Fortran: Use _Float128 rather than __float128 for c_float128 kind.

The GNU Fortran manual documents that the c_float128 kind corresponds
to __float128, but in fact the implementation uses float128_type_node,
which is _Float128.  Both refer to the 128-bit IEEE/ISO encoding, but
some targets including aarch64 only define _Float128 and not __float128,
and do not provide quadmath.h.  This caused errors in some test cases
referring to __float128.

This patch changes the documentation (including code comments) and
test cases to use _Float128 to match the implementation.

2021-09-16  Sandra Loosemore  <sandra@codesourcery.com>

gcc/fortran/

	* intrinsic.texi (ISO_C_BINDING): Change C_FLOAT128 to correspond
	to _Float128 rather than __float128.
	* iso-c-binding.def (c_float128): Update comments.
	* trans-intrinsic.c (gfc_builtin_decl_for_float_kind): Likewise.
	(build_round_expr): Likewise.
	(gfc_build_intrinsic_lib_fndcecls): Likewise.
	* trans-types.h (gfc_real16_is_float128): Likewise.

gcc/testsuite/
	* gfortran.dg/PR100914.c: Do not include quadmath.h.  Use
	_Float128 _Complex instead of __complex128.
	* gfortran.dg/PR100914.f90: Add -Wno-pedantic to suppress error
	about use of _Float128.
	* gfortran.dg/c-interop/typecodes-array-float128-c.c: Use
	_Float128 instead of __float128.
	* gfortran.dg/c-interop/typecodes-sanity-c.c: Likewise.
	* gfortran.dg/c-interop/typecodes-scalar-float128-c.c: Likewise.
	* lib/target-supports.exp
	(check_effective_target_fortran_real_c_float128): Update comments.

libgfortran/
	* ISO_Fortran_binding.h: Update comments.
	* runtime/ISO_Fortran_binding.c: Likewise.

gcc/fortran/intrinsic.texi

@@ -15193,8 +15193,8 @@ In addition to the integer named constants required by the Fortran 2003
 standard and @code{C_PTRDIFF_T} of TS 29113, GNU Fortran provides as an
 extension named constants for the 128-bit integer types supported by the
 C compiler: @code{C_INT128_T, C_INT_LEAST128_T, C_INT_FAST128_T}.
-Furthermore, if @code{__float128} is supported in C, the named constants
+Furthermore, if @code{_Float128} is supported in C, the named constants
-@code{C_FLOAT128, C_FLOAT128_COMPLEX} are defined.
+@code{C_FLOAT128} and @code{C_FLOAT128_COMPLEX} are defined.
 
 @multitable @columnfractions .15 .35 .35 .35
 @headitem Fortran Type  @tab Named constant         @tab C type                                @tab Extension
@@ -15225,11 +15225,11 @@ Furthermore, if @code{__float128} is supported in C, the named constants
 @item @code{REAL}   @tab @code{C_FLOAT}         @tab @code{float}
 @item @code{REAL}   @tab @code{C_DOUBLE}        @tab @code{double}
 @item @code{REAL}   @tab @code{C_LONG_DOUBLE}   @tab @code{long double}
-@item @code{REAL}   @tab @code{C_FLOAT128}      @tab @code{__float128}                    @tab Ext.
+@item @code{REAL}   @tab @code{C_FLOAT128}      @tab @code{_Float128}                    @tab Ext.
 @item @code{COMPLEX}@tab @code{C_FLOAT_COMPLEX} @tab @code{float _Complex}
 @item @code{COMPLEX}@tab @code{C_DOUBLE_COMPLEX}@tab @code{double _Complex}
 @item @code{COMPLEX}@tab @code{C_LONG_DOUBLE_COMPLEX}@tab @code{long double _Complex}
-@item @code{REAL}   @tab @code{C_FLOAT128_COMPLEX}   @tab @code{__float128 _Complex}      @tab Ext.
+@item @code{COMPLEX}@tab @code{C_FLOAT128_COMPLEX}   @tab @code{_Float128 _Complex}      @tab Ext.
 @item @code{LOGICAL}@tab @code{C_BOOL}          @tab @code{_Bool}
 @item @code{CHARACTER}@tab @code{C_CHAR}        @tab @code{char}
 @end multitable

gcc/fortran/iso-c-binding.def

@@ -116,7 +116,7 @@ NAMED_REALCST (ISOCBINDING_LONG_DOUBLE, "c_long_double", \
                get_real_kind_from_node (long_double_type_node), GFC_STD_F2003)
 
