comparison gcc/ada/exp_util.ads @ 111:04ced10e8804

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author kono
date Fri, 27 Oct 2017 22:46:09 +0900
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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- E X P _ U T I L --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1992-2017, 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 -- Package containing utility procedures used throughout the expander
27
28 with Exp_Tss; use Exp_Tss;
29 with Namet; use Namet;
30 with Rtsfind; use Rtsfind;
31 with Sinfo; use Sinfo;
32 with Types; use Types;
33 with Uintp; use Uintp;
34
35 package Exp_Util is
36
37 -----------------------------------------------
38 -- Handling of Actions Associated with Nodes --
39 -----------------------------------------------
40
41 -- The evaluation of certain expression nodes involves the elaboration
42 -- of associated types and other declarations, and the execution of
43 -- statement sequences. Expansion routines generating such actions must
44 -- find an appropriate place in the tree to hang the actions so that
45 -- they will be evaluated at the appropriate point.
46
47 -- Some cases are simple:
48
49 -- For an expression occurring in a simple statement that is in a list
50 -- of statements, the actions are simply inserted into the list before
51 -- the associated statement.
52
53 -- For an expression occurring in a declaration (declarations always
54 -- appear in lists), the actions are similarly inserted into the list
55 -- just before the associated declaration.
56
57 -- The following special cases arise:
58
59 -- For actions associated with the right operand of a short circuit
60 -- form, the actions are first stored in the short circuit form node
61 -- in the Actions field. The expansion of these forms subsequently
62 -- expands the short circuit forms into if statements which can then
63 -- be moved as described above.
64
65 -- For actions appearing in the Condition expression of a while loop,
66 -- or an elsif clause, the actions are similarly temporarily stored in
67 -- in the node (N_Elsif_Part or N_Iteration_Scheme) associated with
68 -- the expression using the Condition_Actions field. Subsequently, the
69 -- expansion of these nodes rewrites the control structures involved to
70 -- reposition the actions in normal statement sequence.
71
72 -- For actions appearing in the then or else expression of a conditional
73 -- expression, these actions are similarly placed in the node, using the
74 -- Then_Actions or Else_Actions field as appropriate. Once again the
75 -- expansion of the N_If_Expression node rewrites the node so that the
76 -- actions can be positioned normally.
77
78 -- For actions coming from expansion of the expression in an expression
79 -- with actions node, the action is appended to the list of actions.
80
81 -- Basically what we do is to climb up to the tree looking for the
82 -- proper insertion point, as described by one of the above cases,
83 -- and then insert the appropriate action or actions.
84
85 -- Note if more than one insert call is made specifying the same
86 -- Assoc_Node, then the actions are elaborated in the order of the
87 -- calls, and this guarantee is preserved for the special cases above.
88
89 procedure Insert_Action
90 (Assoc_Node : Node_Id;
91 Ins_Action : Node_Id);
92 -- Insert the action Ins_Action at the appropriate point as described
93 -- above. The action is analyzed using the default checks after it is
94 -- inserted. Assoc_Node is the node with which the action is associated.
95
96 procedure Insert_Action
97 (Assoc_Node : Node_Id;
98 Ins_Action : Node_Id;
99 Suppress : Check_Id);
100 -- Insert the action Ins_Action at the appropriate point as described
101 -- above. The action is analyzed using the default checks as modified
102 -- by the given Suppress argument after it is inserted. Assoc_Node is
103 -- the node with which the action is associated.
104
105 procedure Insert_Actions
106 (Assoc_Node : Node_Id;
107 Ins_Actions : List_Id);
108 -- Insert the list of action Ins_Actions at the appropriate point as
109 -- described above. The actions are analyzed using the default checks
110 -- after they are inserted. Assoc_Node is the node with which the actions
111 -- are associated. Ins_Actions may be No_List, in which case the call has
112 -- no effect.
113
114 procedure Insert_Actions
115 (Assoc_Node : Node_Id;
116 Ins_Actions : List_Id;
117 Suppress : Check_Id);
118 -- Insert the list of action Ins_Actions at the appropriate point as
119 -- described above. The actions are analyzed using the default checks
120 -- as modified by the given Suppress argument after they are inserted.
121 -- Assoc_Node is the node with which the actions are associated.
122 -- Ins_Actions may be No_List, in which case the call has no effect.
123
124 procedure Insert_Action_After
125 (Assoc_Node : Node_Id;
126 Ins_Action : Node_Id);
127 -- Assoc_Node must be a node in a list. Same as Insert_Action but the
128 -- action will be inserted after N in a manner that is compatible with
129 -- the transient scope mechanism.
130 --
131 -- Note: If several successive calls to Insert_Action_After are made for
132 -- the same node, they will each in turn be inserted just after the node.
133 -- This means they will end up being executed in reverse order. Use the
134 -- call to Insert_Actions_After to insert a list of actions to be executed
135 -- in the sequence in which they are given in the list.
136
137 procedure Insert_Actions_After
138 (Assoc_Node : Node_Id;
139 Ins_Actions : List_Id);
140 -- Assoc_Node must be a node in a list. Same as Insert_Actions but
141 -- actions will be inserted after N in a manner that is compatible with
142 -- the transient scope mechanism. This procedure must be used instead
143 -- of Insert_List_After if Assoc_Node may be in a transient scope.
144 --
145 -- Implementation limitation: Assoc_Node must be a statement. We can
146 -- generalize to expressions if there is a need but this is tricky to
147 -- implement because of short-circuits (among other things).???
148
149 procedure Insert_Declaration (N : Node_Id; Decl : Node_Id);
150 -- N must be a subexpression (Nkind in N_Subexpr). This is similar to
151 -- Insert_Action (N, Decl), but inserts Decl outside the expression in
152 -- which N appears. This is called Insert_Declaration because the intended
153 -- use is for declarations that have no associated code. We can't go
154 -- moving other kinds of things out of the current expression, since they
155 -- could be executed conditionally (e.g. right operand of short circuit,
156 -- or THEN/ELSE of if expression). This is currently used only in
157 -- Modify_Tree_For_C mode, where it is needed because in C we have no
158 -- way of having declarations within an expression (a really annoying
159 -- limitation).
160
161 procedure Insert_Library_Level_Action (N : Node_Id);
162 -- This procedure inserts and analyzes the node N as an action at the
163 -- library level for the current unit (i.e. it is attached to the
164 -- Actions field of the N_Compilation_Aux node for the main unit).
165
166 procedure Insert_Library_Level_Actions (L : List_Id);
167 -- Similar, but inserts a list of actions
168
169 -----------------------
170 -- Other Subprograms --
171 -----------------------
172
173 procedure Activate_Atomic_Synchronization (N : Node_Id);
174 -- N is a node for which atomic synchronization may be required (it is
175 -- either an identifier, expanded name, or selected/indexed component or
176 -- an explicit dereference). The caller has checked the basic conditions
177 -- (atomic variable appearing and Atomic_Sync not disabled). This function
178 -- checks if atomic synchronization is required and if so sets the flag
179 -- and if appropriate generates a warning (in -gnatw.n mode).
