• Rasmus Villemoes's avatar
    lib/lz4: Pull out constant tables · bea2b592
    Rasmus Villemoes authored
    There's no reason to allocate the dec{32,64}table on the stack; it
    just wastes a bunch of instructions setting them up and, of course,
    also consumes quite a bit of stack. Using size_t for such small
    integers is a little excessive.
    
    $ scripts/bloat-o-meter /tmp/built-in.o lib/built-in.o
    add/remove: 2/2 grow/shrink: 2/0 up/down: 1304/-1548 (-244)
    function                                     old     new   delta
    lz4_decompress_unknownoutputsize              55     718    +663
    lz4_decompress                                55     632    +577
    dec64table                                     -      32     +32
    dec32table                                     -      32     +32
    lz4_uncompress                               747       -    -747
    lz4_uncompress_unknownoutputsize             801       -    -801
    
    The now inlined lz4_uncompress functions used to have a stack
    footprint of 176 bytes (according to -fstack-usage); their inlinees
    have increased their stack use from 32 bytes to 48 and 80 bytes,
    respectively.
    Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    bea2b592
lz4_decompress.c 7.81 KB