diff options
Diffstat (limited to 'gcc/ada/exp_util.adb')
| -rw-r--r-- | gcc/ada/exp_util.adb | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb index 6845d45..dd3aa49 100644 --- a/gcc/ada/exp_util.adb +++ b/gcc/ada/exp_util.adb @@ -169,6 +169,16 @@ package body Exp_Util is -- Determine whether pragma Default_Initial_Condition denoted by Prag has -- an assertion expression that should be verified at run time. + function Is_Uninitialized_Aggregate + (Exp : Node_Id; + T : Entity_Id) return Boolean; + -- Determine whether an array aggregate used in an object declaration + -- is uninitialized, when the aggregate is declared with a box and + -- the component type has no default value. Such an aggregate can be + -- optimized away to prevent the copying of uninitialized data, and + -- the bounds of the aggregate can be propagated directly to the + -- object declaration. + function Make_CW_Equivalent_Type (T : Entity_Id; E : Node_Id) return Entity_Id; @@ -5346,6 +5356,17 @@ package body Exp_Util is elsif Is_Build_In_Place_Function_Call (Exp) then null; + -- If the exprewsion is an uninitialized aggregate, no need to build + -- a subtype from the expression. because this may require the use + -- of dynamic memory to create the object. + + elsif Is_Uninitialized_Aggregate (Exp, Exp_Typ) then + Rewrite (Subtype_Indic, New_Occurrence_Of (Etype (Exp), Sloc (N))); + if Nkind (N) = N_Object_Declaration then + Set_Expression (N, Empty); + Set_No_Initialization (N); + end if; + else Remove_Side_Effects (Exp); Rewrite (Subtype_Indic, @@ -8794,6 +8815,47 @@ package body Exp_Util is and then Etype (Expression (Expr)) = RTE (RE_Tag); end Is_Tag_To_Class_Wide_Conversion; + -------------------------------- + -- Is_Uninitialized_Aggregate -- + -------------------------------- + + function Is_Uninitialized_Aggregate + (Exp : Node_Id; + T : Entity_Id) return Boolean + is + Comp : Node_Id; + Comp_Type : Entity_Id; + Typ : Entity_Id; + + begin + if Nkind (Exp) /= N_Aggregate then + return False; + end if; + + Preanalyze_And_Resolve (Exp, T); + Typ := Etype (Exp); + + if No (Typ) + or else Ekind (Typ) /= E_Array_Subtype + or else Present (Expressions (Exp)) + or else No (Component_Associations (Exp)) + then + return False; + else + Comp_Type := Component_Type (Typ); + Comp := First (Component_Associations (Exp)); + + if not Box_Present (Comp) + or else Present (Next (Comp)) + then + return False; + end if; + + return Is_Scalar_Type (Comp_Type) + and then No (Default_Aspect_Component_Value (Typ)); + end if; + end Is_Uninitialized_Aggregate; + ---------------------------- -- Is_Untagged_Derivation -- ---------------------------- |