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) 1992-2020, 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 BIP_Suffix_Kind (E : Entity_Id) return BIP_Formal_Kind;
 106    --  Ada 2005 (AI-318-02): Returns the kind of the given BIP extra formal.
 107
 108    function Build_In_Place_Formal
 109      (Func : Entity_Id;
 110       Kind : BIP_Formal_Kind) return Entity_Id;
 111    --  Ada 2005 (AI-318-02): Locates and returns the entity for the implicit
 112    --  build-in-place formal parameter of the given kind associated with the
 113    --  function Func, and returns its Entity_Id. It is a bug if not found; the
 114    --  caller should ensure this is called only when the extra formal exists.
 115
 116    function Build_Procedure_Body_Form
 117      (Func_Id : Entity_Id; Func_Body : Node_Id) return Node_Id;
 118    --  Create a procedure body which emulates the behavior of function Func_Id.
 119    --  Func_Body is the root of the body of the function before its analysis.
 120    --  The returned node is the root of the procedure body which will replace
 121    --  the original function body, which is not needed for the C program.
 122
 123    function Is_Build_In_Place_Entity (E : Entity_Id) return Boolean;
 124    --  Ada 2005 (AI-318-02): Returns True if E is a BIP entity.
 125
 126    function Is_Build_In_Place_Result_Type (Typ : Entity_Id) return Boolean;
 127    --  Ada 2005 (AI-318-02): Returns True if functions returning the type use
 128    --  build-in-place protocols. For inherently limited types, this must be
 129    --  True in >= Ada 2005, and must be False in Ada 95. For other types, it
 130    --  can be True or False, and the decision should be based on efficiency,
 131    --  and should be the same for all language versions, so that mixed-dialect
 132    --  programs will work.
 133    --
 134    --  For inherently limited types in Ada 2005, True means that calls will
 135    --  actually be build-in-place in all cases. For other types, build-in-place
 136    --  will be used when possible, but we need to make a copy at the call site
 137    --  in some cases, notably assignment statements.
 138
 139    function Is_Build_In_Place_Function (E : Entity_Id) return Boolean;
 140    --  Ada 2005 (AI-318-02): Returns True if E denotes a function, generic
 141    --  function, or access-to-function type for which
 142    --  Is_Build_In_Place_Result_Type is True. However, we never use
 143    --  build-in-place if the convention is other than Ada, because that would
 144    --  disturb mixed-language programs.
 145
 146    function Is_Build_In_Place_Function_Call (N : Node_Id) return Boolean;
 147    --  Ada 2005 (AI-318-02): Returns True if N denotes a call to a function
 148    --  that requires handling as a build-in-place call (possibly qualified or
 149    --  converted).
 150
 151    function Is_Null_Procedure (Subp : Entity_Id) return Boolean;
 152    --  Predicate to recognize stubbed procedures and null procedures, which
 153    --  can be inlined unconditionally in all cases.
 154
 155    procedure Make_Build_In_Place_Call_In_Allocator
 156      (Allocator     : Node_Id;
 157       Function_Call : Node_Id);
 158    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 159    --  occurs as the expression initializing an allocator, by passing access
 160    --  to the allocated object as an additional parameter of the function call.
 161    --  A new access object is declared that is initialized to the result of the
 162    --  allocator, passed to the function, and the allocator is rewritten to
 163    --  refer to that access object. Function_Call must denote either an
 164    --  N_Function_Call node for which Is_Build_In_Place_Call is True, or else
 165    --  an N_Qualified_Expression node applied to such a function call.
 166
 167    procedure Make_Build_In_Place_Call_In_Anonymous_Context
 168      (Function_Call : Node_Id);
 169    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 170    --  occurs in a context that does not provide a separate object. A temporary
 171    --  object is created to act as the return object and an access to the
 172    --  temporary is passed as an additional parameter of the call. This occurs
 173    --  in contexts such as subprogram call actuals and object renamings.
 174    --  Function_Call must denote either an N_Function_Call node for which
 175    --  Is_Build_In_Place_Call is True, or else an N_Qualified_Expression node
 176    --  applied to such a function call.
 177
 178    procedure Make_Build_In_Place_Call_In_Assignment
 179      (Assign        : Node_Id;
 180       Function_Call : Node_Id);
 181    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 182    --  occurs as the right-hand side of an assignment statement by passing
 183    --  access to the left-hand side as an additional parameter of the function
 184    --  call. Assign must denote a N_Assignment_Statement. Function_Call must
 185    --  denote either an N_Function_Call node for which Is_Build_In_Place_Call
 186    --  is True, or an N_Qualified_Expression node applied to such a function
 187    --  call.