 /* GNU Extension.  Note that the equivalence here is specifically to
-   the IEEE 128-bit type __float128; if that does not map onto a type
+   the IEEE 128-bit type _Float128; if that does not map onto a type
    otherwise supported by the Fortran front end, get_real_kind_from_node
    will reject it as unsupported.  */
 NAMED_REALCST (ISOCBINDING_FLOAT128, "c_float128", \

gcc/fortran/trans-intrinsic.c

@@ -175,7 +175,7 @@ gfc_builtin_decl_for_float_kind (enum built_in_function double_built_in,
 
   if (gfc_real_kinds[i].c_float128)
     {
-      /* For __float128, the story is a bit different, because we return
+      /* For _Float128, the story is a bit different, because we return
 	 a decl to a library function rather than a built-in.  */
       gfc_intrinsic_map_t *m;
       for (m = gfc_intrinsic_map; m->double_built_in != double_built_in ; m++)
@@ -387,7 +387,7 @@ build_round_expr (tree arg, tree restype)
   resprec = TYPE_PRECISION (restype);
 
   /* Depending on the type of the result, choose the int intrinsic (iround,
-     available only as a builtin, therefore cannot use it for __float128), long
+     available only as a builtin, therefore cannot use it for _Float128), long
      int intrinsic (lround family) or long long intrinsic (llround).  If we
      don't have an appropriate function that converts directly to the integer
      type (such as kind == 16), just use ROUND, and then convert the result to
@@ -689,7 +689,7 @@ gfc_build_intrinsic_lib_fndecls (void)
   if (gfc_real16_is_float128)
   {
     /* If we have soft-float types, we create the decls for their
-       C99-like library functions.  For now, we only handle __float128
+       C99-like library functions.  For now, we only handle _Float128
        q-suffixed functions.  */
 
     tree type, complex_type, func_1, func_2, func_cabs, func_frexp;

gcc/fortran/trans-types.h

@@ -55,7 +55,7 @@ extern GTY(()) tree gfc_charlen_type_node;
 
 /* The following flags give us information on the correspondence of
    real (and complex) kinds with C floating-point types long double
-   and __float128.  */
+   and _Float128.  */
 extern bool gfc_real16_is_float128;
 
 enum gfc_packed {

gcc/testsuite/gfortran.dg/PR100914.c

@@ -5,7 +5,6 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <math.h>
-#include <quadmath.h>
 
 #include <ISO_Fortran_binding.h>
 
@@ -29,7 +28,7 @@
 #define CMPLXL(x, y) ((long double complex)((long double)(x) + (long double complex)I * (long double)(y)))
 
 #undef CMPLX
-#define CMPLX(x, y) ((__complex128 )((double)(x) + (double complex)I * (double)(y)))
+#define CMPLX(x, y) ((_Float128 _Complex )((double)(x) + (double complex)I * (double)(y)))
 
 #define N 11
 #define M 7
@@ -37,7 +36,7 @@
 typedef float _Complex c_float_complex;
 typedef double _Complex c_double_complex;
 typedef long double _Complex c_long_double_complex;
-typedef __complex128 c_float128_complex;
+typedef _Float128 _Complex c_float128_complex;
 
 bool c_vrfy_c_float_complex (const CFI_cdesc_t *restrict);
 

gcc/testsuite/gfortran.dg/PR100914.f90

@@ -2,6 +2,7 @@
 ! { dg-do run { xfail { { x86_64*-*-* i?86*-*-* } && longdouble128 } } }
 ! { dg-additional-sources PR100914.c }
 ! { dg-require-effective-target fortran_real_c_float128 }
+! { dg-additional-options "-Wno-pedantic" }
 !
 ! Test the fix for PR100914
 ! 

