[libstdc++] numeric_limits: is_iec559

[Richard Henderson]

Other than true IEC 559 targets, we have three variations:

  (1) Really really non-IEEE, e.g. VAX.
  (2a) IEEE, except missing Infinities, NaNs and denormals.
  (2b) IEEE, except missing denormals.

In case 1, in no supported case do we have infinities or NaNs,
so the definition used below is correct.

In case 2a, the c++ standard requires that has_infinity,
has_quiet_NaN, and has_signaling_NaN all be true, so we cannot
set is_iec599.

For case 2b, I cannot find a requirement that denormals be supported.
Indeed, the example numeric_limits<float> in section 18.2.1.5 shows
has_denorm=denorm_absent but is_iec559=true.  Not that it matters at
the moment, since we don't have an target that has this case.


Ok?


r~



	* include/std/std_limits.h (__glibcpp_f32_is_iec559,
	__glibcpp_f64_is_iec559, __glibcpp_f80_is_iec559,
	__glibcpp_f96_is_iec559, __glibcpp_f128_is_iec559,
	__glibcpp_float_is_iec559, __glibcpp_double_is_iec559,
	__glibcpp_long_double_is_iec559): Remove.
	(numeric_limits<float>::is_iec559): Use has_infinity & has_quiet_NaN.
	(numeric_limits<double>, numeric_limits<long double>): Similarly.

--- std_limits.h.orig	Sat Sep 21 11:26:38 2002
+++ std_limits.h	Sat Sep 21 11:28:10 2002
@@ -150,34 +150,6 @@
 #define __glibcpp_u64_digits 64
 #define __glibcpp_u64_digits10 19
 
-#if __GCC_FLOAT_FORMAT__ == __IEEE_FORMAT__
-#  define __glibcpp_f32_is_iec559  true
-#endif
-#ifndef __glibcpp_f32_is_iec559
-#  define __glibcpp_f32_is_iec559 false
-#endif 
-#if __GCC_FLOAT_FORMAT__ == __IEEE_FORMAT__
-#  define __glibcpp_f64_is_iec559 true
-#endif
-#ifndef __glibcpp_f64_is_iec559
-#  define __glibcpp_f64_is_iec559 false
-#endif 
-#if __GCC_FLOAT_FORMAT__ == __IEEE_FORMAT__
-#  define __glibcpp_f80_is_iec559 true
-#endif
-#ifndef __glibcpp_f80_is_iec559
-#  define __glibcpp_f80_is_iec559 false
-#endif 
-#if __GCC_FLOAT_FORMAT__ == __IEEE_FORMAT__
-#  define __glibcpp_f96_is_iec559 true
-#endif
-#if __GCC_FLOAT_FORMAT__ == __IEEE_FORMAT__
-#  define __glibcpp_f128_is_iec559 true
-#endif
-#ifndef __glibcpp_f128_is_iec559
-#  define __glibcpp_f128_is_iec559 false
-#endif
-
 // bool-specific hooks:
 //     __glibcpp_bool_digits  __glibcpp_int_traps __glibcpp_long_traps
 
@@ -497,16 +469,6 @@
 // float
 //
 
-#if __FLOAT_BIT__ == 32
-#  define __glibcpp_float_is_iec559 __glibcpp_f32_is_iec559
-#elif __FLOAT_BIT__ == 64
-#  define __glibcpp_float_is_iec559 __glibcpp_f64_is_iec559
-#elif __FLOAT_BIT__ == 80
-#  define __glibcpp_float_is_iec559 __glibcpp_f80_is_iec559
-#else
-// You must define these macros in the configuration file.
-#endif
-
 // Default values.  Should be overriden in configuration files if necessary.
 
 #ifndef __glibcpp_float_has_denorm_loss
@@ -517,10 +479,6 @@
 #  define __glibcpp_float_is_bounded true
 #endif
 
-#ifndef __glibcpp_float_is_iec559
-#  define __glibcpp_float_is_iec559 false
-#endif
-
 #ifndef __glibcpp_float_is_modulo
 #  define __glibcpp_float_is_modulo false
 #endif
@@ -535,26 +493,12 @@
 
 // double
 
-#if __DOUBLE_BIT__ == 32
-#  define __glibcpp_double_is_iec559 __glibcpp_f32_is_iec559
-#elif __DOUBLE_BIT__ == 64
-#  define __glibcpp_double_is_iec559 __glibcpp_f64_is_iec559
-#elif __DOUBLE_BIT__ == 80
-#  define __glibcpp_double_is_iec559 __glibcpp_f80_is_iec559
-#else
-// You must define these macros in the configuration file.
-#endif
-
 // Default values.  Should be overriden in configuration files if necessary.
 
