSSE into x86-specific flag since it doesn't have any meaning 
>>>> on non-x86 platforms.
>>>
>>> That part seems okay.
>>>
>>>> As a cleanup, I made all the code which assumes UseSSE<2 x86-32 
>>>> specific. (x86-64 ABI requires SSE2.)
>>>
>>> This made things more obscure for me so I'll leave it to compiler 
>>> folk to validate.
>>>
>>>> Also, as a precaution, I made UseSSE obsolete on non-x86 platforms.
>>>
>>> I took the liberty of filing a very short CSR request for this and 
>>> added myself as Reviewer. Please change it to "Finalized" and await 
>>> approval before pushing.
>>>
>>> Thanks,
>>> David
>>>
>>>> Testing: hs-precheckin-comp, tier1-5, linux x86-32 fastdebug build.
>>>>
>>>> Thanks!
>>>>
>>>> Best regards,
>>>> Vladimir Ivanov