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Re: AIX regression due to DFA scheduler merge
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Vladimir Makarov <vmakarov at redhat dot com>
- Cc: Jeffrey Law <law at redhat dot com>, gcc-patches at gcc dot gnu dot org, Mark Mitchell <mark at codesourcery dot com>
- Date: Thu, 30 May 2002 22:22:25 -0400
- Subject: Re: AIX regression due to DFA scheduler merge
>>>>> Vladimir Makarov writes:
Vlad> Ok, David. I'll look at this. But I can guess (knowing the sources) it
Vlad> is not because of the merge. There were other changes besides the
Vlad> merge.
Some additional datapoints: -mcpu=604e fails. -mcpu=630 fails.
-mcpu=750 works. -mcpu=7400 works. -mcpu=7450 works.
I believe that the automatic regression tester is not failing
because sysv4.h defines:
#define PROCESSOR_DEFAULT PROCESSOR_PPC750
AIX defaults to PPC604.
I can send you the ChangeLog diff between the last working version
and the version that began to fail. The dfa-branch merge is the only
relevant change.
I am not saying that the DFA changes are inherently faulty, but I
think that the merge may have exposed a latent bug. After the merge, GCC
schedules the instructions differently with the exact same, old
description. We may have just been lucky with the scheduling before.
David