• Kirill Smelkov's avatar
    Tell the world we gave up on pushing CC_OPTIMIZE_FOR_SIZE · 3a55fb0d
    Kirill Smelkov authored
    In commit 281dc5c5 ("Give up on pushing CC_OPTIMIZE_FOR_SIZE") we
    already changed the actual default value, but the help-text still
    suggested 'y'. Fix the help text too, for all the same reasons.
    
    Sadly, -Os keeps on generating some very suboptimal code for certain
    cases, to the point where any I$ miss upside is swamped by the downside.
    The main ones are:
    
     - using "rep movsb" for memcpy, even on CPU's where that is
       horrendously bad for performance.
    
     - not honoring branch prediction information, so any I$ footprint you
       win from smaller code, you lose from less code density in the I$.
    
     - using divide instructions when that is very expensive.
    Signed-off-by: default avatarKirill Smelkov <kirr@mns.spb.ru>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    3a55fb0d
Kconfig 55.5 KB