Re: [HACKERS] powerpc(32) point/polygon regression failures on Debian Jessie - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] powerpc(32) point/polygon regression failures on Debian Jessie
Date
Msg-id 13825.1487607143@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] powerpc(32) point/polygon regression failures onDebian Jessie  (Christoph Berg <christoph.berg@credativ.de>)
Responses Re: [HACKERS] powerpc(32) point/polygon regression failures onDebian Jessie  (Christoph Berg <christoph.berg@credativ.de>)
List pgsql-hackers
Christoph Berg <christoph.berg@credativ.de> writes:
> Re: Tom Lane 2017-02-20 <30737.1487598355@sss.pgh.pa.us>
>> Hmph.  We haven't touched that code in awhile, and certainly not in the
>> 9.4.x branch.  I'd have to agree that this must be a toolchain change.

> FYI, in the meantime we could indeed trace it back to an libc issue on
> Jessie:

I wonder whether it's a compiler change, maybe along the lines of
rearranging the computation so that it gives a slightly different result.
Although you'd think that 10.0/10.0 would give exactly 1.0 no matter what.
Still, it'd be worth comparing the assembly code for your test program.
        regards, tom lane



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