639 lines
35 KiB
Ada
639 lines
35 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- E X P _ U T I L --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2007, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNAT; see file COPYING3. If not, go to --
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-- http://www.gnu.org/licenses for a complete copy of the license. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- Package containing utility procedures used throughout the expander
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with Exp_Tss; use Exp_Tss;
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with Namet; use Namet;
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with Rtsfind; use Rtsfind;
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with Sinfo; use Sinfo;
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with Types; use Types;
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package Exp_Util is
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-----------------------------------------------
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-- Handling of Actions Associated with Nodes --
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-----------------------------------------------
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-- The evaluation of certain expression nodes involves the elaboration
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-- of associated types and other declarations, and the execution of
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-- statement sequences. Expansion routines generating such actions must
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-- find an appropriate place in the tree to hang the actions so that
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-- they will be evaluated at the appropriate point.
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-- Some cases are simple:
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-- For an expression occurring in a simple statement that is in a list
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-- of statements, the actions are simply inserted into the list before
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-- the associated statement.
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-- For an expression occurring in a declaration (declarations always
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-- appear in lists), the actions are similarly inserted into the list
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-- just before the associated declaration.
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-- The following special cases arise:
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-- For actions associated with the right operand of a short circuit
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-- form, the actions are first stored in the short circuit form node
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-- in the Actions field. The expansion of these forms subsequently
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-- expands the short circuit forms into if statements which can then
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-- be moved as described above.
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-- For actions appearing in the Condition expression of a while loop,
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-- or an elsif clause, the actions are similarly temporarily stored in
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-- in the node (N_Elsif_Part or N_Iteration_Scheme) associated with
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-- the expression using the Condition_Actions field. Subsequently, the
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-- expansion of these nodes rewrites the control structures involved to
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-- reposition the actions in normal statement sequence.
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-- For actions appearing in the then or else expression of a conditional
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-- expression, these actions are similarly placed in the node, using the
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-- Then_Actions or Else_Actions field as appropriate. Once again the
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-- expansion of the N_Conditional_Expression node rewrites the node so
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-- that the actions can be normally positioned.
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-- Basically what we do is to climb up to the tree looking for the
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-- proper insertion point, as described by one of the above cases,
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-- and then insert the appropriate action or actions.
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-- Note if more than one insert call is made specifying the same
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-- Assoc_Node, then the actions are elaborated in the order of the
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-- calls, and this guarantee is preserved for the special cases above.
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procedure Insert_Action
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(Assoc_Node : Node_Id;
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Ins_Action : Node_Id);
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-- Insert the action Ins_Action at the appropriate point as described
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-- above. The action is analyzed using the default checks after it is
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-- inserted. Assoc_Node is the node with which the action is associated.
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procedure Insert_Action
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(Assoc_Node : Node_Id;
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Ins_Action : Node_Id;
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Suppress : Check_Id);
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-- Insert the action Ins_Action at the appropriate point as described
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-- above. The action is analyzed using the default checks as modified
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-- by the given Suppress argument after it is inserted. Assoc_Node is
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-- the node with which the action is associated.
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procedure Insert_Actions
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(Assoc_Node : Node_Id;
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Ins_Actions : List_Id);
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-- Insert the list of action Ins_Actions at the appropriate point as
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-- described above. The actions are analyzed using the default checks
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-- after they are inserted. Assoc_Node is the node with which the actions
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-- are associated. Ins_Actions may be No_List, in which case the call has
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-- no effect.
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procedure Insert_Actions
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(Assoc_Node : Node_Id;
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Ins_Actions : List_Id;
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Suppress : Check_Id);
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-- Insert the list of action Ins_Actions at the appropriate point as
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-- described above. The actions are analyzed using the default checks
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-- as modified by the given Suppress argument after they are inserted.
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-- Assoc_Node is the node with which the actions are associated.
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-- Ins_Actions may be No_List, in which case the call has no effect.
