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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- E X P _ U T I L -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2012, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING3. If not, go to -- -- http://www.gnu.org/licenses for a complete copy of the license. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- Package containing utility procedures used throughout the expander with Exp_Tss; use Exp_Tss; with Namet; use Namet; with Rtsfind; use Rtsfind; with Sinfo; use Sinfo; with Types; use Types; with Uintp; use Uintp; package Exp_Util is ----------------------------------------------- -- Handling of Actions Associated with Nodes -- ----------------------------------------------- -- The evaluation of certain expression nodes involves the elaboration -- of associated types and other declarations, and the execution of -- statement sequences. Expansion routines generating such actions must -- find an appropriate place in the tree to hang the actions so that -- they will be evaluated at the appropriate point. -- Some cases are simple: -- For an expression occurring in a simple statement that is in a list -- of statements, the actions are simply inserted into the list before -- the associated statement. -- For an expression occurring in a declaration (declarations always -- appear in lists), the actions are similarly inserted into the list -- just before the associated declaration. -- The following special cases arise: -- For actions associated with the right operand of a short circuit -- form, the actions are first stored in the short circuit form node -- in the Actions field. The expansion of these forms subsequently -- expands the short circuit forms into if statements which can then -- be moved as described above. -- For actions appearing in the Condition expression of a while loop, -- or an elsif clause, the actions are similarly temporarily stored in -- in the node (N_Elsif_Part or N_Iteration_Scheme) associated with -- the expression using the Condition_Actions field. Subsequently, the -- expansion of these nodes rewrites the control structures involved to -- reposition the actions in normal statement sequence. -- For actions appearing in the then or else expression of a conditional -- expression, these actions are similarly placed in the node, using the -- Then_Actions or Else_Actions field as appropriate. Once again the -- expansion of the N_Conditional_Expression node rewrites the node so -- that the actions can be normally positioned. -- Basically what we do is to climb up to the tree looking for the -- proper insertion point, as described by one of the above cases, -- and then insert the appropriate action or actions. -- Note if more than one insert call is made specifying the same -- Assoc_Node, then the actions are elaborated in the order of the -- calls, and this guarantee is preserved for the special cases above. procedure Insert_Action (Assoc_Node : Node_Id; Ins_Action : Node_Id); -- Insert the action Ins_Action at the appropriate point as described -- above. The action is analyzed using the default checks after it is -- inserted. Assoc_Node is the node with which the action is associated. procedure Insert_Action (Assoc_Node : Node_Id; Ins_Action : Node_Id; Suppress : Check_Id); -- Insert the action Ins_Action at the appropriate point as described -- above. The action is analyzed using the default checks as modified -- by the given Suppress argument after it is inserted. Assoc_Node is -- the node with which the action is associated. procedure Insert_Actions (Assoc_Node : Node_Id; Ins_Actions : List_Id); -- Insert the list of action Ins_Actions at the appropriate point as -- described above. The actions are analyzed using the default checks -- after they are inserted. Assoc_Node is the node with which the actions -- are associated. Ins_Actions may be No_List, in which case the call has -- no effect. procedure Insert_Actions (Assoc_Node : Node_Id; Ins_Actions : List_Id; Suppress : Check_Id); -- Insert the list of action Ins_Actions at the appropriate point as -- described above. The actions are analyzed using the default checks -- as modified by the given Suppress argument after they are inserted. -- Assoc_Node is the node with which the actions are associated. -- Ins_Actions may be No_List, in which case the call has no effect. procedure Insert_Action_After (Assoc_Node : Node_Id; Ins_Action : Node_Id); -- Assoc_Node must be a node in a list. Same as Insert_Action but the -- action will be inserted after N in a manner that is compatible with -- the transient scope mechanism. procedure Insert_Actions_After (Assoc_Node : Node_Id; Ins_Actions : List_Id); -- Assoc_Node must be a node in a list. Same as Insert_Actions but -- actions will be inserted after N in a manner that is compatible with -- the transient scope mechanism. This procedure must be used instead -- of Insert_List_After if Assoc_Node may be in a transient scope. -- -- Implementation limitation: Assoc_Node must be a statement. We can -- generalize