gcc/ada/exp_code.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P _ C O D E                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1996-2004 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 2,  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 COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- GNAT was originally developed  by the GNAT team at  New York University. --
  23 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  24 --                                                                          --
  25 ------------------------------------------------------------------------------
  26
  27 with Atree;    use Atree;
  28 with Einfo;    use Einfo;
  29 with Errout;   use Errout;
  30 with Fname;    use Fname;
  31 with Lib;      use Lib;
  32 with Namet;    use Namet;
  33 with Nlists;   use Nlists;
  34 with Nmake;    use Nmake;
  35 with Opt;      use Opt;
  36 with Rtsfind;  use Rtsfind;
  37 with Sem_Eval; use Sem_Eval;
  38 with Sem_Util; use Sem_Util;
  39 with Sinfo;    use Sinfo;
  40 with Stringt;  use Stringt;
  41 with Tbuild;   use Tbuild;
  42
  43 package body Exp_Code is
  44
  45    -----------------------
  46    -- Local_Subprograms --
  47    -----------------------
  48
  49    function Asm_Constraint (Operand_Var : Node_Id) return Node_Id;
  50    --  Common processing for Asm_Input_Constraint and Asm_Output_Constraint.
  51    --  Obtains the constraint argument from the global operand variable
  52    --  Operand_Var, which must be non-Empty.
  53
  54    function Asm_Operand (Operand_Var : Node_Id) return Node_Id;
  55    --  Common processing for Asm_Input_Value and Asm_Output_Variable. Obtains
  56    --  the value/variable argument from Operand_Var, the global operand
  57    --  variable. Returns Empty if no operand available.
  58
  59    function Get_String_Node (S : Node_Id) return Node_Id;
  60    --  Given S, a static expression node of type String, returns the
  61    --  string literal node. This is needed to deal with the use of constants
  62    --  for these expressions, which is perfectly permissible.
  63
  64    procedure Next_Asm_Operand (Operand_Var : in out Node_Id);
  65    --  Common processing for Next_Asm_Input and Next_Asm_Output, updates
  66    --  the value of the global operand variable Operand_Var appropriately.
  67
  68    procedure Setup_Asm_IO_Args (Arg : Node_Id; Operand_Var : out Node_Id);
  69    --  Common processing for Setup_Asm_Inputs and Setup_Asm_Outputs. Arg
  70    --  is the actual parameter from the call, and Operand_Var is the global
  71    --  operand variable to be initialized to the first operand.
  72
  73    ----------------------
  74    -- Global Variables --
  75    ----------------------
  76
  77    Current_Input_Operand : Node_Id := Empty;
  78    --  Points to current Asm_Input_Operand attribute reference. Initialized
  79    --  by Setup_Asm_Inputs, updated by Next_Asm_Input, and referenced by
  80    --  Asm_Input_Constraint and Asm_Input_Value.
  81
  82    Current_Output_Operand : Node_Id := Empty;
  83    --  Points to current Asm_Output_Operand attribute reference. Initialized
  84    --  by Setup_Asm_Outputs, updated by Next_Asm_Output, and referenced by
  85    --  Asm_Output_Constraint and Asm_Output_Variable.