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procedure Insert_Actions_After
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(Assoc_Node : Node_Id;
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Ins_Actions : List_Id);
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-- Assoc_Node must be a node in a list. Same as Insert_Actions but
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-- actions will be inserted after N in a manner that is compatible with
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-- the transient scope mechanism. This procedure must be used instead
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-- of Insert_List_After if Assoc_Node may be in a transient scope.
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--
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-- Implementation limitation: Assoc_Node must be a statement. We can
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-- generalize to expressions if there is a need but this is tricky to
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-- implement because of short-circuits (among other things).???
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procedure Insert_Library_Level_Action (N : Node_Id);
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-- This procedure inserts and analyzes the node N as an action at the
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-- library level for the current unit (i.e. it is attached to the
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-- Actions field of the N_Compilation_Aux node for the main unit).
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procedure Insert_Library_Level_Actions (L : List_Id);
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-- Similar, but inserts a list of actions
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-----------------------
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-- Other Subprograms --
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-----------------------
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procedure Adjust_Condition (N : Node_Id);
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-- The node N is an expression whose root-type is Boolean, and which
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-- represents a boolean value used as a condition (i.e. a True/False
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-- value). This routine handles the case of C and Fortran convention
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-- boolean types, which have zero/non-zero semantics rather than the normal
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-- 0/1 semantics, and also the case of an enumeration rep clause that
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-- specifies a non-standard representation. On return, node N always has
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-- the type Standard.Boolean, with a value that is a standard Boolean
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-- values of 0/1 for False/True. This procedure is used in two situations.
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-- First, the processing for a condition field always calls
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-- Adjust_Condition, so that the boolean value presented to the backend is
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-- a standard value. Second, for the code for boolean operations such as
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-- AND, Adjust_Condition is called on both operands, and then the operation
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-- is done in the domain of Standard_Boolean, then Adjust_Result_Type is
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-- called on the result to possibly reset the original type. This procedure
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-- also takes care of validity checking if Validity_Checks = Tests.
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procedure Adjust_Result_Type (N : Node_Id; T : Entity_Id);
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-- The processing of boolean operations like AND uses the procedure
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-- Adjust_Condition so that it can operate on Standard.Boolean, which is
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-- the only boolean type on which the backend needs to be able to implement
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-- such operators. This means that the result is also of type
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-- Standard.Boolean. In general the type must be reset back to the original
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-- type to get proper semantics, and that is the purpose of this procedure.
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-- N is the node (of type Standard.Boolean), and T is the desired type. As
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-- an optimization, this procedure leaves the type as Standard.Boolean in
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-- contexts where this is permissible (in particular for Condition fields,
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-- and for operands of other logical operations higher up the tree). The
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-- call to this procedure is completely ignored if the argument N is not of
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-- type Boolean.
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procedure Append_Freeze_Action (T : Entity_Id; N : Node_Id);
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-- Add a new freeze action for the given type. The freeze action is
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-- attached to the freeze node for the type. Actions will be elaborated in
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-- the order in which they are added. Note that the added node is not
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-- analyzed. The analyze call is found in Exp_Ch13.Expand_N_Freeze_Entity.
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procedure Append_Freeze_Actions (T : Entity_Id; L : List_Id);
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-- Adds the given list of freeze actions (declarations or statements) for
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-- the given type. The freeze actions are attached to the freeze node for
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-- the type. Actions will be elaborated in the order in which they are
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-- added, and the actions within the list will be elaborated in list order.
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-- Note that the added nodes are not analyzed. The analyze call is found in
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-- Exp_Ch13.Expand_N_Freeze_Entity.
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function Build_Runtime_Call (Loc : Source_Ptr; RE : RE_Id) return Node_Id;
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-- Build an N_Procedure_Call_Statement calling the given runtime entity.
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-- The call has no parameters. The first argument provides the location
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-- information for the tree and for error messages. The call node is not
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-- analyzed on return, the caller is responsible for analyzing it.
