From: Yikun Jiang <yikunk...@gmail.com>
This patch uses the prefetch instruction to pre-load the
next_match into cache to improve the performance, also makes
an unrolling change to decrease the number of if branch usage.
---
deflate.c | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/deflate.c b/deflate.c
index 5ed2a9b..008c032 100644
--- a/deflate.c
+++ b/deflate.c
@@ -378,6 +378,9 @@ longest_match(IPos cur_match)
register int len; /* length of current match
*/
int best_len = prev_length; /* best match length so
far */
IPos limit = strstart > (IPos)MAX_DIST ? strstart - (IPos)MAX_DIST :
NIL;
+#ifdef __aarch64__
+ IPos next_match;
+#endif
/* Stop when cur_match becomes <= limit. To simplify the code,
* we prevent matches with the string of window index 0.
*/
@@ -411,6 +414,10 @@ longest_match(IPos cur_match)
do {
Assert(cur_match < strstart, "no future");
match = window + cur_match;
+#ifdef __aarch64__
+ next_match = prev[cur_match & WMASK];
+ __asm__("PRFM PLDL1STRM, [%0]"::"r"(&(prev[next_match &
WMASK])));
+#endif
/* Skip to next match if the match length cannot increase
* or if the match length is less than 2:
@@ -488,8 +495,14 @@ longest_match(IPos cur_match)
scan_end = scan[best_len];
#endif
}
- } while ((cur_match = prev[cur_match & WMASK]) > limit
- && --chain_length != 0);
+ }
+#ifdef __aarch64__
+ while ((cur_match = next_match) > limit
+ && --chain_length != 0);
+#else
+ while ((cur_match = prev[cur_match & WMASK]) > limit
+ && --chain_length != 0);
+#endif
return best_len;
}
@@ -777,7 +790,20 @@ deflate (int pack_level)
lookahead -= prev_length-1;
prev_length -= 2;
RSYNC_ROLL(strstart, prev_length+1);
+
+ while (prev_length >= 4) {
+ prev_length -= 4;
+ strstart++;
+ INSERT_STRING(strstart, hash_head);
+ strstart++;
+ INSERT_STRING(strstart, hash_head);
+ strstart++;
+ INSERT_STRING(strstart, hash_head);
+ strstart++;
+ INSERT_STRING(strstart, hash_head);
+ }
do {
+ if (prev_length == 0) break;
strstart++;
INSERT_STRING(strstart, hash_head);
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
--
2.17.1