to expressions if there is a need but this is tricky to -- implement because of short-circuits (among other things).??? procedure Insert_Library_Level_Action (N : Node_Id); -- This procedure inserts and analyzes the node N as an action at the -- library level for the current unit (i.e. it is attached to the -- Actions field of the N_Compilation_Aux node for the main unit). procedure Insert_Library_Level_Actions (L : List_Id); -- Similar, but inserts a list of actions ----------------------- -- Other Subprograms -- ----------------------- procedure Activate_Atomic_Synchronization (N : Node_Id); -- N is a node for which atomic synchronization may be required (it is -- either an identifier, expanded name, or selected/indexed component or -- an explicit dereference). The caller has checked the basic conditions -- (atomic variable appearing and Atomic_Sync not disabled). This function -- checks if atomic synchronization is required and if so sets the flag -- and if appropriate generates a warning (in -gnatw.n mode). procedure Adjust_Condition (N : Node_Id); -- The node N is an expression whose root-type is Boolean, and which -- represents a boolean value used as a condition (i.e. a True/False -- value). This routine handles the case of C and Fortran convention -- boolean types, which have zero/non-zero semantics rather than the normal -- 0/1 semantics, and also the case of an enumeration rep clause that -- specifies a non-standard representation. On return, node N always has -- the type Standard.Boolean, with a value that is a standard Boolean -- values of 0/1 for False/True. This procedure is used in two situations. -- First, the processing for a condition field always calls -- Adjust_Condition, so that the boolean value presented to the backend is -- a standard value. Second, for the code for boolean operations such as -- AND, Adjust_Condition is called on both operands, and then the operation -- is done in the domain of Standard_Boolean, then Adjust_Result_Type is -- called on the result to possibly reset the original type. This procedure -- also takes care of validity checking if Validity_Checks = Tests. procedure Adjust_Result_Type (N : Node_Id; T : Entity_Id); -- The processing of boolean operations like AND uses the procedure -- Adjust_Condition so that it can operate on Standard.Boolean, which is -- the only boolean type on which the backend needs to be able to implement -- such operators. This means that the result is also of type -- Standard.Boolean. In general the type must be reset back to the original -- type to get proper semantics, and that is the purpose of this procedure. -- N is the node (of type Standard.Boolean), and T is the desired type. As -- an optimization, this procedure leaves the type as Standard.Boolean in -- contexts where this is permissible (in particular for Condition fields, -- and for operands of other logical operations higher up the tree). The -- call to this procedure is completely ignored if the argument N is not of -- type Boolean. procedure Append_Freeze_Action (T : Entity_Id; N : Node_Id); -- Add a new freeze action for the given type. The freeze action is -- attached to the freeze node for the type. Actions will be elaborated in -- the order in which they are added. Note that the added node is not -- analyzed. The analyze call is found in Exp_Ch13.Expand_N_Freeze_Entity. procedure Append_Freeze_Actions (T : Entity_Id; L : List_Id); -- Adds the given list of freeze actions (declarations or statements) for -- the given type. The freeze actions are attached to the freeze node for -- the type. Actions will be elaborated in the order in which they are -- added, and the actions within the list will be elaborated in list order. -- Note that the added nodes are not analyzed. The analyze call is found in -- Exp_Ch13.Expand_N_Freeze_Entity. procedure Build_Allocate_Deallocate_Proc (N : Node_Id; Is_Allocate : Boolean); -- Create a custom Allocate/Deallocate to be associated with an allocation -- or deallocation: -- -- 1) controlled objects -- 2) class-wide objects -- 3) any kind of object on a subpool -- -- N must be an allocator or the declaration of a temporary variable which -- represents the expression of the original allocator node, otherwise N -- must be a free statement. If flag Is_Allocate is set, the generated -- routine is allocate, deallocate otherwise. function Build_Runtime_Call (Loc : Source_Ptr; RE : RE_Id) return Node_Id; -- Build an N_Procedure_Call_Statement calling the given runtime entity. -- The call has no parameters. The first argument provides the location -- information for the tree and for error messages. The call node is not -- analyzed on return, the caller is responsible for analyzing it. function Build_Task_Image_Decls (Loc : Source_Ptr; Id_Ref : Node_Id; A_Type : Entity_Id; In_Init_Proc : Boolean := False) return List_Id; -- Build declaration for a variable that holds an identifying string to be -- used as a task name. Id_Ref is an identifier if the task is a variable, -- and a selected or indexed component if the task is