Re: [avr-gcc-list] Shift by multiple of 8 is really shifting...

[E. Weddington]

Ben Jackson wrote:

> Here I'm doing something like
>
>                 l = ((ulong)i << 16) + ...;
>
> It's actually loading the i, expanding it, then shifting it.  Once
> again I'm sure I've seen gcc do better (on i386 or PPC, not sure).
> If it's not useful for me to point out these problems as I run
> across them, feel free to tell me to shut up.  :-)  Better yet,
> give me an idea of where in gcc I should fix this (clearly it could
> be fixed with a peephole rule of some kind, but I bet it's also
> possible to just generate better code).
>  

Oh, it's definitely useful, but I would suggest a slightly different 
process:

- Submit bug reports to the GCC bug tracker (bugzilla). You can mark 
bugs as "enhancements". Feel free to put my email address in the CC list 
and, at least, I can help keep track of the status of it. It's very 
important to submit bug reports because often times anything that goes 
to a mailing list can be easily forgotten. The GCC bug tracker is here: 
<http://gcc.gnu.org/bugzilla/>

- If you are serious about helping out on the code of the AVR port, then 
be sure to go through the process of submitting copyright assignment 
paperwork to the FSF. See the page on Contributing to GCC: 
<http://gcc.gnu.org/contribute.html>

- Also read the GCC internals manual if you want to do some coding on 
the AVR port.

- If you want to make changes to the AVR port, it would be best to do 
them in CVS HEAD (which currently will be 4.1), rather than any GCC 
3.4.x release. A number of changes have gone in between the two.

- And also let this list know of any bug reports / enhancements that you 
file.

- Lastly, be sure to note the difference between bugs/enhancements in 
the compiler and in the library, avr-libc. avr-libc has it's own project 
(repository, bug list, etc.) on Savannah.

And thanks for taking a look at the tools in detail! Any and all help is 
very appreciated!

Eric