* [Ada] Use static discriminant value for discriminated task record
@ 2019-09-18 8:42 Pierre-Marie de Rodat
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From: Pierre-Marie de Rodat @ 2019-09-18 8:42 UTC (permalink / raw)
To: gcc-patches; +Cc: Ed Schonberg
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This patch allows the construction of a static subtype for the generated
constrained Secondary_Stack component of a task for which a stack size
is specified, when compiling for a restricted run-time that forbids
dynamic allocation. Needed for LLVM.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-09-18 Ed Schonberg <schonberg@adacore.com>
gcc/ada/
* sem_ch3.adb (Constrain_Component_Type): For a discriminated
type, handle the case of a constraint given by a conversion of a
discriminant of the enclosing type. Necessary when compiling a
discriminated task for a restricted run-time, when the generated
Secondary_Stack component may be set by means of an aspect on
the task type.
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--- gcc/ada/sem_ch3.adb
+++ gcc/ada/sem_ch3.adb
@@ -13258,7 +13258,9 @@ package body Sem_Ch3 is
function Build_Constrained_Discriminated_Type
(Old_Type : Entity_Id) return Entity_Id;
- -- Ditto for record components
+ -- Ditto for record components. Handle the case where the constraint
+ -- is a conversion of the discriminant value, introduced during
+ -- expansion.
function Build_Constrained_Access_Type
(Old_Type : Entity_Id) return Entity_Id;
@@ -13443,6 +13445,17 @@ package body Sem_Ch3 is
if Is_Discriminant (Expr) then
Need_To_Create_Itype := True;
+
+ -- After expansion of discriminated task types, the value
+ -- of the discriminant may be converted to a run-time type
+ -- for restricted run-times. Propagate the value of the
+ -- discriminant ss well, so that e.g. the secondary stack
+ -- component has a static constraint. Necessry for LLVM.
+
+ elsif Nkind (Expr) = N_Type_Conversion
+ and then Is_Discriminant (Expression (Expr))
+ then
+ Need_To_Create_Itype := True;
end if;
Next_Elmt (Old_Constraint);
@@ -13457,6 +13470,12 @@ package body Sem_Ch3 is
if Is_Discriminant (Expr) then
Expr := Get_Discr_Value (Expr);
+
+ elsif Nkind (Expr) = N_Type_Conversion
+ and then Is_Discriminant (Expression (Expr))
+ then
+ Expr := New_Copy_Tree (Expr);
+ Set_Expression (Expr, Get_Discr_Value (Expression (Expr)));
end if;
Append (New_Copy_Tree (Expr), To => Constr_List);
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