This completes the previous fix, which is not sufficient when the Size
attribute is applied to a formal object of mode In Out and the generic
is instantiated on a slice of a bit-packed array whose size is not a
multiple of the storage unit.
The hurdle here is that introducing a temporary may change the value
of the Size attribute, because a temporary is a stand-alone object and
the size of stand-alone objects is always a multiple of the storage
unit with GNAT.
Instead of trying to look through them in Expand_Size_Attribute, this
changes the expansion done by Expand_N_Slice to avoid creating these
problematic temporaries for slices of bit-packed arrays that are the
prefix of the Size attribute.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-12-12 Eric Botcazou <ebotca...@adacore.com>
gcc/ada/
* exp_attr.adb (Expand_Size_Attribute): Look directly at the
prefix to detect the bit-packed slices. Apply the checks last
in case the attribute needs to be processed by the back-end.
* exp_ch4.adb (Expand_N_Slice): Do not create a temporary for
a prefix of the Size attribute.--- gcc/ada/exp_attr.adb
+++ gcc/ada/exp_attr.adb
@@ -7455,8 +7455,6 @@ package body Exp_Attr is
-- All other cases are handled by the back end
else
- Apply_Universal_Integer_Attribute_Checks (N);
-
-- If Size is applied to a formal parameter that is of a packed
-- array subtype, then apply Size to the actual subtype.
@@ -7489,9 +7487,7 @@ package body Exp_Attr is
-- System.Unsigned_Types.Packed_Byte for code generation purposes so
-- the size is always rounded up in the back end.
- elsif Nkind (Original_Node (Pref)) = N_Slice
- and then Is_Bit_Packed_Array (Ptyp)
- then
+ elsif Nkind (Pref) = N_Slice and then Is_Bit_Packed_Array (Ptyp) then
Rewrite (N,
Make_Op_Multiply (Loc,
Make_Attribute_Reference (Loc,
@@ -7503,6 +7499,9 @@ package body Exp_Attr is
Analyze_And_Resolve (N, Typ);
end if;
+ -- Apply the required checks last, after rewriting has taken place
+
+ Apply_Universal_Integer_Attribute_Checks (N);
return;
end if;
--- gcc/ada/exp_ch4.adb
+++ gcc/ada/exp_ch4.adb
@@ -11013,7 +11013,8 @@ package body Exp_Ch4 is
-- 5. Prefix of an address attribute (this is an error which is caught
-- elsewhere, and the expansion would interfere with generating the
- -- error message).
+ -- error message) or of a size attribute (because 'Size may change
+ -- when applied to the temporary instead of the slice directly).
if not Is_Packed (Typ) then
@@ -11039,7 +11040,8 @@ package body Exp_Ch4 is
return;
elsif Nkind (Parent (N)) = N_Attribute_Reference
- and then Attribute_Name (Parent (N)) = Name_Address
+ and then (Attribute_Name (Parent (N)) = Name_Address
+ or else Attribute_Name (Parent (N)) = Name_Size)
then
return;
