main/gcc/ada/inline.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                               I N L I N E                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2014, 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 --  This module handles four kinds of inlining activity:
  27
  28 --  a) Instantiation of generic bodies. This is done unconditionally, after
  29 --  analysis and expansion of the main unit.
  30
  31 --  b) Compilation of unit bodies that contain the bodies of inlined sub-
  32 --  programs. This is done only if inlining is enabled (-gnatn). Full inlining
  33 --  requires that a) an b) be mutually recursive, because each step may
  34 --  generate another generic expansion and further inlined calls. For now each
  35 --  of them uses a workpile algorithm, but they are called independently from
  36 --  Frontend, and thus are not mutually recursive.
  37
  38 --  c) Front-end inlining for Inline_Always subprograms. This is primarily an
  39 --  expansion activity that is performed for performance reasons, and when the
  40 --  target does not use the gcc backend.
  41
  42 --  d) Front-end inlining for GNATprove, to perform source transformations
  43 --  to simplify formal verification. The machinery used is the same than for
  44 --  Inline_Always subprograms, but there are fewer restrictions on the source
  45 --  of subprograms.
  46
  47 with Alloc;
  48 with Opt;    use Opt;
  49 with Sem;    use Sem;
  50 with Table;
  51 with Types;  use Types;
  52 with Warnsw; use Warnsw;
  53
  54 package Inline is
  55
  56    --------------------------------
  57    -- Generic Body Instantiation --
  58    --------------------------------
  59
  60    --  The bodies of generic instantiations are built after semantic analysis
  61    --  of the main unit is complete. Generic instantiations are saved in a
  62    --  global data structure, and the bodies constructed by means of a separate
  63    --  analysis and expansion step.
  64
  65    --  See full description in body of Sem_Ch12 for more details
  66
  67    type Pending_Body_Info is record
  68       Inst_Node : Node_Id;
  69       --  Node for instantiation that requires the body
  70
  71       Act_Decl : Node_Id;
  72       --  Declaration for package or subprogram spec for instantiation
  73
  74       Expander_Status : Boolean;
  75       --  If the body is instantiated only for semantic checking, expansion
  76       --  must be inhibited.
  77
  78       Current_Sem_Unit : Unit_Number_Type;
  79       --  The semantic unit within which the instantiation is found. Must
  80       --  be restored when compiling the body, to insure that internal enti-
  81       --  ties use the same counter and are unique over spec and body.
  82
  83       Scope_Suppress           : Suppress_Record;
  84       Local_Suppress_Stack_Top : Suppress_Stack_Entry_Ptr;
  85       --  Save suppress information at the point of instantiation. Used to
  86       --  properly inherit check status active at this point (see RM 11.5
  87       --  (7.2/2), AI95-00224-01):
  88       --
  89       --    "If a checking pragma applies to a generic instantiation, then the
  90       --    checking pragma also applies to the instance. If a checking pragma
  91       --    applies to a call to a subprogram that has a pragma Inline applied
  92       --    to it, then the checking pragma also applies to the inlined
  93       --    subprogram body".
  94       --
  95       --  This means we have to capture this information from the current scope
  96       --  at the point of instantiation.
  97
  98       Version : Ada_Version_Type;
  99       --  The body must be compiled with the same language version as the
 100       --  spec. The version may be set by a configuration pragma in a separate
 101       --  file or in the current file, and may differ from body to body.
 102
 103       Version_Pragma : Node_Id;
 104       --  This is linked with the Version value
 105
 106       Warnings : Warning_Record;
 107       --  Capture values of warning flags
 108
 109       SPARK_Mode        : SPARK_Mode_Type;
 110       SPARK_Mode_Pragma : Node_Id;
 111       --  SPARK_Mode for an instance is the one applicable at the point of
 112       --  instantiation. SPARK_Mode_Pragma is the related active pragma.
 113    end record;
 114
 115    package Pending_Instantiations is new Table.Table (
 116      Table_Component_Type => Pending_Body_Info,
 117      Table_Index_Type     => Int,
 118      Table_Low_Bound      => 0,
 119      Table_Initial        => Alloc.Pending_Instantiations_Initial,
 120      Table_Increment      => Alloc.Pending_Instantiations_Increment,
 121      Table_Name           => "Pending_Instantiations");
 122
 123    --  The following table records subprograms and packages for which
 124    --  generation of subprogram descriptors must be delayed.
 125
 126    package Pending_Descriptor is new Table.Table (
 127      Table_Component_Type => Entity_Id,
 128      Table_Index_Type     => Int,
 129      Table_Low_Bound      => 0,
 130      Table_Initial        => Alloc.Pending_Instantiations_Initial,
 131      Table_Increment      => Alloc.Pending_Instantiations_Increment,
 132      Table_Name           => "Pending_Descriptor");
 133
 134    --  The following should be initialized in an init call in Frontend, we
 135    --  have thoughts of making the frontend reusable in future ???
 136
 137    -----------------
 138    -- Subprograms --
 139    -----------------
 140
 141    procedure Initialize;
 142    --  Initialize internal tables
 143
 144    procedure Lock;
 145    --  Lock internal tables before calling backend
 146
 147    procedure Instantiate_Bodies;
 148    --  This procedure is called after semantic analysis is complete, to
 149    --  instantiate the bodies of generic instantiations that appear in the
 150    --  compilation unit.
 151
 152    procedure Add_Inlined_Body (E : Entity_Id);
 153    --  E is an inlined subprogram appearing in a call, either explicitly, or
 154    --  a discriminant check for which gigi builds a call.  Add E's enclosing
 155    --  unit to Inlined_Bodies so that body of E can be subsequently retrieved
 156    --  and analyzed.
