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) 1992-2024, 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_Return_When_Statement     (N : Node_Id);
  36    procedure Expand_N_Simple_Return_Statement   (N : Node_Id);
  37    procedure Expand_N_Subprogram_Body           (N : Node_Id);
  38    procedure Expand_N_Subprogram_Body_Stub      (N : Node_Id);
  39    procedure Expand_N_Subprogram_Declaration    (N : Node_Id);
  40
  41    procedure Expand_Call (N : Node_Id);
  42    --  This procedure contains common processing for Expand_N_Function_Call,
  43    --  Expand_N_Procedure_Statement, and Expand_N_Entry_Call.
  44
  45    procedure Freeze_Subprogram (N : Node_Id);
  46    --  generate the appropriate expansions related to Subprogram freeze
  47    --  nodes (e.g. the filling of the corresponding Dispatch Table for
  48    --  Primitive Operations)
  49
  50    --  The following type defines the various forms of allocation used for the
  51    --  results of build-in-place function calls.
  52
  53    type BIP_Allocation_Form is
  54      (Unspecified,
  55       Caller_Allocation,
  56       Secondary_Stack,
  57       Global_Heap,
  58       User_Storage_Pool);
  59
  60    type BIP_Formal_Kind is
  61    --  Ada 2005 (AI-318-02): This type defines the kinds of implicit extra
  62    --  formals created for build-in-place functions. The order of these
  63    --  enumeration literals matches the order in which the formals are
  64    --  declared. See Sem_Ch6.Create_Extra_Formals.
  65
  66      (BIP_Alloc_Form,
  67       --  Present if result subtype is unconstrained or tagged. Indicates
  68       --  whether the return object is allocated by the caller or callee, and
  69       --  if the callee, whether to use the secondary stack or the heap. See
  70       --  Create_Extra_Formals.
  71
  72       BIP_Storage_Pool,
  73       --  Present if result subtype is unconstrained or tagged. If
  74       --  BIP_Alloc_Form = User_Storage_Pool, this is a pointer to the pool
  75       --  (of type access to Root_Storage_Pool'Class). Otherwise null.
  76
  77       BIP_Finalization_Master,
  78       --  Present if result type needs finalization. Pointer to caller's
  79       --  finalization master.
  80
  81       BIP_Task_Master,
  82       --  Present if result type contains tasks. Master associated with
  83       --  calling context.
  84
  85       BIP_Activation_Chain,
  86       --  Present if result type contains tasks. Caller's activation chain
  87
  88       BIP_Object_Access);
  89       --  Present for all build-in-place functions. Address at which to place
  90       --  the return object, or null if BIP_Alloc_Form indicates allocated by
  91       --  callee.
  92       --
  93       --  ??? We might also need to be able to pass in a constrained flag.
  94
  95    procedure Add_Extra_Actual_To_Call
  96      (Subprogram_Call : Node_Id;
  97       Extra_Formal    : Entity_Id;
  98       Extra_Actual    : Node_Id);
  99    --  Adds Extra_Actual as a named parameter association for the formal
 100    --  Extra_Formal in Subprogram_Call.
 101
 102    procedure Apply_CW_Accessibility_Check (Exp : Node_Id; Func : Entity_Id);
 103    --  Ada 2005 (AI95-344): If the result type is class-wide, insert a check
 104    --  that the level of the return expression's underlying type is not deeper
 105    --  than the level of the master enclosing the function. Always generate the
 106    --  check when the type of the return expression is class-wide, when it's a
 107    --  type conversion, or when it's a formal parameter. Otherwise suppress the
 108    --  check in the case where the return expression has a specific type whose
 109    --  level is known not to be statically deeper than the result type of the
 110    --  function.
 111
 112    function BIP_Formal_Suffix (Kind : BIP_Formal_Kind) return String;
 113    --  Ada 2005 (AI-318-02): Returns a string to be used as the suffix of names
 114    --  for build-in-place formal parameters of the given kind.
 115
 116    function BIP_Suffix_Kind (E : Entity_Id) return BIP_Formal_Kind;
 117    --  Ada 2005 (AI-318-02): Returns the kind of the given BIP extra formal.
 118
 119    function Build_In_Place_Formal
 120      (Func : Entity_Id;
 121       Kind : BIP_Formal_Kind) return Entity_Id;
 122    --  Ada 2005 (AI-318-02): Locates and returns the entity for the implicit
 123    --  build-in-place formal parameter of the given kind associated with the
 124    --  function Func, and returns its Entity_Id. It is a bug if not found; the
 125    --  caller should ensure this is called only when the extra formal exists.
 126
 127    function Build_Procedure_Body_Form
 128      (Func_Id : Entity_Id; Func_Body : Node_Id) return Node_Id;
 129    --  Create a procedure body which emulates the behavior of function Func_Id.
