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Subject[PATCH] lib/memweight.c: optimize by inlining bitmap_weight()
Date
This patch inlines bitmap_weight() call. Thus, removing the BUG_ON,
and 'longs to bits -> bits to longs' conversion by directly calling
hweight_long().

./scripts/bloat-o-meter lib/memweight.o.old lib/memweight.o.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-10 (-10)
Function old new delta
memweight 162 152 -10

Co-developed-by: Erdem Tumurov <erdemus@gmail.com>
Co-developed-by: Vladimir Shelekhov <vshel@iis.nsk.su>
Signed-off-by: Erdem Tumurov <erdemus@gmail.com>
Signed-off-by: Vladimir Shelekhov <vshel@iis.nsk.su>
Signed-off-by: Denis Efremov <efremov@ispras.ru>
---
lib/memweight.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/memweight.c b/lib/memweight.c
index 94dd72ccaa7f..f050b2b4c5e2 100644
--- a/lib/memweight.c
+++ b/lib/memweight.c
@@ -20,11 +20,13 @@ size_t memweight(const void *ptr, size_t bytes)

longs = bytes / sizeof(long);
if (longs) {
- BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
- ret += bitmap_weight((unsigned long *)bitmap,
- longs * BITS_PER_LONG);
+ const unsigned long *bitmap_long =
+ (const unsigned long *)bitmap;
+
bytes -= longs * sizeof(long);
- bitmap += longs * sizeof(long);
+ for (; longs > 0; longs--, bitmap_long++)
+ ret += hweight_long(*bitmap_long);
+ bitmap = (const unsigned char *)bitmap_long;
}
/*
* The reason that this last loop is distinct from the preceding
--
2.21.0
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