• Ralf Baechle's avatar
    MIPS: Use ARCH_USE_BUILTIN_BSWAP. · 1ee3630a
    Ralf Baechle authored
    ARCH_USE_BUILTIN_BSWAP will use __builtin_bswap16(), __builtin_bswap32()
    and __builtin_bswap64() where available.  This allows better instruction
    scheduling.  On pre-R2 processors it will result in 32 bit and 64 bit
    swapping being performed in a call to a __bswapsi2() rsp. __bswapdi2()
    functions, so we add these, too.
    
    For a 4.2 kernel with GCC 4.9 this yields the following kernel sizes:
    
       text    data     bss     dec     hex filename
    3996071  155804   88992 4240867  40b5e3 vmlinux         ip22 baseline
    3985687  159900   88992 4234579  409d53 vmlinux         ip22 + bswap patch
    6913157  378552  251024 7542733  7317cd vmlinux         ip27 baseline
    6878581  378552  251024 7508157  7290bd vmlinux         ip27 + bswap patch
    5773777  268752  187424 6229953  5f0fc1 vmlinux         malta baseline
    5773401  268752  187424 6229577  5f0e49 vmlinux         malta + bswap patch
    
    Presumably the code size improvments yield better cache hit rate thus
    better performance compensating for the extra function call but this
    will still need to be benchmarked.
    Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
    1ee3630a
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