gcc/ada/exp_ch6.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                              E X P _ C H 6                               --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2017, 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 --  Expand routines for chapter 6 constructs
  27
  28 with Types; use Types;
  29
  30 package Exp_Ch6 is
  31
  32    procedure Expand_N_Extended_Return_Statement (N : Node_Id);
  33    procedure Expand_N_Function_Call             (N : Node_Id);
  34    procedure Expand_N_Procedure_Call_Statement  (N : Node_Id);
  35    procedure Expand_N_Simple_Return_Statement   (N : Node_Id);
  36    procedure Expand_N_Subprogram_Body           (N : Node_Id);
  37    procedure Expand_N_Subprogram_Body_Stub      (N : Node_Id);
  38    procedure Expand_N_Subprogram_Declaration    (N : Node_Id);
  39
  40    procedure Expand_Call (N : Node_Id);
  41    --  This procedure contains common processing for Expand_N_Function_Call,
  42    --  Expand_N_Procedure_Statement, and Expand_N_Entry_Call.
  43
  44    procedure Freeze_Subprogram (N : Node_Id);
  45    --  generate the appropriate expansions related to Subprogram freeze
  46    --  nodes (e.g. the filling of the corresponding Dispatch Table for
  47    --  Primitive Operations)
  48
  49    --  The following type defines the various forms of allocation used for the
  50    --  results of build-in-place function calls.
  51
  52    type BIP_Allocation_Form is
  53      (Unspecified,
  54       Caller_Allocation,
  55       Secondary_Stack,
  56       Global_Heap,
  57       User_Storage_Pool);
  58
  59    type BIP_Formal_Kind is
  60    --  Ada 2005 (AI-318-02): This type defines the kinds of implicit extra
  61    --  formals created for build-in-place functions. The order of these
  62    --  enumeration literals matches the order in which the formals are
  63    --  declared. See Sem_Ch6.Create_Extra_Formals.
  64
  65      (BIP_Alloc_Form,
  66       --  Present if result subtype is unconstrained or tagged. Indicates
  67       --  whether the return object is allocated by the caller or callee, and
  68       --  if the callee, whether to use the secondary stack or the heap. See
  69       --  Create_Extra_Formals.
  70
  71       BIP_Storage_Pool,
  72       --  Present if result subtype is unconstrained or tagged. If
  73       --  BIP_Alloc_Form = User_Storage_Pool, this is a pointer to the pool
  74       --  (of type access to Root_Storage_Pool'Class). Otherwise null.
  75
  76       BIP_Finalization_Master,
  77       --  Present if result type needs finalization. Pointer to caller's
  78       --  finalization master.
  79
  80       BIP_Task_Master,
  81       --  Present if result type contains tasks. Master associated with
  82       --  calling context.
  83
  84       BIP_Activation_Chain,
  85       --  Present if result type contains tasks. Caller's activation chain
  86
  87       BIP_Object_Access);
  88       --  Present for all build-in-place functions. Address at which to place
  89       --  the return object, or null if BIP_Alloc_Form indicates allocated by
  90       --  callee.
  91       --
  92       --  ??? We might also need to be able to pass in a constrained flag.
  93
  94    procedure Add_Extra_Actual_To_Call
  95      (Subprogram_Call : Node_Id;
  96       Extra_Formal    : Entity_Id;
  97       Extra_Actual    : Node_Id);
  98    --  Adds Extra_Actual as a named parameter association for the formal
  99    --  Extra_Formal in Subprogram_Call.
 100
 101    function BIP_Formal_Suffix (Kind : BIP_Formal_Kind) return String;
 102    --  Ada 2005 (AI-318-02): Returns a string to be used as the suffix of names
 103    --  for build-in-place formal parameters of the given kind.
 104
 105    function Build_In_Place_Formal
 106      (Func : Entity_Id;
 107       Kind : BIP_Formal_Kind) return Entity_Id;
 108    --  Ada 2005 (AI-318-02): Locates and returns the entity for the implicit
 109    --  build-in-place formal parameter of the given kind associated with the
 110    --  function Func, and returns its Entity_Id. It is a bug if not found; the
 111    --  caller should ensure this is called only when the extra formal exists.