180
181 procedure Adjust_Condition (N : Node_Id);
182 -- The node N is an expression whose root-type is Boolean, and which
183 -- represents a boolean value used as a condition (i.e. a True/False
184 -- value). This routine handles the case of C and Fortran convention
185 -- boolean types, which have zero/non-zero semantics rather than the normal
186 -- 0/1 semantics, and also the case of an enumeration rep clause that
187 -- specifies a non-standard representation. On return, node N always has
188 -- the type Standard.Boolean, with a value that is a standard Boolean
189 -- values of 0/1 for False/True. This procedure is used in two situations.
190 -- First, the processing for a condition field always calls
191 -- Adjust_Condition, so that the boolean value presented to the backend is
192 -- a standard value. Second, for the code for boolean operations such as
193 -- AND, Adjust_Condition is called on both operands, and then the operation
194 -- is done in the domain of Standard_Boolean, then Adjust_Result_Type is
195 -- called on the result to possibly reset the original type. This procedure
196 -- also takes care of validity checking if Validity_Checks = Tests.
197
198 procedure Adjust_Result_Type (N : Node_Id; T : Entity_Id);
199 -- The processing of boolean operations like AND uses the procedure
200 -- Adjust_Condition so that it can operate on Standard.Boolean, which is
201 -- the only boolean type on which the backend needs to be able to implement
202 -- such operators. This means that the result is also of type
203 -- Standard.Boolean. In general the type must be reset back to the original
204 -- type to get proper semantics, and that is the purpose of this procedure.
205 -- N is the node (of type Standard.Boolean), and T is the desired type. As
206 -- an optimization, this procedure leaves the type as Standard.Boolean in
207 -- contexts where this is permissible (in particular for Condition fields,
208 -- and for operands of other logical operations higher up the tree). The
209 -- call to this procedure is completely ignored if the argument N is not of
210 -- type Boolean.
211
212 procedure Append_Freeze_Action (T : Entity_Id; N : Node_Id);
213 -- Add a new freeze action for the given type. The freeze action is
214 -- attached to the freeze node for the type. Actions will be elaborated in
215 -- the order in which they are added. Note that the added node is not
216 -- analyzed. The analyze call is found in Exp_Ch13.Expand_N_Freeze_Entity.
217
218 procedure Append_Freeze_Actions (T : Entity_Id; L : List_Id);
219 -- Adds the given list of freeze actions (declarations or statements) for
220 -- the given type. The freeze actions are attached to the freeze node for
221 -- the type. Actions will be elaborated in the order in which they are
222 -- added, and the actions within the list will be elaborated in list order.
223 -- Note that the added nodes are not analyzed. The analyze call is found in
224 -- Exp_Ch13.Expand_N_Freeze_Entity.
225
226 procedure Build_Allocate_Deallocate_Proc
227 (N : Node_Id;
228 Is_Allocate : Boolean);
229 -- Create a custom Allocate/Deallocate to be associated with an allocation
230 -- or deallocation:
231 --
232 -- 1) controlled objects
233 -- 2) class-wide objects
234 -- 3) any kind of object on a subpool
235 --
236 -- N must be an allocator or the declaration of a temporary variable which
237 -- represents the expression of the original allocator node, otherwise N
238 -- must be a free statement. If flag Is_Allocate is set, the generated
239 -- routine is allocate, deallocate otherwise.
240
241 function Build_Abort_Undefer_Block
242 (Loc : Source_Ptr;
243 Stmts : List_Id;
244 Context : Node_Id) return Node_Id;
245 -- Wrap statements Stmts in a block where the AT END handler contains a
246 -- call to Abort_Undefer_Direct. Context is the node which prompted the
247 -- inlining of the abort undefer routine. Note that this routine does
248 -- not install a call to Abort_Defer.
249
250 procedure Build_Class_Wide_Expression
251 (Prag : Node_Id;
252 Subp : Entity_Id;
253 Par_Subp : Entity_Id;
254 Adjust_Sloc : Boolean;
255 Needs_Wrapper : out Boolean);
256 -- Build the expression for an inherited class-wide condition. Prag is
257 -- the pragma constructed from the corresponding aspect of the parent
258 -- subprogram, and Subp is the overriding operation, and Par_Subp is
259 -- the overridden operation that has the condition. Adjust_Sloc is True
260 -- when the sloc of nodes traversed should be adjusted for the inherited
261 -- pragma. The routine is also called to check whether an inherited
262 -- operation that is not overridden but has inherited conditions needs
263 -- a wrapper, because the inherited condition includes calls to other
264 -- primitives that have been overridden. In that case the first argument
265 -- is the expression of the original class-wide aspect. In SPARK_Mode, such
266 -- operation which are just inherited but have modified pre/postconditions
267 -- are illegal.
268 -- If there are calls to overridden operations in the condition, and the
269 -- pragma applies to an inherited operation, a wrapper must be built for
270 -- it to capture the new inherited condition. The flag Needs_Wrapper is
271 -- set in that case so that the wrapper can be built, when the controlling
272 -- type is frozen.
273
274 function Build_DIC_Call
275 (Loc : Source_Ptr;
276 Obj_Id : Entity_Id;
277 Typ : Entity_Id) return Node_Id;
278 -- Build a call to the DIC procedure of type Typ with Obj_Id as the actual
279 -- parameter.
280
281 procedure Build_DIC_Procedure_Body
282 (Typ : Entity_Id;
283 For_Freeze : Boolean := False);
284 -- Create the body of the procedure which verifies the assertion expression
285 -- of pragma Default_Initial_Condition at run time. Flag For_Freeze should
286 -- be set when the body is constructed as part of the freezing actions for
287 -- Typ.
288
289 procedure Build_DIC_Procedure_Declaration (Typ : Entity_Id);
290 -- Create the declaration of the procedure which verifies the assertion
291 -- expression of pragma Default_Initial_Condition at run time.
292
293 procedure Build_Invariant_Procedure_Body
294 (Typ : Entity_Id;
295 Partial_Invariant : Boolean := False);
296 -- Create the body of the procedure which verifies the invariants of type
297 -- Typ at runtime. Flag Partial_Invariant should be set when Typ denotes a
298 -- private type, otherwise it is assumed that Typ denotes the full view of
299 -- a private type.
300
301 procedure Build_Invariant_Procedure_Declaration
302 (Typ : Entity_Id;
303 Partial_Invariant : Boolean := False);
304 -- Create the declaration of the procedure which verifies the invariants of
305 -- type Typ at runtime. Flag Partial_Invariant should be set when building
306 -- the invariant procedure for a private type.
307
308 procedure Build_Procedure_Form (N : Node_Id);
309 -- Create a procedure declaration which emulates the behavior of a function
310 -- that returns an array type, for C-compatible generation.
311
312 function Build_Runtime_Call (Loc : Source_Ptr; RE : RE_Id) return Node_Id;
313 -- Build an N_Procedure_Call_Statement calling the given runtime entity.
314 -- The call has no parameters. The first argument provides the location
315 -- information for the tree and for error messages. The call node is not
316 -- analyzed on return, the caller is responsible for analyzing it.
317
318 function Build_SS_Mark_Call
319 (Loc : Source_Ptr;
320 Mark : Entity_Id) return Node_Id;
321 -- Build a call to routine System.Secondary_Stack.Mark. Mark denotes the
322 -- entity of the secondary stack mark.