component of an -- object. If it is an indexed component, A_Type is the corresponding array -- type. Its index types are used to build the string as an image of the -- index values. For composite types, the result includes two declarations: -- one for a generated function that computes the image without using -- concatenation, and one for the variable that holds the result. -- -- If In_Init_Proc is true, the call is part of the initialization of -- a component of a composite type, and the enclosing initialization -- procedure must be flagged as using the secondary stack. If In_Init_Proc -- is false, the call is for a stand-alone object, and the generated -- function itself must do its own cleanups. function Component_May_Be_Bit_Aligned (Comp : Entity_Id) return Boolean; -- This function is in charge of detecting record components that may -- cause trouble in the back end if an attempt is made to assign the -- component. The back end can handle such assignments with no problem if -- the components involved are small (64-bits or less) records or scalar -- items (including bit-packed arrays represented with modular types) or -- are both aligned on a byte boundary (starting on a byte boundary, and -- occupying an integral number of bytes). -- -- However, problems arise for records larger than 64 bits, or for arrays -- (other than bit-packed arrays represented with a modular type) if the -- component starts on a non-byte boundary, or does not occupy an integral -- number of bytes (i.e. there are some bits possibly shared with fields -- at the start or beginning of the component). The back end cannot handle -- loading and storing such components in a single operation. -- -- This function is used to detect the troublesome situation. it is -- conservative in the sense that it produces True unless it knows for -- sure that the component is safe (as outlined in the first paragraph -- above). The code generation for record and array assignment checks for -- trouble using this function, and if so the assignment is generated -- component-wise, which the back end is required to handle correctly. -- -- Note that in GNAT 3, the back end will reject such components anyway, -- so the hard work in checking for this case is wasted in GNAT 3, but -- it is harmless, so it is easier to do it in all cases, rather than -- conditionalize it in GNAT 5 or beyond. procedure Convert_To_Actual_Subtype (Exp : Node_Id); -- The Etype of an expression is the nominal type of the expression, -- not the actual subtype. Often these are the same, but not always. -- For example, a reference to a formal of unconstrained type has the -- unconstrained type as its Etype, but the actual subtype is obtained by -- applying the actual bounds. This routine is given an expression, Exp, -- and (if necessary), replaces it using Rewrite, with a conversion to -- the actual subtype, building the actual subtype if necessary. If the -- expression is already of the requested type, then it is unchanged. function Corresponding_Runtime_Package (Typ : Entity_Id) return RTU_Id; -- Return the id of the runtime package that will provide support for -- concurrent type Typ. Currently only protected types are supported, -- and the returned value is one of the following: -- System_Tasking_Protected_Objects -- System_Tasking_Protected_Objects_Entries -- System_Tasking_Protected_Objects_Single_Entry function Current_Sem_Unit_Declarations return List_Id; -- Return the place where it is fine to insert declarations for the -- current semantic unit. If the unit is a package body, return the -- visible declarations of the corresponding spec. For RCI stubs, this -- is necessary because the point at which they are generated may not -- be the earliest point at which they are used. function Duplicate_Subexpr (Exp : Node_Id; Name_Req : Boolean := False) return Node_Id; -- Given the node for a subexpression, this function makes a logical copy -- of the subexpression, and returns it. This is intended for use when the -- expansion of an expression needs to repeat part of it. For example, -- replacing a**2 by a*a requires two references to a which may be a -- complex subexpression. Duplicate_Subexpr guarantees not to duplicate -- side effects. If necessary, it generates actions to save the expression -- value in a temporary, inserting these actions into the tree using -- Insert_Actions with Exp as the insertion location. The original -- expression and the returned result then become references to this saved -- value. Exp must be analyzed on entry. On return, Exp is analyzed, but -- the caller is responsible for analyzing the returned copy after it is -- attached to the tree. The Name_Req flag is set to ensure that the result -- is suitable for use in a context requiring name (e.g. the prefix of an -- attribute reference). -- -- Note that if there are any run time checks in Exp, these same checks -- will be duplicated in the returned duplicated expression. The two -- following functions allow this behavior to be modified. function Duplicate_Subexpr_No_Checks (Exp : Node_Id; Name_Req : Boolean := False) return Node_Id; -- Identical in effect to Duplicate_Subexpr, except that Remove_Checks -- is called on the result, so that the duplicated expression does not -- include checks. This is appropriate for use when Exp, the original -- expression is unconditionally elaborated before the duplicated -- expression, so that there is no need to repeat any checks. function Duplicate_Subexpr_Move_Checks (Exp : Node_Id; Name_Req : Boolean := False) return Node_Id; -- Identical in effect to Duplicate_Subexpr, except that Remove_Checks is -- called on Exp after the duplication is complete, so that the original -- expression does not include checks. In this case the result returned -- (the duplicated expression) will retain the original checks. This is -- appropriate for use when the duplicated expression is sure to be -- elaborated before the original expression Exp, so that there is no need -- to repeat the checks. procedure Ensure_Defined (Typ : Entity_Id; N : Node_Id); -- This procedure ensures that type referenced by Typ is defined. For the -- case of a type other than an Itype, nothing needs to be done, since -- all such types have declaration nodes. For Itypes, an N_Itype_Reference -- node is generated and inserted at the given node N. This is typically -- used to ensure that an Itype is properly defined outside a conditional -- construct when it is referenced in more than one branch. function Entry_Names_OK return Boolean; -- Determine whether it is appropriate to dynamically allocate strings -- which represent entry [family member] names. These strings are created -- by the compiler and used by GDB. procedure Evaluate_Name (Nam : Node_Id); -- Remove the all side effects from a name which appears as part of an -- object renaming declaration. More comments are needed here that explain -- how this differs from Force_Evaluation and Remove_Side_Effects ??? procedure Evolve_And_Then (Cond : in out Node_Id; Cond1 : Node_Id); -- Rewrites Cond with the expression: Cond and then Cond1. If Cond is -- Empty, then simply returns Cond1 (this allows the use of Empty to -- initialize a series of checks evolved by this routine, with a final -- result of Empty indicating that no checks were required). The Sloc field -- of the constructed N_And_Then node is copied from Cond1. procedure Evolve_Or_Else (Cond : in out Node_Id; Cond1 : Node_Id); -- Rewrites Cond with the expression: Cond or else Cond1. If Cond is Empty, -- then simply returns Cond1 (this allows the use of Empty to initialize a -- series of checks evolved by this routine, with a final result of Empty -- indicating that no checks were required). The Sloc field of the -- constructed N_Or_Else node is copied from Cond1. procedure Expand_Subtype_From_Expr (N : Node_Id; Unc_Type : Entity_Id; Subtype_Indic : Node_Id; Exp : Node_Id); -- Build a constrained subtype from the initial value in object -- declarations and/or allocations when the type is indefinite (including -- class-wide). function Find_Init_Call (Var : Entity_Id; Rep_Clause : Node_Id) return Node_Id; -- Look for init_proc call for variable Var, either among declarations -- between that of Var and a subsequent Rep_Clause applying to Var, or -- in the list of freeze actions associated with Var, and if found, return -- that call node. function Find_Interface_ADT (T : Entity_Id; Iface : Entity_Id) return Elmt_Id; -- Ada 2005 (AI-251): Given a type T implementing the interface Iface, -- return the element of Access_Disp_Table containing the tag of the -- interface. function Find_Interface_Tag (T : Entity_Id; Iface : Entity_Id) return Entity_Id; -- Ada 2005 (AI-251): Given a type T implementing the interface Iface, -- return the record component containing the tag of Iface. function Find_Prim_Op (T : Entity_Id; Name : Name_Id) return Entity_Id; -- Find the first primitive operation of type T whose name is 'Name'. -- This function allows the use of a primitive operation which is not -- directly visible. If T is a class wide type, then the reference is -- to an operation of the corresponding root type. Raises Program_Error -- exception if no primitive operation is found. This is normally an -- internal error, but in some cases is an expected consequence of -- illegalities elsewhere. function Find_Prim_Op (T : Entity_Id; Name : TSS_Name_Type) return Entity_Id; -- Find the first primitive operation of type T whose name has the form -- indicated by the name parameter (i.e. is a type support subprogram -- with the indicated suffix). This function allows use of a primitive -- operation which is not directly visible. If T is a class wide type, -- then the reference is to an operation of the corresponding root type. -- Raises Program_Error exception if no primitive operation is found. -- This is normally an internal error, but in some cases is an expected -- consequence of illegalities elsewhere. function Find_Protection_Object (Scop : Entity_Id) return Entity_Id; -- Traverse the scope stack starting from Scop and look for an entry, -- entry family, or a subprogram that has a Protection_Object and return -- it. Raises Program_Error if no such entity is found since the context -- in which this routine is invoked should always have a protection -- object. function Find_Protection_Type (Conc_Typ : Entity_Id) return Entity_Id; -- Given a protected type or its corresponding record, find the type of -- field _object. procedure Force_Evaluation (Exp : Node_Id; Name_Req : Boolean := False); -- Force the evaluation of the expression right away. Similar behavior -- to Remove_Side_Effects when Variable_Ref is set to TRUE. That is to -- say, it removes the side-effects and captures the values of the -- variables. Remove_Side_Effects guarantees that multiple evaluations -- of the same expression won't generate multiple side effects, whereas -- Force_Evaluation further guarantees that all evaluations will yield -- the same result. function Fully_Qualified_Name_String (E : Entity_Id) return String_Id; -- Generates the string literal corresponding to the fully qualified name -- of entity E with an ASCII.NUL appended at the end of the name. procedure Generate_Poll_Call (N : Node_Id); -- If polling is active, then a call to the Poll routine is built, -- and then inserted before the given node N and analyzed. procedure Get_Current_Value_Condition (Var : Node_Id; Op : out Node_Kind; Val : out Node_Id); -- This routine processes the Current_Value field of the variable Var. If -- the Current_Value field is null or if it represents a known value, then -- on return Cond is set to N_Empty, and Val is set to Empty. -- -- The other case is when Current_Value points to an N_If_Statement or an -- N_Elsif_Part or a N_Iteration_Scheme node (see description in Einfo for -- exact details). In this case, Get_Current_Condition digs out the -- condition, and then checks if the condition is known false, known true, -- or not known at all. In the first two cases, Get_Current_Condition will -- return with Op set to the appropriate conditional operator (inverted if -- the condition is known false), and Val set to the constant value. If the -- condition is not known, then Op and Val are set for the empty case -- (N_Empty and Empty). -- -- The check for whether the condition is true/false unknown depends -- on the case: -- -- For an IF, the condition is known true in the THEN part, known false -- in any ELSIF or ELSE part, and not known outside the IF statement in -- question. -- -- For an ELSIF, the condition is known true in the ELSIF part, known -- FALSE in any subsequent ELSIF, or ELSE part, and not known before the -- ELSIF, or after the end of the IF statement. -- -- The caller can use this result to determine the value (for the case of -- N_Op_Eq), or to determine the result of some other test in other cases -- (e.g. no access check required if N_Op_Ne Null). function Get_Stream_Size (E : Entity_Id) return Uint; -- Return the stream size value of the subtype E function Has_Access_Constraint (E : Entity_Id) return Boolean; -- Given object or type E, determine if a discriminant is of an access type function Has_Following_Address_Clause (D : Node_Id) return Boolean; -- D is the node for an object declaration. This function searches the -- current declarative part to look for an address clause for the object -- being declared, and returns True if one is found. function Homonym_Number (Subp : Entity_Id) return Nat; -- Here subp is the entity for a subprogram. This routine returns the -- homonym number used to disambiguate overloaded subprograms in the same -- scope (the number is used as part of constructed names to make sure that -- they are unique). The number is the ordinal position on the Homonym -- chain, counting only entries in the current scope. If an entity is not -- overloaded, the returned number will be one. function Inside_Init_Proc return Boolean; -- Returns True if current scope is within an init proc function In_Library_Level_Package_Body (Id : Entity_Id) return Boolean; -- Given an arbitrary entity, determine whether it appears at the library -- level of a package body. function In_Unconditional_Context (Node : Node_Id) return Boolean; -- Node is the node for a statement or a component of a statement. This -- function determines if the statement appears in a context that is -- unconditionally executed, i.e. it is not within a loop or a conditional -- or a case statement etc. function Is_All_Null_Statements (L : List_Id) return Boolean; -- Return True if all the items of the list are N_Null_Statement nodes. -- False otherwise. True for an empty list. It is an error to call this -- routine with No_List as the argument. function Is_Displacement_Of_Ctrl_Function_Result (Obj_Id : Entity_Id) return Boolean; -- Determine whether Obj_Id is a source object that has been initialized by -- a controlled function call later rewritten as a class-wide conversion of -- Ada.Tags.Displace. function Is_Finalizable_Transient (Decl : Node_Id; Rel_Node : Node_Id) return Boolean; -- Determine whether declaration Decl denotes a controlled transient which -- should be finalized. Rel_Node