Implement -mmemcpy-strategy= and -mmemset-strategy= options
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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) 1992-2013, 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 ------------------------------------------------------------------------------
26 -- Package containing utility procedures used throughout the expander
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;
35 package Exp_Util is
37 -----------------------------------------------
38 -- Handling of Actions Associated with Nodes --
39 -----------------------------------------------
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.
47 -- Some cases are simple:
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.
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.
57 -- The following special cases arise:
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
131 procedure Insert_Actions_After
132 (Assoc_Node : Node_Id;
133 Ins_Actions : List_Id);
134 -- Assoc_Node must be a node in a list. Same as Insert_Actions but
135 -- actions will be inserted after N in a manner that is compatible with
136 -- the transient scope mechanism. This procedure must be used instead
137 -- of Insert_List_After if Assoc_Node may be in a transient scope.
139 -- Implementation limitation: Assoc_Node must be a statement. We can
140 -- generalize to expressions if there is a need but this is tricky to
141 -- implement because of short-circuits (among other things).???
143 procedure Insert_Library_Level_Action (N : Node_Id);
144 -- This procedure inserts and analyzes the node N as an action at the
145 -- library level for the current unit (i.e. it is attached to the
146 -- Actions field of the N_Compilation_Aux node for the main unit).
148 procedure Insert_Library_Level_Actions (L : List_Id);
149 -- Similar, but inserts a list of actions
151 -----------------------
152 -- Other Subprograms --
153 -----------------------
155 procedure Activate_Atomic_Synchronization (N : Node_Id);
156 -- N is a node for which atomic synchronization may be required (it is
157 -- either an identifier, expanded name, or selected/indexed component or
158 -- an explicit dereference). The caller has checked the basic conditions
159 -- (atomic variable appearing and Atomic_Sync not disabled). This function
160 -- checks if atomic synchronization is required and if so sets the flag
161 -- and if appropriate generates a warning (in -gnatw.n mode).
163 procedure Adjust_Condition (N : Node_Id);
164 -- The node N is an expression whose root-type is Boolean, and which
165 -- represents a boolean value used as a condition (i.e. a True/False
166 -- value). This routine handles the case of C and Fortran convention
167 -- boolean types, which have zero/non-zero semantics rather than the normal
168 -- 0/1 semantics, and also the case of an enumeration rep clause that
169 -- specifies a non-standard representation. On return, node N always has
170 -- the type Standard.Boolean, with a value that is a standard Boolean
171 -- values of 0/1 for False/True. This procedure is used in two situations.
172 -- First, the processing for a condition field always calls
173 -- Adjust_Condition, so that the boolean value presented to the backend is
174 -- a standard value. Second, for the code for boolean operations such as
175 -- AND, Adjust_Condition is called on both operands, and then the operation
176 -- is done in the domain of Standard_Boolean, then Adjust_Result_Type is
177 -- called on the result to possibly reset the original type. This procedure
178 -- also takes care of validity checking if Validity_Checks = Tests.
180 procedure Adjust_Result_Type (N : Node_Id; T : Entity_Id);
181 -- The processing of boolean operations like AND uses the procedure
182 -- Adjust_Condition so that it can operate on Standard.Boolean, which is
183 -- the only boolean type on which the backend needs to be able to implement
184 -- such operators. This means that the result is also of type
185 -- Standard.Boolean. In general the type must be reset back to the original
186 -- type to get proper semantics, and that is the purpose of this procedure.
187 -- N is the node (of type Standard.Boolean), and T is the desired type. As
188 -- an optimization, this procedure leaves the type as Standard.Boolean in
189 -- contexts where this is permissible (in particular for Condition fields,
190 -- and for operands of other logical operations higher up the tree). The
191 -- call to this procedure is completely ignored if the argument N is not of
192 -- type Boolean.
194 procedure Append_Freeze_Action (T : Entity_Id; N : Node_Id);
195 -- Add a new freeze action for the given type. The freeze action is
196 -- attached to the freeze node for the type. Actions will be elaborated in
197 -- the order in which they are added. Note that the added node is not
198 -- analyzed. The analyze call is found in Exp_Ch13.Expand_N_Freeze_Entity.
200 procedure Append_Freeze_Actions (T : Entity_Id; L : List_Id);
201 -- Adds the given list of freeze actions (declarations or statements) for
202 -- the given type. The freeze actions are attached to the freeze node for
203 -- the type. Actions will be elaborated in the order in which they are
204 -- added, and the actions within the list will be elaborated in list order.
205 -- Note that the added nodes are not analyzed. The analyze call is found in
206 -- Exp_Ch13.Expand_N_Freeze_Entity.