323
324 function Build_SS_Release_Call
325 (Loc : Source_Ptr;
326 Mark : Entity_Id) return Node_Id;
327 -- Build a call to routine System.Secondary_Stack.Release. Mark denotes the
328 -- entity of the secondary stack mark.
329
330 function Build_Task_Image_Decls
331 (Loc : Source_Ptr;
332 Id_Ref : Node_Id;
333 A_Type : Entity_Id;
334 In_Init_Proc : Boolean := False) return List_Id;
335 -- Build declaration for a variable that holds an identifying string to be
336 -- used as a task name. Id_Ref is an identifier if the task is a variable,
337 -- and a selected or indexed component if the task is component of an
338 -- object. If it is an indexed component, A_Type is the corresponding array
339 -- type. Its index types are used to build the string as an image of the
340 -- index values. For composite types, the result includes two declarations:
341 -- one for a generated function that computes the image without using
342 -- concatenation, and one for the variable that holds the result.
343 --
344 -- If In_Init_Proc is true, the call is part of the initialization of
345 -- a component of a composite type, and the enclosing initialization
346 -- procedure must be flagged as using the secondary stack. If In_Init_Proc
347 -- is false, the call is for a stand-alone object, and the generated
348 -- function itself must do its own cleanups.
349
350 procedure Build_Transient_Object_Statements
351 (Obj_Decl : Node_Id;
352 Fin_Call : out Node_Id;
353 Hook_Assign : out Node_Id;
354 Hook_Clear : out Node_Id;
355 Hook_Decl : out Node_Id;
356 Ptr_Decl : out Node_Id;
357 Finalize_Obj : Boolean := True);
358 -- Subsidiary to the processing of transient objects in transient scopes,
359 -- if expressions, case expressions, expression_with_action nodes, array
360 -- aggregates, and record aggregates. Obj_Decl denotes the declaration of
361 -- the transient object. Generate the following nodes:
362 --
363 -- * Fin_Call - the call to [Deep_]Finalize which cleans up the transient
364 -- object if flag Finalize_Obj is set to True, or finalizes the hook when
365 -- the flag is False.
366 --
367 -- * Hook_Assign - the assignment statement which captures a reference to
368 -- the transient object in the hook.
369 --
370 -- * Hook_Clear - the assignment statement which resets the hook to null
371 --
372 -- * Hook_Decl - the declaration of the hook object
373 --
374 -- * Ptr_Decl - the full type declaration of the hook type
375 --
376 -- These nodes are inserted in specific places depending on the context by
377 -- the various Process_Transient_xxx routines.
378
379 procedure Check_Float_Op_Overflow (N : Node_Id);
380 -- Called where we could have a floating-point binary operator where we
381 -- must check for infinities if we are operating in Check_Float_Overflow
382 -- mode. Note that we don't need to worry about unary operator cases,
383 -- since for floating-point, abs, unary "-", and unary "+" can never
384 -- case overflow.
385
386 function Component_May_Be_Bit_Aligned (Comp : Entity_Id) return Boolean;
387 -- This function is in charge of detecting record components that may
388 -- cause trouble in the back end if an attempt is made to assign the
389 -- component. The back end can handle such assignments with no problem if
390 -- the components involved are small (64-bits or less) records or scalar
391 -- items (including bit-packed arrays represented with modular types) or
392 -- are both aligned on a byte boundary (starting on a byte boundary, and
393 -- occupying an integral number of bytes).
394 --
395 -- However, problems arise for records larger than 64 bits, or for arrays
396 -- (other than bit-packed arrays represented with a modular type) if the
397 -- component starts on a non-byte boundary, or does not occupy an integral
398 -- number of bytes (i.e. there are some bits possibly shared with fields
399 -- at the start or beginning of the component). The back end cannot handle
400 -- loading and storing such components in a single operation.
401 --
402 -- This function is used to detect the troublesome situation. it is
403 -- conservative in the sense that it produces True unless it knows for
404 -- sure that the component is safe (as outlined in the first paragraph
405 -- above). The code generation for record and array assignment checks for
406 -- trouble using this function, and if so the assignment is generated
407 -- component-wise, which the back end is required to handle correctly.
408 --
409 -- Note that in GNAT 3, the back end will reject such components anyway,
410 -- so the hard work in checking for this case is wasted in GNAT 3, but
411 -- it is harmless, so it is easier to do it in all cases, rather than
412 -- conditionalize it in GNAT 5 or beyond.
413
414 function Containing_Package_With_Ext_Axioms
415 (E : Entity_Id) return Entity_Id;
416 -- Returns the package entity with an external axiomatization containing E,
417 -- if any, or Empty if none.
418
419 procedure Convert_To_Actual_Subtype (Exp : Node_Id);
420 -- The Etype of an expression is the nominal type of the expression,
421 -- not the actual subtype. Often these are the same, but not always.
422 -- For example, a reference to a formal of unconstrained type has the
423 -- unconstrained type as its Etype, but the actual subtype is obtained by
424 -- applying the actual bounds. This routine is given an expression, Exp,
425 -- and (if necessary), replaces it using Rewrite, with a conversion to
426 -- the actual subtype, building the actual subtype if necessary. If the
427 -- expression is already of the requested type, then it is unchanged.
428
429 function Corresponding_Runtime_Package (Typ : Entity_Id) return RTU_Id;
430 -- Return the id of the runtime package that will provide support for
431 -- concurrent type Typ. Currently only protected types are supported,
432 -- and the returned value is one of the following:
433 -- System_Tasking_Protected_Objects
434 -- System_Tasking_Protected_Objects_Entries
435 -- System_Tasking_Protected_Objects_Single_Entry
436
437 function Current_Sem_Unit_Declarations return List_Id;
438 -- Return the place where it is fine to insert declarations for the
439 -- current semantic unit. If the unit is a package body, return the
440 -- visible declarations of the corresponding spec. For RCI stubs, this
441 -- is necessary because the point at which they are generated may not
442 -- be the earliest point at which they are used.
443
444 function Duplicate_Subexpr
445 (Exp : Node_Id;
446 Name_Req : Boolean := False;
447 Renaming_Req : Boolean := False) return Node_Id;
448 -- Given the node for a subexpression, this function makes a logical copy
449 -- of the subexpression, and returns it. This is intended for use when the
450 -- expansion of an expression needs to repeat part of it. For example,
451 -- replacing a**2 by a*a requires two references to a which may be a
452 -- complex subexpression. Duplicate_Subexpr guarantees not to duplicate
453 -- side effects. If necessary, it generates actions to save the expression
454 -- value in a temporary, inserting these actions into the tree using
455 -- Insert_Actions with Exp as the insertion location. The original
456 -- expression and the returned result then become references to this saved
457 -- value. Exp must be analyzed on entry. On return, Exp is analyzed, but
458 -- the caller is responsible for analyzing the returned copy after it is
459 -- attached to the tree.
460 --
461 -- The Name_Req flag is set to ensure that the result is suitable for use
462 -- in a context requiring a name (for example, the prefix of an attribute
463 -- reference) (can't this just be a qualification in Ada 2012???).
464 --
465 -- The Renaming_Req flag is set to produce an object renaming declaration
466 -- rather than an object declaration. This is valid only if the expression
467 -- Exp designates a renamable object. This is used for example in the case
468 -- of an unchecked deallocation, to make sure the object gets set to null.
