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    gcov: disable tree-loop-im to reduce stack usage · c87bf431
    Arnd Bergmann 提交于
    Enabling CONFIG_GCOV_PROFILE_ALL produces us a lot of warnings like
    
    lib/lz4/lz4hc_compress.c: In function 'lz4_compresshcctx':
    lib/lz4/lz4hc_compress.c:514:1: warning: the frame size of 1504 bytes is larger than 1024 bytes [-Wframe-larger-than=]
    
    After some investigation, I found that this behavior started with gcc-4.9,
    and opened https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69702.
    A suggested workaround for it is to use the -fno-tree-loop-im
    flag that turns off one of the optimization stages in gcc, so the
    code runs a little slower but does not use excessive amounts
    of stack.
    
    We could make this conditional on the gcc version, but I could not
    find an easy way to do this in Kbuild and the benefit would be
    fairly small, given that most of the gcc version in production are
    affected now.
    
    I'm marking this for 'stable' backports because it addresses a bug
    with code generation in gcc that exists in all kernel versions
    with the affected gcc releases.
    Signed-off-by: NArnd Bergmann <arnd@arndb.de>
    Acked-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: NMichal Marek <mmarek@suse.com>
    c87bf431
Makefile 55.9 KB