is the related context. Even though some -- transient are controlled, they may act as renamings of other objects or -- function calls. function Is_Fully_Repped_Tagged_Type (T : Entity_Id) return Boolean; -- Tests given type T, and returns True if T is a non-discriminated tagged -- type which has a record representation clause that specifies the layout -- of all the components, including recursively components in all parent -- types. We exclude discriminated types for convenience, it is extremely -- unlikely that the special processing associated with the use of this -- routine is useful for the case of a discriminated type, and testing for -- component overlap would be a pain. function Is_Library_Level_Tagged_Type (Typ : Entity_Id) return Boolean; -- Return True if Typ is a library level tagged type. Currently we use -- this information to build statically allocated dispatch tables. function Is_Null_Access_BIP_Func_Call (Expr : Node_Id) return Boolean; -- Determine whether node Expr denotes a build-in-place function call with -- a value of "null" for extra formal BIPaccess. function Is_Non_BIP_Func_Call (Expr : Node_Id) return Boolean; -- Determine whether node Expr denotes a non build-in-place function call function Is_Ref_To_Bit_Packed_Array (N : Node_Id) return Boolean; -- Determine whether the node P is a reference to a bit packed array, i.e. -- whether the designated object is a component of a bit packed array, or a -- subcomponent of such a component. If so, then all subscripts in P are -- evaluated with a call to Force_Evaluation, and True is returned. -- Otherwise False is returned, and P is not affected. function Is_Ref_To_Bit_Packed_Slice (N : Node_Id) return Boolean; -- Determine whether the node P is a reference to a bit packed slice, i.e. -- whether the designated object is bit packed slice or a component of a -- bit packed slice. Return True if so. function Is_Related_To_Func_Return (Id : Entity_Id) return Boolean; -- Determine whether object Id is related to an expanded return statement. -- The case concerned is "return Id.all;". function Is_Possibly_Unaligned_Slice (N : Node_Id) return Boolean; -- Determine whether the node P is a slice of an array where the slice -- result may cause alignment problems because it has an alignment that -- is not compatible with the type. Return True if so. function Is_Possibly_Unaligned_Object (N : Node_Id) return Boolean; -- Node N is an object reference. This function returns True if it is -- possible that the object may not be aligned according to the normal -- default alignment requirement for its type (e.g. if it appears in a -- packed record, or as part of a component that has a component clause.) function Is_Renamed_Object (N : Node_Id) return Boolean; -- Returns True if the node N is a renamed object. An expression is -- considered to be a renamed object if either it is the Name of an object -- renaming declaration, or is the prefix of a name which is a renamed -- object. For example, in: -- -- x : r renames a (1 .. 2) (1); -- -- We consider that a (1 .. 2) is a renamed object since it is the prefix -- of the name in the renaming declaration. function Is_Tag_To_Class_Wide_Conversion (Obj_Id : Entity_Id) return Boolean; -- Determine whether object Obj_Id is the result of a tag-to-class-wide -- type conversion. function Is_Untagged_Derivation (T : Entity_Id) return Boolean; -- Returns true if type T is not tagged and is a derived type, -- or is a private type whose completion is such a type. function Is_Volatile_Reference (N : Node_Id) return Boolean; -- Checks if the node N represents a volatile reference, which can be -- either a direct reference to a variable treated as volatile, or an -- indexed/selected component where the prefix is treated as volatile, -- or has Volatile_Components set. A slice of a volatile variable is -- also volatile. function Is_VM_By_Copy_Actual (N : Node_Id) return Boolean; -- Returns True if we are compiling on VM targets and N is a node that -- requires pass-by-copy in these targets. procedure Kill_Dead_Code (N : Node_Id; Warn : Boolean := False); -- N represents a node for a section of code that is known to be dead. Any -- exception handler references and warning messages relating to this code -- are removed. If Warn is True, a warning will be output at the start of N -- indicating the deletion of the code. Note that the tree for the deleted -- code is left intact so that e.g. cross-reference data is still valid. procedure Kill_Dead_Code (L : List_Id; Warn : Boolean := False); -- Like the above procedure, but applies to every element in the given -- list. If Warn is True, a warning will be output at the start of N -- indicating the deletion of the code. function Known_Non_Negative (Opnd : Node_Id) return Boolean; -- Given a node for a subexpression, determines if it represents a value -- that cannot possibly be negative, and if so returns True. A value of -- False means that it is not known if the value is positive or negative. function Known_Non_Null (N : Node_Id) return Boolean; -- Given a node