469 --
470 -- Note that if there are any run time checks in Exp, these same checks
471 -- will be duplicated in the returned duplicated expression. The two
472 -- following functions allow this behavior to be modified.
473
474 function Duplicate_Subexpr_No_Checks
475 (Exp : Node_Id;
476 Name_Req : Boolean := False;
477 Renaming_Req : Boolean := False;
478 Related_Id : Entity_Id := Empty;
479 Is_Low_Bound : Boolean := False;
480 Is_High_Bound : Boolean := False) return Node_Id;
481 -- Identical in effect to Duplicate_Subexpr, except that Remove_Checks is
482 -- called on the result, so that the duplicated expression does not include
483 -- checks. This is appropriate for use when Exp, the original expression is
484 -- unconditionally elaborated before the duplicated expression, so that
485 -- there is no need to repeat any checks.
486 --
487 -- Related_Id denotes the entity of the context where Expr appears. Flags
488 -- Is_Low_Bound and Is_High_Bound specify whether the expression to check
489 -- is the low or the high bound of a range. These three optional arguments
490 -- signal Remove_Side_Effects to create an external symbol of the form
491 -- Chars (Related_Id)_FIRST/_LAST. For suggested use of these parameters
492 -- see the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
493
494 function Duplicate_Subexpr_Move_Checks
495 (Exp : Node_Id;
496 Name_Req : Boolean := False;
497 Renaming_Req : Boolean := False) return Node_Id;
498 -- Identical in effect to Duplicate_Subexpr, except that Remove_Checks is
499 -- called on Exp after the duplication is complete, so that the original
500 -- expression does not include checks. In this case the result returned
501 -- (the duplicated expression) will retain the original checks. This is
502 -- appropriate for use when the duplicated expression is sure to be
503 -- elaborated before the original expression Exp, so that there is no need
504 -- to repeat the checks.
505
506 procedure Ensure_Defined (Typ : Entity_Id; N : Node_Id);
507 -- This procedure ensures that type referenced by Typ is defined. For the
508 -- case of a type other than an Itype, nothing needs to be done, since
509 -- all such types have declaration nodes. For Itypes, an N_Itype_Reference
510 -- node is generated and inserted as an action on node N. This is typically
511 -- used to ensure that an Itype is properly defined outside a conditional
512 -- construct when it is referenced in more than one branch.
513
514 function Entry_Names_OK return Boolean;
515 -- Determine whether it is appropriate to dynamically allocate strings
516 -- which represent entry [family member] names. These strings are created
517 -- by the compiler and used by GDB.
518
519 procedure Evaluate_Name (Nam : Node_Id);
520 -- Remove all side effects from a name which appears as part of an object
521 -- renaming declaration. Similarly to Force_Evaluation, it removes the
522 -- side effects and captures the values of the variables, except for the
523 -- variable being renamed. Hence this differs from Force_Evaluation and
524 -- Remove_Side_Effects (but it calls Force_Evaluation on subexpressions
525 -- whose value needs to be fixed).
526
527 procedure Evolve_And_Then (Cond : in out Node_Id; Cond1 : Node_Id);
528 -- Rewrites Cond with the expression: Cond and then Cond1. If Cond is
529 -- Empty, then simply returns Cond1 (this allows the use of Empty to
530 -- initialize a series of checks evolved by this routine, with a final
531 -- result of Empty indicating that no checks were required). The Sloc field
532 -- of the constructed N_And_Then node is copied from Cond1.
533
534 procedure Evolve_Or_Else (Cond : in out Node_Id; Cond1 : Node_Id);
535 -- Rewrites Cond with the expression: Cond or else Cond1. If Cond is Empty,
536 -- then simply returns Cond1 (this allows the use of Empty to initialize a
537 -- series of checks evolved by this routine, with a final result of Empty
538 -- indicating that no checks were required). The Sloc field of the
539 -- constructed N_Or_Else node is copied from Cond1.
540
541 function Exceptions_In_Finalization_OK return Boolean;
542 -- Determine whether the finalization machinery can safely add exception
543 -- handlers and recovery circuitry.
544
545 procedure Expand_Static_Predicates_In_Choices (N : Node_Id);
546 -- N is either a case alternative or a variant. The Discrete_Choices field
547 -- of N points to a list of choices. If any of these choices is the name
548 -- of a (statically) predicated subtype, then it is rewritten as the series
549 -- of choices that correspond to the values allowed for the subtype.
550
551 procedure Expand_Subtype_From_Expr
552 (N : Node_Id;
553 Unc_Type : Entity_Id;
554 Subtype_Indic : Node_Id;
555 Exp : Node_Id;
556 Related_Id : Entity_Id := Empty);
557 -- Build a constrained subtype from the initial value in object
558 -- declarations and/or allocations when the type is indefinite (including
559 -- class-wide). Set Related_Id to request an external name for the subtype
560 -- rather than an internal temporary.
561
562 function Expression_Contains_Primitives_Calls_Of
563 (Expr : Node_Id;
564 Typ : Entity_Id) return Boolean;
565 -- Return True if the expression Expr contains a nondispatching call to a
566 -- function which is a primitive of the tagged type Typ.
567
568 function Finalize_Address (Typ : Entity_Id) return Entity_Id;
569 -- Locate TSS primitive Finalize_Address in type Typ. Return Empty if the
570 -- subprogram is not available.
571
572 function Find_Interface_ADT
573 (T : Entity_Id;
574 Iface : Entity_Id) return Elmt_Id;
575 -- Ada 2005 (AI-251): Given a type T implementing the interface Iface,
576 -- return the element of Access_Disp_Table containing the tag of the
577 -- interface.
578
579 function Find_Interface_Tag
580 (T : Entity_Id;
581 Iface : Entity_Id) return Entity_Id;
582 -- Ada 2005 (AI-251): Given a type T implementing the interface Iface,
583 -- return the record component containing the tag of Iface.
584
585 function Find_Prim_Op (T : Entity_Id; Name : Name_Id) return Entity_Id;
586 -- Find the first primitive operation of a tagged type T with name Name.
587 -- This function allows the use of a primitive operation which is not
588 -- directly visible. If T is a class wide type, then the reference is to an
589 -- operation of the corresponding root type. It is an error if no primitive
590 -- operation with the given name is found.
591
592 function Find_Prim_Op
593 (T : Entity_Id;
594 Name : TSS_Name_Type) return Entity_Id;
595 -- Same as Find_Prim_Op above, except we're searching for an op that has
596 -- the form indicated by Name (i.e. is a type support subprogram with the
597 -- indicated suffix).
598
599 function Find_Optional_Prim_Op
600 (T : Entity_Id; Name : Name_Id) return Entity_Id;
601 function Find_Optional_Prim_Op
602 (T : Entity_Id;
603 Name : TSS_Name_Type) return Entity_Id;
604 -- Same as Find_Prim_Op, except returns Empty if not found
605
606 function Find_Protection_Object (Scop : Entity_Id) return Entity_Id;
607 -- Traverse the scope stack starting from Scop and look for an entry, entry
608 -- family, or a subprogram that has a Protection_Object and return it. Must
609 -- always return a value since the context in which this routine is invoked
610 -- should always have a protection object.
