[gcc r14-1271] ada: Remove redundant protection against empty lists

Marc Poulhi?s dkm@gcc.gnu.org
Fri May 26 07:36:28 GMT 2023


https://gcc.gnu.org/g:e3fe66ea55761315879985fe9b03989e9033e734

commit r14-1271-ge3fe66ea55761315879985fe9b03989e9033e734
Author: Piotr Trojanek <trojanek@adacore.com>
Date:   Tue Mar 21 10:29:39 2023 +0100

    ada: Remove redundant protection against empty lists
    
    Calls to Length on No_List intentionally return 0, so explicit guards
    against No_List are unnecessary. Code cleanup; semantics is unaffected.
    
    gcc/ada/
    
            * sem_ch13.adb (Check_Component_List): Local variable Compl is now
            a constant; a nested block is no longer needed.

Diff:
---
 gcc/ada/sem_ch13.adb | 238 +++++++++++++++++++++++++--------------------------
 1 file changed, 116 insertions(+), 122 deletions(-)

diff --git a/gcc/ada/sem_ch13.adb b/gcc/ada/sem_ch13.adb
index 593e6f8c169..b13af26b561 100644
--- a/gcc/ada/sem_ch13.adb
+++ b/gcc/ada/sem_ch13.adb
@@ -11978,163 +11978,157 @@ package body Sem_Ch13 is
             Sbit : Uint;
             Abit : out Uint)
          is
-            Compl : Integer;
+            Compl : constant Natural :=
+              Natural (List_Length (Component_Items (CL)) + List_Length (DS));
 
-         begin
-            Compl := Integer (List_Length (Component_Items (CL)));
-
-            if DS /= No_List then
-               Compl := Compl + Integer (List_Length (DS));
-            end if;
-
-            declare
-               Comps : array (Natural range 0 .. Compl) of Entity_Id;
-               --  Gather components (zero entry is for sort routine)
+            Comps : array (Natural range 0 .. Compl) of Entity_Id;
+            --  Gather components (zero entry is for sort routine)
 
-               Ncomps : Natural := 0;
-               --  Number of entries stored in Comps (starting at Comps (1))
+            Ncomps : Natural := 0;
+            --  Number of entries stored in Comps (starting at Comps (1))
 
-               Citem : Node_Id;
-               --  One component item or discriminant specification
+            Citem : Node_Id;
+            --  One component item or discriminant specification
 
-               Nbit  : Uint;
-               --  Starting bit for next component
+            Nbit  : Uint;
+            --  Starting bit for next component
 
-               CEnt  : Entity_Id;
-               --  Component entity
+            CEnt  : Entity_Id;
+            --  Component entity
 
-               Variant : Node_Id;
-               --  One variant
+            Variant : Node_Id;
+            --  One variant
 
-               function Lt (Op1, Op2 : Natural) return Boolean;
-               --  Compare routine for Sort
+            function Lt (Op1, Op2 : Natural) return Boolean;
+            --  Compare routine for Sort
 
-               procedure Move (From : Natural; To : Natural);
-               --  Move routine for Sort
+            procedure Move (From : Natural; To : Natural);
+            --  Move routine for Sort
 
-               package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
+            package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
 
-               --------
-               -- Lt --
-               --------
+            --------
+            -- Lt --
+            --------
 
-               function Lt (Op1, Op2 : Natural) return Boolean is
-                  K1 : constant Boolean :=
-                    Known_Component_Bit_Offset (Comps (Op1));
-                  K2 : constant Boolean :=
-                    Known_Component_Bit_Offset (Comps (Op2));
-                  --  Record representation clauses can be incomplete, so the
-                  --  Component_Bit_Offsets can be unknown.
-               begin
-                  if K1 then
-                     if K2 then
-                        return Component_Bit_Offset (Comps (Op1))
-                             < Component_Bit_Offset (Comps (Op2));
-                     else
-                        return True;
-                     end if;
+            function Lt (Op1, Op2 : Natural) return Boolean is
+               K1 : constant Boolean :=
+                 Known_Component_Bit_Offset (Comps (Op1));
+               K2 : constant Boolean :=
+                 Known_Component_Bit_Offset (Comps (Op2));
+               --  Record representation clauses can be incomplete, so the
+               --  Component_Bit_Offsets can be unknown.
+            begin
+               if K1 then
+                  if K2 then
+                     return Component_Bit_Offset (Comps (Op1))
+                          < Component_Bit_Offset (Comps (Op2));
                   else
-                     return K2;
+                     return True;
                   end if;
-               end Lt;
+               else
+                  return K2;
+               end if;
+            end Lt;
 
-               ----------
-               -- Move --
-               ----------
-
-               procedure Move (From : Natural; To : Natural) is
-               begin
-                  Comps (To) := Comps (From);
-               end Move;
+            ----------
+            -- Move --
+            ----------
 
+            procedure Move (From : Natural; To : Natural) is
             begin
-               --  Gather discriminants into Comp
+               Comps (To) := Comps (From);
+            end Move;
 
