4 files changed, 69 insertions, 0 deletions
diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index 8856a97..d35b087 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -317,6 +317,16 @@ builtin_define_float_constants (const char *name_prefix,
       sprintf (name, "__FP_FAST_FMA%s", fma_suffix);
       builtin_define_with_int_value (name, 1);
     }
+
+  /* For C2x *_IS_IEC_60559.  0 means the type does not match an IEC
+     60559 format, 1 that it matches a format but not operations and 2
+     that it matches a format and operations (but may not conform to
+     Annex F; we take this as meaning exceptions and rounding modes
+     need not be supported).  */
+  sprintf (name, "__%s_IS_IEC_60559__", name_prefix);
+  builtin_define_with_int_value (name,
+				 (fmt->ieee_bits == 0
+				  ? 0 : (fmt->round_towards_zero ? 1 : 2)));
 }
 
 /* Define __DECx__ constants for TYPE using NAME_PREFIX and SUFFIX. */
diff --git a/gcc/ginclude/float.h b/gcc/ginclude/float.h
index 0fa0046..83c5ad5 100644
--- a/gcc/ginclude/float.h
+++ b/gcc/ginclude/float.h
@@ -248,6 +248,15 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define DBL_NORM_MAX	__DBL_NORM_MAX__
 #define LDBL_NORM_MAX	__LDBL_NORM_MAX__
 
+/* Whether each type matches an IEC 60559 format (1 for format, 2 for
+   format and operations).  */
+#undef FLT_IS_IEC_60559
+#undef DBL_IS_IEC_60559
+#undef LDBL_IS_IEC_60559
+#define FLT_IS_IEC_60559	__FLT_IS_IEC_60559__
+#define DBL_IS_IEC_60559	__DBL_IS_IEC_60559__
+#define LDBL_IS_IEC_60559	__LDBL_IS_IEC_60559__
+
 /* Infinity in type float, or overflow if infinity not supported.  */
 #undef INFINITY
 #define INFINITY	(__builtin_inff ())
diff --git a/gcc/testsuite/gcc.dg/c11-float-6.c b/gcc/testsuite/gcc.dg/c11-float-6.c
new file mode 100644
index 0000000..b0381e5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c11-float-6.c
@@ -0,0 +1,17 @@
+/* Test *_IS_IEC_60559 not defined for C11.  */
+/* { dg-do preprocess } */
+/* { dg-options "-std=c11 -pedantic-errors" } */
+
+#include <float.h>
+
+#ifdef FLT_IS_IEC_60559
+#error "FLT_IS_IEC_60559 defined"
+#endif
+
+#ifdef DBL_IS_IEC_60559
+#error "DBL_IS_IEC_60559 defined"
+#endif
+
+#ifdef LDBL_IS_IEC_60559
+#error "LDBL_IS_IEC_60559 defined"
+#endif
diff --git a/gcc/testsuite/gcc.dg/c2x-float-10.c b/gcc/testsuite/gcc.dg/c2x-float-10.c
new file mode 100644
index 0000000..7b53a6a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-float-10.c
@@ -0,0 +1,33 @@
+/* Test *_IS_IEC_60559 macros.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c2x -pedantic-errors" } */
+
+#include <float.h>
+
+#ifndef FLT_IS_IEC_60559
+#error "FLT_IS_IEC_60559 undefined"
+#endif
+
+#ifndef DBL_IS_IEC_60559
+#error "DBL_IS_IEC_60559 undefined"
+#endif
+
+#ifndef LDBL_IS_IEC_60559
+#error "LDBL_IS_IEC_60559 undefined"
+#endif
+
+#if defined __pdp11__ || defined __vax__
+_Static_assert (FLT_IS_IEC_60559 == 0);
+_Static_assert (DBL_IS_IEC_60559 == 0);
+_Static_assert (LDBL_IS_IEC_60559 == 0);
+#else
+_Static_assert (FLT_IS_IEC_60559 == 2);
+_Static_assert (DBL_IS_IEC_60559 == 2);
+#if LDBL_MANT_DIG == 106 || LDBL_MIN_EXP == -16382
+/* IBM long double and m68k extended format do not meet the definition
+   of an IEC 60559 interchange or extended format.  */
+_Static_assert (LDBL_IS_IEC_60559 == 0);
+#else
+_Static_assert (LDBL_IS_IEC_60559 == 2);
+#endif
+#endif