Multilib support for 68040

Joel Sherrill joel.sherrill@OARcorp.com
Tue Jan 22 12:52:00 GMT 2002


"Aaron J. Grier" wrote:
> 
> On Mon, Jan 21, 2002 at 12:26:18PM -0800, Glynn Smith wrote:
> > I am using gcc 2.95.2 configured as a Cross m68k compiler hosted on
> > PPC-LINUX.  The standard multi-lib support seems to be for 68000 68020
> > 68881 & soft-float.
> 
> and cpu32 and m5200.  :)

And at least one person I know wants the 68060 added so you can avoid
generating instructions that it has to emulate.

> > Question 1
> >
> > Can this version or a later version of the GCC compiler be configured
> > so that it generates a 68040 multilib branch uses only floating point
> > instruction from the set of instructions that are supported by the
> > 68040 FPCP and does NOT emulate the unsupported instructions using
> > FLINE TRAPS
> 
> according to the documentation for 2.95.2, yes:
> 
> `-m68040'
>      Generate output for a 68040.  This is the default when the
>      compiler is configured for 68040-based systems.
> 
>      This option inhibits the use of 68881/68882 instructions that have
>      to be emulated by software on the 68040.  Use this option if your
>      68040 does not have code to emulate those instructions.
> 
> > Question 2
> > Motorola FPCPs have the option of setting them up so that the floating
> > point precession is embedded in each floating point instruction rather
> > that setting the precession in the FPCR (Control register) before each
> > operation.  Is there a compiler flag to enable this option?
> 
> I have no idea.  have you disassembled code to see what the compiler
> default is?
> 
> --
>   Aaron J. Grier  |   Frye Electronics, Tigard, OR   |  aaron@frye.com
>      "In a few thousand years people will be scratching their heads
>        wondering how on earth the first computer was invented and
>           bootstrapped without a prior computer to do it with."
>                     --  Chris Malcolm, on comp.arch
> 
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-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel@OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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