From: Javier Miranda <mira...@adacore.com> When the sources have a type conversion from an interface type T2 to some ancestor interface type T1 (that is, T2 extends T1) the tag check added by the compiler may fail at runtime.
gcc/ada/ * exp_disp.adb (Has_Dispatching_Constructor_Call): Removed. (Expand_Interface_Conversion): Reverse patch. Tested on x86_64-pc-linux-gnu, committed on master. --- gcc/ada/exp_disp.adb | 94 ++------------------------------------------ 1 file changed, 4 insertions(+), 90 deletions(-) diff --git a/gcc/ada/exp_disp.adb b/gcc/ada/exp_disp.adb index 9381ceee60c..9e0c87a5095 100644 --- a/gcc/ada/exp_disp.adb +++ b/gcc/ada/exp_disp.adb @@ -1242,92 +1242,9 @@ package body Exp_Disp is procedure Expand_Interface_Conversion (N : Node_Id) is - function Has_Dispatching_Constructor_Call - (Expr : Node_Id) return Boolean; - -- Determines if the expression has a dispatching constructor call - function Underlying_Record_Type (Typ : Entity_Id) return Entity_Id; -- Return the underlying record type of Typ - -------------------------------------- - -- Has_Dispatching_Constructor_Call -- - -------------------------------------- - - function Has_Dispatching_Constructor_Call (Expr : Node_Id) return Boolean - is - function Is_Dispatching_Constructor_Call (N : Node_Id) return Boolean; - -- Determines if N is a dispatching constructor call - - function Process (Nod : Node_Id) return Traverse_Result; - -- Traverse the expression searching for constructor calls - - ------------------------------------- - -- Is_Dispatching_Constructor_Call -- - ------------------------------------- - - function Is_Dispatching_Constructor_Call (N : Node_Id) return Boolean - is - Param : Node_Id; - Param_Type : Entity_Id; - Assoc_Node : Node_Id; - Gen_Func_Id : Entity_Id; - - begin - if Nkind (N) = N_Function_Call - and then Present (Parameter_Associations (N)) - then - Param := First (Parameter_Associations (N)); - - if Nkind (Param) = N_Parameter_Association then - Param := Selector_Name (Param); - end if; - - Param_Type := Etype (Param); - - if Is_Itype (Param_Type) then - Assoc_Node := Associated_Node_For_Itype (Param_Type); - - if Nkind (Assoc_Node) = N_Function_Specification - and then Present (Generic_Parent (Assoc_Node)) - then - Gen_Func_Id := Generic_Parent (Assoc_Node); - - if Is_Intrinsic_Subprogram (Gen_Func_Id) - and then Chars (Gen_Func_Id) - = Name_Generic_Dispatching_Constructor - then - return True; - end if; - end if; - end if; - end if; - - return False; - end Is_Dispatching_Constructor_Call; - - ------------- - -- Process -- - ------------- - - function Process (Nod : Node_Id) return Traverse_Result is - begin - if Nkind (Nod) = N_Function_Call - and then Is_Dispatching_Constructor_Call (Nod) - then - return Abandon; - end if; - - return OK; - end Process; - - function Traverse_Expression is new Traverse_Func (Process); - - -- Start of processing for Has_Dispatching_Constructor_Call - - begin - return Traverse_Expression (Expr) = Abandon; - end Has_Dispatching_Constructor_Call; - ---------------------------- -- Underlying_Record_Type -- ---------------------------- @@ -1430,16 +1347,13 @@ package body Exp_Disp is -- object to reference the corresponding secondary dispatch table -- (cf. Make_DT and Expand_Dispatching_Constructor_Call)). - -- Under regular runtime this is a minor optimization that improves - -- the generated code; under configurable runtime (where generic - -- dispatching constructors are not supported) this optimization - -- allows supporting this interface conversion, which otherwise - -- would require calling the runtime routine to displace the - -- pointer to the object. + -- Under configurable runtime it is safe to skip generating code to + -- displace the pointer to the object, because generic dispatching + -- constructors are not supported. elsif Is_Interface (Iface_Typ) and then Is_Ancestor (Iface_Typ, Opnd, Use_Full_View => True) - and then not Has_Dispatching_Constructor_Call (Operand) + and then not RTE_Available (RE_Displace) then return; end if; -- 2.40.0