208 procedure Build_Allocate_Deallocate_Proc
209 (N : Node_Id;
210 Is_Allocate : Boolean);
211 -- Create a custom Allocate/Deallocate to be associated with an allocation
212 -- or deallocation:
214 -- 1) controlled objects
215 -- 2) class-wide objects
216 -- 3) any kind of object on a subpool
218 -- N must be an allocator or the declaration of a temporary variable which
219 -- represents the expression of the original allocator node, otherwise N
220 -- must be a free statement. If flag Is_Allocate is set, the generated
221 -- routine is allocate, deallocate otherwise.
223 function Build_Runtime_Call (Loc : Source_Ptr; RE : RE_Id) return Node_Id;
224 -- Build an N_Procedure_Call_Statement calling the given runtime entity.
225 -- The call has no parameters. The first argument provides the location
226 -- information for the tree and for error messages. The call node is not
227 -- analyzed on return, the caller is responsible for analyzing it.
229 function Build_Task_Image_Decls
230 (Loc : Source_Ptr;
231 Id_Ref : Node_Id;
232 A_Type : Entity_Id;
233 In_Init_Proc : Boolean := False) return List_Id;
234 -- Build declaration for a variable that holds an identifying string to be
235 -- used as a task name. Id_Ref is an identifier if the task is a variable,
236 -- and a selected or indexed component if the task is component of an
237 -- object. If it is an indexed component, A_Type is the corresponding array
238 -- type. Its index types are used to build the string as an image of the
239 -- index values. For composite types, the result includes two declarations:
240 -- one for a generated function that computes the image without using
241 -- concatenation, and one for the variable that holds the result.
243 -- If In_Init_Proc is true, the call is part of the initialization of
244 -- a component of a composite type, and the enclosing initialization
245 -- procedure must be flagged as using the secondary stack. If In_Init_Proc
246 -- is false, the call is for a stand-alone object, and the generated
247 -- function itself must do its own cleanups.
249 function Component_May_Be_Bit_Aligned (Comp : Entity_Id) return Boolean;
250 -- This function is in charge of detecting record components that may
251 -- cause trouble in the back end if an attempt is made to assign the
252 -- component. The back end can handle such assignments with no problem if
253 -- the components involved are small (64-bits or less) records or scalar
254 -- items (including bit-packed arrays represented with modular types) or
255 -- are both aligned on a byte boundary (starting on a byte boundary, and
256 -- occupying an integral number of bytes).
258 -- However, problems arise for records larger than 64 bits, or for arrays
259 -- (other than bit-packed arrays represented with a modular type) if the
260 -- component starts on a non-byte boundary, or does not occupy an integral
261 -- number of bytes (i.e. there are some bits possibly shared with fields
262 -- at the start or beginning of the component). The back end cannot handle
263 -- loading and storing such components in a single operation.
265 -- This function is used to detect the troublesome situation. it is
266 -- conservative in the sense that it produces True unless it knows for
267 -- sure that the component is safe (as outlined in the first paragraph
268 -- above). The code generation for record and array assignment checks for
269 -- trouble using this function, and if so the assignment is generated
270 -- component-wise, which the back end is required to handle correctly.
272 -- Note that in GNAT 3, the back end will reject such components anyway,
273 -- so the hard work in checking for this case is wasted in GNAT 3, but
274 -- it is harmless, so it is easier to do it in all cases, rather than
275 -- conditionalize it in GNAT 5 or beyond.
277 procedure Convert_To_Actual_Subtype (Exp : Node_Id);
278 -- The Etype of an expression is the nominal type of the expression,
279 -- not the actual subtype. Often these are the same, but not always.
280 -- For example, a reference to a formal of unconstrained type has the
281 -- unconstrained type as its Etype, but the actual subtype is obtained by
282 -- applying the actual bounds. This routine is given an expression, Exp,
283 -- and (if necessary), replaces it using Rewrite, with a conversion to
284 -- the actual subtype, building the actual subtype if necessary. If the
285 -- expression is already of the requested type, then it is unchanged.
287 function Corresponding_Runtime_Package (Typ : Entity_Id) return RTU_Id;
288 -- Return the id of the runtime package that will provide support for
289 -- concurrent type Typ. Currently only protected types are supported,
290 -- and the returned value is one of the following:
291 -- System_Tasking_Protected_Objects
292 -- System_Tasking_Protected_Objects_Entries
293 -- System_Tasking_Protected_Objects_Single_Entry
295 function Current_Sem_Unit_Declarations return List_Id;
296 -- Return the place where it is fine to insert declarations for the
297 -- current semantic unit. If the unit is a package body, return the
298 -- visible declarations of the corresponding spec. For RCI stubs, this
299 -- is necessary because the point at which they are generated may not
300 -- be the earliest point at which they are used.
