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Re: ARM float ordering
On Fri, Jun 20, 2003 at 05:31:09PM +0100, Richard Earnshaw wrote:
> > I was looking at xscale-elf.h this morning, and noticed this:
> >
> > #define SUBTARGET_EXTRA_ASM_SPEC "%{!mcpu=*:-mcpu=xscale} \
> > %{mhard-float:-mfpu=fpa} \
> > %{!mhard-float: %{msoft-float:-mfpu=softfpa;:-mfpu=softvfp}}"
> >
> > This comes from:
> > revision 1.6 date: 2003/04/09 15:14:23; author: nickc; state: Exp; lines: +24 -1
> > * doc/install.texi: Note that ARM toolchains need binutils 2.13 or newer.
> > * config/arm/elf.h (SUBTARGET_ASM_FLOAT_SPEC): Pass -mfpu=softfpa instead of -mno-fpu.
> > * config/arm/semi.h (ASM_SPEC): Likewise.
> > * config/arm/xscale-elf.h (SUBTARGET_EXTRA_ASM_SPEC): Likewise,
> > but only if -msoft-float is specified pass. Otherwise pass -mfpu=softvfp.
> >
> >
> > So, if -mhard-float we specify -mfpu=fpa; for -msoft-float we specify
> > -mfpu=softfpa; and for neither we specify -mfpu=softvfp. However, nowhere
> > that I can find does this set a flag for the compiler. This never triggers
> > TARGET_VFP, so arm_float_words_big_endian will always be wrong for
> > little-endian Xscale with default options.
> >
> > Am I missing something?
> >
>
> Not really, the patch that makes softvfp available as a user-selectable
> option hasn't been contributed yet... I want to kill (well, deprecate)
> the -msoft/hard-float options and replace them with a -mfpu= option which
> behaves the same way as the assembler flag of the same name.
> Unfortunately, my ideas for implementing this were complicated somewhat by
> the contribution of the Cirrus Maverick code, where the separation of
> floating point from other features of the Maverick co-processor are
> blurred -- I haven't had time recently to sort the issues out. I suspect
> I shall want to separate the Maverick features into two distinct parts:
> floating point and non-fp.
Thanks, that makes sense. I'm just worried about producing VFP-tagged
binaries with FPA-ordered floats in 'em :)
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer