I assume no more progress has been made on this? ---------------------------------------------------------------------------
Tom Lane wrote: > I wrote: > > Michael Paesold <[EMAIL PROTECTED]> writes: > >> I am definatly not going to use -march=pentium4 in any production > >> system. Should I open a bug report with RedHat (gcc vendor)? > > > Yeah, but they'll probably want a smaller test case than "Postgres fails > > its regression tests" :-( > > I have just confirmed that the problem still exists in FC4's current > compiler (gcc 4.0.1, gcc-4.0.1-4.fc4), which probably will boost up the > priority of the complaint quite a long way in Red Hat's eyes. > > I've also confirmed that the problem is in interval_div; you can > reproduce the failure with > > select '41 years 1 mon 11 days'::interval / 10; > > which should give '4 years 1 mon 9 days 26:24:00', but when > timestamp.o is compiled with "-mcpu=pentium4 -march=pentium4", > you get '4 years 1 mon 10 days 02:24:00'. --enable-integer-datetimes > is not relevant because the interesting part is all double/integer > arithmetic. > > Looking at this, though, I wonder if the pentium4 answer isn't "more > correct". If I'm doing the math by hand correctly, what we end up > with is having to cascade 3/10ths of a month down into the days field, > and since the conversion factor is supposed to be 30 days/month, that > should be exactly 9 days. Plus the one full day from the 11/10 days > gives 10 days. I think what is happening on all the non-Pentium > platforms is that (3.0/10.0)*30.0 is producing something just a shade > less than 9.0, whereas the Pentium gives 9.0 or a shade over, possibly > due to rearrangement of the calculation. I think we can still file this > as a compiler bug, because I'm pretty sure the C spec does not allow > rearrangement of floating-point calculations ... but we might want to > think about tweaking the code's roundoff behavior just a bit. > > An example that's a little easier to look at is > > select '41 years 1 mon'::interval / 10; > > I get '4 years 1 mon 9 days' with the pentium4 optimization, and > '4 years 1 mon 8 days 24:00:00' without, and the former seems more > correct... > > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings > -- Bruce Momjian http://candle.pha.pa.us EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
