Re: [PATCH] MIPS: Fix write_gc0_* macros when writing zero

[Ralf Baechle <ralf@linux-mips.org>]

On Fri, May 20, 2016 at 09:31:15AM +0100, Maciej W. Rozycki wrote:

> On Fri, 20 May 2016, James Hogan wrote:
> 
> > >  NB `z' here is an "operand code" in GCC-speak.  There's a list of the 
> > > MIPS-specific ones in gcc/config/mips/mips.c above `mips_print_operand'.  
> > > There are a few generic operand codes as well, most notably `a' to print 
> > > an address, matching the `p' constraint.  I think it would be good to have 
> > > this all documented in the GCC manual sometime.
> > 
> > Thanks Maciej! To be honest I pretty much guessed at what they were
> > called. Good to see 'z' does do what I thought. I couldn't find any
> > documentation online for the MIPS specific operand codes, so having them
> > documented with GCC would be an excellent idea!
> 
>  Yeah, this stuff is a bit obscure (the other one being %-sequences for 
> the specs) and I always find myself chasing sources when I need any of 
> this.  Frankly by now I have already remembered roughly where to look for.
> 
>  Once tracked down however the description within sources is pretty good 
> actually, so please refer there for the time being.

Material for a wiki page?

  Ralf