+2016-05-02 Javier Miranda <miranda@adacore.com>
+
+ * exp_util.ads, exp_util.adb (Force_Evaluation): Adding new formal.
+ (Remove_Side_Effects): Adding a new formal.
+ * exp_ch6.adb (Expand_Simple_Function_Return): Generating the
+ call to the _Postconditions procedure ensure that side-effects
+ are unconditionally removed.
+
+2016-05-02 Ed Schonberg <schonberg@adacore.com>
+
+ * sem_ch12.adb (Check_Formal_Package_Instance, Check_Mismatch):
+ Use original node to determine whether the declaration is for
+ a formal type declaration, to take into account that formwl
+ private types are rewritten as private extension declarations
+ to simplify semantic analysis.
+
2016-05-02 Gary Dismukes <dismukes@adacore.com>
* exp_ch9.adb, sem_ch6.adb, sem_ch6.ads: Minor reformatting and typo
-- once in the call to _Postconditions, and once in the actual return
-- statement, but we can't have side effects happening twice.
- Remove_Side_Effects (Exp);
+ Force_Evaluation (Exp, Mode => Strict);
-- Generate call to _Postconditions
Name_Req : Boolean := False;
Related_Id : Entity_Id := Empty;
Is_Low_Bound : Boolean := False;
- Is_High_Bound : Boolean := False)
+ Is_High_Bound : Boolean := False;
+ Mode : Force_Evaluation_Mode := Relaxed)
is
begin
Remove_Side_Effects
Renaming_Req => False,
Related_Id => Related_Id,
Is_Low_Bound => Is_Low_Bound,
- Is_High_Bound => Is_High_Bound);
+ Is_High_Bound => Is_High_Bound,
+ Check_Side_Effects =>
+ Is_Static_Expression (Exp)
+ or else Mode = Relaxed);
end Force_Evaluation;
---------------------------------
-------------------------
procedure Remove_Side_Effects
- (Exp : Node_Id;
- Name_Req : Boolean := False;
- Renaming_Req : Boolean := False;
- Variable_Ref : Boolean := False;
- Related_Id : Entity_Id := Empty;
- Is_Low_Bound : Boolean := False;
- Is_High_Bound : Boolean := False)
+ (Exp : Node_Id;
+ Name_Req : Boolean := False;
+ Renaming_Req : Boolean := False;
+ Variable_Ref : Boolean := False;
+ Related_Id : Entity_Id := Empty;
+ Is_Low_Bound : Boolean := False;
+ Is_High_Bound : Boolean := False;
+ Check_Side_Effects : Boolean := True)
is
function Build_Temporary
(Loc : Source_Ptr;
-- No action needed for side-effect free expressions
- elsif Side_Effect_Free (Exp, Name_Req, Variable_Ref) then
+ elsif Check_Side_Effects
+ and then Side_Effect_Free (Exp, Name_Req, Variable_Ref)
+ then
return;
end if;
-- Note: currently this function does not scan the private part, that seems
-- like a potential bug ???
+ type Force_Evaluation_Mode is (Relaxed, Strict);
+
procedure Force_Evaluation
(Exp : Node_Id;
Name_Req : Boolean := False;
Related_Id : Entity_Id := Empty;
Is_Low_Bound : Boolean := False;
- Is_High_Bound : Boolean := False);
+ Is_High_Bound : Boolean := False;
+ Mode : Force_Evaluation_Mode := Relaxed);
-- 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.
+ -- the same result. If Mode is Relaxed then calls to this subprogram have
+ -- no effect if Exp is side-effects free; if Mode is Strict and Exp is not
+ -- a static expression then no side-effects check is performed on Exp and
+ -- temporaries are unconditionally generated.
--
-- Related_Id denotes the entity of the context where Expr appears. Flags
-- Is_Low_Bound and Is_High_Bound specify whether the expression to check
-- associated with Var, and if found, remove and return that call node.
procedure Remove_Side_Effects
- (Exp : Node_Id;
- Name_Req : Boolean := False;
- Renaming_Req : Boolean := False;
- Variable_Ref : Boolean := False;
- Related_Id : Entity_Id := Empty;
- Is_Low_Bound : Boolean := False;
- Is_High_Bound : Boolean := False);
+ (Exp : Node_Id;
+ Name_Req : Boolean := False;
+ Renaming_Req : Boolean := False;
+ Variable_Ref : Boolean := False;
+ Related_Id : Entity_Id := Empty;
+ Is_Low_Bound : Boolean := False;
+ Is_High_Bound : Boolean := False;
+ Check_Side_Effects : Boolean := True);
-- 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
-- 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.
+ -- of the resulting expression. If Check_Side_Effects is set to True then
+ -- no action is performed if Exp is known to be side-effect free.
--
-- Related_Id denotes the entity of the context where Expr appears. Flags
-- Is_Low_Bound and Is_High_Bound specify whether the expression to check
--------------------
procedure Check_Mismatch (B : Boolean) is
- Kind : constant Node_Kind := Nkind (Parent (E2));
+ -- a Formal_Type_Declaration for a derived private type is rewritten
+ -- as a private extension decl. (see Analyze_Formal_Derived_Type),
+ -- which is why we examine the original node.
+
+ Kind : constant Node_Kind := Nkind (Original_Node (Parent (E2)));
begin
if Kind = N_Formal_Type_Declaration then
-- If the formal entity comes from a formal declaration, it was
-- defaulted in the formal package, and no check is needed on it.
- elsif Nkind (Parent (E2)) = N_Formal_Object_Declaration then
+ elsif
+ Nkind_In (Original_Node (Parent (E2)),
+ N_Formal_Object_Declaration, N_Formal_Type_Declaration)
+ then
goto Next_E;
-- Ditto for defaulted formal subprograms.
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