Re: Patch: New implementation of -Wstrict-aliasing

["Richard Guenther" <richard dot guenther at gmail dot com>]

On 1/20/07, Andrew Pinski <pinskia@physics.uc.edu> wrote:
> > Patch Description
> > =================
> >
> > The proposed patch contains a new implementation of -Wstrict-aliasing.
> > The proposed implementation lives in the backend and is based on
> > flow-sensitive
> > points-to information, which is computed by analyzing the entire source of
> > each function.  It is not perfect (the problem is undecidable), but it
> > improves
> > in all three directions: it checks whether pointers get dereferenced,
> > it detects aliasing across multiple statements and it produces more
> > meaningful messages.
>
> The only problem with this implementation I can see is that once
> we start folding *(int*)&float_var into using VIEW_CONVERT_EXPR, we
> are no longer going to warn about this specific aliasing issue (even
> though after that, we will get it correct, we should warn about it).

You could mark such folded trees somehow to tell the strict-aliasing
warning machinery to warn about the VIEW_CONVERT_EXPR.
(using TREE_NO_WARNING with a reversed sense comes to my mind)

Richard.