lib/lz4: Pull out constant tables
authorRasmus Villemoes <linux@rasmusvillemoes.dk>
Tue, 10 Feb 2015 10:12:21 +0000 (11:12 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 25 Mar 2015 14:04:57 +0000 (15:04 +0100)
commitbea2b592fd18eb8ffa3fc4ad380610632d03a38f
tree82a139e42a1812111dacc5a23b8b5fcb39058396
parent7085a7401ba54e92bbb5aa24d6f428071e18e509
lib/lz4: Pull out constant tables

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: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
lib/lz4/lz4_decompress.c