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

[Vladimir Ivanov]

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 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