Re: A Far Less Ambitous Altivec patch

[Ian Lance Taylor <ian at wasabisystems dot com>]

Alan Modra <amodra@bigpond.net.au> writes:

> On Wed, Jan 14, 2004 at 09:50:06AM +0100, Hartmut Penner wrote:
> > I think gas supports %v0 and 0, but not v0.
> 
> True for -mno-regnames (the default on linux).  With -mregnames, you can
> also use the unadorned regs, like v0.
> 
> > Alan, any reason, why this is this way ?
> 
> I suppose so that you can define and use symbols that happen to look
> like a reg name.

That is a good reason.  The real historical reason is that the AIX
assembler only supported 0.  If you wanted to use names for registers,
you had to #include a file which defined them all.  That file can be
found in gcc/config/rs6000/ppc-asm.h.

The -mregnames option, and the % prefix, can later when people writing
assembly code found this to be too irritating.

Ian