[LLVMdev] arm compiler benchmarks

[Jim Grosbach]

I've not run any on non-iOS devices, and haven't looked at GCC since v4.2.1 due to licensing issues, so I don't have a good feel for comparative benchmarking.

-Jim

On Feb 26, 2013, at 4:20 PM, Reed Kotler <rkotler at mips.com> wrote:

> What about benchmarks on other Arm devices?
> 
> On 02/26/2013 02:52 PM, Jim Grosbach wrote:
>> Cortex-M0 is a Thumb1 only device. There hasn't been any concerted
>> effort to tune LLVM's Thumb1 output in quite a long time. Even back then
>> (2008 or so), the effort was mainly to get it to work acceptably, with
>> the real performance tuning work being done for Thumb2. I'm not
>> surprised that an embedded market focussed compiler like IAR is better
>> tuned for a chip like that.
>> 
>> -Jim
>> 
>> On Feb 26, 2013, at 2:11 PM, matic at nimp.co.uk <mailto:matic at nimp.co.uk>
>> wrote:
>> 
>>> Hi,
>>> 
>>> 
>>> I didn't do any serious benchmarking but so far I never found a case
>>> where LLVM does better than IAR on CortexM0, but I saw a lot of cases
>>> where IAR output is better than LLVM...
>>> 
>>> That said I did not use -Os or -Oz, I just used -O3.
>>> 
>>> A recurrent situation is that LLVM push/pop one or two extra registers
>>> compared to IAR, I guess it does so in order to comply with a standard
>>> ABI or something but in the world of deeply embedded system, we don't
>>> care of such things 99.99% of the time...
>>> 
>>> If you want to see some good code output, take a look at IAR, there is
>>> a free version limited in code size online.
>>> 
>>> Cheers,
>>> 
>>> Sebastien
>>> 
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>> 
>> 
>> 
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