On 12/03/2011 09:00 AM, Simon Josefsson wrote: > What does -funit-at-a-time really do? My gcc 4.4 manual says: > > `-funit-at-a-time' > This option is left for compatibility reasons. `-funit-at-a-time' > has no effect, while `-fno-unit-at-a-time' implies > `-fno-toplevel-reorder' and `-fno-section-anchors'. > > Enabled by default.
That's the case for 4.4 and later. But in gcc 4.3, it was not unconditionally enabled, and as I said earlier, at least coreutils ran into a situation where gcc 4.3. failed to compile at -Werror because -Wdisabled-optimization warned that -fno-unit-at-a-time was required, which warning turned into an error. At this point, gcc 4.3 is slowly phasing out; most Linux distros and Cygwin have moved on to newer compilers, where the problem is less likely to happen. > > The manual for -ipa-pure-const says: > > `-fipa-pure-const' > Discover which functions are pure or constant. Enabled by default > at `-O' and higher. > > That seems harmless and as far I understand would not modify code > generation. It doesn't modify code generation, but it DOES modify warning generation, and in a way that negatively interacts with libtool: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=10197 -- Eric Blake [email protected] +1-919-301-3266 Libvirt virtualization library http://libvirt.org
signature.asc
Description: OpenPGP digital signature
