Re: [patchv2] compile: Fix crash on cv-qualified self-reference

Jan Kratochvil
2015-07-01T13:24:13Z

On Wed, 01 Jul 2015 13:21:32 +0200, Yao Qi wrote:
> Jan Kratochvil <jan.kratochvil@redhat.com> writes:
>
> > + quals = 0;
> > + if (TYPE_CONST (type))
> > + quals |= GCC_QUALIFIER_CONST;
> > + if (TYPE_VOLATILE (type))
> > + quals |= GCC_QUALIFIER_VOLATILE;
> > + if (TYPE_RESTRICT (type))
> > + quals |= GCC_QUALIFIER_RESTRICT;
> > + result = C_CTX (context)->c_ops->build_qualified_type (C_CTX (context),
> > + result, quals);
> > insert_type (context, type, result);
>
> Can we use convert_qualified instead? I find code we added here is
> quite similar to convert_qualified.

Not directly to use convert_qualified() but convert_qualified() could be split
in halves and one half could be used here, I agree.

> > for (i = 0; i < TYPE_NFIELDS (type); ++i)
> > @@ -329,10 +342,13 @@ static gcc_type
> > convert_type_basic (struct compile_c_instance *context, struct type *type)
> > {
> > /* If we are converting a qualified type, first convert the
> > - unqualified type and then apply the qualifiers. */
> > + unqualified type and then apply the qualifiers, except for the
> > + types handling qualifiers on their own. */
> > if ((TYPE_INSTANCE_FLAGS (type) & (TYPE_INSTANCE_FLAG_CONST
> > | TYPE_INSTANCE_FLAG_VOLATILE
> > - | TYPE_INSTANCE_FLAG_RESTRICT)) != 0)
> > + | TYPE_INSTANCE_FLAG_RESTRICT)) != 0
> > + && (TYPE_CODE (type) != TYPE_CODE_STRUCT
> > + && TYPE_CODE (type) != TYPE_CODE_UNION))
> > return convert_qualified (context, type);
>
> It looks right to me, however, isn't cleaner to do in this way?
>
> /* Comments on why we do this first */
> if (TYPE_CODE (type) == TYPE_CODE_STRUCT
> || TYPE_CODE (type) == TYPE_CODE_UNION)
> return convert_struct_or_union (context, type);
>
> /* If we are converting a qualified type, first convert the
> unqualified type and then apply the qualifiers. */
> if ((TYPE_INSTANCE_FLAGS (type) & (TYPE_INSTANCE_FLAG_CONST
> | TYPE_INSTANCE_FLAG_VOLATILE
> | TYPE_INSTANCE_FLAG_RESTRICT)) != 0)
> return convert_qualified (context, type);
>
> switch (TYPE_CODE (type))
> {
> /* Don't need to handle TYPE_CODE_STRUCT and TYPE_CODE_UNION
> here. */
> }

I can change it that way but when you ask "isn't cleaner" then no, I think
your hack is even a bit more ugly than my ugly hack.

There should be two virtual methods, one pure for 'switch (TYPE_CODE (type))'
and the other one checking TYPE_INSTANCE_FLAG* in superclass overriden only by
TYPE_CODE_STRUCT and TYPE_CODE_UNION (there would be no TYPE_CODE_*, though).

> Otherwise, the patch looks good to me.

OK, thanks. Just it causes a regression with latest GCC now as I have asked
Alexandre Oliva off-list how it really should be fixed.

Jan