gcc/ada/exp_alfa.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P _ A L F A                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2012, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 with Atree;    use Atree;
  27 with Einfo;    use Einfo;
  28 with Exp_Attr; use Exp_Attr;
  29 with Exp_Ch4;  use Exp_Ch4;
  30 with Exp_Ch6;  use Exp_Ch6;
  31 with Exp_Dbug; use Exp_Dbug;
  32 with Exp_Util; use Exp_Util;
  33 with Nlists;   use Nlists;
  34 with Rtsfind;  use Rtsfind;
  35 with Sem_Aux;  use Sem_Aux;
  36 with Sem_Res;  use Sem_Res;
  37 with Sem_Util; use Sem_Util;
  38 with Sinfo;    use Sinfo;
  39 with Snames;   use Snames;
  40 with Stand;    use Stand;
  41 with Tbuild;   use Tbuild;
  42
  43 package body Exp_Alfa is
  44
  45    -----------------------
  46    -- Local Subprograms --
  47    -----------------------
  48
  49    procedure Expand_Alfa_Call (N : Node_Id);
  50    --  This procedure contains common processing for function and procedure
  51    --  calls:
  52    --    * expansion of actuals to introduce necessary temporaries
  53    --    * replacement of renaming by subprogram renamed
  54
  55    procedure Expand_Alfa_N_Attribute_Reference (N : Node_Id);
  56    --  Expand attributes 'Old and 'Result only
  57
  58    procedure Expand_Alfa_N_In (N : Node_Id);
  59    --  Expand set membership into individual ones
  60
  61    procedure Expand_Alfa_N_Object_Renaming_Declaration (N : Node_Id);
  62    --  Perform name evaluation for a renamed object
  63
  64    procedure Expand_Alfa_N_Simple_Return_Statement (N : Node_Id);
  65    --  Insert conversion on function return if necessary
  66
  67    procedure Expand_Alfa_Simple_Function_Return (N : Node_Id);
  68    --  Expand simple return from function
  69
  70    procedure Expand_Potential_Renaming (N : Node_Id);
  71    --  N denotes a N_Identifier or N_Expanded_Name. If N references a renaming,
  72    --  replace N with the renamed object.
  73
  74    -----------------
  75    -- Expand_Alfa --
  76    -----------------
  77
  78    procedure Expand_Alfa (N : Node_Id) is
  79    begin
  80       case Nkind (N) is
  81          when N_Attribute_Reference =>
  82             Expand_Alfa_N_Attribute_Reference (N);
  83
  84          when N_Block_Statement     |
  85               N_Package_Body        |
  86               N_Package_Declaration |
  87               N_Subprogram_Body     =>
  88             Qualify_Entity_Names (N);
  89
  90          when N_Subprogram_Call     =>
  91             Expand_Alfa_Call (N);
  92
  93          when N_Expanded_Name |
  94               N_Identifier    =>
  95             Expand_Potential_Renaming (N);
  96
  97          when N_In =>
  98             Expand_Alfa_N_In (N);
  99
 100          when N_Not_In =>
 101             Expand_N_Not_In (N);
 102
 103          when N_Object_Renaming_Declaration =>
 104             Expand_Alfa_N_Object_Renaming_Declaration (N);
 105
 106          when N_Simple_Return_Statement =>
 107             Expand_Alfa_N_Simple_Return_Statement (N);
 108
 109          when others =>
 110             null;
 111       end case;
 112    end Expand_Alfa;
 113
 114    ----------------------
 115    -- Expand_Alfa_Call --
 116    ----------------------
 117
 118    procedure Expand_Alfa_Call (N : Node_Id) is
 119       Call_Node   : constant Node_Id := N;
 120       Parent_Subp : Entity_Id;
 121       Subp        : Entity_Id;
 122
 123    begin
 124       --  Ignore if previous error
 125
 126       if Nkind (Call_Node) in N_Has_Etype
 127         and then Etype (Call_Node) = Any_Type
 128       then
 129          return;
 130       end if;
 131
 132       --  Call using access to subprogram with explicit dereference
 133
 134       if Nkind (Name (Call_Node)) = N_Explicit_Dereference then
 135          Subp        := Etype (Name (Call_Node));
 136          Parent_Subp := Empty;
 137
 138       --  Case of call to simple entry, where the Name is a selected component
 139       --  whose prefix is the task, and whose selector name is the entry name
 140
 141       elsif Nkind (Name (Call_Node)) = N_Selected_Component then
 142          Subp        := Entity (Selector_Name (Name (Call_Node)));
 143          Parent_Subp := Empty;
 144
 145       --  Case of call to member of entry family, where Name is an indexed
 146       --  component, with the prefix being a selected component giving the
 147       --  task and entry family name, and the index being the entry index.
 148
 149       elsif Nkind (Name (Call_Node)) = N_Indexed_Component then
 150          Subp        := Entity (Selector_Name (Prefix (Name (Call_Node))));
 151          Parent_Subp := Empty;
 152
 153       --  Normal case
 154
 155       else
 156          Subp        := Entity (Name (Call_Node));
 157          Parent_Subp := Alias (Subp);
 158       end if;
 159
 160       --  Various expansion activities for actuals are carried out
 161
 162       Expand_Actuals (N, Subp);
 163
 164       --  If the subprogram is a renaming, replace it in the call with the name
 165       --  of the actual subprogram being called.
