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Re: ppc64 floating point usage [was Re: PPC64 Compiler bug !!]
- From: Michael S. Zick <mszick at goquest dot com>
- To: linas at austin dot ibm dot com,David Edelsohn <dje at watson dot ibm dot com>
- Cc: Jakub Jelinek <jakub at redhat dot com>,gcc-patches at gcc dot gnu dot org,gcc at gcc dot gnu dot org
- Date: Fri, 13 Jun 2003 16:07:45 -0500
- Subject: Re: ppc64 floating point usage [was Re: PPC64 Compiler bug !!]
- References: <jakub@redhat.com> <200306132009.QAA28822@makai.watson.ibm.com> <20030613160225.C24682@forte.austin.ibm.com>
On Friday 13 June 2003 04:02 pm, linas@austin.ibm.com wrote:
> On Fri, Jun 13, 2003 at 04:09:06PM -0400, David Edelsohn wrote:
>
> Bird in hand vs. two in the bush. We have Alan Modra's patch now, we
> don't have an acceptable -mno-implicit-float patch.
>
> There is concern that Alan's patch will negatively impact performance
> of fp code. Is there a way to unambiguously resolve this issue, or
> at least resolve it to everyones satisfaction?
>
A patch for a related issue just appeared for gas-arm-Linux and
gas-arm-NetBSD...
<http://sources.redhat.com/ml/binutils/2003-06/msg00494.html>
<http://sources.redhat.com/ml/binutils/2003-06/msg00497.html>
Perhaps a similar route could be followed (I.E: -mfpu=none) to
support developers that need the "never, ever, for any reason"
touch the fp registers.
I imagine that option would just select a register/mode description
that does not mention fp registers. Ports might have to add
descriptor support for this option.
Mike
>
> How would one do this? Visually inspect generated fp code? Run
> benchmarks? Which benchmarks?
>
> --linas