611
612 function Find_Protection_Type (Conc_Typ : Entity_Id) return Entity_Id;
613 -- Given a protected type or its corresponding record, find the type of
614 -- field _object.
615
616 function Find_Hook_Context (N : Node_Id) return Node_Id;
617 -- Determine a suitable node on which to attach actions related to N that
618 -- need to be elaborated unconditionally. In general this is the topmost
619 -- expression of which N is a subexpression, which in turn may or may not
620 -- be evaluated, for example if N is the right operand of a short circuit
621 -- operator.
622
623 function Following_Address_Clause (D : Node_Id) return Node_Id;
624 -- D is the node for an object declaration. This function searches the
625 -- current declarative part to look for an address clause for the object
626 -- being declared, and returns the clause if one is found, returns
627 -- Empty otherwise.
628 --
629 -- Note: this function can be costly and must be invoked with special care.
630 -- Possibly we could introduce a flag at parse time indicating the presence
631 -- of an address clause to speed this up???
632 --
633 -- Note: currently this function does not scan the private part, that seems
634 -- like a potential bug ???
635
636 type Force_Evaluation_Mode is (Relaxed, Strict);
637
638 procedure Force_Evaluation
639 (Exp : Node_Id;
640 Name_Req : Boolean := False;
641 Related_Id : Entity_Id := Empty;
642 Is_Low_Bound : Boolean := False;
643 Is_High_Bound : Boolean := False;
644 Mode : Force_Evaluation_Mode := Relaxed);
645 -- Force the evaluation of the expression right away. Similar behavior
646 -- to Remove_Side_Effects when Variable_Ref is set to TRUE. That is to
647 -- say, it removes the side effects and captures the values of the
648 -- variables. Remove_Side_Effects guarantees that multiple evaluations
649 -- of the same expression won't generate multiple side effects, whereas
650 -- Force_Evaluation further guarantees that all evaluations will yield
651 -- the same result. If Mode is Relaxed then calls to this subprogram have
652 -- no effect if Exp is side-effect free; if Mode is Strict and Exp is not
653 -- a static expression then no side-effect check is performed on Exp and
654 -- temporaries are unconditionally generated.
655 --
656 -- Related_Id denotes the entity of the context where Expr appears. Flags
657 -- Is_Low_Bound and Is_High_Bound specify whether the expression to check
658 -- is the low or the high bound of a range. These three optional arguments
659 -- signal Remove_Side_Effects to create an external symbol of the form
660 -- Chars (Related_Id)_FIRST/_LAST. If Related_Id is set, then exactly one
661 -- of the Is_xxx_Bound flags must be set. For use of these parameters see
662 -- the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
663
664 function Fully_Qualified_Name_String
665 (E : Entity_Id;
666 Append_NUL : Boolean := True) return String_Id;
667 -- Generates the string literal corresponding to the fully qualified name
668 -- of entity E, in all upper case, with an ASCII.NUL appended at the end
669 -- of the name if Append_NUL is True.
670
671 procedure Generate_Poll_Call (N : Node_Id);
672 -- If polling is active, then a call to the Poll routine is built,
673 -- and then inserted before the given node N and analyzed.
674
675 procedure Get_Current_Value_Condition
676 (Var : Node_Id;
677 Op : out Node_Kind;
678 Val : out Node_Id);
679 -- This routine processes the Current_Value field of the variable Var. If
680 -- the Current_Value field is null or if it represents a known value, then
681 -- on return Cond is set to N_Empty, and Val is set to Empty.
682 --
683 -- The other case is when Current_Value points to an N_If_Statement or an
684 -- N_Elsif_Part or a N_Iteration_Scheme node (see description in Einfo for
685 -- exact details). In this case, Get_Current_Condition digs out the
686 -- condition, and then checks if the condition is known false, known true,
687 -- or not known at all. In the first two cases, Get_Current_Condition will
688 -- return with Op set to the appropriate conditional operator (inverted if
689 -- the condition is known false), and Val set to the constant value. If the
690 -- condition is not known, then Op and Val are set for the empty case
691 -- (N_Empty and Empty).
692 --
693 -- The check for whether the condition is true/false unknown depends
694 -- on the case:
695 --
696 -- For an IF, the condition is known true in the THEN part, known false
697 -- in any ELSIF or ELSE part, and not known outside the IF statement in
698 -- question.
699 --
700 -- For an ELSIF, the condition is known true in the ELSIF part, known
701 -- FALSE in any subsequent ELSIF, or ELSE part, and not known before the
702 -- ELSIF, or after the end of the IF statement.
703 --
704 -- The caller can use this result to determine the value (for the case of
705 -- N_Op_Eq), or to determine the result of some other test in other cases
706 -- (e.g. no access check required if N_Op_Ne Null).
707
708 function Get_Stream_Size (E : Entity_Id) return Uint;
709 -- Return the stream size value of the subtype E
710
711 function Has_Access_Constraint (E : Entity_Id) return Boolean;
712 -- Given object or type E, determine if a discriminant is of an access type
713
714 function Has_Annotate_Pragma_For_External_Axiomatization
715 (E : Entity_Id) return Boolean;
716 -- Returns whether E is a package entity, for which the initial list of
717 -- pragmas at the start of the package declaration contains
718 -- pragma Annotate (GNATprove, External_Axiomatization);
719
720 function Homonym_Number (Subp : Entity_Id) return Nat;
721 -- Here subp is the entity for a subprogram. This routine returns the
722 -- homonym number used to disambiguate overloaded subprograms in the same
723 -- scope (the number is used as part of constructed names to make sure that
724 -- they are unique). The number is the ordinal position on the Homonym
725 -- chain, counting only entries in the current scope. If an entity is not
726 -- overloaded, the returned number will be one.
727
728 function Inside_Init_Proc return Boolean;
729 -- Returns True if current scope is within an init proc
730
731 function In_Library_Level_Package_Body (Id : Entity_Id) return Boolean;
732 -- Given an arbitrary entity, determine whether it appears at the library
733 -- level of a package body.
734
735 function In_Unconditional_Context (Node : Node_Id) return Boolean;
736 -- Node is the node for a statement or a component of a statement. This
737 -- function determines if the statement appears in a context that is
738 -- unconditionally executed, i.e. it is not within a loop or a conditional
739 -- or a case statement etc.
740
741 function Is_All_Null_Statements (L : List_Id) return Boolean;
742 -- Return True if all the items of the list are N_Null_Statement nodes.
743 -- False otherwise. True for an empty list. It is an error to call this
744 -- routine with No_List as the argument.
745
746 function Is_Displacement_Of_Object_Or_Function_Result
747 (Obj_Id : Entity_Id) return Boolean;
748 -- Determine whether Obj_Id is a source entity that has been initialized by
749 -- either a controlled function call or the assignment of another source
750 -- object. In both cases the initialization expression is rewritten as a
751 -- class-wide conversion of Ada.Tags.Displace.
752
753 function Is_Finalizable_Transient
754 (Decl : Node_Id;
755 Rel_Node : Node_Id) return Boolean;
756 -- Determine whether declaration Decl denotes a controlled transient which
757 -- should be finalized. Rel_Node is the related context. Even though some
758 -- transients are controlled, they may act as renamings of other objects or
759 -- function calls.