 166
 167       if Present (Parent_Subp) then
 168          Parent_Subp := Ultimate_Alias (Parent_Subp);
 169
 170          --  The below setting of Entity is suspect, see F109-018 discussion???
 171
 172          Set_Entity (Name (Call_Node), Parent_Subp);
 173       end if;
 174    end Expand_Alfa_Call;
 175
 176    ---------------------------------------
 177    -- Expand_Alfa_N_Attribute_Reference --
 178    ---------------------------------------
 179
 180    procedure Expand_Alfa_N_Attribute_Reference (N : Node_Id) is
 181       Id : constant Attribute_Id := Get_Attribute_Id (Attribute_Name (N));
 182
 183    begin
 184       case Id is
 185          when Attribute_Old    |
 186               Attribute_Result =>
 187             Expand_N_Attribute_Reference (N);
 188
 189          when others =>
 190             null;
 191       end case;
 192    end Expand_Alfa_N_Attribute_Reference;
 193
 194    ----------------------
 195    -- Expand_Alfa_N_In --
 196    ----------------------
 197
 198    procedure Expand_Alfa_N_In (N : Node_Id) is
 199    begin
 200       if Present (Alternatives (N)) then
 201          Expand_Set_Membership (N);
 202       end if;
 203    end Expand_Alfa_N_In;
 204
 205    -----------------------------------------------
 206    -- Expand_Alfa_N_Object_Renaming_Declaration --
 207    -----------------------------------------------
 208
 209    procedure Expand_Alfa_N_Object_Renaming_Declaration (N : Node_Id) is
 210    begin
 211       --  Unconditionally remove all side effects from the name
 212
 213       Evaluate_Name (Name (N));
 214    end Expand_Alfa_N_Object_Renaming_Declaration;
 215
 216    -------------------------------------------
 217    -- Expand_Alfa_N_Simple_Return_Statement --
 218    -------------------------------------------
 219
 220    procedure Expand_Alfa_N_Simple_Return_Statement (N : Node_Id) is
 221    begin
 222       --  Defend against previous errors (i.e. the return statement calls a
 223       --  function that is not available in configurable runtime).
 224
 225       if Present (Expression (N))
 226         and then Nkind (Expression (N)) = N_Empty
 227       then
 228          return;
 229       end if;
 230
 231       --  Distinguish the function and non-function cases:
 232
 233       case Ekind (Return_Applies_To (Return_Statement_Entity (N))) is
 234
 235          when E_Function          |
 236               E_Generic_Function  =>
 237             Expand_Alfa_Simple_Function_Return (N);
 238
 239          when E_Procedure         |
 240               E_Generic_Procedure |
 241               E_Entry             |
 242               E_Entry_Family      |
 243               E_Return_Statement =>
 244             null;
 245
 246          when others =>
 247             raise Program_Error;
 248       end case;
 249
 250    exception
 251       when RE_Not_Available =>
 252          return;
 253    end Expand_Alfa_N_Simple_Return_Statement;
 254
 255    ----------------------------------------
 256    -- Expand_Alfa_Simple_Function_Return --
 257    ----------------------------------------
 258
 259    procedure Expand_Alfa_Simple_Function_Return (N : Node_Id) is
 260       Scope_Id : constant Entity_Id :=
 261                    Return_Applies_To (Return_Statement_Entity (N));
 262       --  The function we are returning from
 263
 264       R_Type : constant Entity_Id := Etype (Scope_Id);
 265       --  The result type of the function
 266
 267       Exp : constant Node_Id := Expression (N);
 268       pragma Assert (Present (Exp));
 269
 270       Exptyp : constant Entity_Id := Etype (Exp);
 271       --  The type of the expression (not necessarily the same as R_Type)
 272
 273    begin
 274       --  Check the result expression of a scalar function against the subtype
 275       --  of the function by inserting a conversion. This conversion must
 276       --  eventually be performed for other classes of types, but for now it's
 277       --  only done for scalars.
 278       --  ???
 279
 280       if Is_Scalar_Type (Exptyp) then
 281          Rewrite (Exp, Convert_To (R_Type, Exp));
 282
 283          --  The expression is resolved to ensure that the conversion gets
 284          --  expanded to generate a possible constraint check.
 285
 286          Analyze_And_Resolve (Exp, R_Type);
 287       end if;
 288    end Expand_Alfa_Simple_Function_Return;
 289
 290    -------------------------------
 291    -- Expand_Potential_Renaming --
 292    -------------------------------
 293
 294    procedure Expand_Potential_Renaming (N : Node_Id) is
 295       E : constant Entity_Id := Entity (N);
 296       T : constant Entity_Id := Etype (N);
 297
 298    begin
 299       --  Replace a reference to a renaming with the actual renamed object
 300
 301       if Ekind (E) in Object_Kind and then Present (Renamed_Object (E)) then
 302          Rewrite (N, New_Copy_Tree (Renamed_Object (E)));
 303          Reset_Analyzed_Flags (N);
 304          Analyze_And_Resolve (N, T);
 305       end if;
 306    end Expand_Potential_Renaming;
 307
 308 end Exp_Alfa;