GCC 4.2 branch comparision failure building Java

[Ian Lance Taylor]

"Joseph S. Myers" <joseph@codesourcery.com> writes:

> On Tue, 13 Mar 2007, Mark Mitchell wrote:
> 
> > The GCC 4.2.0 RC1 build has failed (on x86_64-unknown-linux-gnu) with:
> > 
> > Comparing stages 2 and 3
> > Bootstrap comparison failure!
> > ./java/parse.o differs
> > ./java/parse-scan.o differs
> > 
> > Has anyone else seen this?
> 
> I'm now looking at this (or at a possibly related bootstrap comparison 
> failure seen on i686-pc-linux-gnu).

For what it's worth, I bootstrapped on a few different GNU/Linux
systems with different kernels and base compilers.  I only saw
bootstrap comparison failures on one; that one was running Red Hat 9
and had gcc 3.2.2 installed in /usr/bin.  On that one, a bootstrap4
worked.  So I assumed that that one was due to some miscompilation of
stage1.  I saw one other similar case recently: an older compiler
miscompiled stage1 in a way that introduced a bootstrap comparison
failure; unfortunately I don't recall the exact details.

Anyhow, the point is: first see if a bootstrap4/compare3 works.  If it
does, look at your base compiler.

Ian