From: Yury Norov <yury.norov@xxxxxxxxx>
Subject: find: micro-optimize for_each_{set,clear}_bit()
The macros iterate thru all set/clear bits in a bitmap. They search a
first bit using find_first_bit(), and the rest bits using find_next_bit().
Since find_next_bit() is called shortly after find_first_bit(), we can
save few lines of I-cache by not using find_first_bit().
Link: https://lkml.kernel.org/r/20210814211713.180533-12-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
Tested-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Lobakin <alobakin@xxxxx>
Cc: Alexey Klimov <aklimov@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/find.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/include/linux/find.h~find-micro-optimize-for_each_setclear_bit
+++ a/include/linux/find.h
@@ -280,7 +280,7 @@ unsigned long find_next_bit_le(const voi
#endif
#define for_each_set_bit(bit, addr, size) \
- for ((bit) = find_first_bit((addr), (size)); \
+ for ((bit) = find_next_bit((addr), (size), 0); \
(bit) < (size); \
(bit) = find_next_bit((addr), (size), (bit) + 1))
@@ -291,7 +291,7 @@ unsigned long find_next_bit_le(const voi
(bit) = find_next_bit((addr), (size), (bit) + 1))
#define for_each_clear_bit(bit, addr, size) \
- for ((bit) = find_first_zero_bit((addr), (size)); \
+ for ((bit) = find_next_zero_bit((addr), (size), 0); \
(bit) < (size); \
(bit) = find_next_zero_bit((addr), (size), (bit) + 1))
_
