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Re: [patch, binutils] Patch elf/mips.h for -mfp64 support.

"Maciej W. Rozycki" <> writes:
> On Tue, 10 Sep 2013, Richard Sandiford wrote:
>> >  Also how about just EF_MIPS_FP64 for brevity and to match the name 
>> > chosen for the corresponding attribute?
>> That might be a bit confusing though, since we only set it for -mgp32 -mfp64,
>> not normal -mgp64 -mfp64.
>  It may or it may not.  I don't think we need to carry all the available 
> information in macro names, this is what documentation is for (a revised 
> MIPS psABI document would be most welcome as the latest stuff we've got 
> from SGI has by now become painfully obsolete).  An -mgp64 -mfp32 ABI is 
> non-standard, I doubt anyone uses such a configuration, so for any 
> practical purposes it has always been a norm that GP64 ABIs also have 
> 64-bit FPRs.

Well, the R5900 was basically used as -mgp64 -mfp32.  I agree it was
nonstandard, but it was used...

> So I believe it'll be generally understood that the flag is only there
> to denote the exceptional use of 64-bit FPRs with a GP32 ABI.
>  And I find it more confusing that EF_MIPS_32BITMODE_FP64 is so similar to 
> EF_MIPS_32BITMODE while the two are not related to each other at all -- 
> the former asks for a 64-bit FPU for 32-bit code while the latter says 
> code is 32-bit even though the ISA level is 64-bit.  And the latter flag 
> is actually a good precedent -- just as we don't set EF_MIPS_32BITMODE for 
> all 32-bit code (e.g. my MIPS I binaries don't have it set even though 
> they are firm-32-bit code), we won't set the new flag for all 64-bit FPU 
> code.  So just as we don't call the former flag EF_MIPS_GP64_32BITMODE or 
> whatever we don't have to call the new flag EF_MIPS_32BITMODE_FP64 either.

Yeah, good point.  EF_MIPS_GP32_FP64 might avoid that confusion while
still being more precise than EF_MIPS_FP64.

But I suppose I don't have a strong opinion either way.  Doug, if neither
you nor Steve care, the patch is OK with EF_MIPS_FP64.  In answer to your
other question, anyone can commit it.


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