 #ifndef __glibcpp_double_has_denorm_loss
 #  define __glibcpp_double_has_denorm_loss false
 #endif
 
-#ifndef __glibcpp_double_is_iec559
-#  define __glibcpp_double_is_iec559 false
-#endif
-
 #ifndef __glibcpp_double_is_bounded
 #  define __glibcpp_double_is_bounded true
 #endif
@@ -573,30 +517,12 @@
 
 // long double
 
-#if __LONG_DOUBLE_BIT__ == 32
-#  define __glibcpp_long_double_is_iec559 __glibcpp_f32_is_iec559
-#elif __LONG_DOUBLE_BIT__ == 64
-#  define __glibcpp_long_double_is_iec559 __glibcpp_f64_is_iec559
-#elif __LONG_DOUBLE_BIT__ == 80
-#  define __glibcpp_long_double_is_iec559 __glibcpp_f80_is_iec559
-#elif __LONG_DOUBLE_BIT__ == 96
-#  define __glibcpp_long_double_is_iec559 __glibcpp_f96_is_iec559
-#elif __LONG_DOUBLE_BIT__ == 128
-#  define __glibcpp_long_double_is_iec559 __glibcpp_f128_is_iec559
-#else
-// You must define these macros in the configuration file.
-#endif
-
 // Default values.  Should be overriden in configuration files if necessary.
 
 #ifndef __glibcpp_long_double_has_denorm_loss
 #  define __glibcpp_long_double_has_denorm_loss false
 #endif
 
-#ifndef __glibcpp_long_double_is_iec559
-#  define __glibcpp_long_double_is_iec559 false
-#endif
-
 #ifndef __glibcpp_long_double_is_bounded
 #  define __glibcpp_long_double_is_bounded true
 #endif
@@ -1502,7 +1428,7 @@
       static float denorm_min() throw()
       { return __FLT_DENORM_MIN__; }
 
-      static const bool is_iec559 = __glibcpp_float_is_iec559;
+      static const bool is_iec559 = has_infinity && has_quiet_NaN;
       static const bool is_bounded = __glibcpp_float_is_bounded;
       static const bool is_modulo = __glibcpp_float_is_modulo;
 
@@ -1512,7 +1438,6 @@
     };
 
 #undef __glibcpp_float_has_denorm_loss
-#undef __glibcpp_float_is_iec559
 #undef __glibcpp_float_is_bounded
 #undef __glibcpp_float_is_modulo
 #undef __glibcpp_float_traps
@@ -1562,7 +1487,7 @@
       static double denorm_min() throw()
       { return __DBL_DENORM_MIN__; }
 
-      static const bool is_iec559 = __glibcpp_double_is_iec559;
+      static const bool is_iec559 = has_infinity && has_quiet_NaN;
       static const bool is_bounded = __glibcpp_double_is_bounded;
       static const bool is_modulo = __glibcpp_double_is_modulo;
 
@@ -1572,7 +1497,6 @@
     };
 
 #undef __glibcpp_double_has_denorm_loss
-#undef __glibcpp_double_is_iec559
 #undef __glibcpp_double_is_bounded
 #undef __glibcpp_double_is_modulo
 #undef __glibcpp_double_traps
@@ -1624,7 +1548,7 @@
       static long double denorm_min() throw()
       { return __LDBL_DENORM_MIN__; }
 
-      static const bool is_iec559 = __glibcpp_long_double_is_iec559;
+      static const bool is_iec559 = has_infinity && has_quiet_NaN;
       static const bool is_bounded = __glibcpp_long_double_is_bounded;
       static const bool is_modulo = __glibcpp_long_double_is_modulo;
 
@@ -1634,7 +1558,6 @@
     };
 
 #undef __glibcpp_long_double_has_denorm_loss
-#undef __glibcpp_long_double_is_iec559
 #undef __glibcpp_long_double_is_bounded
 #undef __glibcpp_long_double_is_modulo
 #undef __glibcpp_long_double_traps