[patch] Fix PR fortran/96983

[patch] Fix PR fortran/96983

[Eric Botcazou]

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Hi,

AFAICS the code in build_round_expr implicitly assumes that __float128 exists, 
which is *not* the common case among 64-bit architectures since "long double" 
is generally already 128-bit for them.

Tested on x86-64/Linux and SPARC64/Linux, OK for the mainline?


2021-03-08  Eric Botcazou  <ebotcazou@adacore.com>

	PR fortran/96983
	* trans-intrinsic.c (build_round_expr): Do not implicitly assume
	that __float128 is the 128-bit floating-point type.

-- 
Eric Botcazou

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diff --git a/gcc/fortran/trans-intrinsic.c b/gcc/fortran/trans-intrinsic.c
index 5c9258c65c3..ae359a07973 100644
--- a/gcc/fortran/trans-intrinsic.c
+++ b/gcc/fortran/trans-intrinsic.c
@@ -407,7 +407,10 @@ build_round_expr (tree arg, tree restype)
       if (kind < 0)
 	gfc_internal_error ("Could not find real kind with at least %d bits",
 			    resprec);
-      arg = fold_convert (gfc_float128_type_node, arg);
+      if (gfc_real16_is_float128)
+	arg = fold_convert (gfc_float128_type_node, arg);
+      else
+	arg = fold_convert (long_double_type_node, arg);
       fn = gfc_builtin_decl_for_float_kind (BUILT_IN_ROUND, kind);
     }
   else

Re: [patch] Fix PR fortran/96983

[Tobias Burnus]

Hi,

On 08.03.21 17:25, Eric Botcazou wrote:
> AFAICS the code in build_round_expr implicitly assumes that __float128 exists,
> which is *not* the common case among 64-bit architectures since "long double"
> is generally already 128-bit for them.

Crossref: Introduced by the Patch for PR96711, https://gcc.gnu.org/pipermail/fortran/2020-August/054920.html

Its testcase causes the fails/this PR, hence, gfortran.dg/pr96711.f90 is the
testcase for this patch.

> Tested on x86-64/Linux and SPARC64/Linux, OK for the mainline?
>
> 2021-03-08  Eric Botcazou  <ebotcazou@adacore.com>
>
>       PR fortran/96983
>       * trans-intrinsic.c (build_round_expr): Do not implicitly assume
>       that __float128 is the 128-bit floating-point type.

I think it is a bad idea to hard-code the real type.
Does the following work for you? If so, I think that
patch is obvious and you can go ahead and commit it.

--- a/gcc/fortran/trans-intrinsic.c
+++ b/gcc/fortran/trans-intrinsic.c
@@ -407,7 +407,7 @@ build_round_expr (tree arg, tree restype)
        if (kind < 0)
         gfc_internal_error ("Could not find real kind with at least %d bits",
                             resprec);
-      arg = fold_convert (gfc_float128_type_node, arg);
+      arg = fold_convert (gfc_get_real_type (kind), arg);
        fn = gfc_builtin_decl_for_float_kind (BUILT_IN_ROUND, kind);
      }
    else

Tobias

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Re: [patch] Fix PR fortran/96983

[Eric Botcazou]

> I think it is a bad idea to hard-code the real type.
> Does the following work for you? If so, I think that
> patch is obvious and you can go ahead and commit it.
> 
> --- a/gcc/fortran/trans-intrinsic.c
> +++ b/gcc/fortran/trans-intrinsic.c
> @@ -407,7 +407,7 @@ build_round_expr (tree arg, tree restype)
>         if (kind < 0)
>          gfc_internal_error ("Could not find real kind with at least %d
> bits", resprec);
> -      arg = fold_convert (gfc_float128_type_node, arg);
> +      arg = fold_convert (gfc_get_real_type (kind), arg);
>         fn = gfc_builtin_decl_for_float_kind (BUILT_IN_ROUND, kind);
>       }
>     else

Yes, it works fine on x86-64/Linux and SPARC64/Linux, applied, thanks.

-- 
Eric Botcazou