[Ada] Avoid redundant checks for empty lists

[Pierre-Marie de Rodat via Gcc-patches]

Simplify "No (L) or else Is_Empty_List (L)" into "Is_Empty_List (L)",
since Is_Empty_List can be called on No_List and returns True.

Code cleanup; semantics is unaffected.

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

gcc/ada/

        * exp_ch4.adb (Expand_N_Expression_With_Actions): Avoid
        redundant check.
        * exp_ch5.adb (Expand_N_If_Statement): Likewise.
        * exp_ch7.adb (Process_Declarations): Likewise.
        * sem_elab.adb (Freeze_Node_Location): Likewise.
        * exp_util.adb (Insert_Actions): Likewise.
        (Is_OK_PF_Pragma): Likewise.
        (Requires_Cleanup_Actions): Remove early exit; ordinary
        processing path will similarly do nothing.
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
@@ -5697,7 +5697,7 @@ package body Exp_Ch4 is
       --  Do not evaluate the expression when there are no actions because the
       --  expression_with_actions node will be replaced by the expression.
 
-      elsif No (Acts) or else Is_Empty_List (Acts) then
+      elsif Is_Empty_List (Acts) then
          null;
 
       --  Force the evaluation of the expression by capturing its value in a


diff --git a/gcc/ada/exp_ch5.adb b/gcc/ada/exp_ch5.adb
--- a/gcc/ada/exp_ch5.adb
+++ b/gcc/ada/exp_ch5.adb
@@ -4475,9 +4475,7 @@ package body Exp_Ch5 is
             --  entire if statement by the sequence of else statements.
 
             if No (Elsif_Parts (N)) then
-               if No (Else_Statements (N))
-                 or else Is_Empty_List (Else_Statements (N))
-               then
+               if Is_Empty_List (Else_Statements (N)) then
                   Rewrite (N,
                     Make_Null_Statement (Sloc (N)));
                else


diff --git a/gcc/ada/exp_ch7.adb b/gcc/ada/exp_ch7.adb
--- a/gcc/ada/exp_ch7.adb
+++ b/gcc/ada/exp_ch7.adb
@@ -2249,7 +2249,7 @@ package body Exp_Ch7 is
       --  Start of processing for Process_Declarations
 
       begin
-         if No (Decls) or else Is_Empty_List (Decls) then
+         if Is_Empty_List (Decls) then
             return;
          end if;
 


diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -7172,7 +7172,7 @@ package body Exp_Util is
       Wrapped_Node : Node_Id := Empty;
 
    begin
-      if No (Ins_Actions) or else Is_Empty_List (Ins_Actions) then
+      if Is_Empty_List (Ins_Actions) then
          return;
       end if;
 
@@ -9963,7 +9963,7 @@ package body Exp_Util is
             --  Nothing to do when the pragma lacks arguments, in which case it
             --  is illegal.
 
-            elsif No (Args) or else Is_Empty_List (Args) then
+            elsif Is_Empty_List (Args) then
                return False;
             end if;
 
@@ -12674,10 +12674,6 @@ package body Exp_Util is
       Typ     : Entity_Id;
 
    begin
-      if No (L) or else Is_Empty_List (L) then
-         return False;
-      end if;
-
       Decl := First (L);
       while Present (Decl) loop
 


diff --git a/gcc/ada/sem_elab.adb b/gcc/ada/sem_elab.adb
--- a/gcc/ada/sem_elab.adb
+++ b/gcc/ada/sem_elab.adb
@@ -15382,7 +15382,7 @@ package body Sem_Elab is
 
                elsif Present (Vis_Decls)
                  and then List_Containing (FNode) = Vis_Decls
-                 and then (No (Prv_Decls) or else Is_Empty_List (Prv_Decls))
+                 and then Is_Empty_List (Prv_Decls)
                then
                   null;