760
761 function Is_Fully_Repped_Tagged_Type (T : Entity_Id) return Boolean;
762 -- Tests given type T, and returns True if T is a non-discriminated tagged
763 -- type which has a record representation clause that specifies the layout
764 -- of all the components, including recursively components in all parent
765 -- types. We exclude discriminated types for convenience, it is extremely
766 -- unlikely that the special processing associated with the use of this
767 -- routine is useful for the case of a discriminated type, and testing for
768 -- component overlap would be a pain.
769
770 function Is_Library_Level_Tagged_Type (Typ : Entity_Id) return Boolean;
771 -- Return True if Typ is a library level tagged type. Currently we use
772 -- this information to build statically allocated dispatch tables.
773
774 function Is_Non_BIP_Func_Call (Expr : Node_Id) return Boolean;
775 -- Determine whether node Expr denotes a non build-in-place function call
776
777 function Is_Possibly_Unaligned_Object (N : Node_Id) return Boolean;
778 -- Node N is an object reference. This function returns True if it is
779 -- possible that the object may not be aligned according to the normal
780 -- default alignment requirement for its type (e.g. if it appears in a
781 -- packed record, or as part of a component that has a component clause.)
782
783 function Is_Possibly_Unaligned_Slice (N : Node_Id) return Boolean;
784 -- Determine whether the node P is a slice of an array where the slice
785 -- result may cause alignment problems because it has an alignment that
786 -- is not compatible with the type. Return True if so.
787
788 function Is_Ref_To_Bit_Packed_Array (N : Node_Id) return Boolean;
789 -- Determine whether the node P is a reference to a bit packed array, i.e.
790 -- whether the designated object is a component of a bit packed array, or a
791 -- subcomponent of such a component. If so, then all subscripts in P are
792 -- evaluated with a call to Force_Evaluation, and True is returned.
793 -- Otherwise False is returned, and P is not affected.
794
795 function Is_Ref_To_Bit_Packed_Slice (N : Node_Id) return Boolean;
796 -- Determine whether the node P is a reference to a bit packed slice, i.e.
797 -- whether the designated object is bit packed slice or a component of a
798 -- bit packed slice. Return True if so.
799
800 function Is_Related_To_Func_Return (Id : Entity_Id) return Boolean;
801 -- Determine whether object Id is related to an expanded return statement.
802 -- The case concerned is "return Id.all;".
803
804 function Is_Renamed_Object (N : Node_Id) return Boolean;
805 -- Returns True if the node N is a renamed object. An expression is
806 -- considered to be a renamed object if either it is the Name of an object
807 -- renaming declaration, or is the prefix of a name which is a renamed
808 -- object. For example, in:
809 --
810 -- x : r renames a (1 .. 2) (1);
811 --
812 -- We consider that a (1 .. 2) is a renamed object since it is the prefix
813 -- of the name in the renaming declaration.
814
815 function Is_Secondary_Stack_BIP_Func_Call (Expr : Node_Id) return Boolean;
816 -- Determine whether Expr denotes a build-in-place function which returns
817 -- its result on the secondary stack.
818
819 function Is_Tag_To_Class_Wide_Conversion
820 (Obj_Id : Entity_Id) return Boolean;
821 -- Determine whether object Obj_Id is the result of a tag-to-class-wide
822 -- type conversion.
823
824 function Is_Untagged_Derivation (T : Entity_Id) return Boolean;
825 -- Returns true if type T is not tagged and is a derived type,
826 -- or is a private type whose completion is such a type.
827
828 function Is_Untagged_Private_Derivation
829 (Priv_Typ : Entity_Id;
830 Full_Typ : Entity_Id) return Boolean;
831 -- Determine whether private type Priv_Typ and its full view Full_Typ
832 -- represent an untagged derivation from a private parent.
833
834 function Is_Volatile_Reference (N : Node_Id) return Boolean;
835 -- Checks if the node N represents a volatile reference, which can be
836 -- either a direct reference to a variable treated as volatile, or an
837 -- indexed/selected component where the prefix is treated as volatile,
838 -- or has Volatile_Components set. A slice of a volatile variable is
839 -- also volatile.
840
841 procedure Kill_Dead_Code (N : Node_Id; Warn : Boolean := False);
842 -- N represents a node for a section of code that is known to be dead. Any
843 -- exception handler references and warning messages relating to this code
844 -- are removed. If Warn is True, a warning will be output at the start of N
845 -- indicating the deletion of the code. Note that the tree for the deleted
846 -- code is left intact so that e.g. cross-reference data is still valid.
847
848 procedure Kill_Dead_Code (L : List_Id; Warn : Boolean := False);
849 -- Like the above procedure, but applies to every element in the given
850 -- list. If Warn is True, a warning will be output at the start of N
851 -- indicating the deletion of the code.
852
853 function Known_Non_Negative (Opnd : Node_Id) return Boolean;
854 -- Given a node for a subexpression, determines if it represents a value
855 -- that cannot possibly be negative, and if so returns True. A value of
856 -- False means that it is not known if the value is positive or negative.
857
858 function Make_Invariant_Call (Expr : Node_Id) return Node_Id;
859 -- Generate a call to the Invariant_Procedure associated with the type of
860 -- expression Expr. Expr is passed as an actual parameter in the call.
861
862 function Make_Predicate_Call
863 (Typ : Entity_Id;
864 Expr : Node_Id;
865 Mem : Boolean := False) return Node_Id;
866 -- Typ is a type with Predicate_Function set. This routine builds a call to
867 -- this function passing Expr as the argument, and returns it unanalyzed.
868 -- If Mem is set True, this is the special call for the membership case,
869 -- and the function called is the Predicate_Function_M if present.
870
871 function Make_Predicate_Check
872 (Typ : Entity_Id;
873 Expr : Node_Id) return Node_Id;
874 -- Typ is a type with Predicate_Function set. This routine builds a Check
875 -- pragma whose first argument is Predicate, and the second argument is
876 -- a call to the predicate function of Typ with Expr as the argument. If
877 -- Predicate_Check is suppressed then a null statement is returned instead.
878
879 function Make_Subtype_From_Expr
880 (E : Node_Id;
881 Unc_Typ : Entity_Id;
882 Related_Id : Entity_Id := Empty) return Node_Id;
883 -- Returns a subtype indication corresponding to the actual type of an
884 -- expression E. Unc_Typ is an unconstrained array or record, or a class-
885 -- wide type. Set Related_Id to request an external name for the subtype
886 -- rather than an internal temporary.
887
888 procedure Map_Types (Parent_Type : Entity_Id; Derived_Type : Entity_Id);
889 -- Establish the following mapping between the attributes of tagged parent
890 -- type Parent_Type and tagged derived type Derived_Type.
891 --
892 -- * Map each discriminant of Parent_Type to ether the corresponding
893 -- discriminant of Derived_Type or come constraint.
894
895 -- * Map each primitive operation of Parent_Type to the corresponding
896 -- primitive of Derived_Type.
897 --
898 -- The mapping Parent_Type -> Derived_Type is also added to the table in
899 -- order to prevent subsequent attempts of the same mapping.
