The compiler can mishandle a Component_Size clause on an array type specifying
a size multiple of the storage unit, when this size is not a multiple of the
alignment of the component type.
Tested on x86-64/Linux, applied on the mainline.
2020-05-25 Eric Botcazou <ebotca...@adacore.com>
* gcc-interface/decl.c (gnat_to_gnu_component_type): Cap the alignment
of the component type according to the component size.
2020-05-25 Eric Botcazou <ebotca...@adacore.com>
* gnat.dg/array40.adb: New test.
* gnat.dg/array40_pkg.ads: New helper.
--
Eric Botcazoudiff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index a36b1298bed..ab6e79ce3c1 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -5153,7 +5153,7 @@ gnat_to_gnu_component_type (Entity_Id gnat_array, bool definition,
unsigned int max_align;
/* If an alignment is specified, use it as a cap on the component type
- so that it can be honored for the whole type. But ignore it for the
+ so that it can be honored for the whole type, but ignore it for the
original type of packed array types. */
if (No (Packed_Array_Impl_Type (gnat_array))
&& Known_Alignment (gnat_array))
@@ -5200,6 +5200,7 @@ gnat_to_gnu_component_type (Entity_Id gnat_array, bool definition,
if (gnu_comp_size && !is_bit_packed)
{
tree orig_type = gnu_type;
+ unsigned int gnu_comp_align;
gnu_type = make_type_from_size (gnu_type, gnu_comp_size, false);
if (max_align > 0 && TYPE_ALIGN (gnu_type) > max_align)
@@ -5207,8 +5208,22 @@ gnat_to_gnu_component_type (Entity_Id gnat_array, bool definition,
else
orig_type = gnu_type;
- gnu_type = maybe_pad_type (gnu_type, gnu_comp_size, 0, gnat_array,
- true, definition, true);
+ /* We need to make sure that the size is a multiple of the alignment.
+ But we do not misalign the component type because of the alignment
+ of the array type here; this either must have been done earlier in
+ the packed case or should be rejected in the non-packed case. */
+ if (TREE_CODE (gnu_comp_size) == INTEGER_CST)
+ {
+ const unsigned HOST_WIDE_INT int_size = tree_to_uhwi (gnu_comp_size);
+ gnu_comp_align = int_size & -int_size;
+ if (gnu_comp_align > TYPE_ALIGN (gnu_type))
+ gnu_comp_align = 0;
+ }
+ else
+ gnu_comp_align = 0;
+
+ gnu_type = maybe_pad_type (gnu_type, gnu_comp_size, gnu_comp_align,
+ gnat_array, true, definition, true);
/* If a padding record was made, declare it now since it will never be
declared otherwise. This is necessary to ensure that its subtrees
-- { dg-do run }
-- { dg-options "-gnatws" }
with System.Storage_Elements;
with Array40_Pkg; use Array40_Pkg;
procedure Array40 is
use System;
use System.Storage_Elements;
begin
if A(1)'Size /= 40 then
raise Program_Error;
end if;
if (A(2)'Address - A(1)'Address) * System.Storage_Unit /= 40 then
raise Program_Error;
end if;
end;
package Array40_Pkg is
type Rec is record
I : Integer;
end record;
type Arr is array (1 .. 4) of Rec;
for Arr'Component_Size use 40;
A : Arr;
end Array40_Pkg;
