aboutsummaryrefslogtreecommitdiff
path: root/gcc/ada/exp_smem.adb
blob: 8290d5ef79ec5ba6ddf4892ddce20631087f5cf9 (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
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--                             E X P _ S M E M                              --
--                                                                          --
--                                 B o d y                                  --
--                                                                          --
--          Copyright (C) 1998-2019, 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.      --
--                                                                          --
------------------------------------------------------------------------------

with Atree;    use Atree;
with Einfo;    use Einfo;
with Elists;   use Elists;
with Exp_Ch7;  use Exp_Ch7;
with Exp_Ch9;  use Exp_Ch9;
with Exp_Tss;  use Exp_Tss;
with Exp_Util; use Exp_Util;
with Nmake;    use Nmake;
with Namet;    use Namet;
with Nlists;   use Nlists;
with Rtsfind;  use Rtsfind;
with Sem;      use Sem;
with Sem_Aux;  use Sem_Aux;
with Sem_Util; use Sem_Util;
with Sinfo;    use Sinfo;
with Snames;   use Snames;
with Stand;    use Stand;
with Stringt;  use Stringt;
with Tbuild;   use Tbuild;

package body Exp_Smem is

   Insert_Node : Node_Id;
   --  Node after which a write call is to be inserted

   -----------------------
   -- Local Subprograms --
   -----------------------

   procedure Add_Read (N : Node_Id; Call : Node_Id := Empty);
   --  Insert a Shared_Var_ROpen call for variable before node N, unless
   --  Call is a call to an init-proc, in which case the call is inserted
   --  after Call.

   procedure Add_Write_After (N : Node_Id);
   --  Insert a Shared_Var_WOpen call for variable after the node Insert_Node,
   --  as recorded by On_Lhs_Of_Assignment (where it points to the assignment
   --  statement) or Is_Out_Actual (where it points to the subprogram call).
   --  When Insert_Node is a function call, establish a transient scope around
   --  the expression, and insert the write as an after-action of the transient
   --  scope.

   procedure Build_Full_Name (E : Entity_Id; N : out String_Id);
   --  Build the fully qualified string name of a shared variable

   function On_Lhs_Of_Assignment (N : Node_Id) return Boolean;
   --  Determines if N is on the left hand of the assignment. This means that
   --  either it is a simple variable, or it is a record or array variable with
   --  a corresponding selected or indexed component on the left side of an
   --  assignment. If the result is True, then Insert_Node is set to point
   --  to the assignment

   function Is_Out_Actual (N : Node_Id) return Boolean;
   --  In a similar manner, this function determines if N appears as an OUT
   --  or IN OUT parameter to a procedure call. If the result is True, then
   --  Insert_Node is set to point to the call.

   function Build_Shared_Var_Proc_Call
     (Loc : Source_Ptr;
      E   : Node_Id;
      N   : Name_Id) return Node_Id;
   --  Build a call to support procedure N for shared object E (provided by the
   --  instance of System.Shared_Storage.Shared_Var_Procs associated to E).

   --------------------------------
   -- Build_Shared_Var_Proc_Call --
   --------------------------------

   function Build_Shared_Var_Proc_Call
     (Loc : Source_Ptr;
      E   : Entity_Id;
      N   : Name_Id) return Node_Id
   is
   begin
      return Make_Procedure_Call_Statement (Loc,
        Name => Make_Selected_Component (Loc,
          Prefix        =>
            New_Occurrence_Of (Shared_Var_Procs_Instance (E), Loc),
          Selector_Name => Make_Identifier (Loc, N)));
   end Build_Shared_Var_Proc_Call;

