Gnutools: consideration for upgrade to GCC 4.6

[Ilija Kocho]

On 13.01.2012 19:54, Bernard Fouché wrote:
>
> Le 13/01/2012 18:00, Ilija Kocho a écrit :
>>
>> Our GCC 4.3.2 is ageing and perhaps we should consider an upgrade.
>> My motive is it's lacking of support for Cortex-M4 SIMD (aka DSP) and 
>> FPU instructions, but I think that other architectures shall gain 
>> from newer compiler too. I have made some signal processing tests 
>> with GCC 4.6.2 against current eCos compiler and they show 
>> performance gain even with Cortex-M3 setting, though moderate. 
>> Performance is considerable when Cortex-M4 setting is selected and is 
>> tremendous, as expected, when SIMD are used. Recently introduced 
>> Cortex-M products with FPU (Kinetis K70, K61, STM32F4) will further 
>> emphasise the benefit.
>>
> That sounds good! Did you try link time optimization ?

I haven't changed any option except -mcpu=cortex-m4. My objective were 
SIMD instructions (now with K70 FPU).

> I'm curious what kind of gain it could bring with a real world app. 
> eCos seems to fit perfectly for such an optimization, there is no 
> shared lib and at link time everythink is visible to the linker.

Worth to try.

Ilija