Re: bootstrap compare failure in ada/targparm.o on i686-pc-linux-gnu?

[Dale Johannesen <dalej at apple dot com>]

On Apr 4, 2005, at 3:21 PM, Alexandre Oliva wrote:

> On Apr  4, 2005, Dale Johannesen <dalej@apple.com> wrote:
>
> > On Apr 4, 2005, at 2:32 PM, Alexandre Oliva wrote:
> > > On Mar 26, 2005, Graham Stott <graham.stott@btinternet.com> wrote:
> > > > I do regular bootstraps of mainline all languages on FC3
> > > > i686-pc-linuux-gnu and haven't seen any problemss upto Friday. I'm
> > > > using --enable-checking=tree,misc,rtl,rtlflag which might make a
> > > > difference.
>
> > > I'm still observing this problem every now and then.  It's not
> > > consistent or easily reproducible, unfortunately.  I suspect we're
> > > using pointers somewhere, and that stack/mmap/whatever address
> > > randomization is causing different results.  I'm looking into it.
>
> > I've found 2 bugs over the last 6 months where the problem is exposed
> > only if two pointers happen to hash to the same bucket.  It's occurred
> > to me that doing a bootstrap with all hashtable sizes set to 1 might 
> > be
> > a good idea.
>
> Perhaps.  But the fundamental problem is that we shouldn't be hashing
> on pointers, and tree-eh.c does just that for finally_tree and
> throw_stmt_table.

Hmm.  Of the earlier bugs, in
http://gcc.gnu.org/ml/gcc-patches/2004-12/msg01760.html
the hash table in question is built by DOM, and in
http://gcc.gnu.org/ml/gcc-patches/2005-03/msg01810.html
it's built by PRE (VN).  I don't think there's general agreement
that "we shouldn't be hashing on pointers"....