[PATCH] ACPI: NFIT: Optimize nfit_mem_cmp() for efficiency

From: Kuan-Wei Chiu
Date: Thu Oct 12 2023 - 17:59:14 EST


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@xxxxxxxxx>
---
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..eea827d9af08 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 handleA - handleB;
}

static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc)
--
2.25.1