William Stein wrote: > On Tue, Sep 29, 2009 at 5:11 PM, Robert Bradshaw > <rober...@math.washington.edu> wrote: >> >> On Sep 29, 2009, at 3:36 PM, Dr. David Kirkby wrote:
>>> As such, I've set all flags, including those for Fortran, even when >>> not >>> needed. The extra few bytes of code does no significant harm. If the >>> package does not use Fortran, then it will ignore the Fortran flags. >>> >>> The problem with creating a spkg-install with a subset of things >>> set, is >>> that the subset needs carefully testing for each package. My version >>> might waste a couple of KB bytes, but it is safe. >>> >>> So I have tended to write spkg-install's in such a way that they >>> should >>> work with any package. >>> >>> Minh asked me the other day to write this up, though I chose not to >>> just >>> now, as I am not convinced my latest version is as good as possible. >> Sounds like something that could be globally useful, rather than >> having separate logic inside each spkg. > > +1 OK, I'll add this logic to sage-env. I know the variables AR, CP, NM etc are supposed to be user configurable in Sage, but I somewhat doubt many packages respect the rarer ones, given they don't even respect CC and CXX. >>> One of the troublesome packages I noticed when testing with Sun Studio >>> is tachyon, which uses -O6. >>> >>> http://sagetrac.org/sage_trac/ticket/7069 >>> >>> It's not the -O6 which is causing the Solaris problem, though I do >>> think >>> -O6 is unwise. The fact that the tachyon.spkg ignores CC and uses >>> gcc >>> anyway, makes me believe the code is not well thought out. Therefore I >>> suspect there has not been extensive testing to prove -O6 is safe. > > There is no -O6 option to GCC. There are three nonzero numbered > optimization levels: -O1, -O2, and -O3. Do "man gcc". The > optimization options are: > > -O -O0 -O1 -O2 -O3 -Os That does not stop tachyon using -O6 - see http://sagetrac.org/sage_trac/ticket/7069 gcc does not indicate any error. It's anyones guess what it does when passed -O6. > The difference between -O2 and -O3 is: " -O3 turns on all > optimizations specified by -O2 and also turns on the > -finline-functions, -funswitch-loops and -fgcse-after-reload options." > I think these are not *supposed* to generate invalid assembly code -- > if they do, isn't that considered a bug in GCC? Of course there are > bugs in GCC, and using aggressive optimization is much more likely to > uncover them. > > -O3 has drawbacks such as potentially larger binaries, cache misses, etc. > > -- William OK. I'll set it at -O3. I think on Solaris with Sun's compiler, it would be sensible to use just -O, as that will set it to whatever is the default optimisation, which is currently -O3, but Sun could change that in the future. -O Use default optimization level (-xO3) so -O, -x03 and -O3 are all the same, but they might not be in another compiler. Sun say -O3 can break some code, so its not a 100% guarantee, but it would appear such could would be quite rare. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
