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RE: [PATCH] [MIPS] Fix operands for microMIPS SW16, SH16 and SB16



> -----Original Message-----
> From: Moore, Catherine
> Sent: Tuesday, April 15, 2014 8:49 AM
> To: Rozycki, Maciej; Richard Sandiford
> Cc: Matthew Fortune; gcc-patches@gcc.gnu.org; Moore, Catherine
> Subject: RE: [PATCH] [MIPS] Fix operands for microMIPS SW16, SH16 and
> SB16
> 
> 
> 
> > -----Original Message-----
> > From: Maciej W. Rozycki [mailto:macro@codesourcery.com]
> > Sent: Tuesday, April 15, 2014 7:28 AM
> > To: Richard Sandiford
> > Cc: Matthew Fortune; Moore, Catherine; gcc-patches@gcc.gnu.org
> > Subject: Re: [PATCH] [MIPS] Fix operands for microMIPS SW16, SH16 and
> > SB16
> >
> > On Tue, 15 Apr 2014, Richard Sandiford wrote:
> >
> > > >  I believe you need to adjust constraints to ensure constant 0 is
> > > > known to produce a 16-bit instruction encoding where possible.
> > > > Otherwise you'll end up with suboptimal code when the instruction
> > > > is in a branch delay slot.
> > >
> > > Yeah, it'd be good to do that too (although this is a preexisting problem).
> >
> >  Well, it depends on how you look at the problem being solved here --
> > if it is "for SW16, SH16 and SB16 GCC produces broken code for the `s0'
> > source register", then indeed it is, whereas if it is "GCC does not
> > handle the source register set for SW16, SH16 and SB16 correctly",
> > then it is a part of the same problem, not completely corrected.  I
> > can live with that until 4.10/4.9.1 though if you prefer.
> >
> > > I'm relying on you guys to do the microMIPS stuff though -- I don't
> > > have a way of testing it.
> >
> >  An assembly/objdump test is enough to cover this, so you've got all
> > tools at hand, although I understand you may not be inclined to rush
> > working on it. ;)
> >
> I'll take care of this bit.

I've attached an updated patch to address Maciej's concern with $0 and the microMIPS store instructions.
 Does this look okay to install?

Thanks,
Catherine

Attachment: umips-zero.cl
Description: umips-zero.cl

Attachment: umips-zero.patch
Description: umips-zero.patch


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