302 function Duplicate_Subexpr
303 (Exp : Node_Id;
304 Name_Req : Boolean := False) return Node_Id;
305 -- Given the node for a subexpression, this function makes a logical copy
306 -- of the subexpression, and returns it. This is intended for use when the
307 -- expansion of an expression needs to repeat part of it. For example,
308 -- replacing a**2 by a*a requires two references to a which may be a
309 -- complex subexpression. Duplicate_Subexpr guarantees not to duplicate
310 -- side effects. If necessary, it generates actions to save the expression
311 -- value in a temporary, inserting these actions into the tree using
312 -- Insert_Actions with Exp as the insertion location. The original
313 -- expression and the returned result then become references to this saved
314 -- value. Exp must be analyzed on entry. On return, Exp is analyzed, but
315 -- the caller is responsible for analyzing the returned copy after it is
316 -- attached to the tree. The Name_Req flag is set to ensure that the result
317 -- is suitable for use in a context requiring name (e.g. the prefix of an
318 -- attribute reference).
320 -- Note that if there are any run time checks in Exp, these same checks
321 -- will be duplicated in the returned duplicated expression. The two
322 -- following functions allow this behavior to be modified.
324 function Duplicate_Subexpr_No_Checks
325 (Exp : Node_Id;
326 Name_Req : Boolean := False) return Node_Id;
327 -- Identical in effect to Duplicate_Subexpr, except that Remove_Checks
328 -- is called on the result, so that the duplicated expression does not
329 -- include checks. This is appropriate for use when Exp, the original
330 -- expression is unconditionally elaborated before the duplicated
331 -- expression, so that there is no need to repeat any checks.
333 function Duplicate_Subexpr_Move_Checks
334 (Exp : Node_Id;
335 Name_Req : Boolean := False) return Node_Id;
336 -- Identical in effect to Duplicate_Subexpr, except that Remove_Checks is
337 -- called on Exp after the duplication is complete, so that the original
338 -- expression does not include checks. In this case the result returned
339 -- (the duplicated expression) will retain the original checks. This is
340 -- appropriate for use when the duplicated expression is sure to be
341 -- elaborated before the original expression Exp, so that there is no need
342 -- to repeat the checks.
344 procedure Ensure_Defined (Typ : Entity_Id; N : Node_Id);
345 -- This procedure ensures that type referenced by Typ is defined. For the
346 -- case of a type other than an Itype, nothing needs to be done, since
347 -- all such types have declaration nodes. For Itypes, an N_Itype_Reference
348 -- node is generated and inserted as an action on node N. This is typically
349 -- used to ensure that an Itype is properly defined outside a conditional
350 -- construct when it is referenced in more than one branch.
352 function Entity_Of (N : Node_Id) return Entity_Id;
353 -- Return the entity of N or Empty. If N is a renaming, return the entity
354 -- of the root renamed object.
356 function Entry_Names_OK return Boolean;
357 -- Determine whether it is appropriate to dynamically allocate strings
358 -- which represent entry [family member] names. These strings are created
359 -- by the compiler and used by GDB.
361 procedure Evaluate_Name (Nam : Node_Id);
362 -- Remove the all side effects from a name which appears as part of an
363 -- object renaming declaration. More comments are needed here that explain
364 -- how this differs from Force_Evaluation and Remove_Side_Effects ???
366 procedure Evolve_And_Then (Cond : in out Node_Id; Cond1 : Node_Id);
367 -- Rewrites Cond with the expression: Cond and then Cond1. If Cond is
368 -- Empty, then simply returns Cond1 (this allows the use of Empty to
369 -- initialize a series of checks evolved by this routine, with a final
370 -- result of Empty indicating that no checks were required). The Sloc field
371 -- of the constructed N_And_Then node is copied from Cond1.
373 procedure Evolve_Or_Else (Cond : in out Node_Id; Cond1 : Node_Id);
374 -- Rewrites Cond with the expression: Cond or else Cond1. If Cond is Empty,
375 -- then simply returns Cond1 (this allows the use of Empty to initialize a
376 -- series of checks evolved by this routine, with a final result of Empty
377 -- indicating that no checks were required). The Sloc field of the
378 -- constructed N_Or_Else node is copied from Cond1.
380 procedure Expand_Subtype_From_Expr
381 (N : Node_Id;
382 Unc_Type : Entity_Id;
383 Subtype_Indic : Node_Id;
384 Exp : Node_Id);
385 -- Build a constrained subtype from the initial value in object
386 -- declarations and/or allocations when the type is indefinite (including
387 -- class-wide).