 130    --  Func_Body is the root of the body of the function before its analysis.
 131    --  The returned node is the root of the procedure body which will replace
 132    --  the original function body, which is not needed for the C program.
 133
 134    function Has_BIP_Extra_Formal
 135      (E              : Entity_Id;
 136       Kind           : BIP_Formal_Kind;
 137       Must_Be_Frozen : Boolean := True) return Boolean;
 138    --  Given a subprogram, subprogram type, entry or entry family, return True
 139    --  if E has the BIP extra formal associated with Kind. In general this
 140    --  subprogram must be invoked with a frozen entity or a subprogram type of
 141    --  a dispatching call since we can only rely on the availability of extra
 142    --  formals on these entities; this requirement can be relaxed using the
 143    --  formal Must_Be_Frozen in scenarios where we know that the entity has
 144    --  the extra formals.
 145
 146    procedure Install_Class_Preconditions_Check (Call_Node : Node_Id);
 147    --  Install check of class-wide preconditions on the caller.
 148
 149    function Is_Build_In_Place_Entity (E : Entity_Id) return Boolean;
 150    --  Ada 2005 (AI-318-02): Returns True if E is a BIP entity.
 151
 152    function Is_Build_In_Place_Function (E : Entity_Id) return Boolean;
 153    --  Ada 2005 (AI-318-02): Returns True if E denotes a function, generic
 154    --  function, or access-to-function type for which
 155    --  Is_Build_In_Place_Result_Type is True. However, we never use
 156    --  build-in-place if the convention is other than Ada, because that would
 157    --  disturb mixed-language programs.
 158
 159    function Is_Build_In_Place_Function_Call (N : Node_Id) return Boolean;
 160    --  Ada 2005 (AI-318-02): Returns True if N denotes a call to a function
 161    --  that requires handling as a build-in-place call (possibly qualified or
 162    --  converted).
 163
 164    function Is_Build_In_Place_Result_Type (Typ : Entity_Id) return Boolean;
 165    --  Ada 2005 (AI-318-02): Returns True if functions returning the type use
 166    --  build-in-place protocols. For inherently limited types, this must be
 167    --  True in >= Ada 2005 and must be False in Ada 95.
 168
 169    function Is_Build_In_Place_Return_Object (E : Entity_Id) return Boolean;
 170    --  Ada 2005 (AI-318-02): Return True if E is a return object of a function
 171    --  that uses build-in-place protocols.
 172
 173    function Is_By_Reference_Return_Object (E : Entity_Id) return Boolean;
 174    --  Return True if E is a return object of a function whose return type is
 175    --  required to be passed by reference, as defined in (RM 6.2(4-9)).
 176
 177    function Is_Null_Procedure (Subp : Entity_Id) return Boolean;
 178    --  Predicate to recognize stubbed procedures and null procedures, which
 179    --  can be inlined unconditionally in all cases.
 180
 181    function Is_Secondary_Stack_Return_Object (E : Entity_Id) return Boolean;
 182    --  Return True if E is a return object of a function whose return type is
 183    --  returned on the secondary stack.
 184
 185    function Is_Special_Return_Object (E : Entity_Id) return Boolean;
 186    --  Return True if E is the return object of a function and is handled in a
 187    --  special way by the expander. In most cases, return objects are handled
 188    --  like any other variables or constants but, in a few special cases, they
 189    --  are further expanded into more elaborate constructs, whose common goal
 190    --  is to elide the copy operation associated with the return.
 191
 192    procedure Make_Build_In_Place_Call_In_Allocator
 193      (Allocator     : Node_Id;
 194       Function_Call : Node_Id);
 195    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 196    --  occurs as the expression initializing an allocator, by passing access
 197    --  to the allocated object as an additional parameter of the function call.
 198    --  A new access object is declared that is initialized to the result of the
 199    --  allocator, passed to the function, and the allocator is rewritten to
 200    --  refer to that access object. Function_Call must denote either an
 201    --  N_Function_Call node for which Is_Build_In_Place_Call is True, or else
 202    --  an N_Qualified_Expression node applied to such a function call.
 203
 204    procedure Make_Build_In_Place_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 either an N_Function_Call node for which
 212    --  Is_Build_In_Place_Call is True, or else an N_Qualified_Expression node
 213    --  applied to such a function call.
 214
 215    procedure Make_Build_In_Place_Call_In_Assignment
 216      (Assign        : Node_Id;
 217       Function_Call : Node_Id);
 218    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 219    --  occurs as the right-hand side of an assignment statement by passing
 220    --  access to the left-hand side as an additional parameter of the function
 221    --  call. Assign must denote a N_Assignment_Statement. Function_Call must
 222    --  denote either an N_Function_Call node for which Is_Build_In_Place_Call
 223    --  is True, or an N_Qualified_Expression node applied to such a function
 224    --  call.
