On Fri, 21 Feb 2025 at 14:42, Philippe Mathieu-Daudé <phi...@linaro.org> wrote:
>
> On 17/2/25 13:50, Peter Maydell wrote:
> > Currently we hardcode at compile time whether the floatx80 default
> > Infinity value has the explicit integer bit set or not (x86 sets it;
> > m68k does not). To be able to compile softfloat once for all targets
> > we'd like to move this setting to runtime.
> >
> > Define a new FloatX80Behaviour enum which is a set of flags that
> > define the target's floatx80 handling. Initially we define just one
> > flag, for whether the default Infinity has the Integer bit set or
> > not, but we will expand this in future commits to cover the other
> > floatx80 target specifics that we currently make compile-time
> > settings.
> >
> > Define a new function floatx80_default_inf() which returns the
> > appropriate default Infinity value of the given sign, and use it in
> > the code that was previously directly using the compile-time constant
> > floatx80_infinity_{low,high} values when packing an infinity into a
> > floatx80.
> >
> > Since floatx80 is highly unlikely to be supported in any new
> > architecture, and the existing code is generally written as "default
> > to like x87, with an ifdef for m68k", we make the default value for
> > the floatx80 behaviour flags be "what x87 does". This means we only
> > need to change the m68k target to specify the behaviour flags.
> >
> > (Other users of floatx80 are the Arm NWFPE emulation, which is
> > obsolete and probably not actually doing the right thing anyway, and
> > the PPC xsrqpxp insn. Making the default be "like x87" avoids our
> > needing to review and test for behaviour changes there.)
> >
> > We will clean up the remaining uses of the floatx80_infinity global
> > constant in subsequent commits.
> >
> > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> > ---
> > include/fpu/softfloat-helpers.h | 12 ++++++++++++
> > include/fpu/softfloat-types.h | 13 +++++++++++++
> > include/fpu/softfloat.h | 1 +
> > fpu/softfloat.c | 7 +++----
> > target/m68k/cpu.c | 6 ++++++
> > fpu/softfloat-specialize.c.inc | 10 ++++++++++
> > 6 files changed, 45 insertions(+), 4 deletions(-)
>
>
> > diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> > index f4fed9bfda9..b12ad2b42a9 100644
> > --- a/fpu/softfloat.c
> > +++ b/fpu/softfloat.c
> > @@ -1860,7 +1860,8 @@ static floatx80
> > floatx80_round_pack_canonical(FloatParts128 *p,
> >
> > case float_class_inf:
> > /* x86 and m68k differ in the setting of the integer bit. */
> > - frac = floatx80_infinity_low;
> > + frac = s->floatx80_behaviour &
> > floatx80_default_inf_int_bit_is_zero ?
> > + 0 : (1ULL << 63);
>
> Indent off
This is the indent emacs uses here, and it's the usual
"4 spaces in for an expression continued onto the next line"
I think.
-- PMM