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function Build_Task_Image_Decls
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(Loc : Source_Ptr;
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Id_Ref : Node_Id;
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A_Type : Entity_Id;
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In_Init_Proc : Boolean := False) return List_Id;
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-- Build declaration for a variable that holds an identifying string to be
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-- used as a task name. Id_Ref is an identifier if the task is a variable,
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-- and a selected or indexed component if the task is component of an
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-- object. If it is an indexed component, A_Type is the corresponding array
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-- type. Its index types are used to build the string as an image of the
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-- index values. For composite types, the result includes two declarations:
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-- one for a generated function that computes the image without using
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-- concatenation, and one for the variable that holds the result.
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-- If In_Init_Proc is true, the call is part of the initialization of
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-- a component of a composite type, and the enclosing initialization
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-- procedure must be flagged as using the secondary stack. If In_Init_Proc
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-- is false, the call is for a stand-alone object, and the generated
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-- function itself must do its own cleanups.
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function Component_May_Be_Bit_Aligned (Comp : Entity_Id) return Boolean;
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-- This function is in charge of detecting record components that may cause
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-- trouble in the back end if an attempt is made to assign the component.
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-- The back end can handle such assignments with no problem if the
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-- components involved are small (64-bits or less) records or scalar items
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-- (including bit-packed arrays represented with modular types) or are both
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-- aligned on a byte boundary (starting on a byte boundary, and occupying
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-- an integral number of bytes).
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--
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-- However, problems arise for records larger than 64 bits, or for arrays
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-- (other than bit-packed arrays represented with a modular type) if the
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-- component starts on a non-byte boundary, or does not occupy an integral
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-- number of bytes (i.e. there are some bits possibly shared with fields at
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-- the start or beginning of the component). The back end cannot handle
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-- loading and storing such components in a single operation.
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--
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-- This function is used to detect the troublesome situation. it is
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-- conservative in the sense that it produces True unless it knows for sure
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-- that the component is safe (as outlined in the first paragraph above).
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-- The code generation for record and array assignment checks for trouble
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-- using this function, and if so the assignment is generated
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-- component-wise, which the back end is required to handle correctly.
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--
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-- Note that in GNAT 3, the back end will reject such components anyway, so
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-- the hard work in checking for this case is wasted in GNAT 3, but it's
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-- harmless, so it is easier to do it in all cases, rather than
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-- conditionalize it in GNAT 5 or beyond.
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procedure Convert_To_Actual_Subtype (Exp : Node_Id);
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-- The Etype of an expression is the nominal type of the expression, not
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-- the actual subtype. Often these are the same, but not always. For
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-- example, a reference to a formal of unconstrained type has the
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-- unconstrained type as its Etype, but the actual subtype is obtained by
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-- applying the actual bounds. This routine is given an expression, Exp,
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-- and (if necessary), replaces it using Rewrite, with a conversion to the
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-- actual subtype, building the actual subtype if necessary. If the
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-- expression is already of the requested type, then it is unchanged.
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function Current_Sem_Unit_Declarations return List_Id;
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-- Return the a place where it is fine to insert declarations for the
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-- current semantic unit. If the unit is a package body, return the
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-- visible declarations of the corresponding spec. For RCI stubs, this
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-- is necessary because the point at which they are generated may not
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-- be the earliest point at which they are used.
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function Duplicate_Subexpr
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(Exp : Node_Id;
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Name_Req : Boolean := False) return Node_Id;
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-- Given the node for a subexpression, this function makes a logical copy
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-- of the subexpression, and returns it. This is intended for use when the
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-- expansion of an expression needs to repeat part of it. For example,
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-- replacing a**2 by a*a requires two references to a which may be a
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-- complex subexpression. Duplicate_Subexpr guarantees not to duplicate
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-- side effects. If necessary, it generates actions to save the expression
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-- value in a temporary, inserting these actions into the tree using
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-- Insert_Actions with Exp as the insertion location. The original
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-- expression and the returned result then become references to this saved
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-- value. Exp must be analyzed on entry. On return, Exp is analyzed, but
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-- the caller is responsible for analyzing the returned copy after it is
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-- attached to the tree. The Name_Req flag is set to ensure that the result
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-- is suitable for use in a context requiring name (e.g. the prefix of an
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-- attribute reference).