N for a subexpression of an access type, determines if -- this subexpression yields a value that is known at compile time to -- be non-null and returns True if so. Returns False otherwise. It is -- an error to call this function if N is not of an access type. function Known_Null (N : Node_Id) return Boolean; -- Given a node N for a subexpression of an access type, determines if this -- subexpression yields a value that is known at compile time to be null -- and returns True if so. Returns False otherwise. It is an error to call -- this function if N is not of an access type. function Make_Invariant_Call (Expr : Node_Id) return Node_Id; -- Expr is an object of a type which Has_Invariants set (and which thus -- also has an Invariant_Procedure set). If invariants are enabled, this -- function returns a call to the Invariant procedure passing Expr as the -- argument, and returns it unanalyzed. If invariants are not enabled, -- returns a null statement. function Make_Predicate_Call (Typ : Entity_Id; Expr : Node_Id) return Node_Id; -- Typ is a type with Predicate_Function set. This routine builds a call to -- this function passing Expr as the argument, and returns it unanalyzed. function Make_Predicate_Check (Typ : Entity_Id; Expr : Node_Id) return Node_Id; -- Typ is a type with Predicate_Function set. This routine builds a Check -- pragma whose first argument is Predicate, and the second argument is a -- call to the this predicate function with Expr as the argument. function Make_Subtype_From_Expr (E : Node_Id; Unc_Typ : Entity_Id) return Node_Id; -- Returns a subtype indication corresponding to the actual type of an -- expression E. Unc_Typ is an unconstrained array or record, or -- a classwide type. function May_Generate_Large_Temp (Typ : Entity_Id) return Boolean; -- Determines if the given type, Typ, may require a large temporary of the -- kind that causes back-end trouble if stack checking is enabled. The -- result is True only the size of the type is known at compile time and -- large, where large is defined heuristically by the body of this routine. -- The purpose of this routine is to help avoid generating troublesome -- temporaries that interfere with stack checking mechanism. Note that the -- caller has to check whether stack checking is actually enabled in order -- to guide the expansion (typically of a function call). function Needs_Constant_Address (Decl : Node_Id; Typ : Entity_Id) return Boolean; -- Check whether the expression in an address clause is restricted to -- consist of constants, when the object has a non-trivial initialization -- or is controlled. function Needs_Finalization (T : Entity_Id) return Boolean; -- True if type T is controlled, or has controlled subcomponents. Also -- True if T is a class-wide type, because some type extension might add -- controlled subcomponents, except that if pragma Restrictions -- (No_Finalization) applies, this is False for class-wide types. function Non_Limited_Designated_Type (T : Entity_Id) return Entity_Id; -- An anonymous access type may designate a limited view. Check whether -- non-limited view is available during expansion, to examine components -- or other characteristics of the full type. function OK_To_Do_Constant_Replacement (E : Entity_Id) return Boolean; -- This function is used when testing whether or not to replace a reference -- to entity E by a known constant value. Such replacement must be done -- only in a scope known to be safe for such replacements. In particular, -- if we are within a subprogram and the entity E is declared outside the -- subprogram then we cannot do the replacement, since we do not attempt to -- trace subprogram call flow. It is also unsafe to replace statically -- allocated values (since they can be modified outside the scope), and we -- also inhibit replacement of Volatile or aliased objects since their -- address might be captured in a way we do not detect. A value of True is -- returned only if the replacement is safe. function Possible_Bit_Aligned_Component (N : Node_Id) return Boolean; -- This function is used during processing the assignment of a record or -- indexed component. The argument N is either the left hand or right hand -- side of an assignment, and this function determines if there is a record -- component reference where the record may be bit aligned in a manner that -- causes trouble for the back end (see Component_May_Be_Bit_Aligned for -- further details). procedure Process_Statements_For_Controlled_Objects (N : Node_Id); -- N is a node which contains a non-handled statement list. Inspect the -- statements looking for declarations of controlled objects. If at least -- one such object is found, wrap the statement list in a block. procedure Remove_Side_Effects (Exp : Node_Id; Name_Req : Boolean := False; Variable_Ref : Boolean := False); -- Given the node for a subexpression, this function replaces the node if -- necessary by an equivalent subexpression that is guaranteed to be side -- effect free. This is done by extracting any actions that could cause -- side