[gcc r12-2122] [Ada] Code cleanups in System.Atomic_Counters

[gcc r12-2122] [Ada] Code cleanups in System.Atomic_Counters

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:347d939028d648d55e72738c7500743ddcc70147

commit r12-2122-g347d939028d648d55e72738c7500743ddcc70147
Author: Arnaud Charlet <charlet@adacore.com>
Date:   Wed May 12 05:28:29 2021 -0400

    [Ada] Code cleanups in System.Atomic_Counters
    
    gcc/ada/
    
            * libgnat/s-atocou.ads, libgnat/s-atocou__builtin.adb: Code
            cleanups.

Diff:
---
 gcc/ada/libgnat/s-atocou.ads          |  1 -
 gcc/ada/libgnat/s-atocou__builtin.adb | 20 +++++---------------
 2 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/gcc/ada/libgnat/s-atocou.ads b/gcc/ada/libgnat/s-atocou.ads
index a75173acaa1..9488b6dd731 100644
--- a/gcc/ada/libgnat/s-atocou.ads
+++ b/gcc/ada/libgnat/s-atocou.ads
@@ -101,7 +101,6 @@ private
 
    type Atomic_Counter is record
       Value : aliased Atomic_Unsigned := 1;
-      pragma Atomic (Value);
    end record;
 
 end System.Atomic_Counters;
diff --git a/gcc/ada/libgnat/s-atocou__builtin.adb b/gcc/ada/libgnat/s-atocou__builtin.adb
index 2ca8b9ec6e9..d87f9ad7494 100644
--- a/gcc/ada/libgnat/s-atocou__builtin.adb
+++ b/gcc/ada/libgnat/s-atocou__builtin.adb
@@ -51,24 +51,19 @@ package body System.Atomic_Counters is
 
    procedure Decrement (Item : aliased in out Atomic_Unsigned) is
    begin
-      if Sync_Sub_And_Fetch (Item'Unrestricted_Access, 1) = 0 then
+      if Sync_Sub_And_Fetch (Item'Unchecked_Access, 1) = 0 then
          null;
       end if;
    end Decrement;
 
    function Decrement (Item : aliased in out Atomic_Unsigned) return Boolean is
    begin
-      return Sync_Sub_And_Fetch (Item'Unrestricted_Access, 1) = 0;
+      return Sync_Sub_And_Fetch (Item'Unchecked_Access, 1) = 0;
    end Decrement;
 
    function Decrement (Item : in out Atomic_Counter) return Boolean is
    begin
-      --  Note: the use of Unrestricted_Access here is required because we
-      --  are obtaining an access-to-volatile pointer to a non-volatile object.
-      --  This is not allowed for [Unchecked_]Access, but is safe in this case
-      --  because we know that no aliases are being created.
-
-      return Sync_Sub_And_Fetch (Item.Value'Unrestricted_Access, 1) = 0;
+      return Sync_Sub_And_Fetch (Item.Value'Unchecked_Access, 1) = 0;
    end Decrement;
 
    ---------------
@@ -77,17 +72,12 @@ package body System.Atomic_Counters is
 
    procedure Increment (Item : aliased in out Atomic_Unsigned) is
    begin
-      Sync_Add_And_Fetch (Item'Unrestricted_Access, 1);
+      Sync_Add_And_Fetch (Item'Unchecked_Access, 1);
    end Increment;
 
    procedure Increment (Item : in out Atomic_Counter) is
    begin
-      --  Note: the use of Unrestricted_Access here is required because we are
-      --  obtaining an access-to-volatile pointer to a non-volatile object.
-      --  This is not allowed for [Unchecked_]Access, but is safe in this case
-      --  because we know that no aliases are being created.
-
-      Sync_Add_And_Fetch (Item.Value'Unrestricted_Access, 1);
+      Sync_Add_And_Fetch (Item.Value'Unchecked_Access, 1);
    end Increment;
 
    ----------------