[cfe-dev] GCC 4.6, LLVM/Clang 2.9, DragonEgg Five-System Benchmarks

[Michael Larabel]

On 03/30/2011 01:08 PM, Eric Christopher wrote:
> On Mar 30, 2011, at 11:04 AM, C. Bergström wrote:
>
>> Eric Christopher wrote:
>>> On Mar 30, 2011, at 10:11 AM, Evan Cheng wrote:
>>>
>>>
>>>> Himeno is built -O0, which makes zero sense as a performance benchmark. And you are right GraphicsMagick uses OpenMP, which means the comparison between Clang and the rest of the compilers are totally meaningless. 7-Zip builds just fine for me with Clang, I have no idea why they couldn't get it to build.

Yes, I've already discussed some of this with Eric in a private thread 
the other day.

While the latest upstream Himeno release will be pulled, which evidently 
is now multi-threaded and uses -O3, I would argue though that in the 
context of benchmarking defaults, even '-O0' does matter if looking at 
the compiler performance. Such as for software projects that may not 
specify any optimization flag, I really doubt __most users__ when 
pulling down new code are checking what a given program is using as 
their compiler flags.

>>>> I think it's worthwhile to relay these information and hopefully they will correct these mistakes. But color me skeptical.
>>>>
>>> I sent him email and received not much in the way of a hopeful response.
>>>
>> phoronix is an ad machine and solely strives to make the graphs more interesting....  I've added Michael on cc and who has always corrected blatant errata for me in the past.
>>
> I've talked with Michael over email. He was very polite, I just don't know if anything was going to be mentioned or changed.
>

Yes, the Himeno test will be updated against the latest upstream release 
as soon as time allows, etc.

>> With regard to OpenMP -  Did it say if the -omp flags were used?  If not then I don't think gcc automatically turns it on.
>>
> It should be on for an openmp enabled GraphicsMagick by default if it detects you are gcc. I should think at least.
>
> -eric

Right, GraphicsMagick uses OpenMP and as discussed in the private 
exchange with Eric the other days, that's likely why Clang is behind GCC.