On Wednesday 30 of November 2011, Tom Tromey wrote: > >>>>> "Stephan" == Stephan Bergmann <sberg...@redhat.com> writes: > Stephan> On 11/30/2011 05:37 PM, Lionel Elie Mamane wrote: > >> Any opinion about this patch? I have it in my local repo, and it helps > >> me when running under gdb, as gdb now knows about macros! > > Stephan> Would -ggdb3 excessively increase object size compared to -ggdb2? > > The short answer is yes, but there is a more complicated answer. > > First, one must consider the tradeoffs. I always use -g3 when building > gdb, because gdb uses macros fairly heavily, and because I just don't > care about the extra space. I prefer the convenience. YMMV of course, > and I don't know enough about LibreOffice to offer an opinion.
There is hope that LibreOffice is C++ enough to actually not use macros that need to be stepped through. As a sidenote, this gave me an interesting idea that I want to try somewhen. It might be actually helpful to explicitly not have debug info about macros and enclose bodies of some functions like uno::Reference::operator->() or boost::shared_ptr stuff in one huge macro that'd avoid stepping through them (which I really hate, as it's mostly pointless). > If you really want to shrink debuginfo, use -gdwarf-4 and > -fdebug-types-section. The former has been in GCC for a while, I don't > remember when the latter was added. -fdebug-types-section is very new (few months), but it seems the addition was actually -fno-debug-types-section, allowing disabling of the feature for tools that cannot cope with it. > These options cause debuginfo for > most big types to be shared across compilation units, a huge size win. > This also makes gdb use less memory. I've tried it and it seems to save about 1/3 of .so size, so it indeed is very noticeable. Would it make sense to have this even enabled by default if gcc supports the option? > The downside of this feature is that not all tools have been upgraded to > understand it. gdb works fine, but the 7 dwarves, and systemtap, and I > think valgrind, will barf. They will all come around eventually, though > I am not sure when. I have gcc-4.5.1, gdb-7.2 and valgrind 3.6.1 (openSUSE 11.4) and after some quick tests I didn't notice any problems with -gdwarf-4. So -gdwarf-4 looks like a sensible default to me. Even if not, I'm going to use it (quick hack: modify your LO make script to add it to $CXXFLAGS). -- Lubos Lunak l.lu...@suse.cz _______________________________________________ LibreOffice mailing list LibreOffice@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/libreoffice