gcc/testsuite/gfortran.dg/c-interop/typecodes-array-float128-c.c

@@ -32,7 +32,7 @@ void
 ctest (CFI_cdesc_t *arg_float128,
        CFI_cdesc_t *arg_complex128)
 {
-  check (arg_float128, sizeof (__float128), CFI_type_float128);
+  check (arg_float128, sizeof (_Float128), CFI_type_float128);
-  check (arg_complex128, sizeof (__float128) * 2,
+  check (arg_complex128, sizeof (_Float128) * 2,
 	 CFI_type_float128_Complex);
 }

gcc/testsuite/gfortran.dg/c-interop/typecodes-sanity-c.c

@@ -23,8 +23,7 @@ static struct tc_info tc_table[] =
 {
   /* Extension types.
      Note there is no portable C equivalent type for CFI_type_ucs4_char type
-     (4-byte Unicode characters), and GCC rejects "__float128 _Complex",
+     (4-byte Unicode characters), so this is kind of hacky...  */
-     so this is kind of hacky...  */
 #if CFI_type_int128_t > 0
   { CFI_type_int128_t, "CFI_type_int128_t",
     sizeof (__int128), 1 },
@@ -38,9 +37,9 @@ static struct tc_info tc_table[] =
 #endif
 #if CFI_type_float128 > 0  
   { CFI_type_float128, "CFI_type_float128",
-    sizeof (__float128), 1 },
+    sizeof (_Float128), 1 },
   { CFI_type_float128_Complex, "CFI_type_float128_Complex",
-    sizeof (__float128) * 2, 1 },
+    sizeof (_Float128 _Complex), 1 },
 #endif
 #if CFI_type_cfunptr > 0  
   { CFI_type_cfunptr, "CFI_type_cfunptr",

gcc/testsuite/gfortran.dg/c-interop/typecodes-scalar-float128-c.c

@@ -31,8 +31,8 @@ void
 ctest (CFI_cdesc_t *arg_float128,
        CFI_cdesc_t *arg_complex128)
 {
-  check (arg_float128, sizeof (__float128), CFI_type_float128);
+  check (arg_float128, sizeof (_Float128), CFI_type_float128);
-  check (arg_complex128, sizeof (__float128) * 2,
+  check (arg_complex128, sizeof (_Float128) * 2,
 	 CFI_type_float128_Complex);
 }
 

gcc/testsuite/lib/target-supports.exp

@@ -1578,8 +1578,8 @@ proc check_effective_target_fortran_real_10 { } {
 
 # Return 1 if the target supports Fortran real kind C_FLOAT128,
 # 0 otherwise.  This differs from check_effective_target_fortran_real_16
-# because __float128 has the additional requirement that it be the
+# because _Float128 has the additional requirement that it be the
-# 128-bit IEEE encoding; even if __float128 is available in C, it may not
+# 128-bit IEEE encoding; even if _Float128 is available in C, it may not
 # have a corresponding Fortran kind on targets (PowerPC) that use some 
 # other encoding for long double/TFmode/real(16).
 proc check_effective_target_fortran_real_c_float128 { } {

libgfortran/ISO_Fortran_binding.h

@@ -281,7 +281,7 @@ extern int CFI_setpointer (CFI_cdesc_t *, CFI_cdesc_t *, const CFI_index_t []);
 #define CFI_type_long_double (CFI_type_Real + (10 << CFI_type_kind_shift))
 #define CFI_type_long_double_Complex (CFI_type_Complex + (10 << CFI_type_kind_shift))
 
-/* This is the IEEE 128-bit encoding, same as float128.  */
+/* This is the IEEE 128-bit encoding, same as _Float128.  */
 #elif (__CFI_LDBL_MANT_DIG__ == 113 \
        && __CFI_LDBL_MIN_EXP__ == -16381 \
        && __CFI_LDBL_MAX_EXP__ == 16384)
@@ -303,7 +303,7 @@ extern int CFI_setpointer (CFI_cdesc_t *, CFI_cdesc_t *, const CFI_index_t []);
 #error "Can't determine kind of long double"
 #endif
 
-/* Similarly for __float128.  This always refers to the IEEE encoding
+/* Similarly for _Float128.  This always refers to the IEEE encoding
    and not some other 128-bit representation, so if we already used
    kind 16 for a non-IEEE representation, this one must be unsupported
    in Fortran even if it's available in C.  */

libgfortran/runtime/ISO_Fortran_binding.c

@@ -222,7 +222,7 @@ gfc_desc_to_cfi_desc (CFI_cdesc_t **d_ptr, const gfc_array_void *s)
      elem_len and not the kind, we get into trouble with long double kinds
      that do not correspond directly to the elem_len, specifically the
      kind 10 80-bit long double on x86 targets.  On x86_64, this has size
-     16 and cannot be differentiated from true __float128.  Prefer the
+     16 and cannot be differentiated from true _Float128.  Prefer the
      standard long double type over the GNU extension in that case.  */
   if (d->type == CFI_type_Real && kind == sizeof (long double))
     d->type = CFI_type_long_double;