389 function Find_Interface_ADT
390 (T : Entity_Id;
391 Iface : Entity_Id) return Elmt_Id;
392 -- Ada 2005 (AI-251): Given a type T implementing the interface Iface,
393 -- return the element of Access_Disp_Table containing the tag of the
394 -- interface.
396 function Find_Interface_Tag
397 (T : Entity_Id;
398 Iface : Entity_Id) return Entity_Id;
399 -- Ada 2005 (AI-251): Given a type T implementing the interface Iface,
400 -- return the record component containing the tag of Iface.
402 function Find_Prim_Op (T : Entity_Id; Name : Name_Id) return Entity_Id;
403 -- Find the first primitive operation of type T whose name is 'Name'.
404 -- This function allows the use of a primitive operation which is not
405 -- directly visible. If T is a class wide type, then the reference is
406 -- to an operation of the corresponding root type. Raises Program_Error
407 -- exception if no primitive operation is found. This is normally an
408 -- internal error, but in some cases is an expected consequence of
409 -- illegalities elsewhere.
411 function Find_Prim_Op
412 (T : Entity_Id;
413 Name : TSS_Name_Type) return Entity_Id;
414 -- Find the first primitive operation of type T whose name has the form
415 -- indicated by the name parameter (i.e. is a type support subprogram
416 -- with the indicated suffix). This function allows use of a primitive
417 -- operation which is not directly visible. If T is a class wide type,
418 -- then the reference is to an operation of the corresponding root type.
419 -- Raises Program_Error exception if no primitive operation is found.
420 -- This is normally an internal error, but in some cases is an expected
421 -- consequence of illegalities elsewhere.
423 function Find_Protection_Object (Scop : Entity_Id) return Entity_Id;
424 -- Traverse the scope stack starting from Scop and look for an entry,
425 -- entry family, or a subprogram that has a Protection_Object and return
426 -- it. Raises Program_Error if no such entity is found since the context
427 -- in which this routine is invoked should always have a protection
428 -- object.
430 function Find_Protection_Type (Conc_Typ : Entity_Id) return Entity_Id;
431 -- Given a protected type or its corresponding record, find the type of
432 -- field _object.
434 procedure Force_Evaluation
435 (Exp : Node_Id;
436 Name_Req : Boolean := False);
437 -- Force the evaluation of the expression right away. Similar behavior
438 -- to Remove_Side_Effects when Variable_Ref is set to TRUE. That is to
439 -- say, it removes the side-effects and captures the values of the
440 -- variables. Remove_Side_Effects guarantees that multiple evaluations
441 -- of the same expression won't generate multiple side effects, whereas
442 -- Force_Evaluation further guarantees that all evaluations will yield
443 -- the same result.
445 function Fully_Qualified_Name_String
446 (E : Entity_Id;
447 Append_NUL : Boolean := True) return String_Id;
448 -- Generates the string literal corresponding to the fully qualified name
449 -- of entity E, in all upper case, with an ASCII.NUL appended at the end
450 -- of the name if Append_NUL is True.
452 procedure Generate_Poll_Call (N : Node_Id);
453 -- If polling is active, then a call to the Poll routine is built,
454 -- and then inserted before the given node N and analyzed.
456 procedure Get_Current_Value_Condition
457 (Var : Node_Id;
458 Op : out Node_Kind;
459 Val : out Node_Id);
460 -- This routine processes the Current_Value field of the variable Var. If
461 -- the Current_Value field is null or if it represents a known value, then
462 -- on return Cond is set to N_Empty, and Val is set to Empty.
464 -- The other case is when Current_Value points to an N_If_Statement or an
465 -- N_Elsif_Part or a N_Iteration_Scheme node (see description in Einfo for
466 -- exact details). In this case, Get_Current_Condition digs out the
467 -- condition, and then checks if the condition is known false, known true,
468 -- or not known at all. In the first two cases, Get_Current_Condition will
469 -- return with Op set to the appropriate conditional operator (inverted if
470 -- the condition is known false), and Val set to the constant value. If the
471 -- condition is not known, then Op and Val are set for the empty case
472 -- (N_Empty and Empty).
474 -- The check for whether the condition is true/false unknown depends
475 -- on the case:
477 -- For an IF, the condition is known true in the THEN part, known false
478 -- in any ELSIF or ELSE part, and not known outside the IF statement in
479 -- question.
481 -- For an ELSIF, the condition is known true in the ELSIF part, known
482 -- FALSE in any subsequent ELSIF, or ELSE part, and not known before the
483 -- ELSIF, or after the end of the IF statement.