   --------------
   -- Add_Read --
   --------------

   procedure Add_Read (N : Node_Id; Call : Node_Id := Empty) is
      Loc : constant Source_Ptr := Sloc (N);
      Ent : constant Node_Id    := Entity (N);
      SVC : Node_Id;

   begin
      if Present (Shared_Var_Procs_Instance (Ent)) then
         SVC := Build_Shared_Var_Proc_Call (Loc, Ent, Name_Read);

         if Present (Call) and then Is_Init_Proc (Name (Call)) then
            Insert_After_And_Analyze (Call, SVC);
         else
            Insert_Action (N, SVC);
         end if;
      end if;
   end Add_Read;

   -------------------------------
   -- Add_Shared_Var_Lock_Procs --
   -------------------------------

   procedure Add_Shared_Var_Lock_Procs (N : Node_Id) is
      Loc : constant Source_Ptr := Sloc (N);
      Obj : constant Entity_Id  := Entity (Expression (First_Actual (N)));
      Vnm : String_Id;
      Vid : Entity_Id;
      Vde : Node_Id;
      Aft : constant List_Id := New_List;

      In_Transient : constant Boolean := Scope_Is_Transient;

      function Build_Shared_Var_Lock_Call (RE : RE_Id) return Node_Id;
      --  Return a procedure call statement for lock proc RTE

      --------------------------------
      -- Build_Shared_Var_Lock_Call --
      --------------------------------

      function Build_Shared_Var_Lock_Call (RE : RE_Id) return Node_Id is
      begin
         return
           Make_Procedure_Call_Statement (Loc,
             Name                   =>
               New_Occurrence_Of (RTE (RE), Loc),
             Parameter_Associations =>
               New_List (New_Occurrence_Of (Vid, Loc)));
      end Build_Shared_Var_Lock_Call;

   --  Start of processing for Add_Shared_Var_Lock_Procs

   begin
      --  Discussion of transient scopes: we need to have a transient scope
      --  to hold the required lock/unlock actions. Either the current scope
      --  is transient, in which case we reuse it, or we establish a new
      --  transient scope. If this is a function call with unconstrained
      --  return type, we can't introduce a transient scope here (because
      --  Wrap_Transient_Expression would need to declare a temporary with
      --  the unconstrained type outside of the transient block), but in that
      --  case we know that we have already established one at an outer level
      --  for secondary stack management purposes.

      --  If the lock/read/write/unlock actions for this object have already
      --  been emitted in the current scope, no need to perform them anew.

      if In_Transient
        and then Contains (Scope_Stack.Table (Scope_Stack.Last)
                             .Locked_Shared_Objects,
                           Obj)
      then
         return;
      end if;

      Build_Full_Name (Obj, Vnm);

      --  Declare a constant string to hold the name of the shared object.
      --  Note that this must occur outside of the transient scope, as the
      --  scope's finalizer needs to have access to this object. Also, it
      --  appears that GIGI does not support elaborating string literal
      --  subtypes in transient scopes.

      Vid := Make_Temporary (Loc, 'N', Obj);
      Vde :=
        Make_Object_Declaration (Loc,
          Defining_Identifier => Vid,
          Constant_Present    => True,
          Object_Definition   => New_Occurrence_Of (Standard_String, Loc),
          Expression          => Make_String_Literal (Loc, Vnm));

      --  Already in a transient scope. Make sure that we insert Vde outside
      --  that scope.

      if In_Transient then
         Insert_Before_And_Analyze (Node_To_Be_Wrapped, Vde);

      --  Not in a transient scope yet: insert Vde as an action on N prior to
      --  establishing one.

      else
         Insert_Action (N, Vde);
         Establish_Transient_Scope (N, Manage_Sec_Stack => False);
      end if;

      --  Mark object as locked in the current (transient) scope

      Append_New_Elmt
        (Obj,
         To => Scope_Stack.Table (Scope_Stack.Last).Locked_Shared_Objects);

      --  First insert the Lock call before

      Insert_Action (N, Build_Shared_Var_Lock_Call (RE_Shared_Var_Lock));

      --  Now, right after the Lock, insert a call to read the object

      Insert_Action (N, Build_Shared_Var_Proc_Call (Loc, Obj, Name_Read));

