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Re: powerpc-ibm-aix4.3.3.0 bootstrap issue


> To: mike stump <mrs@windriver.com>
> cc: john@feith.com, gcc@gcc.gnu.org
> Date: Thu, 04 Oct 2001 23:00:53 -0400
> From: David Edelsohn <dje@watson.ibm.com>

> 	Using a debugger on the compiler producing different output caused
> the compiler to stop emitting different output.  Debugging the compiler
> affected the problem, which is why I think this is a memory layout, memory
> corruption, or memory address issue.

> 	I and others tried debugging tricks #1 through #MAX_INT.  It's not
> that simple.

Standard debugging trick #136 would be to take the .ii file you know
can produce different output, and the date stamp for the compiler, and
have everyone with two or more possible environments update to that
time, build up the same compiler in all possible environments they
can, and then to see which versions of the output they get, and have
people try debug it, and see if we can't find a person with two
environments that yield different outputs that they can debug in.

For example, if one has a cygwin hosted compiler, and a solaris
compiler, one can see if they match, or are different.  Also, by
surveying it, we can deduce things about the environment that is
special.  If it is just gcc-2.95.x that miscompiles reload, then we
can put in the instructions, please compile up, non-bootstrap with a
new tool chain, and then recompile using bootstrap the compiler with
itself...  in this special case.  This sort of advice, is slightly
better than just using -O1, or hacking reload to be somehow different.


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