 188
 189    procedure Make_Build_In_Place_Call_In_Object_Declaration
 190      (Obj_Decl      : Node_Id;
 191       Function_Call : Node_Id);
 192    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 193    --  occurs as the expression initializing an object declaration by
 194    --  passing access to the declared object as an additional parameter of the
 195    --  function call. Function_Call must denote either an N_Function_Call node
 196    --  for which Is_Build_In_Place_Call is True, or an N_Qualified_Expression
 197    --  node applied to such a function call.
 198
 199    procedure Make_Build_In_Place_Iface_Call_In_Allocator
 200      (Allocator     : Node_Id;
 201       Function_Call : Node_Id);
 202    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 203    --  occurs as the expression initializing an allocator, by passing access
 204    --  to the allocated object as an additional parameter of the function call.
 205    --  Function_Call must denote an expression containing a BIP function call
 206    --  and an enclosing call to Ada.Tags.Displace to displace the pointer to
 207    --  the returned BIP object to reference the secondary dispatch table of
 208    --  an interface.
 209
 210    procedure Make_Build_In_Place_Iface_Call_In_Anonymous_Context
 211      (Function_Call : Node_Id);
 212    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 213    --  occurs in a context that does not provide a separate object. A temporary
 214    --  object is created to act as the return object and an access to the
 215    --  temporary is passed as an additional parameter of the call. This occurs
 216    --  in contexts such as subprogram call actuals and object renamings.
 217    --  Function_Call must denote an expression containing a BIP function call
 218    --  and an enclosing call to Ada.Tags.Displace to displace the pointer to
 219    --  the returned BIP object to reference the secondary dispatch table of
 220    --  an interface.
 221
 222    procedure Make_Build_In_Place_Iface_Call_In_Object_Declaration
 223      (Obj_Decl      : Node_Id;
 224       Function_Call : Node_Id);
 225    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 226    --  occurs as the expression initializing an object declaration by passing
 227    --  access to the declared object as an additional parameter of the function
 228    --  call. Function_Call must denote an expression containing a BIP function
 229    --  call and an enclosing call to Ada.Tags.Displace to displace the pointer
 230    --  to the returned BIP object to reference the secondary dispatch table of
 231    --  an interface.
 232
 233    procedure Make_CPP_Constructor_Call_In_Allocator
 234      (Allocator     : Node_Id;
 235       Function_Call : Node_Id);
 236    --  Handle a call to a CPP constructor that occurs as the expression that
 237    --  initializes an allocator, by passing access to the allocated object as
 238    --  an additional parameter of the constructor call. A new access object is
 239    --  declared that is initialized to the result of the allocator, passed to
 240    --  the constructor, and the allocator is rewritten to refer to that access
 241    --  object. Function_Call must denote a call to a CPP_Constructor function.
 242
 243    function Might_Have_Tasks (Typ : Entity_Id) return Boolean;
 244    --  Return True when type Typ has tasks or when it is a limited class-wide
 245    --  type (or subtype), since it might have task components.
 246
 247    function Needs_BIP_Alloc_Form (Func_Id : Entity_Id) return Boolean;
 248    --  Ada 2005 (AI-318-02): Return True if the function needs an implicit
 249    --  BIP_Alloc_Form parameter (see type BIP_Formal_Kind).
 250
 251    function Needs_BIP_Finalization_Master (Func_Id : Entity_Id) return Boolean;
 252    --  Ada 2005 (AI-318-02): Return True if the result subtype of function
 253    --  Func_Id might need finalization actions. This includes build-in-place
 254    --  functions with tagged result types, since they can be invoked via
 255    --  dispatching calls, and descendant types may require finalization.
 256
 257    function Needs_BIP_Task_Actuals (Func_Id : Entity_Id) return Boolean;
 258    --  Return True if the function returns an object of a type that has tasks.
 259
 260    function Unqual_BIP_Iface_Function_Call (Expr : Node_Id) return Node_Id;
 261    --  Return the inner BIP function call removing any qualification from Expr
 262    --  including qualified expressions, type conversions, references, unchecked
 263    --  conversions and calls to displace the pointer to the object, if Expr is
 264    --  an expression containing a call displacing the pointer to the BIP object
 265    --  to reference the secondary dispatch table of an interface; otherwise
 266    --  return Empty.
 267
 268 end Exp_Ch6;