long double vs. double

[Bruno Haible]

On MSVC 9, some tests fail to compile because they assume that
'long double' has an 80-bit representation with a 64-bit mantissa.
But on this platform - and, it turns out, also on Linux/HPPA, Minix,
AIX - 'long double' and 'double' have the same size and same
representation.


2011-10-09  Bruno Haible  <address@hidden>

        isfinite, isinf, isnan tests: Avoid syntax error on MSVC 9.
        * m4/math_h.m4 (gl_LONG_DOUBLE_VS_DOUBLE): New macro.
        * modules/isfinite-tests (configure.ac): Require
        gl_LONG_DOUBLE_VS_DOUBLE.
        * modules/isinf-tests (configure.ac): Likewise.
        * modules/isnan-tests (configure.ac): Likewise.
        * modules/isnanl-tests (configure.ac): Likewise.
        * modules/isnanl-nolibm-tests (configure.ac): Likewise.
        * tests/test-isfinite.c (test_isfinitel): Avoid 80-bit long double
        tests on platforms where 'long double' is the same as 'double'.
        * tests/test-isinf.c (test_isinfl): Likewise.
        * tests/test-isnan.c (test_long_double): Likewise.
        * tests/test-isnanl.h (main): Likewise.

--- m4/math_h.m4.orig   Sun Oct  9 11:21:59 2011
+++ m4/math_h.m4        Sun Oct  9 11:16:54 2011
@@ -1,4 +1,4 @@
-# math_h.m4 serial 46
+# math_h.m4 serial 47
 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -188,3 +188,34 @@
   REPLACE_TRUNCF=0;            AC_SUBST([REPLACE_TRUNCF])
   REPLACE_TRUNCL=0;            AC_SUBST([REPLACE_TRUNCL])
 ])
+
+# gl_LONG_DOUBLE_VS_DOUBLE
+# determines whether 'long double' and 'double' have the same representation.
+# Sets variable HAVE_SAME_LONG_DOUBLE_AS_DOUBLE to 0 or 1, and defines
+# HAVE_SAME_LONG_DOUBLE_AS_DOUBLE accordingly.
+# The currently known platforms where this is the case are:
+# Linux/HPPA, Minix 3.1.8, AIX 5, AIX 6 and 7 with xlc, MSVC 9.
+AC_DEFUN([gl_LONG_DOUBLE_VS_DOUBLE],
+[
+  AC_CACHE_CHECK([whether long double and double are the same],
+    [gl_cv_long_double_equals_double],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[#include <float.h>]],
+          [[typedef int check[sizeof (long double) == sizeof (double)
+                              && LDBL_MANT_DIG == DBL_MANT_DIG
+                              && LDBL_MAX_EXP == DBL_MAX_EXP
+                              && LDBL_MIN_EXP == DBL_MIN_EXP
+                              ? 1 : -1];
+          ]])],
+       [gl_cv_long_double_equals_double=yes],
+       [gl_cv_long_double_equals_double=no])
+    ])
+  if test $gl_cv_long_double_equals_double = yes; then
+    AC_DEFINE([HAVE_SAME_LONG_DOUBLE_AS_DOUBLE], [1],
+      [Define to 1 if 'long double' and 'double' have the same 
representation.])
+    HAVE_SAME_LONG_DOUBLE_AS_DOUBLE=1
+  else
+    HAVE_SAME_LONG_DOUBLE_AS_DOUBLE=0
+  fi
+  AC_SUBST([HAVE_SAME_LONG_DOUBLE_AS_DOUBLE])
+])
--- modules/isfinite-tests.orig Sun Oct  9 11:21:59 2011
+++ modules/isfinite-tests      Sun Oct  9 10:50:43 2011
@@ -10,6 +10,7 @@
 gl_FLOAT_EXPONENT_LOCATION
 gl_DOUBLE_EXPONENT_LOCATION
 gl_LONG_DOUBLE_EXPONENT_LOCATION
+AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
 
 Makefile.am:
 TESTS += test-isfinite
--- modules/isinf-tests.orig    Sun Oct  9 11:21:59 2011
+++ modules/isinf-tests Sun Oct  9 10:50:43 2011
@@ -13,6 +13,7 @@
 gl_FLOAT_EXPONENT_LOCATION
 gl_DOUBLE_EXPONENT_LOCATION
 gl_LONG_DOUBLE_EXPONENT_LOCATION
+AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
 
 Makefile.am:
 TESTS += test-isinf
--- modules/isnan-tests.orig    Sun Oct  9 11:21:59 2011
+++ modules/isnan-tests Sun Oct  9 10:50:43 2011
@@ -12,6 +12,7 @@
 gl_FLOAT_EXPONENT_LOCATION
 gl_DOUBLE_EXPONENT_LOCATION
 gl_LONG_DOUBLE_EXPONENT_LOCATION
+AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
 
 Makefile.am:
 TESTS += test-isnan
--- modules/isnanl-nolibm-tests.orig    Sun Oct  9 11:21:59 2011
+++ modules/isnanl-nolibm-tests Sun Oct  9 10:50:43 2011
@@ -11,6 +11,7 @@
 
 configure.ac:
 gl_LONG_DOUBLE_EXPONENT_LOCATION
+AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
 
 Makefile.am:
 TESTS += test-isnanl-nolibm
--- modules/isnanl-tests.orig   Sun Oct  9 11:21:59 2011
+++ modules/isnanl-tests        Sun Oct  9 10:50:43 2011
@@ -11,6 +11,7 @@
 
 configure.ac:
 gl_LONG_DOUBLE_EXPONENT_LOCATION
+AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
 
 Makefile.am:
 TESTS += test-isnanl
--- tests/test-isfinite.c.orig  Sun Oct  9 11:21:59 2011
+++ tests/test-isfinite.c       Sun Oct  9 10:28:17 2011
@@ -166,7 +166,7 @@
   }
 #endif
 
-#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_))
+#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
 /* Representation of an 80-bit 'long double' as an initializer for a sequence
    of 'unsigned int' words.  */
 # ifdef WORDS_BIGENDIAN
--- tests/test-isinf.c.orig     Sun Oct  9 11:21:59 2011
+++ tests/test-isinf.c  Sun Oct  9 10:28:18 2011
@@ -172,7 +172,7 @@
   }
 #endif
 
-#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_))
+#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
 /* Representation of an 80-bit 'long double' as an initializer for a sequence
    of 'unsigned int' words.  */
 # ifdef WORDS_BIGENDIAN
--- tests/test-isnan.c.orig     Sun Oct  9 11:21:59 2011
+++ tests/test-isnan.c  Sun Oct  9 10:28:18 2011
@@ -153,7 +153,7 @@
   }
 #endif
 
-#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_))
+#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
 /* Representation of an 80-bit 'long double' as an initializer for a sequence
    of 'unsigned int' words.  */
 # ifdef WORDS_BIGENDIAN
--- tests/test-isnanl.h.orig    Sun Oct  9 11:21:59 2011
+++ tests/test-isnanl.h Sun Oct  9 10:28:18 2011
@@ -65,7 +65,7 @@
   }
 #endif
 
-#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_))
+#if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined 
__amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined 
_M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
 /* Representation of an 80-bit 'long double' as an initializer for a sequence
    of 'unsigned int' words.  */
 # ifdef WORDS_BIGENDIAN
-- 
In memoriam Oskar Schindler <http://en.wikipedia.org/wiki/Oskar_Schindler>
<http://www.shoah.dk/Courage/Schindler.htm>