485 -- The caller can use this result to determine the value (for the case of
486 -- N_Op_Eq), or to determine the result of some other test in other cases
487 -- (e.g. no access check required if N_Op_Ne Null).
489 function Get_Stream_Size (E : Entity_Id) return Uint;
490 -- Return the stream size value of the subtype E
492 function Has_Access_Constraint (E : Entity_Id) return Boolean;
493 -- Given object or type E, determine if a discriminant is of an access type
495 function Has_Following_Address_Clause (D : Node_Id) return Boolean;
496 -- D is the node for an object declaration. This function searches the
497 -- current declarative part to look for an address clause for the object
498 -- being declared, and returns True if one is found.
500 function Homonym_Number (Subp : Entity_Id) return Nat;
501 -- Here subp is the entity for a subprogram. This routine returns the
502 -- homonym number used to disambiguate overloaded subprograms in the same
503 -- scope (the number is used as part of constructed names to make sure that
504 -- they are unique). The number is the ordinal position on the Homonym
505 -- chain, counting only entries in the current scope. If an entity is not
506 -- overloaded, the returned number will be one.
508 function Inside_Init_Proc return Boolean;
509 -- Returns True if current scope is within an init proc
511 function In_Library_Level_Package_Body (Id : Entity_Id) return Boolean;
512 -- Given an arbitrary entity, determine whether it appears at the library
513 -- level of a package body.
515 function In_Unconditional_Context (Node : Node_Id) return Boolean;
516 -- Node is the node for a statement or a component of a statement. This
517 -- function determines if the statement appears in a context that is
518 -- unconditionally executed, i.e. it is not within a loop or a conditional
519 -- or a case statement etc.
521 function Is_All_Null_Statements (L : List_Id) return Boolean;
522 -- Return True if all the items of the list are N_Null_Statement nodes.
523 -- False otherwise. True for an empty list. It is an error to call this
524 -- routine with No_List as the argument.
526 function Is_Displacement_Of_Object_Or_Function_Result
527 (Obj_Id : Entity_Id) return Boolean;
528 -- Determine whether Obj_Id is a source entity that has been initialized by
529 -- either a controlled function call or the assignment of another source
530 -- object. In both cases the initialization expression is rewritten as a
531 -- class-wide conversion of Ada.Tags.Displace.
533 function Is_Finalizable_Transient
534 (Decl : Node_Id;
535 Rel_Node : Node_Id) return Boolean;
536 -- Determine whether declaration Decl denotes a controlled transient which
537 -- should be finalized. Rel_Node is the related context. Even though some
538 -- transient are controlled, they may act as renamings of other objects or
539 -- function calls.
541 function Is_Fully_Repped_Tagged_Type (T : Entity_Id) return Boolean;
542 -- Tests given type T, and returns True if T is a non-discriminated tagged
543 -- type which has a record representation clause that specifies the layout
544 -- of all the components, including recursively components in all parent
545 -- types. We exclude discriminated types for convenience, it is extremely
546 -- unlikely that the special processing associated with the use of this
547 -- routine is useful for the case of a discriminated type, and testing for
548 -- component overlap would be a pain.
550 function Is_Library_Level_Tagged_Type (Typ : Entity_Id) return Boolean;
551 -- Return True if Typ is a library level tagged type. Currently we use
552 -- this information to build statically allocated dispatch tables.
554 function Is_Non_BIP_Func_Call (Expr : Node_Id) return Boolean;
555 -- Determine whether node Expr denotes a non build-in-place function call
557 function Is_Possibly_Unaligned_Object (N : Node_Id) return Boolean;
558 -- Node N is an object reference. This function returns True if it is
559 -- possible that the object may not be aligned according to the normal
560 -- default alignment requirement for its type (e.g. if it appears in a
561 -- packed record, or as part of a component that has a component clause.)
563 function Is_Possibly_Unaligned_Slice (N : Node_Id) return Boolean;
564 -- Determine whether the node P is a slice of an array where the slice
565 -- result may cause alignment problems because it has an alignment that
566 -- is not compatible with the type. Return True if so.
568 function Is_Ref_To_Bit_Packed_Array (N : Node_Id) return Boolean;
569 -- Determine whether the node P is a reference to a bit packed array, i.e.
570 -- whether the designated object is a component of a bit packed array, or a
571 -- subcomponent of such a component. If so, then all subscripts in P are
572 -- evaluated with a call to Force_Evaluation, and True is returned.
573 -- Otherwise False is returned, and P is not affected.
575 function Is_Ref_To_Bit_Packed_Slice (N : Node_Id) return Boolean;
576 -- Determine whether the node P is a reference to a bit packed slice, i.e.
