Re: [Qemu-devel] [PATCH] target/m68k: Change fpu_rom from const static array to switch

[Philippe Mathieu-Daudé]

On 09/04/2017 11:09 AM, Laurent Vivier wrote:
> Le 04/09/2017 à 15:54, Kamil Rytarowski a écrit :
> > On 04.09.2017 02:27, Philippe Mathieu-Daudé wrote:
> > > On 09/03/2017 02:05 PM, Laurent Vivier wrote:
> > > > Le 03/09/2017 à 18:31, Kamil Rytarowski a écrit :
> > > > > GCC 4.7.2 on SunOS reports that the values assigned to array members
> > > > > are not
> > > > > real constants:
> > > > >
> > > > > target/m68k/fpu_helper.c:32:5: error: initializer element is not
> > > > > constant
> > > > > target/m68k/fpu_helper.c:32:5: error: (near initialization for
> > > > > 'fpu_rom[0]')
> > > > > rules.mak:66: recipe for target 'target/m68k/fpu_helper.o' failed
> > > > >
> > > > > Convert the array to switch() to workaround the issue.
> > > >
> > > > I don't like the idea. It's really an array and should be managed as an
> > > > array.
> > >
> > > I agree with Laurent.
> > >
> > > > Could you try to use make_floatx80_init() instead of make_floatx80() ?
> > >
> > > I guess the problem comes from the macro which cast as not const:
> > >
> > > #define make_floatx80(exp, mant) ((floatx80) { mant, exp })
> >
> > Adding const to make_floatx80 - ((const floatx80) { mant, exp }) - does
> > not fix the problem.
> >
> > > make_floatx80_init() doesn't cast so it might work,
> > > else we could add a macro such const_floatx80():
> > >
> > > #define const_floatx80(exp, mant) ((const floatx80) { mant, exp })
> >
> > Switching make_floatx80() to make_floatx80_init() in works.
> >
> > How about floatx80_zero, floatx80_one etc? We cannot translate them to
> > make_floatx80_init() as this breaks in other parts of the code in
> > functions like:
> >
> > void helper_fldpi_ST0(CPUX86State *env)
> > {
> >      ST0 = floatx80_pi;
> > }
> >
> > -- target/i386/fpu_helper.c
>
> You can:
>
> either replace the "#define floatx80_pi make_floatx80(...)" by a "const
> floatx80 floatx80_pi = make_floatx80_init(...)"

this won't work with:

const floatx80 2pi = floatx80_mul(floatx80_pi, floatx80_pi, &s);

however this should work fine:

#define floatx80_pi make_floatx80_init(0x4000, 0xc90fdaa22168c235LL)

> or replace all the macros in the m68k/fpu_helper.c array by
> make_floatx80_init(...)
>
> Thanks,
> Laurent