On Wed, May 26, 2010 at 10:47:42PM +0530, K.Prasad wrote: > On Wed, May 26, 2010 at 10:54:41AM +0100, David Howells wrote: > > K.Prasad <[email protected]> wrote: > > > > > > My understanding is weak function definitions must appear in a > > > > different C > > > > file than their call sites to work on some toolchains. > > > > > > > > > > Atleast, there are quite a few precedents inside the Linux kernel for > > > __weak functions being invoked from the file in which they are defined > > > (arch_hwblk_init, arch_enable_nonboot_cpus_begin and hw_perf_disable to > > > name a few). > > > Moreover the online GCC docs haven't any such constraints mentioned. > > > > I've seen problems in this area. gcc sometimes inlines a weak function > > that's > > in the same file as the call point. > > > > We've seen such behaviour even otherwise....even with noinline attribute > in place. I'm not sure if this gcc fix > (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16922) helped correct the > behaviour, but the lesson has been to not trust a function to be > inlined/remain non-inline consistently.
If we can't put the call to the function in the same file of its weak definition, then perf is totally screwed. And in fact it makes __weak basically useless and unusable. I guess that happened in old gcc versions that have been fixed now. Anyway, I'm personally fine with this patch (you can put my hack if you want). Thanks. _______________________________________________ Linuxppc-dev mailing list [email protected] https://lists.ozlabs.org/listinfo/linuxppc-dev
