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Re: Adding Leon processor to the SPARC list of processors
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: Geert Bosch <bosch at adacore dot com>
- Cc: Joern Rennecke <amylaar at spamcop dot net>, gcc at gcc dot gnu dot org, Konrad Eisele <konrad at gaisler dot com>, gcc-patches at gcc dot gnu dot org, iant at google dot com, Luís Vitório Cargnini <lvcargnini at gmail dot com>, Daniel Hellstrom <daniel at gaisler dot com>, Jiri Gaisler <jiri at gaisler dot com>, Jose Ruiz <ruiz at adacore dot com>
- Date: Mon, 22 Nov 2010 09:52:58 +0100
- Subject: Re: Adding Leon processor to the SPARC list of processors
- References: <4CE515CB.7080706@gaisler.com> <201011191753.29923.ebotcazou@adacore.com> <8F323F0E-C1DD-448F-BB45-0C27B5BCAE0E@adacore.com>
> CONFIG_FPU_ENABLE Y/N would correspond to --with-float=hard/soft, and
> I believe setting CONFIG_IU_V8MULDIV to Y/N requires --with-cpu=V8/V7,
> is that correct? I think it would make sense to build these as multilibs,
> so the user can experiment to find out performance impacts of
> the various hardware configurations on generated code.
>
> I wonder if it also would be worthwhile to have compiler options
> for fpu=fast/slow and multiply=fast/slow, so we can schedule
> appropriately. For the FPU, issue-rate/latency are as follows:
> GR FPU: 1/4, with FDIV? 16 and FSQRT? 24 cycles,
> non-pipelined on separate unit
> GR FPU Lite: 8/8, with FDIVS/FDIVD/FSQRTS/FSQRTD 31/57/46/57 cycles,
> non-pipelined on same unit
Let's not make this too complex for a first try, the settings used at AdaCore
seem a good starting point to me.
--
Eric Botcazou