900
901 function Matching_Standard_Type (Typ : Entity_Id) return Entity_Id;
902 -- Given a scalar subtype Typ, returns a matching type in standard that
903 -- has the same object size value. For example, a 16 bit signed type will
904 -- typically return Standard_Short_Integer. For fixed-point types, this
905 -- will return integer types of the corresponding size.
906
907 function May_Generate_Large_Temp (Typ : Entity_Id) return Boolean;
908 -- Determines if the given type, Typ, may require a large temporary of the
909 -- kind that causes back-end trouble if stack checking is enabled. The
910 -- result is True only the size of the type is known at compile time and
911 -- large, where large is defined heuristically by the body of this routine.
912 -- The purpose of this routine is to help avoid generating troublesome
913 -- temporaries that interfere with stack checking mechanism. Note that the
914 -- caller has to check whether stack checking is actually enabled in order
915 -- to guide the expansion (typically of a function call).
916
917 function Needs_Constant_Address
918 (Decl : Node_Id;
919 Typ : Entity_Id) return Boolean;
920 -- Check whether the expression in an address clause is restricted to
921 -- consist of constants, when the object has a nontrivial initialization
922 -- or is controlled.
923
924 function Needs_Finalization (Typ : Entity_Id) return Boolean;
925 -- Determine whether type Typ is controlled and this requires finalization
926 -- actions.
927
928 function Non_Limited_Designated_Type (T : Entity_Id) return Entity_Id;
929 -- An anonymous access type may designate a limited view. Check whether
930 -- non-limited view is available during expansion, to examine components
931 -- or other characteristics of the full type.
932
933 function OK_To_Do_Constant_Replacement (E : Entity_Id) return Boolean;
934 -- This function is used when testing whether or not to replace a reference
935 -- to entity E by a known constant value. Such replacement must be done
936 -- only in a scope known to be safe for such replacements. In particular,
937 -- if we are within a subprogram and the entity E is declared outside the
938 -- subprogram then we cannot do the replacement, since we do not attempt to
939 -- trace subprogram call flow. It is also unsafe to replace statically
940 -- allocated values (since they can be modified outside the scope), and we
941 -- also inhibit replacement of Volatile or aliased objects since their
942 -- address might be captured in a way we do not detect. A value of True is
943 -- returned only if the replacement is safe.
944
945 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
946 -- This function is used during processing the assignment of a record or
947 -- indexed component. The argument N is either the left hand or right hand
948 -- side of an assignment, and this function determines if there is a record
949 -- component reference where the record may be bit aligned in a manner that
950 -- causes trouble for the back end (see Component_May_Be_Bit_Aligned for
951 -- further details).
952
953 function Power_Of_Two (N : Node_Id) return Nat;
954 -- Determines if N is a known at compile time value which is of the form
955 -- 2**K, where K is in the range 1 .. M, where the Esize of N is 2**(M+1).
956 -- If so, returns the value K, otherwise returns zero. The caller checks
957 -- that N is of an integer type.
958
959 procedure Process_Statements_For_Controlled_Objects (N : Node_Id);
960 -- N is a node which contains a non-handled statement list. Inspect the
961 -- statements looking for declarations of controlled objects. If at least
962 -- one such object is found, wrap the statement list in a block.
963
964 function Remove_Init_Call
965 (Var : Entity_Id;
966 Rep_Clause : Node_Id) return Node_Id;
967 -- Look for init_proc call or aggregate initialization statements for
968 -- variable Var, either among declarations between that of Var and a
969 -- subsequent Rep_Clause applying to Var, or in the list of freeze actions
970 -- associated with Var, and if found, remove and return that call node.
971
972 procedure Remove_Side_Effects
973 (Exp : Node_Id;
974 Name_Req : Boolean := False;
975 Renaming_Req : Boolean := False;
976 Variable_Ref : Boolean := False;
977 Related_Id : Entity_Id := Empty;
978 Is_Low_Bound : Boolean := False;
979 Is_High_Bound : Boolean := False;
980 Check_Side_Effects : Boolean := True);
981 -- Given the node for a subexpression, this function replaces the node if
982 -- necessary by an equivalent subexpression that is guaranteed to be side
983 -- effect free. This is done by extracting any actions that could cause
984 -- side effects, and inserting them using Insert_Actions into the tree
985 -- to which Exp is attached. Exp must be analyzed and resolved before the
986 -- call and is analyzed and resolved on return. Name_Req may only be set to
987 -- True if Exp has the form of a name, and the effect is to guarantee that
988 -- any replacement maintains the form of name. If Renaming_Req is set to
989 -- True, the routine produces an object renaming reclaration capturing the
990 -- expression. If Variable_Ref is set to True, a variable is considered as
991 -- side effect (used in implementing Force_Evaluation). Note: after call to
992 -- Remove_Side_Effects, it is safe to call New_Copy_Tree to obtain a copy
993 -- of the resulting expression. If Check_Side_Effects is set to True then
994 -- no action is performed if Exp is known to be side-effect free.
995 --
996 -- Related_Id denotes the entity of the context where Expr appears. Flags
997 -- Is_Low_Bound and Is_High_Bound specify whether the expression to check
998 -- is the low or the high bound of a range. These three optional arguments
999 -- signal Remove_Side_Effects to create an external symbol of the form
1000 -- Chars (Related_Id)_FIRST/_LAST. If Related_Id is set, then exactly one
1001 -- of the Is_xxx_Bound flags must be set. For use of these parameters see
1002 -- the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
1003 --
1004 -- The side effects are captured using one of the following methods:
1005 --
1006 -- 1) a constant initialized with the value of the subexpression
1007 -- 2) a renaming of the subexpression
1008 -- 3) a reference to the subexpression
1009 --
1010 -- For elementary types, methods 1) and 2) are used; for composite types,
1011 -- methods 2) and 3) are used. The renaming (method 2) is used only when
1012 -- the subexpression denotes a name, so that it can be elaborated by gigi
1013 -- without evaluating the subexpression.
1014 --
1015 -- Historical note: the reference (method 3) used to be the common fallback
1016 -- method but it gives rise to aliasing issues if the subexpression denotes
1017 -- a name that is not aliased, since it is equivalent to taking the address
1018 -- in this case. The renaming (method 2) used to be applied to any objects
1019 -- in the RM sense, that is to say to the cases where a renaming is legal
1020 -- in Ada. But for some of these cases, most notably functions calls, the
1021 -- renaming cannot be elaborated without evaluating the subexpression, so
1022 -- gigi would resort to method 1) or 3) under the hood for them.
1023
1024 procedure Replace_References
1025 (Expr : Node_Id;
1026 Par_Typ : Entity_Id;
1027 Deriv_Typ : Entity_Id;
1028 Par_Obj : Entity_Id := Empty;
1029 Deriv_Obj : Entity_Id := Empty);
1030 -- Expr denotes an arbitrary expression. Par_Typ is a tagged parent type
1031 -- in a type hierarchy. Deriv_Typ is a tagged type derived from Par_Typ
1032 -- with optional ancestors in between. Par_Obj is a formal parameter
1033 -- which emulates the current instance of Par_Typ. Deriv_Obj is a formal
1034 -- parameter which emulates the current instance of Deriv_Typ. Perform the
1035 -- following substitutions in Expr:
1036 --
1037 -- * Replace a reference to Par_Obj with a reference to Deriv_Obj
1038 --
1039 -- * Replace a reference to a discriminant of Par_Typ with a suitable
1040 -- value from the point of view of Deriv_Typ.