  86
  87    --------------------
  88    -- Asm_Constraint --
  89    --------------------
  90
  91    function Asm_Constraint (Operand_Var : Node_Id) return Node_Id is
  92    begin
  93       pragma Assert (Present (Operand_Var));
  94       return Get_String_Node (First (Expressions (Operand_Var)));
  95    end Asm_Constraint;
  96
  97    --------------------------
  98    -- Asm_Input_Constraint --
  99    --------------------------
 100
 101    --  Note: error checking on Asm_Input attribute done in Sem_Attr
 102
 103    function Asm_Input_Constraint return Node_Id is
 104    begin
 105       return Get_String_Node (Asm_Constraint (Current_Input_Operand));
 106    end Asm_Input_Constraint;
 107
 108    ---------------------
 109    -- Asm_Input_Value --
 110    ---------------------
 111
 112    --  Note: error checking on Asm_Input attribute done in Sem_Attr
 113
 114    function Asm_Input_Value return Node_Id is
 115    begin
 116       return Asm_Operand (Current_Input_Operand);
 117    end Asm_Input_Value;
 118
 119    -----------------
 120    -- Asm_Operand --
 121    -----------------
 122
 123    function Asm_Operand (Operand_Var : Node_Id) return Node_Id is
 124    begin
 125       if No (Operand_Var) then
 126          return Empty;
 127       else
 128          return Next (First (Expressions (Operand_Var)));
 129       end if;
 130    end Asm_Operand;
 131
 132    ---------------------------
 133    -- Asm_Output_Constraint --
 134    ---------------------------
 135
 136    --  Note: error checking on Asm_Output attribute done in Sem_Attr
 137
 138    function Asm_Output_Constraint return Node_Id is
 139    begin
 140       return Asm_Constraint (Current_Output_Operand);
 141    end Asm_Output_Constraint;
 142
 143    -------------------------
 144    -- Asm_Output_Variable --
 145    -------------------------
 146
 147    --  Note: error checking on Asm_Output attribute done in Sem_Attr
 148
 149    function Asm_Output_Variable return Node_Id is
 150    begin
 151       return Asm_Operand (Current_Output_Operand);
 152    end Asm_Output_Variable;
 153
 154    ------------------
 155    -- Asm_Template --
 156    ------------------
 157
 158    function Asm_Template (N : Node_Id) return Node_Id is
 159       Call : constant Node_Id := Expression (Expression (N));
 160       Temp : constant Node_Id := First_Actual (Call);
 161
 162    begin
 163       --  Require static expression for template. We also allow a string
 164       --  literal (this is useful for Ada 83 mode where string expressions
 165       --  are never static).
 166
 167       if Is_OK_Static_Expression (Temp)
 168         or else (Ada_Version = Ada_83
 169                   and then Nkind (Temp) = N_String_Literal)
 170       then
 171          return Get_String_Node (Temp);
 172
 173       else
 174          Flag_Non_Static_Expr ("asm template argument is not static!", Temp);
 175          return Empty;
 176       end if;
 177    end Asm_Template;
 178
 179    ----------------------
 180    -- Clobber_Get_Next --
 181    ----------------------
 182
 183    Clobber_Node : Node_Id;
 184    --  String literal node for clobber string. Initialized by Clobber_Setup,
 185    --  and not modified by Clobber_Get_Next. Empty if clobber string was in
 186    --  error (resulting in no clobber arguments being returned).
 187
 188    Clobber_Ptr : Nat;
 189    --  Pointer to current character of string. Initialized to 1 by the call
 190    --  to Clobber_Setup, and then updated by Clobber_Get_Next.
 191
 192    function Clobber_Get_Next return Address is
 193       Str : constant String_Id := Strval (Clobber_Node);
 194       Len : constant Nat       := String_Length (Str);
 195       C   : Character;
 196
 197    begin
 198       if No (Clobber_Node) then
 199          return Null_Address;
 200       end if;
 201
 202       --  Skip spaces and commas before next register name
 203
 204       loop
 205          --  Return null string if no more names
 206
 207          if Clobber_Ptr > Len then
 208             return Null_Address;
 209          end if;
 210
 211          C := Get_Character (Get_String_Char (Str, Clobber_Ptr));
 212          exit when C /= ',' and then C /= ' ';
 213          Clobber_Ptr := Clobber_Ptr + 1;
 214       end loop;
 215
 216       --  Acquire next register name
 217
 218       Name_Len := 0;
 219       loop
 220          Name_Len := Name_Len + 1;
 221          Name_Buffer (Name_Len) := C;
 222          Clobber_Ptr := Clobber_Ptr + 1;
 223          exit when Clobber_Ptr > Len;
 224          C := Get_Character (Get_String_Char (Str, Clobber_Ptr));
 225          exit when C = ',' or else C = ' ';
 226       end loop;
 227
 228       Name_Buffer (Name_Len + 1) := ASCII.NUL;
 229       return Name_Buffer'Address;
 230
 231    end Clobber_Get_Next;
 232
 233    -------------------
 234    -- Clobber_Setup --
 235    -------------------
 236
 237    procedure Clobber_Setup (N : Node_Id) is
 238       Call : constant Node_Id := Expression (Expression (N));
 239       Clob : constant Node_Id := Next_Actual (
 240                                    Next_Actual (
 241                                      Next_Actual (
 242                                        First_Actual (Call))));
 243
 244    begin
 245       if not Is_OK_Static_Expression (Clob) then
 246          Flag_Non_Static_Expr ("asm clobber argument is not static!", Clob);
 247          Clobber_Node := Empty;
 248
 249       else
 250          Clobber_Node := Get_String_Node (Clob);
 251          Clobber_Ptr := 1;
 252       end if;
 253    end Clobber_Setup;
 254
 255    ---------------------
 256    -- Expand_Asm_Call --
 257    ---------------------
 258
 259    procedure Expand_Asm_Call (N : Node_Id) is
 260       Loc : constant Source_Ptr := Sloc (N);
 261
 262       procedure Check_IO_Operand (N : Node_Id);
 263       --  Check for incorrect input or output operand
 264
 265       procedure Check_IO_Operand (N : Node_Id) is
 266          Err : Node_Id := N;
 267
 268       begin
 269          --  The only identifier allows is No_xxput_Operands. Since we
 270          --  know the type is right, it is sufficient to see if the
 271          --  referenced entity is in a runtime routine.
