aboutsummaryrefslogtreecommitdiff
path: root/gcc/ada/inline.ads
blob: 05aaac751e6120987a6a22007d3e618132cfb546 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                               I N L I N E                                --
--                                                                          --
--                                 S p e c                                  --
--                                                                          --
--          Copyright (C) 1992-2022, Free Software Foundation, Inc.         --
--                                                                          --
-- GNAT is free software;  you can  redistribute it  and/or modify it under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
-- for  more details.  You should have  received  a copy of the GNU General --
-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license.          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  This module handles four kinds of inlining activity:

--  a) Instantiation of generic bodies. This is done unconditionally, after
--  analysis and expansion of the main unit.

--  b) Compilation of unit bodies that contain the bodies of inlined sub-
--  programs. This is done only if inlining is enabled (-gnatn). Full inlining
--  requires that a) and b) be mutually recursive, because each step may
--  generate another generic expansion and further inlined calls.

--  c) Front-end inlining for Inline_Always subprograms. This is primarily an
--  expansion activity that is performed for performance reasons, and when the
--  target does not use the GCC back end.

--  d) Front-end inlining for GNATprove, to perform source transformations
--  to simplify formal verification. The machinery used is the same as for
--  Inline_Always subprograms, but there are fewer restrictions on the source
--  of subprograms.

with Opt;    use Opt;
with Sem;    use Sem;
with Types;  use Types;
with Warnsw; use Warnsw;

package Inline is

   --------------------------------
   -- Generic Body Instantiation --
   --------------------------------

   --  The bodies of generic instantiations are built after semantic analysis
   --  of the main unit is complete. Generic instantiations are saved in a
   --  global data structure, and the bodies constructed by means of a separate
   --  analysis and expansion step.

   --  See full description in body of Sem_Ch12 for more details

   type Pending_Body_Info is record
      Act_Decl : Node_Id;
      --  Declaration for package or subprogram spec for instantiation

      Config_Switches : Config_Switches_Type;
      --  Capture the values of configuration switches

      Current_Sem_Unit : Unit_Number_Type;
      --  The semantic unit within which the instantiation is found. Must be
      --  restored when compiling the body, to insure that internal entities
      --  use the same counter and are unique over spec and body.

      Expander_Status : Boolean;
      --  If the body is instantiated only for semantic checking, expansion
      --  must be inhibited.

      Inst_Node : Node_Id;
      --  Node for instantiation that requires the body

      Scope_Suppress           : Suppress_Record;
      Local_Suppress_Stack_Top : Suppress_Stack_Entry_Ptr;
      --  Save suppress information at the point of instantiation. Used to
      --  properly inherit check status active at this point (see RM 11.5
      --  (7.2/2), AI95-00224-01):
      --
      --    "If a checking pragma applies to a generic instantiation, then the
      --    checking pragma also applies to the instance. If a checking pragma
      --    applies to a call to a subprogram that has a pragma Inline applied
      --    to it, then the checking pragma also applies to the inlined
      --    subprogram body".
      --
      --  This means we have to capture this information from the current scope
      --  at the point of instantiation.

      Warnings : Warning_Record;
      --  Capture values of warning flags
   end record;

   -----------------
   -- Subprograms --
   -----------------

   procedure Initialize;
   --  Initialize internal tables

   procedure Lock;
   --  Lock internal tables before calling backend

   procedure Instantiate_Bodies;
   --  This procedure is called after semantic analysis is complete, to
   --  instantiate the bodies of generic instantiations that appear in the
   --  compilation unit.

   procedure Add_Inlined_Body (E : Entity_Id; N : Node_Id);
   --  E is an inlined subprogram appearing in a call, either explicitly or in
   --  a discriminant check for which gigi builds a call or an at-end handler.
   --  Add E's enclosing unit to Inlined_Bodies so that E can be subsequently
   --  retrieved and analyzed. N is the node giving rise to the call to E.

   procedure Add_Pending_Instantiation (Inst : Node_Id; Act_Decl : Node_Id);
   --  Add an entry in the table of generic bodies to be instantiated.

   procedure Analyze_Inlined_Bodies;
   --  At end of compilation, analyze the bodies of all units that contain
   --  inlined subprograms that are actually called.

   procedure Build_Body_To_Inline (N : Node_Id; Spec_Id : Entity_Id);
   --  If a subprogram has pragma Inline and inlining is active, use generic
   --  machinery to build an unexpanded body for the subprogram. This body is
   --  subsequently used for inline expansions at call sites. If subprogram can
   --  be inlined (depending on size and nature of local declarations) the
   --  template body is created. Otherwise subprogram body is treated normally
   --  and calls are not inlined in the frontend. If proper warnings are
   --  enabled and the subprogram contains a construct that cannot be inlined,
   --  the problematic construct is flagged accordingly.

   function Call_Can_Be_Inlined_In_GNATprove_Mode
    (N    : Node_Id;
     Subp : Entity_Id) return Boolean;
   --  Returns False if the call in node N to subprogram Subp cannot be inlined
   --  in GNATprove mode, because it may lead to missing a check on type
   --  conversion of input parameters otherwise. Returns True otherwise.

