diff --git a/gcc/ada/exp_ch4.adb b/gcc/ada/exp_ch4.adb
--- a/gcc/ada/exp_ch4.adb
+++ b/gcc/ada/exp_ch4.adb
@@ -6388,7 +6388,7 @@ package body Exp_Ch4 is
             Lcheck : Compare_Result;
             Ucheck : Compare_Result;
 
-            Warn1 : constant Boolean :=
+            Warn : constant Boolean :=
                       Constant_Condition_Warnings
                         and then Comes_From_Source (N)
                         and then not In_Instance;
@@ -6397,16 +6397,6 @@ package body Exp_Ch4 is
             --  also skip these warnings in an instance since it may be the
             --  case that different instantiations have different ranges.
 
-            Warn2 : constant Boolean :=
-                      Warn1
-                        and then Nkind (Original_Node (Rop)) = N_Range
-                        and then Is_Integer_Type (Etype (Lo));
-            --  For the case where only one bound warning is elided, we also
-            --  insist on an explicit range and an integer type. The reason is
-            --  that the use of enumeration ranges including an end point is
-            --  common, as is the use of a subtype name, one of whose bounds is
-            --  the same as the type of the expression.
-
          begin
             --  If test is explicit x'First .. x'Last, replace by valid check
 
@@ -6491,7 +6481,7 @@ package body Exp_Ch4 is
             --  legality checks, because we are constant-folding beyond RM 4.9.
 
             if Lcheck = LT or else Ucheck = GT then
-               if Warn1 then
+               if Warn then
                   Error_Msg_N ("?c?range test optimized away", N);
                   Error_Msg_N ("\?c?value is known to be out of range", N);
                end if;
@@ -6505,7 +6495,7 @@ package body Exp_Ch4 is
             --  since we know we are in range.
 
             elsif Lcheck in Compare_GE and then Ucheck in Compare_LE then
-               if Warn1 then
+               if Warn then
                   Error_Msg_N ("?c?range test optimized away", N);
                   Error_Msg_N ("\?c?value is known to be in range", N);
                end if;
@@ -6520,11 +6510,6 @@ package body Exp_Ch4 is
             --  a comparison against the upper bound.
 
             elsif Lcheck in Compare_GE then
-               if Warn2 and then not In_Instance then
-                  Error_Msg_N ("??lower bound test optimized away", Lo);
-                  Error_Msg_N ("\??value is known to be in range", Lo);
-               end if;
-
                Rewrite (N,
                  Make_Op_Le (Loc,
                    Left_Opnd  => Lop,
@@ -6532,16 +6517,9 @@ package body Exp_Ch4 is
                Analyze_And_Resolve (N, Restyp);
                goto Leave;
 
-            --  If upper bound check succeeds and lower bound check is not
-            --  known to succeed or fail, then replace the range check with
-            --  a comparison against the lower bound.
+            --  Inverse of previous case.
 
             elsif Ucheck in Compare_LE then
-               if Warn2 and then not In_Instance then
-                  Error_Msg_N ("??upper bound test optimized away", Hi);
-                  Error_Msg_N ("\??value is known to be in range", Hi);
-               end if;
-
                Rewrite (N,
                  Make_Op_Ge (Loc,
                    Left_Opnd  => Lop,
@@ -6555,7 +6533,7 @@ package body Exp_Ch4 is
             --  see if we can determine the outcome assuming everything is
             --  valid, and if so give an appropriate warning.
 
-            if Warn1 and then not Assume_No_Invalid_Values then
+            if Warn and then not Assume_No_Invalid_Values then
                Lcheck := Compile_Time_Compare (Lop, Lo, Assume_Valid => True);
                Ucheck := Compile_Time_Compare (Lop, Hi, Assume_Valid => True);
 
@@ -6570,18 +6548,6 @@ package body Exp_Ch4 is
                elsif Lcheck in Compare_GE and then Ucheck in Compare_LE then
                   Error_Msg_N
                     ("?c?value can only be out of range if it is invalid", N);
-
-               --  Lower bound check succeeds if value is valid
-
-               elsif Warn2 and then Lcheck in Compare_GE then
-                  Error_Msg_N
-                    ("?c?lower bound check only fails if it is invalid", Lo);
-
-               --  Upper bound  check succeeds if value is valid
-
-               elsif Warn2 and then Ucheck in Compare_LE then
-                  Error_Msg_N
-                    ("?c?upper bound check only fails for invalid values", Hi);
                end if;
             end if;
          end;


diff --git a/gcc/ada/fe.h b/gcc/ada/fe.h
--- a/gcc/ada/fe.h
+++ b/gcc/ada/fe.h
@@ -203,7 +203,6 @@ extern Boolean In_Extended_Main_Code_Unit	(Entity_Id);
 /* opt: */
 
 #define Ada_Version			opt__ada_version
-#define Assume_No_Invalid_Values	opt__assume_no_invalid_values
 #define Back_End_Inlining		opt__back_end_inlining
 #define Debug_Generated_Code		opt__debug_generated_code
 #define Enable_128bit_Types		opt__enable_128bit_types
@@ -220,7 +219,6 @@ typedef enum {
 } Ada_Version_Type;
 
 extern Ada_Version_Type Ada_Version;
-extern Boolean Assume_No_Invalid_Values;
 extern Boolean Back_End_Inlining;
 extern Boolean Debug_Generated_Code;
 extern Boolean Enable_128bit_Types;


diff --git a/gcc/ada/opt.ads b/gcc/ada/opt.ads
--- a/gcc/ada/opt.ads
+++ b/gcc/ada/opt.ads
@@ -186,12 +186,9 @@ package Opt is
    Assume_No_Invalid_Values : Boolean := False;
    --  GNAT Normally, in accordance with (RM 13.9.1 (9-11)) the front end
    --  assumes that values could have invalid representations, unless it can
-   --  clearly prove that the values are valid. If this switch is set (by
+   --  prove that the values are valid. If this switch is set (by -gnatB or
    --  pragma Assume_No_Invalid_Values (On)), then the compiler assumes values
-   --  are valid and in range of their representations. This feature is now
-   --  fully enabled in the compiler.
-
-   --  WARNING: There is a matching C declaration of this variable in fe.h
+   --  are valid and in range of their representations.
 
    Back_Annotate_Rep_Info : Boolean := False;
    --  GNAT


