[PATCH] i386: Use fldt instead of fld on e_logl.S

[H.J. Lu]

On Thu, Aug 4, 2022 at 2:31 PM Fangrui Song <maskray@google.com> wrote:
>
> On Thu, Aug 4, 2022 at 2:24 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Thu, Aug 4, 2022 at 2:00 PM Adhemerval Zanella
> > <adhemerval.zanella@linaro.org> wrote:
> > >
> > > Clang cannot assemble fldt in the AT&T dialect mode.
> > > ---
> > >  sysdeps/i386/i686/fpu/e_logl.S | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/sysdeps/i386/i686/fpu/e_logl.S b/sysdeps/i386/i686/fpu/e_logl.S
> > > index 63183ac544..5d53f3bb22 100644
> > > --- a/sysdeps/i386/i686/fpu/e_logl.S
> > > +++ b/sysdeps/i386/i686/fpu/e_logl.S
> > > @@ -43,7 +43,7 @@ ENTRY(__ieee754_logl)
> > >         fsubl   MO(one)         // x-1 : x : log(2)
> > >  5:     fld     %st             // x-1 : x-1 : x : log(2)
> > >         fabs                    // |x-1| : x-1 : x : log(2)
> > > -       fld     MO(limit)       // 0.29 : |x-1| : x-1 : x : log(2)
> > > +       fldt    MO(limit)       // 0.29 : |x-1| : x-1 : x : log(2)
> > >         fcomip  %st(1)          // |x-1| : x-1 : x : log(2)
> > >         fstp    %st(0)          // x-1 : x : log(2)
> > >         jc      2f
> > > @@ -76,7 +76,7 @@ ENTRY(__logl_finite)
> > >         fsubl   MO(one)         // x-1 : x : log(2)
> > >         fld     %st             // x-1 : x-1 : x : log(2)
> > >         fabs                    // |x-1| : x-1 : x : log(2)
> > > -       fld     MO(limit)       // 0.29 : |x-1| : x-1 : x : log(2)
> > > +       fldt    MO(limit)       // 0.29 : |x-1| : x-1 : x : log(2)
> > >         fcomip  %st(1)          // |x-1| : x-1 : x : log(2)
> > >         fstp    %st(0)          // x-1 : x : log(2)
> > >         jc      2b
> > > --
> > > 2.34.1
> > >
> >
> > I don't think this is correct since there are
> >
> >         .type limit,@object
> > limit:  .double 0.29
> >
> > It should be fldl.
> >
> > --
> > H.J.
>
> If I am not mistaken, the existing fld has a bug as it is treated as flds

True.  It doesn't seem to cause any issue.

> fld limit@GOTOFF(%edx)    # treated as flds
> flds limit@GOTOFF(%edx)
> fldl limit@GOTOFF(%edx)
> fldt limit@GOTOFF(%edx)
>
> .section .rodata.cst8,"aM",@progbits,8
> .p2align 3
> limit: .double 0.29



-- 
H.J.