 157
 158    procedure Analyze_Inlined_Bodies;
 159    --  At end of compilation, analyze the bodies of all units that contain
 160    --  inlined subprograms that are actually called.
 161
 162    procedure Build_Body_To_Inline (N : Node_Id; Spec_Id : Entity_Id);
 163    --  If a subprogram has pragma Inline and inlining is active, use generic
 164    --  machinery to build an unexpanded body for the subprogram. This body is
 165    --  subsequently used for inline expansions at call sites. If subprogram can
 166    --  be inlined (depending on size and nature of local declarations) the
 167    --  template body is created. Otherwise subprogram body is treated normally
 168    --  and calls are not inlined in the frontend.  If proper warnings are
 169    --  enabled and the subprogram contains a construct that cannot be inlined,
 170    --  the problematic construct is flagged accordingly.
 171
 172    procedure Cannot_Inline
 173      (Msg        : String;
 174       N          : Node_Id;
 175       Subp       : Entity_Id;
 176       Is_Serious : Boolean := False);
 177    --  This procedure is called if the node N, an instance of a call to
 178    --  subprogram Subp, cannot be inlined. Msg is the message to be issued,
 179    --  which ends with ? (it does not end with ?p?, this routine takes care of
 180    --  the need to change ? to ?p?). The behavior of this routine depends on
 181    --  the value of Back_End_Inlining:
 182    --
 183    --    * If Back_End_Inlining is not set (ie. legacy frontend inlining model)
 184    --      then if Subp has a pragma Always_Inlined, then an error message is
 185    --      issued (by removing the last character of Msg). If Subp is not
 186    --      Always_Inlined, then a warning is issued if the flag Ineffective_
 187    --      Inline_Warnings is set, adding ?p to the msg, and if not, the call
 188    --      has no effect.
 189    --
 190    --    * If Back_End_Inlining is set then:
 191    --      - If Is_Serious is true, then an error is reported (by removing the
 192    --        last character of Msg);
 193    --
 194    --      - otherwise:
 195    --
 196    --        * Compiling without optimizations if Subp has a pragma
 197    --          Always_Inlined, then an error message is issued; if Subp is
 198    --          not Always_Inlined, then a warning is issued if the flag
 199    --          Ineffective_Inline_Warnings is set (adding p?), and if not,
 200    --          the call has no effect.
 201    --
 202    --        * Compiling with optimizations then a warning is issued if the
 203    --          flag Ineffective_Inline_Warnings is set (adding p?); otherwise
 204    --          no effect since inlining may be performed by the backend.
 205
 206    procedure Check_And_Split_Unconstrained_Function
 207      (N       : Node_Id;
 208       Spec_Id : Entity_Id;
 209       Body_Id : Entity_Id);
 210    --  Spec_Id and Body_Id are the entities of the specification and body of
 211    --  the subprogram body N. If N can be inlined by the frontend (supported
 212    --  cases documented in Check_Body_To_Inline) then build the body-to-inline
 213    --  associated with N and attach it to the declaration node of Spec_Id.
 214
 215    procedure Check_Package_Body_For_Inlining (N : Node_Id; P : Entity_Id);
 216    --  If front-end inlining is enabled and a package declaration contains
 217    --  inlined subprograms, load and compile the package body to collect the
 218    --  bodies of these subprograms, so they are available to inline calls.
 219    --  N is the compilation unit for the package.
 220
 221    procedure Expand_Inlined_Call
 222     (N         : Node_Id;
 223      Subp      : Entity_Id;
 224      Orig_Subp : Entity_Id);
 225    --  If called subprogram can be inlined by the front-end, retrieve the
 226    --  analyzed body, replace formals with actuals and expand call in place.
 227    --  Generate thunks for actuals that are expressions, and insert the
 228    --  corresponding constant declarations before the call. If the original
 229    --  call is to a derived operation, the return type is the one of the
 230    --  derived operation, but the body is that of the original, so return
 231    --  expressions in the body must be converted to the desired type (which
 232    --  is simply not noted in the tree without inline expansion).
 233
 234    function Has_Excluded_Declaration
 235      (Subp  : Entity_Id;
 236       Decls : List_Id) return Boolean;
 237    --  Check a list of declarations, Decls, that make the inlining of Subp not
 238    --  worthwhile
 239
 240    function Has_Excluded_Statement
 241      (Subp  : Entity_Id;
 242       Stats : List_Id) return Boolean;
 243    --  Check a list of statements, Stats, that make inlining of Subp not
 244    --  worthwhile, including any tasking statement, nested at any level.
 245
 246    procedure List_Inlining_Info;
 247    --  Generate listing of calls inlined by the frontend plus listing of
 248    --  calls to inline subprograms passed to the backend.
 249
 250    procedure Register_Backend_Call (N : Node_Id);
 251    --  Append N to the list Backend_Calls
 252
 253    procedure Remove_Dead_Instance (N : Node_Id);
 254    --  If an instantiation appears in unreachable code, delete the pending
 255    --  body instance.
 256
 257    function Can_Be_Inlined_In_GNATprove_Mode
 258      (Spec_Id : Entity_Id;
 259       Body_Id : Entity_Id) return Boolean;
 260    --  Returns True if the subprogram identified by Spec_Id and Body_Id can
 261    --  be inlined in GNATprove mode. One but not both of Spec_Id and Body_Id
 262    --  can be Empty. Body_Id is Empty when doing a partial check on a call
 263    --  to a subprogram whose body has not been seen yet, to know whether this
 264    --  subprogram could possibly be inlined. GNATprove relies on this to adapt
 265    --  its treatment of the subprogram.
 266
 267 end Inline;