577 -- whether the designated object is bit packed slice or a component of a
578 -- bit packed slice. Return True if so.
580 function Is_Related_To_Func_Return (Id : Entity_Id) return Boolean;
581 -- Determine whether object Id is related to an expanded return statement.
582 -- The case concerned is "return Id.all;".
584 function Is_Renamed_Object (N : Node_Id) return Boolean;
585 -- Returns True if the node N is a renamed object. An expression is
586 -- considered to be a renamed object if either it is the Name of an object
587 -- renaming declaration, or is the prefix of a name which is a renamed
588 -- object. For example, in:
590 -- x : r renames a (1 .. 2) (1);
592 -- We consider that a (1 .. 2) is a renamed object since it is the prefix
593 -- of the name in the renaming declaration.
595 function Is_Secondary_Stack_BIP_Func_Call (Expr : Node_Id) return Boolean;
596 -- Determine whether Expr denotes a build-in-place function which returns
597 -- its result on the secondary stack.
599 function Is_Tag_To_Class_Wide_Conversion
600 (Obj_Id : Entity_Id) return Boolean;
601 -- Determine whether object Obj_Id is the result of a tag-to-class-wide
602 -- type conversion.
604 function Is_Untagged_Derivation (T : Entity_Id) return Boolean;
605 -- Returns true if type T is not tagged and is a derived type,
606 -- or is a private type whose completion is such a type.
608 function Is_Volatile_Reference (N : Node_Id) return Boolean;
609 -- Checks if the node N represents a volatile reference, which can be
610 -- either a direct reference to a variable treated as volatile, or an
611 -- indexed/selected component where the prefix is treated as volatile,
612 -- or has Volatile_Components set. A slice of a volatile variable is
613 -- also volatile.
615 function Is_VM_By_Copy_Actual (N : Node_Id) return Boolean;
616 -- Returns True if we are compiling on VM targets and N is a node that
617 -- requires pass-by-copy in these targets.
619 procedure Kill_Dead_Code (N : Node_Id; Warn : Boolean := False);
620 -- N represents a node for a section of code that is known to be dead. Any
621 -- exception handler references and warning messages relating to this code
622 -- are removed. If Warn is True, a warning will be output at the start of N
623 -- indicating the deletion of the code. Note that the tree for the deleted
624 -- code is left intact so that e.g. cross-reference data is still valid.
626 procedure Kill_Dead_Code (L : List_Id; Warn : Boolean := False);
627 -- Like the above procedure, but applies to every element in the given
628 -- list. If Warn is True, a warning will be output at the start of N
629 -- indicating the deletion of the code.
631 function Known_Non_Negative (Opnd : Node_Id) return Boolean;
632 -- Given a node for a subexpression, determines if it represents a value
633 -- that cannot possibly be negative, and if so returns True. A value of
634 -- False means that it is not known if the value is positive or negative.
636 function Known_Non_Null (N : Node_Id) return Boolean;
637 -- Given a node N for a subexpression of an access type, determines if
638 -- this subexpression yields a value that is known at compile time to
639 -- be non-null and returns True if so. Returns False otherwise. It is
640 -- an error to call this function if N is not of an access type.
642 function Known_Null (N : Node_Id) return Boolean;
643 -- Given a node N for a subexpression of an access type, determines if this
644 -- subexpression yields a value that is known at compile time to be null
645 -- and returns True if so. Returns False otherwise. It is an error to call
646 -- this function if N is not of an access type.
648 function Make_Invariant_Call (Expr : Node_Id) return Node_Id;
649 -- Expr is an object of a type which Has_Invariants set (and which thus
650 -- also has an Invariant_Procedure set). If invariants are enabled, this
651 -- function returns a call to the Invariant procedure passing Expr as the
652 -- argument, and returns it unanalyzed. If invariants are not enabled,
653 -- returns a null statement.
655 function Make_Predicate_Call
656 (Typ : Entity_Id;
657 Expr : Node_Id;
658 Mem : Boolean := False) return Node_Id;
659 -- Typ is a type with Predicate_Function set. This routine builds a call to
660 -- this function passing Expr as the argument, and returns it unanalyzed.
661 -- If Mem is set True, this is the special call for the membership case,
662 -- and the function called is the Predicate_Function_M if present.
664 function Make_Predicate_Check
665 (Typ : Entity_Id;
666 Expr : Node_Id) return Node_Id;
667 -- Typ is a type with Predicate_Function set. This routine builds a Check
668 -- pragma whose first argument is Predicate, and the second argument is
669 -- a call to the predicate function of Typ with Expr as the argument. If
670 -- Predicate_Check is suppressed then a null statement is returned instead.