-               Citem := First (DS);
-               while Present (Citem) loop
-                  if Nkind (Citem) = N_Discriminant_Specification then
-                     declare
-                        Ent : constant Entity_Id :=
-                                Defining_Identifier (Citem);
-                     begin
-                        if Ekind (Ent) = E_Discriminant then
-                           Ncomps := Ncomps + 1;
-                           Comps (Ncomps) := Ent;
-                        end if;
-                     end;
-                  end if;
+         --  Start of processing for Check_Component_List
 
-                  Next (Citem);
-               end loop;
+         begin
+            --  Gather discriminants into Comp
 
-               --  Gather component entities into Comp
+            Citem := First (DS);
+            while Present (Citem) loop
+               if Nkind (Citem) = N_Discriminant_Specification then
+                  declare
+                     Ent : constant Entity_Id :=
+                             Defining_Identifier (Citem);
+                  begin
+                     if Ekind (Ent) = E_Discriminant then
+                        Ncomps := Ncomps + 1;
+                        Comps (Ncomps) := Ent;
+                     end if;
+                  end;
+               end if;
 
-               Citem := First (Component_Items (CL));
-               while Present (Citem) loop
-                  if Nkind (Citem) = N_Component_Declaration then
-                     Ncomps := Ncomps + 1;
-                     Comps (Ncomps) := Defining_Identifier (Citem);
-                  end if;
+               Next (Citem);
+            end loop;
 
-                  Next (Citem);
-               end loop;
+            --  Gather component entities into Comp
 
-               --  Now sort the component entities based on the first bit.
-               --  Note we already know there are no overlapping components.
+            Citem := First (Component_Items (CL));
+            while Present (Citem) loop
+               if Nkind (Citem) = N_Component_Declaration then
+                  Ncomps := Ncomps + 1;
+                  Comps (Ncomps) := Defining_Identifier (Citem);
+               end if;
 
-               Sorting.Sort (Ncomps);
+               Next (Citem);
+            end loop;
 
-               --  Loop through entries checking for holes
+            --  Now sort the component entities based on the first bit.
+            --  Note we already know there are no overlapping components.
 
-               Nbit := Sbit;
-               for J in 1 .. Ncomps loop
-                  CEnt := Comps (J);
-                  pragma Annotate (CodePeer, Modified, CEnt);
+            Sorting.Sort (Ncomps);
 
-                  declare
-                     CBO : constant Uint := Component_Bit_Offset (CEnt);
+            --  Loop through entries checking for holes
 
-                  begin
-                     --  Skip components with unknown offsets
+            Nbit := Sbit;
+            for J in 1 .. Ncomps loop
+               CEnt := Comps (J);
+               pragma Annotate (CodePeer, Modified, CEnt);
 
-                     if Present (CBO) and then CBO >= 0 then
-                        Error_Msg_Uint_1 := CBO - Nbit;
+               declare
+                  CBO : constant Uint := Component_Bit_Offset (CEnt);
 
-                        if Warn and then Error_Msg_Uint_1 > 0 then
-                           Error_Msg_NE
-                             ("?.h?^-bit gap before component&",
-                              Component_Name (Component_Clause (CEnt)),
-                              CEnt);
-                        end if;
+               begin
+                  --  Skip components with unknown offsets
+
+                  if Present (CBO) and then CBO >= 0 then
+                     Error_Msg_Uint_1 := CBO - Nbit;
 
-                        Nbit := CBO + Esize (CEnt);
+                     if Warn and then Error_Msg_Uint_1 > 0 then
+                        Error_Msg_NE
+                          ("?.h?^-bit gap before component&",
+                           Component_Name (Component_Clause (CEnt)),
+                           CEnt);
                      end if;
-                  end;
-               end loop;
 
-               --  Set Abit to just after the last nonvariant component
+                     Nbit := CBO + Esize (CEnt);
+                  end if;
+               end;
+            end loop;
+
+            --  Set Abit to just after the last nonvariant component
 
-               Abit := Nbit;
+            Abit := Nbit;
 
-               --  Process variant parts recursively if present. Set Abit to
-               --  the maximum for all variant parts.
+            --  Process variant parts recursively if present. Set Abit to the
+            --  maximum for all variant parts.
 
-               if Present (Variant_Part (CL)) then
-                  declare
-                     Var_Start : constant Uint := Nbit;
-                  begin
-                     Variant := First (Variants (Variant_Part (CL)));
-                     while Present (Variant) loop
-                        Check_Component_List
-                          (No_List, Component_List (Variant), Var_Start, Nbit);
-                        Next (Variant);
-                        if Nbit > Abit then
-                           Abit := Nbit;
-                        end if;
-                     end loop;
-                  end;
-               end if;
-            end;
+            if Present (Variant_Part (CL)) then
+               declare
+                  Var_Start : constant Uint := Nbit;
+               begin
+                  Variant := First (Variants (Variant_Part (CL)));
+                  while Present (Variant) loop
+                     Check_Component_List
+                       (No_List, Component_List (Variant), Var_Start, Nbit);
+                     Next (Variant);
+                     if Nbit > Abit then
+                        Abit := Nbit;
+                     end if;
+                  end loop;
+               end;
+            end if;
          end Check_Component_List;
 
          --  Local variables


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