      --  For a procedure call only, insert the call to write the object prior
      --  to unlocking.

      if Nkind (N) = N_Procedure_Call_Statement then
         Append_To (Aft, Build_Shared_Var_Proc_Call (Loc, Obj, Name_Write));
      end if;

      --  Finally insert the Unlock call

      Append_To (Aft, Build_Shared_Var_Lock_Call (RE_Shared_Var_Unlock));

      --  Store cleanup actions in transient scope

      Store_Cleanup_Actions_In_Scope (Aft);

      --  If we have established a transient scope here, wrap it now

      if not In_Transient then
         if Nkind (N) = N_Procedure_Call_Statement then
            Wrap_Transient_Statement (N);
         else
            Wrap_Transient_Expression (N);
         end if;
      end if;
   end Add_Shared_Var_Lock_Procs;

   ---------------------
   -- Add_Write_After --
   ---------------------

   procedure Add_Write_After (N : Node_Id) is
      Ent : constant Entity_Id  := Entity (N);
      Loc : constant Source_Ptr := Sloc (N);
      Par : constant Node_Id    := Insert_Node;

   begin
      if Present (Shared_Var_Procs_Instance (Ent)) then
         if Nkind (Insert_Node) = N_Function_Call then
            Establish_Transient_Scope (Insert_Node, Manage_Sec_Stack => False);

            Store_After_Actions_In_Scope (New_List (
              Build_Shared_Var_Proc_Call (Loc, Ent, Name_Write)));
         else
            Insert_After_And_Analyze (Par,
              Build_Shared_Var_Proc_Call (Loc, Ent, Name_Write));
         end if;
      end if;
   end Add_Write_After;

   ---------------------
   -- Build_Full_Name --
   ---------------------

   procedure Build_Full_Name (E : Entity_Id; N : out String_Id) is

      procedure Build_Name (E : Entity_Id);
      --  This is a recursive routine used to construct the fully qualified
      --  string name of the package corresponding to the shared variable.

      ----------------
      -- Build_Name --
      ----------------

      procedure Build_Name (E : Entity_Id) is
      begin
         if Scope (E) /= Standard_Standard then
            Build_Name (Scope (E));
            Store_String_Char ('.');
         end if;

         Get_Decoded_Name_String (Chars (E));
         Store_String_Chars (Name_Buffer (1 .. Name_Len));
      end Build_Name;

   --  Start of processing for Build_Full_Name

   begin
      Start_String;
      Build_Name (E);
      N := End_String;
   end Build_Full_Name;

   ------------------------------------
   -- Expand_Shared_Passive_Variable --
   ------------------------------------

   procedure Expand_Shared_Passive_Variable (N : Node_Id) is
      Typ : constant Entity_Id := Etype (N);

   begin
      --  Nothing to do for protected or limited objects

      if Is_Limited_Type (Typ) or else Is_Concurrent_Type (Typ) then
         return;

      --  If we are on the left hand side of an assignment, then we add the
      --  write call after the assignment.

      elsif On_Lhs_Of_Assignment (N) then
         Add_Write_After (N);

      --  If we are a parameter for an out or in out formal, then in general
      --  we do:

      --    read
      --    call
      --    write

      --  but in the special case of a call to an init proc, we need to first
      --  call the init proc (to set discriminants), then read (to possibly
      --  set other components), then write (to record the updated components
      --  to the backing store):

      --    init-proc-call
      --    read
      --    write

      elsif Is_Out_Actual (N) then

         --  Note: For an init proc call, Add_Read inserts just after the
         --  call node, and we want to have first the read, then the write,
         --  so we need to first Add_Write_After, then Add_Read.