1041 --
1042 -- * Replace a call to an overridden primitive of Par_Typ with a call to
1043 -- an overriding primitive of Deriv_Typ.
1044 --
1045 -- * Replace a call to an inherited primitive of Par_Type with a call to
1046 -- the internally-generated inherited primitive of Deriv_Typ.
1047
1048 procedure Replace_Type_References
1049 (Expr : Node_Id;
1050 Typ : Entity_Id;
1051 Obj_Id : Entity_Id);
1052 -- Substitute all references of the current instance of type Typ with
1053 -- references to formal parameter Obj_Id within expression Expr.
1054
1055 function Represented_As_Scalar (T : Entity_Id) return Boolean;
1056 -- Returns True iff the implementation of this type in code generation
1057 -- terms is scalar. This is true for scalars in the Ada sense, and for
1058 -- packed arrays which are represented by a scalar (modular) type.
1059
1060 function Requires_Cleanup_Actions
1061 (N : Node_Id;
1062 Lib_Level : Boolean) return Boolean;
1063 -- Given a node N, determine whether its declarative and/or statement list
1064 -- contains one of the following:
1065 --
1066 -- 1) controlled objects
1067 -- 2) library-level tagged types
1068 --
1069 -- These cases require special actions on scope exit. The flag Lib_Level
1070 -- is set True if the construct is at library level, and False otherwise.
1071
1072 function Safe_Unchecked_Type_Conversion (Exp : Node_Id) return Boolean;
1073 -- Given the node for an N_Unchecked_Type_Conversion, return True if this
1074 -- is an unchecked conversion that Gigi can handle directly. Otherwise
1075 -- return False if it is one for which the front end must provide a
1076 -- temporary. Note that the node need not be analyzed, and thus the Etype
1077 -- field may not be set, but in that case it must be the case that the
1078 -- Subtype_Mark field of the node is set/analyzed.
1079
1080 procedure Set_Current_Value_Condition (Cnode : Node_Id);
1081 -- Cnode is N_If_Statement, N_Elsif_Part, or N_Iteration_Scheme (the latter
1082 -- when a WHILE condition is present). This call checks whether Condition
1083 -- (Cnode) has embedded expressions of a form that should result in setting
1084 -- the Current_Value field of one or more entities, and if so sets these
1085 -- fields to point to Cnode.
1086
1087 procedure Set_Elaboration_Flag (N : Node_Id; Spec_Id : Entity_Id);
1088 -- N is the node for a subprogram or generic body, and Spec_Id is the
1089 -- entity for the corresponding spec. If an elaboration entity is defined,
1090 -- then this procedure generates an assignment statement to set it True,
1091 -- immediately after the body is elaborated. However, no assignment is
1092 -- generated in the case of library level procedures, since the setting of
1093 -- the flag in this case is generated in the binder. We do that so that we
1094 -- can detect cases where this is the only elaboration action that is
1095 -- required.
1096
1097 procedure Set_Renamed_Subprogram (N : Node_Id; E : Entity_Id);
1098 -- N is an node which is an entity name that represents the name of a
1099 -- renamed subprogram. The node is rewritten to be an identifier that
1100 -- refers directly to the renamed subprogram, given by entity E.
1101
1102 function Side_Effect_Free
1103 (N : Node_Id;
1104 Name_Req : Boolean := False;
1105 Variable_Ref : Boolean := False) return Boolean;
1106 -- Determines if the tree N represents an expression that is known not
1107 -- to have side effects. If this function returns True, then for example
1108 -- a call to Remove_Side_Effects has no effect.
1109 --
1110 -- Name_Req controls the handling of volatile variable references. If
1111 -- Name_Req is False (the normal case), then volatile references are
1112 -- considered to be side effects. If Name_Req is True, then volatility
1113 -- of variables is ignored.
1114 --
1115 -- If Variable_Ref is True, then all variable references are considered to
1116 -- be side effects (regardless of volatility or the setting of Name_Req).
1117
1118 function Side_Effect_Free
1119 (L : List_Id;
1120 Name_Req : Boolean := False;
1121 Variable_Ref : Boolean := False) return Boolean;
1122 -- Determines if all elements of the list L are side-effect free. Name_Req
1123 -- and Variable_Ref are as described above.
1124
1125 procedure Silly_Boolean_Array_Not_Test (N : Node_Id; T : Entity_Id);
1126 -- N is the node for a boolean array NOT operation, and T is the type of
1127 -- the array. This routine deals with the silly case where the subtype of
1128 -- the boolean array is False..False or True..True, where it is required
1129 -- that a Constraint_Error exception be raised (RM 4.5.6(6)).
1130
1131 procedure Silly_Boolean_Array_Xor_Test (N : Node_Id; T : Entity_Id);
1132 -- N is the node for a boolean array XOR operation, and T is the type of
1133 -- the array. This routine deals with the silly case where the subtype of
1134 -- the boolean array is True..True, where a raise of a Constraint_Error
1135 -- exception is required (RM 4.5.6(6)).
1136
1137 function Target_Has_Fixed_Ops
1138 (Left_Typ : Entity_Id;
1139 Right_Typ : Entity_Id;
1140 Result_Typ : Entity_Id) return Boolean;
1141 -- Returns True if and only if the target machine has direct support
1142 -- for fixed-by-fixed multiplications and divisions for the given
1143 -- operand and result types. This is called in package Exp_Fixd to
1144 -- determine whether to expand such operations.
1145
1146 function Type_May_Have_Bit_Aligned_Components
1147 (Typ : Entity_Id) return Boolean;
1148 -- Determines if Typ is a composite type that has within it (looking down
1149 -- recursively at any subcomponents), a record type which has component
1150 -- that may be bit aligned (see Possible_Bit_Aligned_Component). The result
1151 -- is conservative, in that a result of False is decisive. A result of True
1152 -- means that such a component may or may not be present.
1153
1154 procedure Update_Primitives_Mapping
1155 (Inher_Id : Entity_Id;
1156 Subp_Id : Entity_Id);
1157 -- Map primitive operations of the parent type to the corresponding
1158 -- operations of the descendant. Note that the descendant type may not be
1159 -- frozen yet, so we cannot use the dispatch table directly. This is called
1160 -- when elaborating a contract for a subprogram, and when freezing a type
1161 -- extension to verify legality rules on inherited conditions.
1162
1163 function Within_Case_Or_If_Expression (N : Node_Id) return Boolean;
1164 -- Determine whether arbitrary node N is within a case or an if expression
1165
1166 function Within_Internal_Subprogram return Boolean;
1167 -- Indicates that some expansion is taking place within the body of a
1168 -- predefined primitive operation. Some expansion activity (e.g. predicate
1169 -- checks) is disabled in such. Because we want to detect invalid uses
1170 -- of function calls within predicates (which lead to infinite recursion)
1171 -- predicate functions themselves are not considered internal here.
1172
1173 private
1174 pragma Inline (Duplicate_Subexpr);
1175 pragma Inline (Force_Evaluation);
1176 pragma Inline (Is_Library_Level_Tagged_Type);
1177 end Exp_Util;