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[Ada] Code cleanups in System.Atomic_Counters

Message ID 20210707162533.GA2543152@adacore.com
State New
Headers show
Series [Ada] Code cleanups in System.Atomic_Counters | expand

Commit Message

Pierre-Marie de Rodat July 7, 2021, 4:25 p.m. UTC 
In particular, now that we are using Atomic_Unsigned which is marked
Atomic, we no longer need to mark Atomic_Counter.Value explicitly
atomic.

We can also get rid of all uses of 'Unrestricted_Access

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* libgnat/s-atocou.ads, libgnat/s-atocou__builtin.adb: Code
	cleanups.
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Patch

diff --git a/gcc/ada/libgnat/s-atocou.ads b/gcc/ada/libgnat/s-atocou.ads
--- 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
--- 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;
 
    ----------------