 272
 273          if Is_Entity_Name (N)
 274            and then
 275              Is_Predefined_File_Name (Unit_File_Name
 276                                        (Get_Source_Unit (Entity (N))))
 277          then
 278             return;
 279
 280          --  An attribute reference is fine, again the analysis reasonably
 281          --  guarantees that the attribute must be subtype'Asm_??put.
 282
 283          elsif Nkind (N) = N_Attribute_Reference then
 284             return;
 285
 286          --  The only other allowed form is an array aggregate in which
 287          --  all the entries are positional and are attribute references.
 288
 289          elsif Nkind (N) = N_Aggregate then
 290             if Present (Component_Associations (N)) then
 291                Err := First (Component_Associations (N));
 292
 293             elsif Present (Expressions (N)) then
 294                Err := First (Expressions (N));
 295                while Present (Err) loop
 296                   exit when Nkind (Err) /= N_Attribute_Reference;
 297                   Next (Err);
 298                end loop;
 299
 300                if No (Err) then
 301                   return;
 302                end if;
 303             end if;
 304          end if;
 305
 306          --  If we fall through, Err is pointing to the bad node
 307
 308          Error_Msg_N ("Asm operand has wrong form", Err);
 309       end Check_IO_Operand;
 310
 311    --  Start of processing for Expand_Asm_Call
 312
 313    begin
 314       --  Check that the input and output operands have the right
 315       --  form, as required by the documentation of the Asm feature:
 316
 317       --  OUTPUT_OPERAND_LIST ::=
 318       --    No_Output_Operands
 319       --  | OUTPUT_OPERAND_ATTRIBUTE
 320       --  | (OUTPUT_OPERAND_ATTRIBUTE @{,OUTPUT_OPERAND_ATTRIBUTE@})
 321
 322       --  OUTPUT_OPERAND_ATTRIBUTE ::=
 323       --    SUBTYPE_MARK'Asm_Output (static_string_EXPRESSION, NAME)
 324
 325       --  INPUT_OPERAND_LIST ::=
 326       --    No_Input_Operands
 327       --  | INPUT_OPERAND_ATTRIBUTE
 328       --  | (INPUT_OPERAND_ATTRIBUTE @{,INPUT_OPERAND_ATTRIBUTE@})
 329
 330       --  INPUT_OPERAND_ATTRIBUTE ::=
 331       --    SUBTYPE_MARK'Asm_Input (static_string_EXPRESSION, EXPRESSION)
 332
 333       declare
 334          Arg_Output : constant Node_Id := Next_Actual (First_Actual (N));
 335          Arg_Input  : constant Node_Id := Next_Actual (Arg_Output);
 336
 337       begin
 338          Check_IO_Operand (Arg_Output);
 339          Check_IO_Operand (Arg_Input);
 340       end;
 341
 342       --  If we have the function call case, we are inside a code statement,
 343       --  and the tree is already in the necessary form for gigi.
 344
 345       if Nkind (N) = N_Function_Call then
 346          null;
 347
 348       --  For the procedure case, we convert the call into a code statement
 349
 350       else
 351          pragma Assert (Nkind (N) = N_Procedure_Call_Statement);
 352
 353          --  Note: strictly we should change the procedure call to a function
 354          --  call in the qualified expression, but since we are not going to
 355          --  reanalyze (see below), and the interface subprograms in this
 356          --  package don't care, we can leave it as a procedure call.
