* [Ada] Crash on predicate involving qualified expression in instance
@ 2018-05-23 10:31 Pierre-Marie de Rodat
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From: Pierre-Marie de Rodat @ 2018-05-23 10:31 UTC (permalink / raw)
To: gcc-patches; +Cc: Ed Schonberg
[-- Attachment #1: Type: text/plain, Size: 2007 bytes --]
This patch inhibits the generation of freeze nodes when pre-analyzing the
domain of iteration of an Ada2012 loop that appears as a quantified
expression in a predicate for an array type. This prevents a back-end
abort on an invisible freeze node that would otherwise appear in an
unexpanded code sequence.
The following must compile quietly:
----
with Id_Manager;
package My_Id_Manager is new Id_Manager (Max_Id_Type => 100_000,
Max_Key_Count => 100);
----
generic
Max_Id_Type : Positive;
Max_Key_Count : Positive;
package Id_Manager is
type Unique_Id_Type is new Integer range 0 .. Max_Id_Type;
Undefined_Id : constant Unique_Id_Type := 0;
type Key_Count is new Integer range 0 .. Max_Key_Count;
subtype Key_Index is Key_Count range 1 .. Key_Count'Last;
type Key_Array is array (Key_Index range <>) of Unique_Id_Type
with Predicate => Key_Array'First = 1;
type Id_Manager_State (Capacity : Key_Count) is private;
procedure Display_Objects (TheObject : Id_Manager_State);
private
type Id_Manager_State (Capacity : Key_Count) is record
Id_Key : Key_Array (1 .. Capacity) := (others => Undefined_Id);
Key_Size : Key_Count := 0;
end record;
end Id_Manager;
----
package body Id_Manager is
procedure Display_Objects (TheObject : Id_Manager_State) is
begin
for Item of TheObject.Id_Key loop
null;
end loop;
end Display_Objects;
end Id_Manager;
Tested on x86_64-pc-linux-gnu, committed on trunk
2018-05-23 Ed Schonberg <schonberg@adacore.com>
gcc/ada/
* sem_ch5.adb (Preanalyze_Range): The pre-analysis of the domain of
iteration of an Ada2012 loop is performed to determine the type of the
domain, but full analysis is performed once the loop is rewritten as a
while-loop during expansion. The pre-analysis suppresses expansion; it
must also suppress the generation of freeze nodes, which may otherwise
appear in the wrong scope before rewritting.
[-- Attachment #2: patch.diff --]
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--- gcc/ada/sem_ch5.adb
+++ gcc/ada/sem_ch5.adb
@@ -4076,6 +4076,17 @@ package body Sem_Ch5 is
Full_Analysis := False;
Expander_Mode_Save_And_Set (False);
+ -- In addition to the above we must ecplicity suppress the
+ -- generation of freeze nodes which might otherwise be generated
+ -- during resolution of the range (e.g. if given by an attribute
+ -- that will freeze its prefix).
+
+ Set_Must_Not_Freeze (R_Copy);
+
+ if Nkind (R_Copy) = N_Attribute_Reference then
+ Set_Must_Not_Freeze (Prefix (R_Copy));
+ end if;
+
Analyze (R_Copy);
if Nkind (R_Copy) in N_Subexpr and then Is_Overloaded (R_Copy) then
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