[PATCH] lib/lz4: make arrays static const, reduces object code size

Colin King
2017-09-21T22:19:39Z

From: Colin Ian King <colin.king@canonical.com>

Don't populate the read-only arrays dec32table and dec64table on the
stack, instead make them both static const. Makes the object code
smaller by over 10K bytes:

Before:
text data bss dec hex filename
31500 0 0 31500 7b0c lib/lz4/lz4_decompress.o

After:
text data bss dec hex filename
20237 176 0 20413 4fbd lib/lz4/lz4_decompress.o

(gcc version 7.2.0 x86_64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
lib/lz4/lz4_decompress.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index bd3574312b82..141734d255e4 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -85,8 +85,8 @@ static FORCE_INLINE int LZ4_decompress_generic(
const BYTE * const lowLimit = lowPrefix - dictSize;

const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize;
- const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
- const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };
+ static const unsigned int dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 };
+ static const int dec64table[] = { 0, 0, 0, -1, 0, 1, 2, 3 };

const int safeDecode = (endOnInput = endOnInputSize);
const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * KB)));
--
2.14.1