bootstrap failure on darwin, compare stages

[mike stump]

> Date: Sun, 23 Sep 2001 13:50:35 +0200
> From: Andreas Tobler <toa@pop.agri.ch>

> "Billinghurst, David (CRTS)" wrote:
>  
> > I see a similar problem on irix6.5 and i686-pc-cygwin.  See
> > http://gcc.gnu.org/ml/gcc-bugs/2001-09/msg00636.html .  You could confirm
> > that the same patch triggers your problem.  If so, the code that it touches
> > may be responsible for the problem.  Of course, they problem may be a latent
> > bug elsewhere.

> Yup, I can confirm! Reverting this patch makes my todays sinced cvs
> bootstrap again.

Just a quick note.  Any internal piece of data that can vary between
hosts cannot be used to make code decisions in the compiler.


For example, you cannot use the address of a piece of data (rtx) to
compute a value in a hash table and then use the `first' entry in the
hash table to canonicalize the value.  This would be wrong.

One _can_ take the CODE and/or the value of a CONST_INT and use those
to build a hash table index however.

Only `new' code in the compiler is so broken, as in the past, we have
ensured that this was not the case.  Any code like this needs to be
tracked down, understood and fixed.