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Re: [MIPS] Avoiding FP operations/register usage
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- Cc: Joseph Myers <joseph at codesourcery dot com>, Rich Fuhler <Rich dot Fuhler at imgtec dot com>, "gcc\ at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Tue, 11 Feb 2014 09:02:04 +0000
- Subject: Re: [MIPS] Avoiding FP operations/register usage
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B0235349A3EA at LEMAIL01 dot le dot imgtec dot org> <Pine dot LNX dot 4 dot 64 dot 1402071730290 dot 7304 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235349AC6B at LEMAIL01 dot le dot imgtec dot org>
Matthew Fortune <Matthew.Fortune@imgtec.com> writes:
> I'm still interested in how successfully the MIPS backend is managing to
> avoid floating point but I am also convinced there are bugs in ld.so
> entry points for MIPS.
It uses the standard mechanism to avoid it, which is marking uses of
FP registers for integer moves, loads and stores with "*". This tells
the register allocator to ignore those alternatives. AFAIK it is
effective and I think any cases where it doesn't work would be fair
bug reports.
It becomes a lot more difficult to define with things like the Loongson
extensions though, since some of those are also useful as scalar integer
operations. And of course the same goes for MSA.
Thanks,
Richard