   function Can_Be_Inlined_In_GNATprove_Mode
     (Spec_Id : Entity_Id;
      Body_Id : Entity_Id) return Boolean;
   --  Returns True if the subprogram identified by Spec_Id and Body_Id can
   --  be inlined in GNATprove mode. One but not both of Spec_Id and Body_Id
   --  can be Empty. Body_Id is Empty when doing a partial check on a call
   --  to a subprogram whose body has not been seen yet, to know whether this
   --  subprogram could possibly be inlined. GNATprove relies on this to adapt
   --  its treatment of the subprogram.

   procedure Cannot_Inline
     (Msg           : String;
      N             : Node_Id;
      Subp          : Entity_Id;
      Is_Serious    : Boolean := False;
      Suppress_Info : Boolean := False);
   --  This procedure is called if the node N, an instance of a call to
   --  subprogram Subp, cannot be inlined. Msg is the message to be issued,
   --  which ends with ? (it does not end with ?p?, this routine takes care of
   --  the need to change ? to ?p?). Suppress_Info is set to True to prevent
   --  issuing an info message in GNATprove mode. The behavior of this routine
   --  depends on the value of Back_End_Inlining:
   --
   --    * If Back_End_Inlining is not set (ie. legacy frontend inlining model)
   --      then if Subp has a pragma Always_Inlined, then an error message is
   --      issued (by removing the last character of Msg). If Subp is not
   --      Always_Inlined, then a warning is issued if the flag Ineffective_
   --      Inline_Warnings is set, adding ?p to the msg, and if not, the call
   --      has no effect.
   --
   --    * If Back_End_Inlining is set then:
   --      - If Is_Serious is true, then an error is reported (by removing the
   --        last character of Msg);
   --
   --      - otherwise:
   --
   --        * Compiling without optimizations if Subp has a pragma
   --          Always_Inlined, then an error message is issued; if Subp is
   --          not Always_Inlined, then a warning is issued if the flag
   --          Ineffective_Inline_Warnings is set (adding p?), and if not,
   --          the call has no effect.
   --
   --        * Compiling with optimizations then a warning is issued if the
   --          flag Ineffective_Inline_Warnings is set (adding p?); otherwise
   --          no effect since inlining may be performed by the backend.

   procedure Check_And_Split_Unconstrained_Function
     (N       : Node_Id;
      Spec_Id : Entity_Id;
      Body_Id : Entity_Id);
   --  Spec_Id and Body_Id are the entities of the specification and body of
   --  the subprogram body N. If N can be inlined by the frontend (supported
   --  cases documented in Check_Body_To_Inline) then build the body-to-inline
   --  associated with N and attach it to the declaration node of Spec_Id.

   procedure Check_Object_Renaming_In_GNATprove_Mode (Spec_Id : Entity_Id)
   with
     Pre => GNATprove_Mode;
   --  This procedure is called only in GNATprove mode, on subprograms for
   --  which a Body_To_Inline was created, to check if the subprogram has
   --  references to object renamings which will be replaced by the special
   --  SPARK expansion into nodes of a different kind, which is not expected
   --  by the inlining mechanism. In that case, the Body_To_Inline is deleted.

   procedure Check_Package_Body_For_Inlining (N : Node_Id; P : Entity_Id);
   --  If front-end inlining is enabled and a package declaration contains
   --  inlined subprograms, load and compile the package body to collect the
   --  bodies of these subprograms, so they are available to inline calls.
   --  N is the compilation unit for the package.

   procedure Expand_Inlined_Call
    (N         : Node_Id;
     Subp      : Entity_Id;
     Orig_Subp : Entity_Id);
   --  If called subprogram can be inlined by the front-end, retrieve the
   --  analyzed body, replace formals with actuals and expand call in place.
   --  Generate thunks for actuals that are expressions, and insert the
   --  corresponding constant declarations before the call. If the original
   --  call is to a derived operation, the return type is the one of the
   --  derived operation, but the body is that of the original, so return
   --  expressions in the body must be converted to the desired type (which
   --  is simply not noted in the tree without inline expansion).

   function Has_Excluded_Declaration
     (Subp  : Entity_Id;
      Decls : List_Id) return Boolean;
   --  Check a list of declarations, Decls, that make the inlining of Subp not
   --  worthwhile

   function Has_Excluded_Statement
     (Subp  : Entity_Id;
      Stats : List_Id) return Boolean;
   --  Check a list of statements, Stats, that make inlining of Subp not
   --  worthwhile, including any tasking statement, nested at any level.

   procedure Inline_Static_Function_Call
     (N : Node_Id; Subp : Entity_Id);
   --  Evaluate static call to a static function Subp, substituting actuals in
   --  place of references to their corresponding formals and rewriting the
   --  call N as a fully folded and static result expression.

   procedure List_Inlining_Info;
   --  Generate listing of calls inlined by the frontend plus listing of
   --  calls to inline subprograms passed to the backend.

   procedure Remove_Dead_Instance (N : Node_Id);
   --  If an instantiation appears in unreachable code, delete the pending
   --  body instance.

end Inline;