672 function Make_Subtype_From_Expr
673 (E : Node_Id;
674 Unc_Typ : Entity_Id) return Node_Id;
675 -- Returns a subtype indication corresponding to the actual type of an
676 -- expression E. Unc_Typ is an unconstrained array or record, or
677 -- a classwide type.
679 function May_Generate_Large_Temp (Typ : Entity_Id) return Boolean;
680 -- Determines if the given type, Typ, may require a large temporary of the
681 -- kind that causes back-end trouble if stack checking is enabled. The
682 -- result is True only the size of the type is known at compile time and
683 -- large, where large is defined heuristically by the body of this routine.
684 -- The purpose of this routine is to help avoid generating troublesome
685 -- temporaries that interfere with stack checking mechanism. Note that the
686 -- caller has to check whether stack checking is actually enabled in order
687 -- to guide the expansion (typically of a function call).
689 function Needs_Constant_Address
690 (Decl : Node_Id;
691 Typ : Entity_Id) return Boolean;
692 -- Check whether the expression in an address clause is restricted to
693 -- consist of constants, when the object has a non-trivial initialization
694 -- or is controlled.
696 function Needs_Finalization (T : Entity_Id) return Boolean;
697 -- True if type T is controlled, or has controlled subcomponents. Also
698 -- True if T is a class-wide type, because some type extension might add
699 -- controlled subcomponents, except that if pragma Restrictions
700 -- (No_Finalization) applies, this is False for class-wide types.
702 function Non_Limited_Designated_Type (T : Entity_Id) return Entity_Id;
703 -- An anonymous access type may designate a limited view. Check whether
704 -- non-limited view is available during expansion, to examine components
705 -- or other characteristics of the full type.
707 function OK_To_Do_Constant_Replacement (E : Entity_Id) return Boolean;
708 -- This function is used when testing whether or not to replace a reference
709 -- to entity E by a known constant value. Such replacement must be done
710 -- only in a scope known to be safe for such replacements. In particular,
711 -- if we are within a subprogram and the entity E is declared outside the
712 -- subprogram then we cannot do the replacement, since we do not attempt to
713 -- trace subprogram call flow. It is also unsafe to replace statically
714 -- allocated values (since they can be modified outside the scope), and we
715 -- also inhibit replacement of Volatile or aliased objects since their
716 -- address might be captured in a way we do not detect. A value of True is
717 -- returned only if the replacement is safe.
719 function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean;
720 -- This function is used during processing the assignment of a record or
721 -- indexed component. The argument N is either the left hand or right hand
722 -- side of an assignment, and this function determines if there is a record
723 -- component reference where the record may be bit aligned in a manner that
724 -- causes trouble for the back end (see Component_May_Be_Bit_Aligned for
725 -- further details).
727 procedure Process_Statements_For_Controlled_Objects (N : Node_Id);
728 -- N is a node which contains a non-handled statement list. Inspect the
729 -- statements looking for declarations of controlled objects. If at least
730 -- one such object is found, wrap the statement list in a block.
732 function Remove_Init_Call
733 (Var : Entity_Id;
734 Rep_Clause : Node_Id) return Node_Id;
735 -- Look for init_proc call or aggregate initialization statements for
736 -- variable Var, either among declarations between that of Var and a
737 -- subsequent Rep_Clause applying to Var, or in the list of freeze actions
738 -- associated with Var, and if found, remove and return that call node.
740 procedure Remove_Side_Effects
741 (Exp : Node_Id;
742 Name_Req : Boolean := False;
743 Variable_Ref : Boolean := False);
744 -- Given the node for a subexpression, this function replaces the node if
745 -- necessary by an equivalent subexpression that is guaranteed to be side
746 -- effect free. This is done by extracting any actions that could cause
747 -- side effects, and inserting them using Insert_Actions into the tree to
748 -- which Exp is attached. Exp must be analyzed and resolved before the call
749 -- and is analyzed and resolved on return. The Name_Req may only be set to
750 -- True if Exp has the form of a name, and the effect is to guarantee that
751 -- any replacement maintains the form of name. If Variable_Ref is set to
752 -- TRUE, a variable is considered as side effect (used in implementing
753 -- Force_Evaluation). Note: after call to Remove_Side_Effects, it is safe
754 -- to call New_Copy_Tree to obtain a copy of the resulting expression.
756 function Represented_As_Scalar (T : Entity_Id) return Boolean;
757 -- Returns True iff the implementation of this type in code generation
758 -- terms is scalar. This is true for scalars in the Ada sense, and for
759 -- packed arrays which are represented by a scalar (modular) type.