 112
 113    function Build_Procedure_Body_Form
 114      (Func_Id : Entity_Id; Func_Body : Node_Id) return Node_Id;
 115    --  Create a procedure body which emulates the behavior of function Func_Id.
 116    --  Func_Body is the root of the body of the function before its analysis.
 117    --  The returned node is the root of the procedure body which will replace
 118    --  the original function body, which is not needed for the C program.
 119
 120    function Is_Build_In_Place_Result_Type (Typ : Entity_Id) return Boolean;
 121    --  Ada 2005 (AI-318-02): Returns True if functions returning the type use
 122    --  build-in-place protocols. For inherently limited types, this must be
 123    --  True in >= Ada 2005, and must be False in Ada 95. For other types, it
 124    --  can be True or False, and the decision should be based on efficiency,
 125    --  and should be the same for all language versions, so that mixed-dialect
 126    --  programs will work.
 127    --
 128    --  For inherently limited types in Ada 2005, True means that calls will
 129    --  actually be build-in-place in all cases. For other types, build-in-place
 130    --  will be used when possible, but we need to make a copy at the call site
 131    --  in some cases, notably assignment statements.
 132
 133    function Is_Build_In_Place_Function (E : Entity_Id) return Boolean;
 134    --  Ada 2005 (AI-318-02): Returns True if E denotes a function, generic
 135    --  function, or access-to-function type for which
 136    --  Is_Build_In_Place_Result_Type is True. However, we never use
 137    --  build-in-place if the convention is other than Ada, because that would
 138    --  disturb mixed-language programs.
 139
 140    function Is_Build_In_Place_Function_Call (N : Node_Id) return Boolean;
 141    --  Ada 2005 (AI-318-02): Returns True if N denotes a call to a function
 142    --  that requires handling as a build-in-place call (possibly qualified or
 143    --  converted).
 144
 145    function Is_Null_Procedure (Subp : Entity_Id) return Boolean;
 146    --  Predicate to recognize stubbed procedures and null procedures, which
 147    --  can be inlined unconditionally in all cases.
 148
 149    procedure Make_Build_In_Place_Call_In_Allocator
 150      (Allocator     : Node_Id;
 151       Function_Call : Node_Id);
 152    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 153    --  occurs as the expression initializing an allocator, by passing access
 154    --  to the allocated object as an additional parameter of the function call.
 155    --  A new access object is declared that is initialized to the result of the
 156    --  allocator, passed to the function, and the allocator is rewritten to
 157    --  refer to that access object. Function_Call must denote either an
 158    --  N_Function_Call node for which Is_Build_In_Place_Call is True, or else
 159    --  an N_Qualified_Expression node applied to such a function call.
 160
 161    procedure Make_Build_In_Place_Call_In_Anonymous_Context
 162      (Function_Call : Node_Id);
 163    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 164    --  occurs in a context that does not provide a separate object. A temporary
 165    --  object is created to act as the return object and an access to the
 166    --  temporary is passed as an additional parameter of the call. This occurs
 167    --  in contexts such as subprogram call actuals and object renamings.
 168    --  Function_Call must denote either an N_Function_Call node for which
 169    --  Is_Build_In_Place_Call is True, or else an N_Qualified_Expression node
 170    --  applied to such a function call.
 171
 172    procedure Make_Build_In_Place_Call_In_Assignment
 173      (Assign        : Node_Id;
 174       Function_Call : Node_Id);
 175    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 176    --  occurs as the right-hand side of an assignment statement by passing
 177    --  access to the left-hand side as an additional parameter of the function
 178    --  call. Assign must denote a N_Assignment_Statement. Function_Call must
 179    --  denote either an N_Function_Call node for which Is_Build_In_Place_Call
 180    --  is True, or an N_Qualified_Expression node applied to such a function
 181    --  call.