 357
 358          Rewrite (N,
 359            Make_Code_Statement (Loc,
 360              Expression =>
 361                Make_Qualified_Expression (Loc,
 362                  Subtype_Mark => New_Occurrence_Of (RTE (RE_Asm_Insn), Loc),
 363                  Expression => Relocate_Node (N))));
 364
 365          --  There is no need to reanalyze this node, it is completely analyzed
 366          --  already, at least sufficiently for the purposes of the abstract
 367          --  procedural interface defined in this package.
 368
 369          Set_Analyzed (N);
 370       end if;
 371    end Expand_Asm_Call;
 372
 373    ---------------------
 374    -- Get_String_Node --
 375    ---------------------
 376
 377    function Get_String_Node (S : Node_Id) return Node_Id is
 378    begin
 379       if Nkind (S) = N_String_Literal then
 380          return S;
 381
 382       else
 383          pragma Assert (Ekind (Entity (S)) = E_Constant);
 384          return Get_String_Node (Constant_Value (Entity (S)));
 385       end if;
 386    end Get_String_Node;
 387
 388    ---------------------
 389    -- Is_Asm_Volatile --
 390    ---------------------
 391
 392    function Is_Asm_Volatile (N : Node_Id) return Boolean is
 393       Call : constant Node_Id := Expression (Expression (N));
 394       Vol  : constant Node_Id :=
 395                Next_Actual (
 396                  Next_Actual (
 397                    Next_Actual (
 398                      Next_Actual (
 399                        First_Actual (Call)))));
 400
 401    begin
 402       if not Is_OK_Static_Expression (Vol) then
 403          Flag_Non_Static_Expr ("asm volatile argument is not static!", Vol);
 404          return False;
 405
 406       else
 407          return Is_True (Expr_Value (Vol));
 408       end if;
 409    end Is_Asm_Volatile;
 410
 411    --------------------
 412    -- Next_Asm_Input --
 413    --------------------
 414
 415    procedure Next_Asm_Input is
 416    begin
 417       Next_Asm_Operand (Current_Input_Operand);
 418    end Next_Asm_Input;
 419
 420    ----------------------
 421    -- Next_Asm_Operand --
 422    ----------------------
 423
 424    procedure Next_Asm_Operand (Operand_Var : in out Node_Id) is
 425    begin
 426       pragma Assert (Present (Operand_Var));
 427
 428       if Nkind (Parent (Operand_Var)) = N_Aggregate then
 429          Operand_Var := Next (Operand_Var);
 430
 431       else
 432          Operand_Var := Empty;
 433       end if;
 434    end Next_Asm_Operand;
 435
 436    ---------------------
 437    -- Next_Asm_Output --
 438    ---------------------
 439
 440    procedure Next_Asm_Output is
 441    begin
 442       Next_Asm_Operand (Current_Output_Operand);
 443    end Next_Asm_Output;
 444
 445    ----------------------
 446    -- Setup_Asm_Inputs --
 447    ----------------------
 448
 449    procedure Setup_Asm_Inputs (N : Node_Id) is
 450       Call : constant Node_Id := Expression (Expression (N));
 451
 452    begin
 453       Setup_Asm_IO_Args
 454         (Next_Actual (Next_Actual (First_Actual (Call))),
 455          Current_Input_Operand);
 456    end Setup_Asm_Inputs;
 457
 458    -----------------------
 459    -- Setup_Asm_IO_Args --
 460    -----------------------
 461
 462    procedure Setup_Asm_IO_Args (Arg : Node_Id; Operand_Var : out Node_Id) is
 463    begin
 464       --  Case of single argument
 465
 466       if Nkind (Arg) = N_Attribute_Reference then
 467          Operand_Var := Arg;
 468
 469       --  Case of list of arguments
 470
 471       elsif Nkind (Arg) = N_Aggregate then
 472          if Expressions (Arg) = No_List then
 473             Operand_Var := Empty;
 474          else
 475             Operand_Var := First (Expressions (Arg));
 476          end if;
 477
 478       --  Otherwise must be default (no operands) case
 479
 480       else
 481          Operand_Var := Empty;
 482       end if;
 483    end Setup_Asm_IO_Args;
 484
 485    -----------------------
 486    -- Setup_Asm_Outputs --
 487    -----------------------
 488
 489    procedure Setup_Asm_Outputs (N : Node_Id) is
 490       Call : constant Node_Id := Expression (Expression (N));
 491
 492    begin
 493       Setup_Asm_IO_Args
 494         (Next_Actual (First_Actual (Call)),
 495          Current_Output_Operand);
 496    end Setup_Asm_Outputs;
 497
 498 end Exp_Code;