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Fix uninitialized variable in Atree.Size_In_Slots

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Size_In_Slots uses the Nkind to look up the size in a table indexed
by Nkind.  This patch fixes a couple of places where the Nkind is
wrong (uninitialized or zeroed out) so Size_In_Slots cannot be used.

gcc/ada/
	PR ada/100564
	* atree.adb (Change_Node): Do not call Zero_Slots on a Node_Id
	when the Nkind has not yet been set; call the other Zero_Slots
	that takes a range of slot offsets.  Call the new Mutate_Kind
	that takes an Old_Size, for the same reason -- the size cannot
	be computed without the Nkind.
	(Mutate_Nkind): New function that allows specifying the Old_Size.
	(Size_In_Slots): Assert that the Nkind has proper (nonzero) value.
	* atree.ads: Minor reformatting.
This commit is contained in:
Bob Duff 2021-05-12 11:56:47 +02:00 • committed by Eric Botcazou
parent 3835aa0eb9
commit ac18ded230
2 changed files with 26 additions and 9 deletions
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32
gcc/ada/atree.adb
View file

@ -216,6 +216,13 @@ package body Atree is
-- cannot be used to modify an already-initialized Nkind field. See also
-- Mutate_Nkind.
procedure Mutate_Nkind
(N : Node_Id; Val : Node_Kind; Old_Size : Field_Offset);
-- Called by the other Mutate_Nkind to do all the work. This is needed
-- because the call in Change_Node, which calls this one directly, happens
-- after zeroing N's slots, which destroys its Nkind, which prevents us
-- from properly computing Old_Size.
package Field_Checking is
function Field_Present
(Kind : Node_Kind; Field : Node_Field) return Boolean;
@ -868,9 +875,8 @@ package body Atree is
end Init_Nkind;
procedure Mutate_Nkind
(N : Node_Id; Val : Node_Kind)
(N : Node_Id; Val : Node_Kind; Old_Size : Field_Offset)
is
Old_Size : constant Field_Offset := Size_In_Slots (N);
New_Size : constant Field_Offset := Size_In_Slots_To_Alloc (Val);
All_Node_Offsets : Node_Offsets.Table_Type renames
@ -905,6 +911,11 @@ package body Atree is
pragma Debug (Validate_Node_Write (N));
end Mutate_Nkind;
procedure Mutate_Nkind (N : Node_Id; Val : Node_Kind) is
begin
Mutate_Nkind (N, Val, Old_Size => Size_In_Slots (N));
end Mutate_Nkind;
Ekind_Offset : constant Field_Offset :=
Entity_Field_Descriptors (Ekind).Offset;
@ -998,13 +1009,19 @@ package body Atree is
end if;
if New_Size > Old_Size then
pragma Debug (Zero_Slots (N));
Node_Offsets.Table (N) := Alloc_Slots (New_Size);
declare
New_Offset : constant Field_Offset := Alloc_Slots (New_Size);
begin
pragma Debug (Zero_Slots (N));
Node_Offsets.Table (N) := New_Offset;
Zero_Slots (New_Offset, New_Offset + New_Size - 1);
end;
else
Zero_Slots (N);
end if;
Zero_Slots (N);
Mutate_Nkind (N, New_Kind);
Mutate_Nkind (N, New_Kind, Old_Size);
Set_Sloc (N, Save_Sloc);
Set_In_List (N, Save_In_List);
@ -2125,6 +2142,7 @@ package body Atree is
function Size_In_Slots (N : Node_Or_Entity_Id) return Field_Offset is
begin
pragma Assert (Nkind (N) /= N_Unused_At_Start);
return
(if Nkind (N) in N_Entity then Einfo.Entities.Max_Entity_Size
else Sinfo.Nodes.Size (Nkind (N)));

3
gcc/ada/atree.ads
View file

@ -571,8 +571,7 @@ package Atree is
(N : Entity_Id; Field : Entity_Field) return Boolean;
-- True if the field value is the initial zero value
procedure Mutate_Nkind
(N : Node_Id; Val : Node_Kind) with Inline;
procedure Mutate_Nkind (N : Node_Id; Val : Node_Kind) with Inline;
-- There is no Set_Nkind in Sinfo.Nodes. We use this instead. This is here,
-- and has a different name, because it does some extra checking. Nkind is
-- like a discriminant, in that it controls which fields exist, and that