Re: planner fails on HEAD

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: planner fails on HEAD
Date: 2011-12-04 22:52:41
Message-ID: CAFj8pRAW+ZOH7i=oysnCXtmmhhi8SabvJ+VhX+xSC+pHmthJHg@mail.gmail.com
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2011/12/4 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
>> 2011/12/4 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>>> [ scratches head ... ]  Given that it got past the previous assertions,
>>> surely that ought to be impossible.  Could we see the values of
>>> cost_mergejoin's local variables, please?
>
>> It is strange
>
>> when I put a fprintf(stderr, "const literal") to exactly before or
>> somewhere after assertion, then assertion is ok. Without fprintf
>> assertion fails again
>
>> it looks like gcc bug - gcc 4.5.1 20100924 (Red Hat 4.5.1) It was
>> configured just with --enable-debug and --enable-cassert
>
> Hmm.  I'm betting that gcc has flushed one value to memory but the other
> one is still in a register that's wider than memory, creating a roundoff
> hazard.  Can you look at the generated assembly code?

I can, but tomorrow evening,

I'll send a code

Regards

Pavel
>
>                        regards, tom lane

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