RFR: 8210425: [x86] sharedRuntimeTrig/sharedRuntimeTrans compiled without optimization

[David Holmes]

On 7/09/2018 12:32 AM, Severin Gehwolf wrote:
> Hi,
> 
> On Thu, 2018-09-06 at 07:29 +1000, David Holmes wrote:
>> Hi Severin,
>>
>> On 6/09/2018 4:36 AM, Severin Gehwolf wrote:
>>> Hi,
>>>
>>> On Linux x86 (32 and 64 bit) sharedRuntime{Trans,Trig}.ccp files get
>>> compiled with -O0. It appears to be for the same (historical?) reason
>>> as for fdlibm files in core-libs. JDK-8210416 is an attempt to make
>>> this consistent on all Linux arches (as s390x/ppc64/aarch64 already use
>>> that) for fdlibm. This patch does the same for the hotspot copies.
>>> Compile it with OPT and -ffp-contract=off instead of no optimization at
>>> all. Thoughts?
>>
>> The code in sharedRuntimeTrig is expected/required to be built the same
>> way as the fdlibm library as it contains the same code. So if it is okay
>> to change the way fdlibm is built then it follows this is okay too. I
>> traced this change to the optimization flags back to 2001 but no details
>> on the exact issue seen with fdlibm.
> 
> Right. I should note that ppc64, s390x and aarch64 ports don't have
> this optimization turned off as those overrides are in a x86 specific
> block. It appears it hasn't caused issues for these ports so far.
> 
> Your comment on JDK-8210416 says that it was introduced for an issue on
> GCC 1.1.1 i386 back in 1998. Wow ;-)
> 
>> Is -ffp-contract=off a gcc-specific flag? If so this should be a gcc
>> conditional not a linux-x86 one.
> 
> clang has it (as noted elsewhere), but I don't know which version.
> What's the "blessed" clang version for JDK 12?

I've no idea sorry.

Once 8210416 has settled on the right approach for the makefiles the 
same can be applied here.

Thanks,
David

> Thanks,
> Severin
> 
>>> webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8210425/webrev.01/
>>> Bug:    https://bugs.openjdk.java.net/browse/JDK-8210425
>>>
>>> Testing: - make run-test-tier1 (no new failures).
>>>            - Currently running through submit.
>>>            - Verified objects get compiled with -O3 -ffp-contract=off in
>>>              build logs.
>>>
>>> Thanks,
>>> Severin
>>>
>