 182
 183    procedure Make_Build_In_Place_Call_In_Object_Declaration
 184      (Obj_Decl      : Node_Id;
 185       Function_Call : Node_Id);
 186    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 187    --  occurs as the expression initializing an object declaration by
 188    --  passing access to the declared object as an additional parameter of the
 189    --  function call. Function_Call must denote either an N_Function_Call node
 190    --  for which Is_Build_In_Place_Call is True, or an N_Qualified_Expression
 191    --  node applied to such a function call.
 192
 193    procedure Make_Build_In_Place_Iface_Call_In_Allocator
 194      (Allocator     : Node_Id;
 195       Function_Call : Node_Id);
 196    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 197    --  occurs as the expression initializing an allocator, by passing access
 198    --  to the allocated object as an additional parameter of the function call.
 199    --  Function_Call must denote an expression containing a BIP function call
 200    --  and an enclosing call to Ada.Tags.Displace to displace the pointer to
 201    --  the returned BIP object to reference the secondary dispatch table of
 202    --  an interface.
 203
 204    procedure Make_Build_In_Place_Iface_Call_In_Anonymous_Context
 205      (Function_Call : Node_Id);
 206    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 207    --  occurs in a context that does not provide a separate object. A temporary
 208    --  object is created to act as the return object and an access to the
 209    --  temporary is passed as an additional parameter of the call. This occurs
 210    --  in contexts such as subprogram call actuals and object renamings.
 211    --  Function_Call must denote an expression containing a BIP function call
 212    --  and an enclosing call to Ada.Tags.Displace to displace the pointer to
 213    --  the returned BIP object to reference the secondary dispatch table of
 214    --  an interface.
 215
 216    procedure Make_Build_In_Place_Iface_Call_In_Object_Declaration
 217      (Obj_Decl      : Node_Id;
 218       Function_Call : Node_Id);
 219    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 220    --  occurs as the expression initializing an object declaration by passing
 221    --  access to the declared object as an additional parameter of the function
 222    --  call. Function_Call must denote an expression containing a BIP function
 223    --  call and an enclosing call to Ada.Tags.Displace to displace the pointer
 224    --  to the returned BIP object to reference the secondary dispatch table of
 225    --  an interface.
 226
 227    procedure Make_CPP_Constructor_Call_In_Allocator
 228      (Allocator     : Node_Id;
 229       Function_Call : Node_Id);
 230    --  Handle a call to a CPP constructor that occurs as the expression that
 231    --  initializes an allocator, by passing access to the allocated object as
 232    --  an additional parameter of the constructor call. A new access object is
 233    --  declared that is initialized to the result of the allocator, passed to
 234    --  the constructor, and the allocator is rewritten to refer to that access
 235    --  object. Function_Call must denote a call to a CPP_Constructor function.
 236
 237    function Needs_BIP_Alloc_Form (Func_Id : Entity_Id) return Boolean;
 238    --  Ada 2005 (AI-318-02): Return True if the function needs an implicit
 239    --  BIP_Alloc_Form parameter (see type BIP_Formal_Kind).
 240
 241    function Needs_BIP_Finalization_Master (Func_Id : Entity_Id) return Boolean;
 242    --  Ada 2005 (AI-318-02): Return True if the result subtype of function
 243    --  Func_Id might need finalization actions. This includes build-in-place
 244    --  functions with tagged result types, since they can be invoked via
 245    --  dispatching calls, and descendant types may require finalization.
 246
 247    function Needs_Result_Accessibility_Level
 248      (Func_Id : Entity_Id) return Boolean;
 249    --  Ada 2012 (AI05-0234): Return True if the function needs an implicit
 250    --  parameter to identify the accessibility level of the function result
 251    --  "determined by the point of call".
 252
 253    function Unqual_BIP_Iface_Function_Call (Expr : Node_Id) return Node_Id;
 254    --  Return the inner BIP function call removing any qualification from Expr
 255    --  including qualified expressions, type conversions, references, unchecked
 256    --  conversions and calls to displace the pointer to the object, if Expr is
 257    --  an expression containing a call displacing the pointer to the BIP object
 258    --  to reference the secondary dispatch table of an interface; otherwise
 259    --  return Empty.
 260
 261 end Exp_Ch6;