lkml.org 
[lkml]   [2023]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2] ACPI: NFIT: Optimize nfit_mem_cmp() for efficiency
Date
The original code used conditional branching in the nfit_mem_cmp
function to compare two values and return -1, 1, or 0 based on the
result. However, the list_sort comparison function only needs results
<0, >0, or =0. This patch optimizes the code to make the comparison
branchless, improving efficiency and reducing code size. This change
reduces the number of comparison operations from 1-2 to a single
subtraction operation, thereby saving the number of instructions.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
v1 -> v2:
- Add explicit type cast in case the sizes of u32 and int differ.

drivers/acpi/nfit/core.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index f96bf32cd368..563a32eba888 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1138,11 +1138,7 @@ static int nfit_mem_cmp(void *priv, const struct list_head *_a,

handleA = __to_nfit_memdev(a)->device_handle;
handleB = __to_nfit_memdev(b)->device_handle;
- if (handleA < handleB)
- return -1;
- else if (handleA > handleB)
- return 1;
- return 0;
+ return (int)handleA - (int)handleB;
}

static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
--
2.25.1
\
 
 \ /
  Last update: 2023-10-13 14:23    [W:0.061 / U:0.136 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site