[multiple changes]

2015-05-26  Javier Miranda  <miranda@adacore.com>

	* sem_aggr.adb (Resolve_Aggregate, Resolve_Extension_Aggregate):
	Code cleanup.
	* sem_ch3.adb (Build_Derived_Record_Type,
	Record_Type_Declaration): Code cleanup.
	* sem_ch4.adb (Has_Arbitrary_Evaluation_Order,
	Stop_Subtree_Climbind): Tables which speed up the identification
	of dangerous calls to Ada 2012 functions with writable actuals
	(AI05-0144).
	(Analyze_Arithmetic_Op, Analyze_Call, Analyze_Comparison_Op,
	Analyze_Equality_Op, Analyze_Logical_Op, Analyze_Membership_Op,
	Analyze_Range): Code cleanup.
	(Is_Arbitrary_Evaluation_Order_Construct): Removed.
	(Check_Writable_Actuals): Code cleanup using the added tables.
	* sem_util.adb (Check_Function_Writable_Actuals): Return
	immediately if the node does not have the flag Check_Actuals
	set to True.

2015-05-26  Eric Botcazou  <ebotcazou@adacore.com>

	* exp_ch6.adb (Add_Call_By_Copy_Code): Remove restrictive
	condition in the detection of the effects of Remove_Side_Effects.
	* exp_util.ads (Remove_Side_Effects): Add general and historical note.
	* exp_util.adb (Is_Name_Reference): New predicate.
	(Remove_Side_Effects): Use it in lieu of Is_Object_Reference
	in order to decide whether to use the renaming to capture the
	side effects of the subexpression.
	(Side_Effect_Free): Remove obsolete test.

From-SVN: r223668

gcc/ada/ChangeLog

+2015-05-26  Javier Miranda  <miranda@adacore.com>
+
+	* sem_aggr.adb (Resolve_Aggregate, Resolve_Extension_Aggregate):
+	Code cleanup.
+	* sem_ch3.adb (Build_Derived_Record_Type,
+	Record_Type_Declaration): Code cleanup.
+	* sem_ch4.adb (Has_Arbitrary_Evaluation_Order,
+	Stop_Subtree_Climbind): Tables which speed up the identification
+	of dangerous calls to Ada 2012 functions with writable actuals
+	(AI05-0144).
+	(Analyze_Arithmetic_Op, Analyze_Call, Analyze_Comparison_Op,
+	Analyze_Equality_Op, Analyze_Logical_Op, Analyze_Membership_Op,
+	Analyze_Range): Code cleanup.
+	(Is_Arbitrary_Evaluation_Order_Construct): Removed.
+	(Check_Writable_Actuals): Code cleanup using the added tables.
+	* sem_util.adb (Check_Function_Writable_Actuals): Return
+	immediately if the node does not have the flag Check_Actuals
+	set to True.
+
+2015-05-26  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* exp_ch6.adb (Add_Call_By_Copy_Code): Remove restrictive
+	condition in the detection of the effects of Remove_Side_Effects.
+	* exp_util.ads (Remove_Side_Effects): Add general and historical note.
+	* exp_util.adb (Is_Name_Reference): New predicate.
+	(Remove_Side_Effects): Use it in lieu of Is_Object_Reference
+	in order to decide whether to use the renaming to capture the
+	side effects of the subexpression.
+	(Side_Effect_Free): Remove obsolete test.
+
 2015-05-26  Robert Dewar  <dewar@adacore.com>
 
 	* aspects.ads, aspects.adb: Add aspect Disable_Controlled.

