> > Added and comitted now.
>
> Thanks. Now on to the wrong code issues. :-)
>
> Up to the change, the useless_type_conversion_p predicate was relying on
> structural equivalence via the TYPE_CANONICAL check, now it only looks at the
> outermost level (size, mode). Now some back-ends, most notably x86-64, do a
> deep structural scan to determine the calling conventions (classify_argument)
> instead of just looking at the size and the mode, so consistency dictates
> that
> the type of the argument and that of the parameter be structurally equivalent
> and this sometimes can only be achieved by a VCE... which is now deleted. :-(
> See the call to derivedIP in the attached testcase which now fails on x86-64.
>
> How do we get away from here?
Hmm, I noticed this in ipa-icf context and wrote checker that two functions are
ABI
compatile (did not pushed it out yet), but of course this is nastier.
I think the problem exists before my patch with LTO - it is just matter of
doing two types which will be considered equivalent by
gimple_canonical_types_compatible_p but have different type conversion. An
example of such type would be:
struct a {
int a[4];
};
struct b {
int a[4];
} __attribute__ ((__aligned__(16)));
I tried to turn this into an testcase, the problem is that I don't know of a way
to obtain VIEW_CONVERT_EXPR between the two types out of C or C++ frontend and
we
don't seem to synthetize these in middle end (even in cases it would make
sense).
I will try to play with it more - would be nice to have a C reproducer.
We may be safe before my patch from wrong code issues if there is no way to
rpduce VIEW_CONVERT_EXPR between types like this in languages that support
aligned attribute.
I think the problem is generally similar to memory references - the gimple type
compatibility should not be tied to ABI details. Probably most consistent
solution would be to extend GIMPLE_CALL to also list types of parameters and do
not rely on whatever type the operand have....
Richard, any ideas?
Honza
>
>
> * gnat.dg/discr44.adb: New test.
>
> --
> Eric Botcazou
> -- { dg-do run }
> -- { dg-options "-gnatws" }
>
> procedure Discr44 is
>
> function Ident (I : Integer) return Integer is
> begin
> return I;
> end;
>
> type Int is range 1 .. 10;
>
> type Str is array (Int range <>) of Character;
>
> type Parent (D1, D2 : Int; B : Boolean) is record
> S : Str (D1 .. D2);
> end record;
>
> type Derived (D : Int) is new Parent (D1 => D, D2 => D, B => False);
>
> X1 : Derived (D => Int (Ident (7)));
>
> begin
> if X1.D /= 7 then
> raise Program_Error;
> end if;
> end;