effects, and inserting them using Insert_Actions into the tree to -- which Exp is attached. Exp must be analyzed and resolved before the call -- and is analyzed and resolved on return. The Name_Req may only be set to -- True if Exp has the form of a name, and the effect is to guarantee that -- any replacement maintains the form of name. If Variable_Ref is set to -- TRUE, a variable is considered as side effect (used in implementing -- Force_Evaluation). Note: after call to Remove_Side_Effects, it is safe -- to call New_Copy_Tree to obtain a copy of the resulting expression. function Represented_As_Scalar (T : Entity_Id) return Boolean; -- Returns True iff the implementation of this type in code generation -- terms is scalar. This is true for scalars in the Ada sense, and for -- packed arrays which are represented by a scalar (modular) type. function Requires_Cleanup_Actions (N : Node_Id) return Boolean; -- Given a node N, determine whether its declarative and/or statement list -- contains one of the following: -- -- 1) controlled objects -- 2) library-level tagged types -- -- The above cases require special actions on scope exit. function Safe_Unchecked_Type_Conversion (Exp : Node_Id) return Boolean; -- Given the node for an N_Unchecked_Type_Conversion, return True if this -- is an unchecked conversion that Gigi can handle directly. Otherwise -- return False if it is one for which the front end must provide a -- temporary. Note that the node need not be analyzed, and thus the Etype -- field may not be set, but in that case it must be the case that the -- Subtype_Mark field of the node is set/analyzed. procedure Set_Current_Value_Condition (Cnode : Node_Id); -- Cnode is N_If_Statement, N_Elsif_Part, or N_Iteration_Scheme (the latter -- when a WHILE condition is present). This call checks whether Condition -- (Cnode) has embedded expressions of a form that should result in setting -- the Current_Value field of one or more entities, and if so sets these -- fields to point to Cnode. procedure Set_Elaboration_Flag (N : Node_Id; Spec_Id : Entity_Id); -- N is the node for a subprogram or generic body, and Spec_Id is the -- entity for the corresponding spec. If an elaboration entity is defined, -- then this procedure generates an assignment statement to set it True, -- immediately after the body is elaborated. However, no assignment is -- generated in the case of library level procedures, since the setting of -- the flag in this case is generated in the binder. We do that so that we -- can detect cases where this is the only elaboration action that is -- required. procedure Set_Renamed_Subprogram (N : Node_Id; E : Entity_Id); -- N is an node which is an entity name that represents the name of a -- renamed subprogram. The node is rewritten to be an identifier that -- refers directly to the renamed subprogram, given by entity E. procedure Silly_Boolean_Array_Not_Test (N : Node_Id; T : Entity_Id); -- N is the node for a boolean array NOT operation, and T is the type of -- the array. This routine deals with the silly case where the subtype of -- the boolean array is False..False or True..True, where it is required -- that a Constraint_Error exception be raised (RM 4.5.6(6)). procedure Silly_Boolean_Array_Xor_Test (N : Node_Id; T : Entity_Id); -- N is the node for a boolean array XOR operation, and T is the type of -- the array. This routine deals with the silly case where the subtype of -- the boolean array is True..True, where a raise of a Constraint_Error -- exception is required (RM 4.5.6(6)). function Target_Has_Fixed_Ops (Left_Typ : Entity_Id; Right_Typ : Entity_Id; Result_Typ : Entity_Id) return Boolean; -- Returns True if and only if the target machine has direct support -- for fixed-by-fixed multiplications and divisions for the given -- operand and result types. This is called in package Exp_Fixd to -- determine whether to expand such operations. function Type_May_Have_Bit_Aligned_Components (Typ : Entity_Id) return Boolean; -- Determines if Typ is a composite type that has within it (looking down -- recursively at any subcomponents), a record type which has component -- that may be bit aligned (see Possible_Bit_Aligned_Component). The result -- is conservative, in that a result of False is decisive. A result of True -- means that such a component may or may not be present. procedure Wrap_Cleanup_Procedure (N : Node_Id); -- Given an N_Subprogram_Body node, this procedure adds an Abort_Defer call -- at the start of the statement sequence, and an Abort_Undefer call at the -- end of the statement sequence. All cleanup routines (i.e. those that are -- called from "at end" handlers) must defer abort on entry and undefer -- abort on exit. Note that it is assumed that the code for the procedure -- does not contain any return statements which would allow the flow of -- control to escape doing the undefer call. private pragma Inline (Duplicate_Subexpr); pragma Inline (Force_Evaluation); pragma Inline (Is_Library_Level_Tagged_Type); end Exp_Util;
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