Feature Request

[Dave Hudson]

L C wrote:
> 1) I don't think the ISO code and unecessary typecasting issues would be 
> a concern since the requested compiler switch would obviously not be the 
> default. You would have to intentionally enable it and therefore realize 
> the ramifications.

One major concern I would have is that it's very easy to make mistakes 
that cause complete chaos in unexpected parts of gcc's infrastructure - 
the new switch would render most of the C torture test suite inoperable 
and thus the quality of the resultant code might be somewhat debatable 
at best - the solution I've taken allows me to continue to use the full 
testsuite and trap many otherwise subtle problems.

> 3) I think for a typical simple embedded systems program the savings 
> would be greater than your 2-2.5%. I changed one arithmetic calculation 
> on my AVR such that I casted every calc back to unsigned char and the 
> code to do the calculation went from about 14 bytes to 4. It would also 
> be especially valuable in interrupt service routines where small code 
> size is key.

I think a lot depends on how you're code works - there are some 
pathalogical integer promotions but I guess it depends what your ratio 
of numeric code is to other code.  I can point to examples where I've 
seen much larger reductions but overall within a pretty general OS, 
device driver, network protocol and application codebase the saving was 
under 3% - obviously some individual cases had savings of 50%+.  The 
code in question probably does have some explicit typecasts but not too 
many.

I guess you could always ask Denis Chertykov his thoughts on this since 
he wrote the AVR port and he looks after the IP2k port in the FSF tree.


Regards,
Dave