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--
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-- Note that if there are any run time checks in Exp, these same checks
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-- will be duplicated in the returned duplicated expression. The two
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-- following functions allow this behavior to be modified.
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function Duplicate_Subexpr_No_Checks
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(Exp : Node_Id;
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Name_Req : Boolean := False) return Node_Id;
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-- Identical in effect to Duplicate_Subexpr, except that Remove_Checks
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-- is called on the result, so that the duplicated expression does not
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-- include checks. This is appropriate for use when Exp, the original
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-- expression is unconditionally elaborated before the duplicated
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-- expression, so that there is no need to repeat any checks.
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function Duplicate_Subexpr_Move_Checks
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(Exp : Node_Id;
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Name_Req : Boolean := False) return Node_Id;
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-- Identical in effect to Duplicate_Subexpr, except that Remove_Checks is
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-- called on Exp after the duplication is complete, so that the original
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-- expression does not include checks. In this case the result returned
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-- (the duplicated expression) will retain the original checks. This is
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-- appropriate for use when the duplicated expression is sure to be
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-- elaborated before the original expression Exp, so that there is no need
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-- to repeat the checks.
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procedure Ensure_Defined (Typ : Entity_Id; N : Node_Id);
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-- This procedure ensures that type referenced by Typ is defined. For the
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-- case of a type other than an Itype, nothing needs to be done, since
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-- all such types have declaration nodes. For Itypes, an N_Itype_Reference
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-- node is generated and inserted at the given node N. This is typically
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-- used to ensure that an Itype is properly defined outside a conditional
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-- construct when it is referenced in more than one branch.
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procedure Evolve_And_Then (Cond : in out Node_Id; Cond1 : Node_Id);
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-- Rewrites Cond with the expression: Cond and then Cond1. If Cond is
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-- Empty, then simply returns Cond1 (this allows the use of Empty to
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-- initialize a series of checks evolved by this routine, with a final
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-- result of Empty indicating that no checks were required). The Sloc field
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-- of the constructed N_And_Then node is copied from Cond1.
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procedure Evolve_Or_Else (Cond : in out Node_Id; Cond1 : Node_Id);
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-- Rewrites Cond with the expression: Cond or else Cond1. If Cond is Empty,
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-- then simply returns Cond1 (this allows the use of Empty to initialize a
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-- series of checks evolved by this routine, with a final result of Empty
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-- indicating that no checks were required). The Sloc field of the
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-- constructed N_Or_Else node is copied from Cond1.
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procedure Expand_Subtype_From_Expr
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(N : Node_Id;
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Unc_Type : Entity_Id;
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Subtype_Indic : Node_Id;
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Exp : Node_Id);
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-- Build a constrained subtype from the initial value in object
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-- declarations and/or allocations when the type is indefinite (including
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-- class-wide).
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function Find_Interface
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(T : Entity_Id;
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Comp : Entity_Id) return Entity_Id;
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-- Ada 2005 (AI-251): Given a tagged type and one of its components
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-- associated with the secondary dispatch table of an abstract interface
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-- type, return the associated abstract interface type.
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function Find_Interface_ADT
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(T : Entity_Id;
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Iface : Entity_Id) return Elmt_Id;
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-- Ada 2005 (AI-251): Given a type T implementing the interface Iface,
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-- return the element of Access_Disp_Table containing the tag of the
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-- interface.
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function Find_Interface_Tag
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(T : Entity_Id;
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Iface : Entity_Id) return Entity_Id;
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-- Ada 2005 (AI-251): Given a type T implementing the interface Iface,
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-- return the record component containing the tag of Iface.
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function Find_Prim_Op (T : Entity_Id; Name : Name_Id) return Entity_Id;
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-- Find the first primitive operation of type T whose name is 'Name'.
