This prevents the compiler from generating an incorrect call to a
memset primitive for the initialization of an array, whose component
type is an enumeration type with a non-standard representation, by
means of an aggregate with a single Others choice.
The predicate Aggr_Assignment_OK_For_Backend is supposed to filter
out the unsuitable values for the single choice in the aggregate,
but it uses Expr_Value to obtain the equivalent integer value, which
doesn't work for enumeration types with non-standard representation.
Tested on x86_64-pc-linux-gnu, committed on trunk
2020-06-05 Eric Botcazou <ebotca...@adacore.com>
gcc/ada/
* exp_aggr.adb (Aggr_Assignment_OK_For_Backend): Use
Expr_Rep_Value instead of Expr_Value to obtain the equivalent
integer value.
* sem_eval.ads (Expr_Value): Document more supported cases.
* sem_eval.adb (Expr_Rep_Value): Copy missing cases from
Exp_Value.--- gcc/ada/exp_aggr.adb
+++ gcc/ada/exp_aggr.adb
@@ -5390,9 +5390,10 @@ package body Exp_Aggr is
return Expr_Value_R (Expr) = Ureal_0;
end if;
- -- For other types, we can look into the value as an integer
+ -- For other types, we can look into the value as an integer, which
+ -- means the representation value for enumeration literals.
- Value := Expr_Value (Expr);
+ Value := Expr_Rep_Value (Expr);
if Has_Biased_Representation (Ctyp) then
Value := Value - Expr_Value (Type_Low_Bound (Ctyp));
--- gcc/ada/sem_eval.adb
+++ gcc/ada/sem_eval.adb
@@ -4203,10 +4203,16 @@ package body Sem_Eval is
pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
return Corresponding_Integer_Value (N);
- -- Otherwise must be character literal
+ -- The NULL access value
- else
- pragma Assert (Kind = N_Character_Literal);
+ elsif Kind = N_Null then
+ pragma Assert (Is_Access_Type (Underlying_Type (Etype (N)))
+ or else Error_Posted (N));
+ return Uint_0;
+
+ -- Character literal
+
+ elsif Kind = N_Character_Literal then
Ent := Entity (N);
-- Since Character literals of type Standard.Character don't have any
@@ -4220,6 +4226,15 @@ package body Sem_Eval is
else
return Enumeration_Rep (Ent);
end if;
+
+ -- Unchecked conversion, which can come from System'To_Address (X)
+ -- where X is a static integer expression. Recursively evaluate X.
+
+ elsif Kind = N_Unchecked_Type_Conversion then
+ return Expr_Rep_Value (Expression (N));
+
+ else
+ raise Program_Error;
end if;
end Expr_Rep_Value;
--- gcc/ada/sem_eval.ads
+++ gcc/ada/sem_eval.ads
@@ -276,7 +276,9 @@ package Sem_Eval is
-- or character literals. In the latter two cases, the value returned is
-- the Pos value in the relevant enumeration type. It can also be used for
-- fixed-point values, in which case it returns the corresponding integer
- -- value. It cannot be used for floating-point values.
+ -- value, but it cannot be used for floating-point values. Finally, it can
+ -- also be used for the Null access value, as well as for the result of an
+ -- unchecked conversion of the aforementioned handled values.
function Expr_Value_E (N : Node_Id) return Entity_Id;
-- Returns the folded value of the expression. This function is called in
