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    SubjectRe: [PATCH 0/4] Compile kernel with -fwhole-program --combine
    On Fri, 2006-08-25 at 08:01 +0200, Jan Engelhardt wrote:
    > >> Compiling files on their own (`make drivers/foo/bar.o`) seems to make
    > >> the optimization void. Sure, most people don't stop compiling in
    > >> between. Just a note
    > >
    > >Actually I'm not entirely sure what you write is true. It'll _build_
    > >fs/jffs2/read.o, for example, but it still won't then use it when I make
    > >the kernel -- it'll just use fs/jffs2/jffs2.o which is built from all
    > >the C files with --combine. So the optimisation isn't lost.
    > Umm then it spends double the time in compilation, doing:
    > read.o <- read.c
    > foo.o <- foo.c
    > bar.o <- bar.c
    > built-in.o <- read.c foo.c bar.c

    Only if you invoke make explicitly for read.o, foo.o and bar.o. If you
    just type 'make' then it won't build those.

    > >So to overcome this, we use GCC's __attribute__((externally_visible))
    > >which, as documented, just makes it global again -- undoing the effect
    > >of -fwhole-program just for this _one_ symbol.
    > Interesting. __attribute__((visibility("default"))) does the same?

    That much you can test for yourself without a fixed compiler. No, it


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      Last update: 2006-08-25 10:59    [W:0.023 / U:32.212 seconds]
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