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Re: [RFC] Introducing MIPS O32 ABI Extension for FR0 and FR1 Interlinking
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- Cc: "gcc\ at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>, Rich Fuhler <Rich dot Fuhler at imgtec dot com>, "macro\ at codesourcery dot com" <macro at codesourcery dot com>, "Joseph Myers \(joseph\ at codesourcery dot com\)" <joseph at codesourcery dot com>, "Moore\, Catherine \(Catherine_Moore\ at mentor dot com\)" <Catherine_Moore at mentor dot com>
- Date: Wed, 05 Mar 2014 18:19:23 +0000
- Subject: Re: [RFC] Introducing MIPS O32 ABI Extension for FR0 and FR1 Interlinking
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B023534AAE6E at LEMAIL01 dot le dot imgtec dot org> <87mwhhg9e5 dot fsf at talisman dot default> <6D39441BF12EF246A7ABCE6654B023534AC1F0 at LEMAIL01 dot le dot imgtec dot org> <878ut0fj45 dot fsf at talisman dot default> <6D39441BF12EF246A7ABCE6654B023534AD16E at LEMAIL01 dot le dot imgtec dot org> <87ppmbdobm dot fsf at talisman dot default> <6D39441BF12EF246A7ABCE6654B023534AEB92 at LEMAIL01 dot le dot imgtec dot org> <6D39441BF12EF246A7ABCE6654B023534B4C29 at LEMAIL01 dot le dot imgtec dot org> <87r46hbybi dot fsf at talisman dot default> <6D39441BF12EF246A7ABCE6654B023534B572B at LEMAIL01 dot le dot imgtec dot org> <87mwh5bslv dot fsf at talisman dot default> <6D39441BF12EF246A7ABCE6654B023534B581D at LEMAIL01 dot le dot imgtec dot org>
Matthew Fortune <Matthew.Fortune@imgtec.com> writes:
> Are you're OK with automatically selecting fpxx if no -mfp option, no
> .module and no .gnu_attribute exists? Such code would currently end up
> as FP ABI Any even if FP code was present, I don't suppose anything
> would get worse if this existing behaviour simply continued though.
The -mfp setting is usually implied by the -mabi setting. I don't
think we should change that. Since this is a new mode, and since
the fpxx markup will be available from the start, everyone using
fpxx should say so explicitly.
E.g. maybe the rules should be:
(1) Any explicit .gnu_attribute 4 is always used, although we might
give a diagnostic if it's incompatible with the module-level setting.
(2) Otherwise, if the code does not use FP then the attribute is left
at the default of 0.
(3) Otherwise, a nonzero .gnu_attribute 4 is implied from the module-level
setting.
(4) For compatibility, -mabi=32 continues to imply -mfp32. fpxx mode must
be selected explicitly.
Which was supposed to be simple, but maybe isn't so much.
Thanks,
Richard