x86: math: Use of __libgcc_cmp_return__ iff compiler supports it

clang does not support '__attribute__ ((mode (__libgcc_cmp_return__)))',
so use a more close related type instead fo the default 'int'.

config.h.in

@@ -323,4 +323,7 @@
 /* Define if compiler allows add attribute after function declaration.  */
 #undef ATTR_AFTER_FUNC_DECL
 
+/* Define if compiler suport __attribute__ ((mode (__libgcc_cmp_return__))).  */
+#undef HAVE_X86_LIBGCC_CMP_RETURN_ATTR
+
 #endif

sysdeps/x86/configure

@@ -392,6 +392,45 @@ else
 
 fi
 
+
+conftest_code="
+int __gcc_CMPtype_GCC __attribute__ ((mode (__libgcc_cmp_return__)));
+"
+
+cat > conftest.c <<EOF
+$conftest_code
+EOF
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for __libgcc_cmp_return__ mode attribute support" >&5
+printf %s "checking for __libgcc_cmp_return__ mode attribute support... " >&6; }
+if test ${libc_cv_cc_x86_libgcc_cmp_return_attribute+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e)   if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $CFLAGS -c conftest.c -o conftest 1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+  then
+    libc_cv_cc_x86_libgcc_cmp_return_attribute=yes
+  else
+    libc_cv_cc_x86_libgcc_cmp_return_attribute=no
+  fi ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_cc_x86_libgcc_cmp_return_attribute" >&5
+printf "%s\n" "$libc_cv_cc_x86_libgcc_cmp_return_attribute" >&6; }
+rm -f conftest*
+if test "$libc_cv_cc_x86_libgcc_cmp_return_attribute" = yes; then
+  printf "%s\n" "#define HAVE_X86_LIBGCC_CMP_RETURN_ATTR 1" >>confdefs.h
+
+else
+  printf "%s\n" "#define HAVE_X86_LIBGCC_CMP_RETURN_ATTR 0" >>confdefs.h
+
+fi
+
+
 if test "${libc_cv_cc_no_direct_extern_access}${libc_cv_test_cc_cflags_no_direct_extern_access}" = yes; then
   libc_cv_protected_data=no
 fi

sysdeps/x86/configure.ac

@@ -223,6 +223,24 @@ else
   AC_DEFINE(HAVE_X86_INLINE_TRUNC, 0)
 fi
 
+
+conftest_code="
+int __gcc_CMPtype_GCC __attribute__ ((mode (__libgcc_cmp_return__)));
+"
+dnl Check if CC support the __libgcc_cmp_return__ mode attribute
+LIBC_TRY_CC_COMMAND([for __libgcc_cmp_return__ mode attribute support],
+  [$conftest_code],
+  [$CFLAGS -c],
+  libc_cv_cc_x86_libgcc_cmp_return_attribute,
+  [libc_cv_cc_x86_libgcc_cmp_return_attribute=yes],
+  [libc_cv_cc_x86_libgcc_cmp_return_attribute=no])
+if test "$libc_cv_cc_x86_libgcc_cmp_return_attribute" = yes; then
+  AC_DEFINE(HAVE_X86_LIBGCC_CMP_RETURN_ATTR, 1)
+else
+  AC_DEFINE(HAVE_X86_LIBGCC_CMP_RETURN_ATTR, 0)
+fi
+
+
 dnl If the building compiler enables no direct external data access by
 dnl default, access to protected data in shared libraries from executables
 dnl must be compiled with no direct external data access.  If the testing

sysdeps/x86/fpu/sfp-machine.h

@@ -1,9 +1,17 @@
 /* Configure soft-fp for building sqrtf128.  Based on sfp-machine.h in
    libgcc, with soft-float and other irrelevant parts removed.  */
 
+#if HAVE_X86_LIBGCC_CMP_RETURN_ATTR
 /* The type of the result of a floating point comparison.  This must
    match `__libgcc_cmp_return__' in GCC for the target.  */
-typedef int __gcc_CMPtype __attribute__ ((mode (__libgcc_cmp_return__)));
+typedef int __gcc_CMPtype_GCC __attribute__ ((mode (__libgcc_cmp_return__)));
+#else
+# ifdef __x86_64__
+typedef long long int __gcc_CMPtype;
+#else
+typedef long int __gcc_CMPtype;
+# endif
+#endif
 #define CMPtype __gcc_CMPtype
 
 #ifdef __x86_64__