RE: [avr-gcc-list] Re: AVR byte swap optimization

[Eric Weddington]

> -----Original Message-----
> From: Steven Bosscher [mailto:address@hidden 
> Sent: Sunday, November 19, 2006 3:55 AM
> To: Eric Weddington
> Cc: Paul Brook; address@hidden; Shaun Jackman; 
> address@hidden
> Subject: Re: [avr-gcc-list] Re: AVR byte swap optimization
> 
> On 11/19/06, Eric Weddington <address@hidden> wrote:
> > > Use gcc head, __builtin_bswap and make sure the AVR backend
> > > implements the
> > > bswap rtl patterns.
> >
> > There's the problem. You can't just glibly say "make sure 
> the AVR backend
> > implements the bswap rtl patterns". There are precious few 
> volunteers who
> > are familiar enough with gcc internals and the avr port in 
> particular to go
> > do just that. AFAIK, there is no bswap rtl pattern in the 
> avr port, at least
> > there doesn't seem to be in 4.1.1.
> 
> Why is that a problem?
> Do you have a different solution in mind?

> 
> > > Future versions of gcc may also be able to recognise these
> > > idioms without
> > > using the builtin, but AFAIK that's not been implemented yet.
> >
> > Plus there is a long lead time between when it is 
> implemented on HEAD, then
> > branched, released from a branch, and then when it shows up 
> in binary
> > distributions.
> 
> That happens with all improvements that are implemented between
> releases, so I don't see your point.

The original message went to the avr-gcc-list mailing list. I wasn't aware
that it also went to the gcc mailing list. There are different sets of
assumptions based on the audience.

A lot depends on where the OP is coming from, in wanting help:
Does the OP want a pre-built toolchain?
Does the OP build the toolchain from source?
Is the OP familiar with even patching the toolchain?

There are a number of people on the avr-gcc-list that when they say they
want help, they want the final, pre-built toolchain from a distributor to
fix their problem. They don't want to build the toolchain from source, or
they don't even know how to. Yes there are also people who can and will
build the toolchain from source but they are a small minority.

The point that I was making was to the original OP: yes, it would be great
to get it fixed, permanently. Historically there has never been enough
volunteers with the knowledge, capability, and the time on the avr port.

The audience on the gcc list is a completely different sort with different
assumptions. My apologies for annoying the people on the gcc list.

And yes I do have a different solution in mind:
Shaun, could you open a GCC bug report on this issue? Rask, could you then
post your implementation to that GCC bug report as a patch? Steven and Paul,
could you eyeball Rask's implementation and see if it is reasonable
impelementation? Rask, do you have FSF paperwork in place? If not, then
could somebody else, with FSF assignments in place, create a patch?

After all, you guys have a process to follow, right? ;-)

Eric Weddington