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Re: [PATCH] [MIPS] Fix operands for microMIPS SW16, SH16 and SB16
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: "Maciej W. Rozycki" <macro at codesourcery dot com>
- Cc: Matthew Fortune <Matthew dot Fortune at imgtec dot com>, "Moore\, Catherine" <Catherine_Moore at mentor dot com>, "gcc-patches\ at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Tue, 15 Apr 2014 10:47:56 +0100
- Subject: Re: [PATCH] [MIPS] Fix operands for microMIPS SW16, SH16 and SB16
- Authentication-results: sourceware.org; auth=none
- References: <FD3DCEAC5B03E9408544A1E416F1124201497ED8A4 at NA-MBX-04 dot mgc dot mentorg dot com> <6D39441BF12EF246A7ABCE6654B023534E17E5 at LEMAIL01 dot le dot imgtec dot org> <87zjjrxb11 dot fsf at talisman dot default> <87r452ygnm dot fsf at talisman dot default> <alpine dot DEB dot 1 dot 10 dot 1404141725530 dot 15259 at tp dot orcam dot me dot uk>
"Maciej W. Rozycki" <macro@codesourcery.com> writes:
> On Sat, 12 Apr 2014, Richard Sandiford wrote:
>
>> I went ahead and applied the adjusted version of the patch to trunk
>> as below (because I wanted to add a testcase too).
>
> 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).
I'm relying on you guys to do the microMIPS stuff though -- I don't have
a way of testing it.
Thanks,
Richard