[PATCH] libgfortran: Correct FP feature macro checks

[Tobias Burnus]

LGTM.

Does this solve all infinity issues? Or is there still code requiring it
implicitly? From the previous exchange, it sounded as if there are still
issues.

Tobias

On 25.11.20 19:14, Maciej W. Rozycki wrote:
> The *_HAS_* floating-point feature macros are defined as 0/1 rather than
> #undef/#define settings by gcc/c-family/c-cppbuiltin.c.  Consequently we
> choose to use infinity and NaN features even with non-IEEE-754 targets
> such as `vax-netbsdelf' that lack them, causing build warnings and
> failures like:
>
> In file included from .../libgfortran/generated/maxval_r4.c:26:
> .../libgfortran/generated/maxval_r4.c: In function 'maxval_r4':
> .../libgfortran/libgfortran.h:292:30: warning: target format does not support infinity
>    292 | # define GFC_REAL_4_INFINITY __builtin_inff ()
>        |                              ^~~~~~~~~~~~~~
> .../libgfortran/generated/maxval_r4.c:149:19:
> note: in expansion of macro 'GFC_REAL_4_INFINITY'
>    149 |         result = -GFC_REAL_4_INFINITY;
>        |                   ^~~~~~~~~~~~~~~~~~~
> .../libgfortran/generated/maxval_r4.c: In function 'mmaxval_r4':
> .../libgfortran/libgfortran.h:292:30: warning: target format does not support infinity
>    292 | # define GFC_REAL_4_INFINITY __builtin_inff ()
>        |                              ^~~~~~~~~~~~~~
> .../libgfortran/generated/maxval_r4.c:363:19:
> note: in expansion of macro 'GFC_REAL_4_INFINITY'
>    363 |         result = -GFC_REAL_4_INFINITY;
>        |                   ^~~~~~~~~~~~~~~~~~~
> {standard input}: Assembler messages:
> {standard input}:204: Fatal error: Can't relocate expression
> make[3]: *** [Makefile:3358: maxval_r4.lo] Error 1
>
> Correct the checks then for __FLT_HAS_INFINITY__, __DBL_HAS_INFINITY__,
> __LDBL_HAS_INFINITY__, __FLT_HAS_QUIET_NAN__, __DBL_HAS_QUIET_NAN__, and
> __LDBL_HAS_QUIET_NAN__ to match semantics and remove build issues coming
> from the misinterpretation of these macros.
>
>       libgfortran/
>       * libgfortran.h: Use #if rather than #ifdef with
>       __FLT_HAS_INFINITY__, __DBL_HAS_INFINITY__,
>       __LDBL_HAS_INFINITY__, __FLT_HAS_QUIET_NAN__,
>       __DBL_HAS_QUIET_NAN__, and __LDBL_HAS_QUIET_NAN__.
> ---
>   libgfortran/libgfortran.h |   12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> gcc-libgfortran-fp-has.diff
> Index: gcc/libgfortran/libgfortran.h
> ===================================================================
> --- gcc.orig/libgfortran/libgfortran.h
> +++ gcc/libgfortran/libgfortran.h
> @@ -288,13 +288,13 @@ typedef GFC_UINTEGER_4 gfc_char4_t;
>
>   /* M{IN,AX}{LOC,VAL} need also infinities and NaNs if supported.  */
>
> -#ifdef __FLT_HAS_INFINITY__
> +#if __FLT_HAS_INFINITY__
>   # define GFC_REAL_4_INFINITY __builtin_inff ()
>   #endif
> -#ifdef __DBL_HAS_INFINITY__
> +#if __DBL_HAS_INFINITY__
>   # define GFC_REAL_8_INFINITY __builtin_inf ()
>   #endif
> -#ifdef __LDBL_HAS_INFINITY__
> +#if __LDBL_HAS_INFINITY__
>   # ifdef HAVE_GFC_REAL_10
>   #  define GFC_REAL_10_INFINITY __builtin_infl ()
>   # endif
> @@ -306,13 +306,13 @@ typedef GFC_UINTEGER_4 gfc_char4_t;
>   #  endif
>   # endif
>   #endif
> -#ifdef __FLT_HAS_QUIET_NAN__
> +#if __FLT_HAS_QUIET_NAN__
>   # define GFC_REAL_4_QUIET_NAN __builtin_nanf ("")
>   #endif
> -#ifdef __DBL_HAS_QUIET_NAN__
> +#if __DBL_HAS_QUIET_NAN__
>   # define GFC_REAL_8_QUIET_NAN __builtin_nan ("")
>   #endif
> -#ifdef __LDBL_HAS_QUIET_NAN__
> +#if __LDBL_HAS_QUIET_NAN__
>   # ifdef HAVE_GFC_REAL_10
>   #  define GFC_REAL_10_QUIET_NAN __builtin_nanl ("")
>   # endif
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