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-- This function allows the use of a primitive operation which is not
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-- directly visible. If T is a class wide type, then the reference is
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-- to an operation of the corresponding root type.
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function Find_Prim_Op
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(T : Entity_Id;
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Name : TSS_Name_Type) return Entity_Id;
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-- Find the first primitive operation of type T whose name has the form
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-- indicated by the name parameter (i.e. is a type support subprogram
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-- with the indicated suffix). This function allows use of a primitive
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-- operation which is not directly visible. If T is a class wide type,
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-- then the reference is to an operation of the corresponding root type.
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procedure Force_Evaluation
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(Exp : Node_Id;
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Name_Req : Boolean := False);
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-- Force the evaluation of the expression right away. Similar behavior
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-- to Remove_Side_Effects when Variable_Ref is set to TRUE. That is to
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-- say, it removes the side-effects and capture the values of the
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-- variables. Remove_Side_Effects guarantees that multiple evaluations
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-- of the same expression won't generate multiple side effects, whereas
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-- Force_Evaluation further guarantees that all evaluations will yield
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-- the same result.
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procedure Generate_Poll_Call (N : Node_Id);
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-- If polling is active, then a call to the Poll routine is built,
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-- and then inserted before the given node N and analyzed.
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procedure Get_Current_Value_Condition
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(Var : Node_Id;
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Op : out Node_Kind;
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Val : out Node_Id);
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-- This routine processes the Current_Value field of the variable Var. If
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-- the Current_Value field is null or if it represents a known value, then
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-- on return Cond is set to N_Empty, and Val is set to Empty.
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--
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-- The other case is when Current_Value points to an N_If_Statement or an
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-- N_Elsif_Part or a N_Iteration_Scheme node (see description in Einfo for
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-- exact details). In this case, Get_Current_Condition digs out the
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-- condition, and then checks if the condition is known false, known true,
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-- or not known at all. In the first two cases, Get_Current_Condition will
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-- return with Op set to the appropriate conditional operator (inverted if
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-- the condition is known false), and Val set to the constant value. If the
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-- condition is not known, then Op and Val are set for the empty case
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-- (N_Empty and Empty).
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--
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-- The check for whether the condition is true/false unknown depends
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-- on the case:
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--
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-- For an IF, the condition is known true in the THEN part, known false
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-- in any ELSIF or ELSE part, and not known outside the IF statement in
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-- question.
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--
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-- For an ELSIF, the condition is known true in the ELSIF part, known
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-- FALSE in any subsequent ELSIF, or ELSE part, and not known before the
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-- ELSIF, or after the end of the IF statement.
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--
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-- The caller can use this result to determine the value (for the case of
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-- N_Op_Eq), or to determine the result of some other test in other cases
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-- (e.g. no access check required if N_Op_Ne Null).
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function Has_Controlled_Coextensions (Typ : Entity_Id) return Boolean;
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-- Determine whether a record type has anonymous access discriminants with
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-- a controlled designated type.
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function Homonym_Number (Subp : Entity_Id) return Nat;
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-- Here subp is the entity for a subprogram. This routine returns the
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-- homonym number used to disambiguate overloaded subprograms in the same
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-- scope (the number is used as part of constructed names to make sure that
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-- they are unique). The number is the ordinal position on the Homonym
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-- chain, counting only entries in the curren scope. If an entity is not
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-- overloaded, the returned number will be one.
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function Inside_Init_Proc return Boolean;
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-- Returns True if current scope is within an init proc
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function In_Unconditional_Context (Node : Node_Id) return Boolean;
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-- Node is the node for a statement or a component of a statement. This
|
|
-- function deteermines 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_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_Predefined_Dispatching_Operation (E : Entity_Id) return Boolean;
|
|
-- Ada 2005 (AI-251): Determines if E is a predefined primitive operation
|
|
|
|
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_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_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.
|
|
|
|
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_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 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 in 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 description
|
|
-- of Exp_Util.Component_May_Be_Bit_Aligned for further details).
|
|
|
|
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 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.
|
|
|
|
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;
|