Re: wishlist: support for shorter pointers

["Rafał Pietrak" <embedded@ztk-rp.eu>]

W dniu 3.07.2023 o 18:57, Richard Earnshaw (lists) pisze:
> On 03/07/2023 17:42, Rafał Pietrak via Gcc wrote:
>> Hi Ian,
[---------]
>> And WiKi reporting up to 40% performance improvements in some corner 
>> cases is impressive and encouraging. I believe, that the reported 
>> average of 5-8% improvement would be significantly better within MCU 
>> tiny resources environment. In MCU world, such improvement could mean 
>> fit-nofit of a project into a particular device.
>>
>> -R
> 
> I think you need to be very careful when reading benchmarketing (sic) 
> numbers like this.  Firstly, this is a 32-bit vs 64-bit measurement; 
> secondly, the benchmark (spec 2000) is very old now and IIRC was not 
> fully optimized for 64-bit processors (it predates the 64-bit version of 
> the x86 instruction set); thirdly, there are benchmarks in SPEC which 
> are very sensitive to cache size and the 32-bit ABI just happened to 
> allow them to fit enough data in the caches to make the numbers leap.

Yes. Sure. I am. I thought I've expressed it clearly, that the 
"fantastic 40%" I regard as just "corner case" - those don't usually 
reflect ordinary usage.

I was only highlighting the fact, that mare 5-8% improvement can result 
on fit-nofit of a particular design into a particular device ... in 
consequence requiring to use 4k-RAM device instead of 2k-RAM one.

Tiny improvements of performance of x64 workhorses can become relatively 
huge in micros like stm32. That's all.

-R