gcc/ada/exp_ch6.adb

@@ -1257,7 +1257,6 @@ package body Exp_Ch6 is
             begin
                if Is_Renaming_Of_Object (Var)
                  and then Nkind (Renamed_Object (Var)) = N_Selected_Component
-                 and then Is_Entity_Name (Prefix (Renamed_Object (Var)))
                  and then Nkind (Original_Node (Prefix (Renamed_Object (Var))))
                    = N_Indexed_Component
                  and then

gcc/ada/exp_util.ads

@@ -872,8 +872,8 @@ package Exp_Util is
    --  call and is analyzed and resolved on return. 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 Renaming_Req is set to
-   --  TRUE, the routine produces an object renaming reclaration capturing the
-   --  expression. If Variable_Ref is set to TRUE, a variable is considered as
+   --  True, the routine produces an object renaming reclaration capturing the
+   --  expression. 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.
@@ -885,6 +885,26 @@ package Exp_Util is
    --  Chars (Related_Id)_FIRST/_LAST. If Related_Id is set, then exactly one
    --  of the Is_xxx_Bound flags must be set. For use of these parameters see
    --  the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
+   --
+   --  The side effects are captured using one of the following methods:
+   --
+   --    1) a constant initialized with the value of the subexpression
+   --    2) a renaming of the subexpression
+   --    3) a reference to the subexpression
+   --
+   --  For elementary types, methods 1) and 2) are used; for composite types,
+   --  methods 2) and 3) are used. The renaming (method 2) is used only when
+   --  the subexpression denotes a name, so that it can be elaborated by gigi
+   --  without evaluating the subexpression.
+   --
+   --  Historical note: the reference (method 3) used to be the common fallback
+   --  method but it gives rise to aliasing issues if the subexpression denotes
+   --  a name that is not aliased, since it is equivalent to taking the address
+   --  in this case. The renaming (method 2) used to be applied to any objects
+   --  in the RM sense, that is to say to the cases where a renaming is legal
+   --  in Ada. But for some of these cases, most notably functions calls, the
+   --  renaming cannot be elaborated without evaluating the subexpression, so
+   --  gigi would resort to method 1) or 3) under the hood for them.
 
    function Represented_As_Scalar (T : Entity_Id) return Boolean;
    --  Returns True iff the implementation of this type in code generation

gcc/ada/sem_aggr.adb

@@ -1161,9 +1161,7 @@ package body Sem_Aggr is
          Set_Analyzed (N);
       end if;
 
-      if Check_Actuals (N) then
-         Check_Function_Writable_Actuals (N);
-      end if;
+      Check_Function_Writable_Actuals (N);
    end Resolve_Aggregate;
 
    -----------------------------
@@ -2906,9 +2904,7 @@ package body Sem_Aggr is
          Error_Msg_N ("no unique type for this aggregate",  A);
       end if;
 
-      if Check_Actuals (N) then
-         Check_Function_Writable_Actuals (N);
-      end if;
+      Check_Function_Writable_Actuals (N);
    end Resolve_Extension_Aggregate;
 
    ------------------------------

gcc/ada/sem_ch3.adb

@@ -8955,9 +8955,7 @@ package body Sem_Ch3 is
            (Class_Wide_Type (Derived_Type), Last_Entity (Derived_Type));
       end if;
 
-      if Check_Actuals (N) then
-         Check_Function_Writable_Actuals (N);
-      end if;
+      Check_Function_Writable_Actuals (N);
    end Build_Derived_Record_Type;
 
    ------------------------
@@ -21122,9 +21120,7 @@ package body Sem_Ch3 is
          Derive_Progenitor_Subprograms (T, T);
       end if;
 
-      if Check_Actuals (N) then
-         Check_Function_Writable_Actuals (N);
-      end if;
+      Check_Function_Writable_Actuals (N);
    end Record_Type_Declaration;
 
    ----------------------------

gcc/ada/sem_util.adb

@@ -2324,11 +2324,12 @@ package body Sem_Util is
    --  Start of processing for Check_Function_Writable_Actuals
 
    begin
-      --  The check only applies to Ada 2012 code, and only to constructs that
-      --  have multiple constituents whose order of evaluation is not specified
-      --  by the language.
+      --  The check only applies to Ada 2012 code on which Check_Actuals has
+      --  been set, and only to constructs that have multiple constituents
+      --  whose order of evaluation is not specified by the language.
 
       if Ada_Version < Ada_2012
+        or else not Check_Actuals (N)
         or else (not (Nkind (N) in N_Op)
                   and then not (Nkind (N) in N_Membership_Test)
                   and then not Nkind_In (N, N_Range,