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Re: Adding Leon processor to the SPARC list of processors


> 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


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