 225
 226    procedure Make_Build_In_Place_Call_In_Object_Declaration
 227      (Obj_Decl      : Node_Id;
 228       Function_Call : Node_Id);
 229    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 230    --  occurs as the expression initializing an object declaration by
 231    --  passing access to the declared object as an additional parameter of the
 232    --  function call. Function_Call must denote either an N_Function_Call node
 233    --  for which Is_Build_In_Place_Call is True, or an N_Qualified_Expression
 234    --  node applied to such a function call.
 235
 236    procedure Make_Build_In_Place_Iface_Call_In_Allocator
 237      (Allocator     : Node_Id;
 238       Function_Call : Node_Id);
 239    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 240    --  occurs as the expression initializing an allocator, by passing access
 241    --  to the allocated object as an additional parameter of the function call.
 242    --  Function_Call must denote an expression containing a BIP function call
 243    --  and an enclosing call to Ada.Tags.Displace to displace the pointer to
 244    --  the returned BIP object to reference the secondary dispatch table of
 245    --  an interface.
 246
 247    procedure Make_Build_In_Place_Iface_Call_In_Anonymous_Context
 248      (Function_Call : Node_Id);
 249    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 250    --  occurs in a context that does not provide a separate object. A temporary
 251    --  object is created to act as the return object and an access to the
 252    --  temporary is passed as an additional parameter of the call. This occurs
 253    --  in contexts such as subprogram call actuals and object renamings.
 254    --  Function_Call must denote an expression containing a BIP function call
 255    --  and an enclosing call to Ada.Tags.Displace to displace the pointer to
 256    --  the returned BIP object to reference the secondary dispatch table of
 257    --  an interface.
 258
 259    procedure Make_Build_In_Place_Iface_Call_In_Object_Declaration
 260      (Obj_Decl      : Node_Id;
 261       Function_Call : Node_Id);
 262    --  Ada 2005 (AI-318-02): Handle a call to a build-in-place function that
 263    --  occurs as the expression initializing an object declaration by passing
 264    --  access to the declared object as an additional parameter of the function
 265    --  call. Function_Call must denote an expression containing a BIP function
 266    --  call and an enclosing call to Ada.Tags.Displace to displace the pointer
 267    --  to the returned BIP object to reference the secondary dispatch table of
 268    --  an interface.
 269
 270    procedure Make_CPP_Constructor_Call_In_Allocator
 271      (Allocator     : Node_Id;
 272       Function_Call : Node_Id);
 273    --  Handle a call to a CPP constructor that occurs as the expression that
 274    --  initializes an allocator, by passing access to the allocated object as
 275    --  an additional parameter of the constructor call. A new access object is
 276    --  declared that is initialized to the result of the allocator, passed to
 277    --  the constructor, and the allocator is rewritten to refer to that access
 278    --  object. Function_Call must denote a call to a CPP_Constructor function.
 279
 280    function Might_Have_Tasks (Typ : Entity_Id) return Boolean;
 281    --  Return True when type Typ has tasks or when it is a limited class-wide
 282    --  type (or subtype), since it might have task components.
 283
 284    function Needs_BIP_Alloc_Form (Func_Id : Entity_Id) return Boolean;
 285    --  Ada 2005 (AI-318-02): Return True if the function needs an implicit
 286    --  BIP_Alloc_Form parameter (see type BIP_Formal_Kind).
 287
 288    function Needs_BIP_Finalization_Master (Func_Id : Entity_Id) return Boolean;
 289    --  Ada 2005 (AI-318-02): Return True if the result subtype of function
 290    --  Func_Id might need finalization actions. This includes build-in-place
 291    --  functions with tagged result types, since they can be invoked via
 292    --  dispatching calls, and descendant types may require finalization.
 293
 294    function Needs_BIP_Task_Actuals (Func_Id : Entity_Id) return Boolean;
 295    --  Return True if the function returns an object of a type that has tasks.
 296
 297    function Unqual_BIP_Iface_Function_Call (Expr : Node_Id) return Node_Id;
 298    --  Return the inner BIP function call removing any qualification from Expr
 299    --  including qualified expressions, type conversions, references, unchecked
 300    --  conversions and calls to displace the pointer to the object, if Expr is
 301    --  an expression containing a call displacing the pointer to the BIP object
 302    --  to reference the secondary dispatch table of an interface; otherwise
 303    --  return Empty.
 304
 305    procedure Validate_Subprogram_Calls (N : Node_Id);
 306    --  Check that the number of actuals (including extra actuals) of calls in
 307    --  the subtree N match their corresponding formals; check also that the
 308    --  names of BIP extra actuals and formals match.
 309
 310 private
 311    pragma Inline (Is_Build_In_Place_Return_Object);
 312
 313 end Exp_Ch6;