re PR ada/18819 (ACATS cdd2a02 fail at runtime)

2006-02-13  Ed Schonberg  <schonberg@adacore.com>
	    Javier Miranda  <miranda@adacore.com>
	    Eric Botcazou  <ebotcazou@adacore.com>

	* exp_util.ads, exp_util.adb (Find_Prim_Op,
	Is_Predefined_Primitive_Operation): When
	searching for the predefined equality operator, verify that operands
	have the same type.
	(Is_Predefined_Dispatching_Operation): Remove the code that looks
	for the last entity in the list of aliased subprograms. This code
	was wrong in case of renamings.
	(Set_Renamed_Subprogram): New procedure
	(Remove_Side_Effects): Replace calls to Etype (Exp) with use of the
	Exp_Type constant computed when entering this subprogram.
	(Known_Null): New function
	(OK_To_Do_Constant_Replacement): New function
	(Known_Non_Null): Check scope before believing Is_Known_Non_Null flag
	(Side_Effect_Free): An attribute reference 'Input is not free of
	side effect, unlike other attributes that are functions. (from code
	reading).
	(Remove_Side_Effects): Expressions that involve packed arrays or records
	are copied at the point of reference, and therefore must be marked as
	renamings of objects.
	(Is_Predefined_Dispatching_Operation): Return false if the operation is
	not a dispatching operation.

	PR ada/18819
	(Remove_Side_Effects): Lift enclosing type conversion nodes for
	elementary types in all cases.

From-SVN: r111069

gcc/ada/exp_util.ads

@@ -6,7 +6,7 @@
 --                                                                          --
 --                                 S p e c                                  --
 --                                                                          --
---          Copyright (C) 1992-2005, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2006, 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- --
@@ -464,10 +464,8 @@ package Exp_Util is
    --  False otherwise. True for an empty list. It is an error to call this
    --  routine with No_List as the argument.
 
-   function Is_Predefined_Dispatching_Operation
-     (Subp : Entity_Id) return Boolean;
-   --  Ada 2005 (AI-251): Determines if Subp is a predefined primitive
-   --  operation.
+   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.
@@ -527,6 +525,12 @@ package Exp_Util is
    --  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;
@@ -544,6 +548,18 @@ package Exp_Util is
    --  caller has to check whether stack checking is actually enabled in order
    --  to guide the expansion (typically of a function call).
 
+   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.
+
    procedure Remove_Side_Effects
      (Exp          : Node_Id;
       Name_Req     : Boolean := False;
@@ -583,6 +599,11 @@ package Exp_Util is
    --  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;