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author | Daniel Wagner <daniel.wagner@bmw-carit.de> | 2015-06-05 15:03:38 +1000 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-06-05 15:03:38 +1000 |
commit | c4af96c9b22fab1ab0dd7d198b56597e0a0beb89 (patch) | |
tree | 500cd0cfbc9a826b6e0e138b952b6890363865d9 | |
parent | 23008da383d2235377e607d525719de2cf12b886 (diff) | |
download | linux-next-c4af96c9b22fab1ab0dd7d198b56597e0a0beb89.tar.gz |
lib/sort: Move the alignment check into a function
Rasmus Villemoes suggestes to move the aliment check into a separate
function in order to improve the readability.
Furthermore, let's avoid the switch statement since gcc might mess it
up. My gcc 4.9.2 produces the same code for the x86_64
configuration. That is
switch (size) {
case 4:
if (alignment_ok(base, 4))
swap_func = u32_swap;
break;
case 8:
if (alignment_ok(base, 8))
swap_func = u64_swap;
break;
}
if (!swap_func)
swap_func = generic_swap;
}
resulted into the same object code.
Link: https://lkml.org/lkml/2015/5/15/89
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r-- | lib/sort.c | 30 |
1 files changed, 9 insertions, 21 deletions
diff --git a/lib/sort.c b/lib/sort.c index 9c6b229049cea4..fc20df42aa6f29 100644 --- a/lib/sort.c +++ b/lib/sort.c @@ -8,6 +8,12 @@ #include <linux/export.h> #include <linux/sort.h> +static int alignment_ok(const void *base, int align) +{ + return IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) || + ((unsigned long)base & (align - 1)) == 0; +} + static void u32_swap(void *a, void *b, int size) { u32 t = *(u32 *)a; @@ -58,29 +64,11 @@ void sort(void *base, size_t num, size_t size, int i = (num/2 - 1) * size, n = num * size, c, r; if (!swap_func) { -#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) - switch (size) { - case 4: + if (size == 4 && alignment_ok(base, 4)) swap_func = u32_swap; - break; - case 8: + else if (size == 8 && alignment_ok(base, 8)) swap_func = u64_swap; - break; - } -#else - switch (size) { - case 4: - if (((unsigned long)base & 3) == 0) - swap_func = u32_swap; - break; - case 8: - if (((unsigned long)base & 7) == 0) - swap_func = u64_swap; - break; - } -#endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ - - if (!swap_func) + else swap_func = generic_swap; } |