--- a/gcc/ada/libgnat/s-fatgen.adb	Fri Oct 27 22:46:09 2017 +0900
+++ b/gcc/ada/libgnat/s-fatgen.adb	Thu Oct 25 07:37:49 2018 +0900
@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2017, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2018, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -394,7 +394,7 @@
 
    function Model (X : T) return T is
    begin
-      return Machine (X);
+      return T'Machine (X);
    end Model;
 
    ----------
@@ -415,16 +415,7 @@
 
       elsif X = T'First then
 
-         --  If not generating infinities, we raise a constraint error
-
-         if T'Machine_Overflows then
-            raise Constraint_Error with "Pred of largest negative number";
-
-         --  Otherwise generate a negative infinity
-
-         else
-            return X / (X - X);
-         end if;
+         raise Constraint_Error with "Pred of largest negative number";
 
       --  For infinities, return unchanged
 
@@ -671,15 +662,10 @@
 
          --  If not generating infinities, we raise a constraint error
 
-         if T'Machine_Overflows then
-            raise Constraint_Error with "Succ of largest negative number";
+         raise Constraint_Error with "Succ of largest positive number";
 
          --  Otherwise generate a positive infinity
 
-         else
-            return X / (X - X);
-         end if;
-
       --  For infinities, return unchanged
 
       elsif X < T'First or else X > T'Last then
@@ -739,10 +725,11 @@
       Result := abs X;
 
       if Result >= Radix_To_M_Minus_1 then
-         return Machine (X);
+         return T'Machine (X);
 
       else
-         Result := Machine (Radix_To_M_Minus_1 + Result) - Radix_To_M_Minus_1;
+         Result :=
+           T'Machine (Radix_To_M_Minus_1 + Result) - Radix_To_M_Minus_1;
 
          if Result > abs X then
             Result := Result - 1.0;