On Fri, Oct 13, 2023 at 2:22 PM Kuan-Wei Chiu <visitorckw@xxxxxxxxx> wrote: > > 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> > --- > 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; Are you sure that you are not losing bits in these conversions? > } > > static int nfit_mem_init(struct acpi_nfit_desc *acpi_desc) > --
