> On 3 Sep 2021, at 08:51, Iain Sandoe <idsan...@googlemail.com> wrote:
>
>
>> On 2 Sep 2021, at 21:03, Joseph Myers <jos...@codesourcery.com> wrote:
>>
>> On Thu, 2 Sep 2021, Iain Sandoe via Gcc-patches wrote:
>>
>>> diff --git a/libgcc/soft-fp/eqdf2.c b/libgcc/soft-fp/eqdf2.c
>>> index 2a44ee377ce..a3bb664f5f1 100644
>>> --- a/libgcc/soft-fp/eqdf2.c
>>> +++ b/libgcc/soft-fp/eqdf2.c
>>> @@ -28,6 +28,7 @@
>>> License along with the GNU C Library; if not, see
>>> <http://www.gnu.org/licenses/>. */
>>>
>>> +#define DarwinMode DF
>>> #include "soft-fp.h"
>>> #include "double.h"
>>
>> All these files are supposed to be taken unmodified from glibc. They
>> shouldn't contain any OS-specific code, such as a define of DarwinMode.
>> sfp-machine.h, however, is libgcc-local, hence putting the definition of
>> strong_alias there.
>
> OK, that makes sense.
>>
>> So you need some other way to extract the argument type of name in order
>> to use it in a declaration of aliasname. E.g.
>>
>> __typeof (_Generic (name,
>> CMPtype (*) (HFtype, HFtype): (HFtype) 0,
>> CMPtype (*) (SFtype, SFtype): (SFtype) 0,
>> CMPtype (*) (DFtype, DFtype): (DFtype) 0,
>> CMPtype (*) (TFtype, TFtype): (TFtype) 0))
>
> thanks for the suggestion
>
>> Now in fact I think the include ordering means none of the *type macros
>> are defined here. But if you do e.g.
>>
>> typedef float alias_SFtype __attribute__ ((mode (SF)));
>>
>> and similar, you could use alias_SFtype in the above. And so keep the
>> changes to the Darwin-specific parts of the libgcc-local sfp-machine.h.
>
> this is what I’m testing - OK if it bootstraps on x86_64-darwin, linux?
(those bootstraps were sucessful)
given that:
a) this fixes Darwin x86-64 bootstrap which has been broken for more than 24h
b) the patch is now Darwin-local.
I’ve pushed the patch below to fix the bootstrap break - but if there are any
futher
recommendations I’m happy to apply a follow-on. It seems that there will be
more
changes for the half-float support anyway,
thanks
Iain
>
> thanks
> Iain
>
>
> [PATCH] libgcc, soft-float: Fix strong_alias macro use for Darwin.
>
> Darwin does not support strong symbol aliases and a work-
> around is provided in sfp-machine.h where a second function
> is created that simply calls the original. However this
> needs the arguments to the synthesized function to track
> the mode of the original function.
>
> So the fix here is to match known floating point modes from
> the incoming function and apply the one found to the new
> function args.
>
> The matching is highly specific to the current set of modes
> and will need adjusting should more cases be added.
>
> Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
>
> libgcc/ChangeLog:
>
> * config/i386/sfp-machine.h (alias_HFtype, alias_SFtype
> alias_DFtype, alias_TFtype): New.
> (ALIAS_SELECTOR): New.
> (strong_alias): Use __typeof and a _Generic selector to
> provide the type to the synthesized function.
> ---
> libgcc/config/i386/sfp-machine.h | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/libgcc/config/i386/sfp-machine.h
> b/libgcc/config/i386/sfp-machine.h
> index f15d29d3755..172ebc70c8d 100644
> --- a/libgcc/config/i386/sfp-machine.h
> +++ b/libgcc/config/i386/sfp-machine.h
> @@ -75,10 +75,24 @@ void __sfp_handle_exceptions (int);
>
> /* Define ALIASNAME as a strong alias for NAME. */
> #if defined __MACH__
> -/* Mach-O doesn't support aliasing. If these functions ever return
> - anything but CMPtype we need to revisit this... */
> +/* Mach-O doesn't support aliasing, so we build a secondary function for
> + the alias - we need to do a bit of a dance to find out what the type of
> + the arguments is and then apply that to the secondary function.
> + If these functions ever return anything but CMPtype we need to revisit
> + this... */
> +typedef float alias_HFtype __attribute__ ((mode (HF)));
> +typedef float alias_SFtype __attribute__ ((mode (SF)));
> +typedef float alias_DFtype __attribute__ ((mode (DF)));
> +typedef float alias_TFtype __attribute__ ((mode (TF)));
> +#define ALIAS_SELECTOR \
> + CMPtype (*) (alias_HFtype, alias_HFtype): (alias_HFtype) 0, \
> + CMPtype (*) (alias_SFtype, alias_SFtype): (alias_SFtype) 0, \
> + CMPtype (*) (alias_DFtype, alias_DFtype): (alias_DFtype) 0, \
> + CMPtype (*) (alias_TFtype, alias_TFtype): (alias_TFtype) 0
> #define strong_alias(name, aliasname) \
> - CMPtype aliasname (TFtype a, TFtype b) { return name(a, b); }
> + CMPtype aliasname (__typeof (_Generic (name, ALIAS_SELECTOR)) a, \
> + __typeof (_Generic (name, ALIAS_SELECTOR)) b) \
> + { return name (a, b); }
> #else
> # define strong_alias(name, aliasname) _strong_alias(name, aliasname)
> # define _strong_alias(name, aliasname) \
> --
>