761 function Requires_Cleanup_Actions
762 (N : Node_Id;
763 Lib_Level : Boolean) return Boolean;
764 -- Given a node N, determine whether its declarative and/or statement list
765 -- contains one of the following:
767 -- 1) controlled objects
768 -- 2) library-level tagged types
770 -- These cases require special actions on scope exit. The flag Lib_Level
771 -- is set True if the construct is at library level, and False otherwise.
773 function Safe_Unchecked_Type_Conversion (Exp : Node_Id) return Boolean;
774 -- Given the node for an N_Unchecked_Type_Conversion, return True if this
775 -- is an unchecked conversion that Gigi can handle directly. Otherwise
776 -- return False if it is one for which the front end must provide a
777 -- temporary. Note that the node need not be analyzed, and thus the Etype
778 -- field may not be set, but in that case it must be the case that the
779 -- Subtype_Mark field of the node is set/analyzed.
781 procedure Set_Current_Value_Condition (Cnode : Node_Id);
782 -- Cnode is N_If_Statement, N_Elsif_Part, or N_Iteration_Scheme (the latter
783 -- when a WHILE condition is present). This call checks whether Condition
784 -- (Cnode) has embedded expressions of a form that should result in setting
785 -- the Current_Value field of one or more entities, and if so sets these
786 -- fields to point to Cnode.
788 procedure Set_Elaboration_Flag (N : Node_Id; Spec_Id : Entity_Id);
789 -- N is the node for a subprogram or generic body, and Spec_Id is the
790 -- entity for the corresponding spec. If an elaboration entity is defined,
791 -- then this procedure generates an assignment statement to set it True,
792 -- immediately after the body is elaborated. However, no assignment is
793 -- generated in the case of library level procedures, since the setting of
794 -- the flag in this case is generated in the binder. We do that so that we
795 -- can detect cases where this is the only elaboration action that is
796 -- required.
798 procedure Set_Renamed_Subprogram (N : Node_Id; E : Entity_Id);
799 -- N is an node which is an entity name that represents the name of a
800 -- renamed subprogram. The node is rewritten to be an identifier that
801 -- refers directly to the renamed subprogram, given by entity E.
803 procedure Silly_Boolean_Array_Not_Test (N : Node_Id; T : Entity_Id);
804 -- N is the node for a boolean array NOT operation, and T is the type of
805 -- the array. This routine deals with the silly case where the subtype of
806 -- the boolean array is False..False or True..True, where it is required
807 -- that a Constraint_Error exception be raised (RM 4.5.6(6)).
809 procedure Silly_Boolean_Array_Xor_Test (N : Node_Id; T : Entity_Id);
810 -- N is the node for a boolean array XOR operation, and T is the type of
811 -- the array. This routine deals with the silly case where the subtype of
812 -- the boolean array is True..True, where a raise of a Constraint_Error
813 -- exception is required (RM 4.5.6(6)).
815 function Target_Has_Fixed_Ops
816 (Left_Typ : Entity_Id;
817 Right_Typ : Entity_Id;
818 Result_Typ : Entity_Id) return Boolean;
819 -- Returns True if and only if the target machine has direct support
820 -- for fixed-by-fixed multiplications and divisions for the given
821 -- operand and result types. This is called in package Exp_Fixd to
822 -- determine whether to expand such operations.
824 function Type_May_Have_Bit_Aligned_Components
825 (Typ : Entity_Id) return Boolean;
826 -- Determines if Typ is a composite type that has within it (looking down
827 -- recursively at any subcomponents), a record type which has component
828 -- that may be bit aligned (see Possible_Bit_Aligned_Component). The result
829 -- is conservative, in that a result of False is decisive. A result of True
830 -- means that such a component may or may not be present.
832 function Within_Case_Or_If_Expression (N : Node_Id) return Boolean;
833 -- Determine whether arbitrary node N is within a case or an if expression
835 procedure Wrap_Cleanup_Procedure (N : Node_Id);
836 -- Given an N_Subprogram_Body node, this procedure adds an Abort_Defer call
837 -- at the start of the statement sequence, and an Abort_Undefer call at the
838 -- end of the statement sequence. All cleanup routines (i.e. those that are
839 -- called from "at end" handlers) must defer abort on entry and undefer
840 -- abort on exit. Note that it is assumed that the code for the procedure
841 -- does not contain any return statements which would allow the flow of
842 -- control to escape doing the undefer call.
844 private
845 pragma Inline (Duplicate_Subexpr);
846 pragma Inline (Force_Evaluation);
847 pragma Inline (Is_Library_Level_Tagged_Type);
848 end Exp_Util;