         Add_Write_After (N);
         Add_Read (N, Call => Insert_Node);

      --  All other cases are simple reads

      else
         Add_Read (N);
      end if;
   end Expand_Shared_Passive_Variable;

   -------------------
   -- Is_Out_Actual --
   -------------------

   function Is_Out_Actual (N : Node_Id) return Boolean is
      Formal : Entity_Id;
      Call   : Node_Id;

   begin
      Find_Actual (N, Formal, Call);

      if No (Formal) then
         return False;

      else
         if Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter) then
            Insert_Node := Call;
            return True;
         else
            return False;
         end if;
      end if;
   end Is_Out_Actual;

   ---------------------------
   -- Make_Shared_Var_Procs --
   ---------------------------

   function Make_Shared_Var_Procs (N : Node_Id) return Node_Id is
      Loc     : constant Source_Ptr := Sloc (N);
      Ent     : constant Entity_Id  := Defining_Identifier (N);
      Typ     : constant Entity_Id  := Etype (Ent);
      Vnm     : String_Id;
      Obj     : Node_Id;
      Obj_Typ : Entity_Id;

      After : constant Node_Id := Next (N);
      --  Node located right after N originally (after insertion of the SV
      --  procs this node is right after the last inserted node).

      SVP_Instance : constant Entity_Id := Make_Defining_Identifier (Loc,
                       Chars => New_External_Name (Chars (Ent), 'G'));
      --  Instance of Shared_Storage.Shared_Var_Procs associated with Ent

      Instantiation : Node_Id;
      --  Package instantiation node for SVP_Instance

   --  Start of processing for Make_Shared_Var_Procs

   begin
      Build_Full_Name (Ent, Vnm);

      --  We turn off Shared_Passive during construction and analysis of the
      --  generic package instantiation, to avoid improper attempts to process
      --  the variable references within these instantiation.

      Set_Is_Shared_Passive (Ent, False);

      --  Construct generic package instantiation

      --  package varG is new Shared_Var_Procs (typ, var, "pkg.var");

      Obj     := New_Occurrence_Of (Ent, Loc);
      Obj_Typ := Typ;
      if Is_Concurrent_Type (Typ) then
         Obj     := Convert_Concurrent (N => Obj, Typ => Typ);
         Obj_Typ := Corresponding_Record_Type (Typ);
      end if;

      Instantiation :=
        Make_Package_Instantiation (Loc,
          Defining_Unit_Name   => SVP_Instance,
          Name                 =>
            New_Occurrence_Of (RTE (RE_Shared_Var_Procs), Loc),
          Generic_Associations => New_List (
            Make_Generic_Association (Loc,
              Explicit_Generic_Actual_Parameter =>
                New_Occurrence_Of (Obj_Typ, Loc)),
            Make_Generic_Association (Loc,
              Explicit_Generic_Actual_Parameter => Obj),
            Make_Generic_Association (Loc,
              Explicit_Generic_Actual_Parameter =>
                Make_String_Literal (Loc, Vnm))));

      Insert_After_And_Analyze (N, Instantiation);

      Set_Is_Shared_Passive (Ent, True);
      Set_Shared_Var_Procs_Instance
        (Ent, Defining_Entity (Instance_Spec (Instantiation)));

      --  Return last node before After

      declare
         Nod : Node_Id := Next (N);

      begin
         while Next (Nod) /= After loop
            Nod := Next (Nod);
         end loop;

         return Nod;
      end;
   end Make_Shared_Var_Procs;

   --------------------------
   -- On_Lhs_Of_Assignment --
   --------------------------

   function On_Lhs_Of_Assignment (N : Node_Id) return Boolean is
      P : constant Node_Id := Parent (N);

   begin
      if Nkind (P) = N_Assignment_Statement then
         if N = Name (P) then
            Insert_Node := P;
            return True;
         else
            return False;
         end if;

      elsif Nkind_In (P, N_Indexed_Component, N_Selected_Component)
        and then N = Prefix (P)
      then
         return On_Lhs_Of_Assignment (P);

      else
         return False;
      end if;
   end On_Lhs_Of_Assignment;

end Exp_Smem;