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Re: bootstrap failure on darwin, compare stages
- To: toa at pop dot agri dot ch
- Subject: Re: bootstrap failure on darwin, compare stages
- From: David Edelsohn <dje at watson dot ibm dot com>
- Date: Fri, 21 Sep 2001 15:56:06 -0400
- cc: GCC <gcc at gcc dot gnu dot org>
>>>>> Andreas Tobler writes:
Andreas> since yesterday bootstrapping fails on darwin. My question is not 'what
Andreas> is the fix' I'd like to know how to track down the problem.
Andreas> Unfortunately the trapping fails in the stage of comparing the stage 1
Andreas> with 2. The failing part is insn-emit.o which differs. How can I find
Andreas> out what's going wrong?
The first thing is to disassemble the object files or recompile
the source into assembly output with the two different stage compilers.
Then see what differs between the two files.
I have been seeing stage compare failures for GCC on AIX ever
since the conversion of HOST_WIDE_INT to "long long" for 64-bit targets
built on 32-bit hosts. The problem never produces incorrect code, but
something non-deterministic is occurring in the compiler. The example of
the comparison failure on AIX is one assembly file duplicating a TOC entry
while the other file re-uses the old entry through an alias. It seems
like something not hashing to the same value or some wild write, but I and
others have not been able to track it down after looking all Summer.
David