First of all, 1 << 31 is technically undefined behaviour, so let's just
use an unsigned literal.
If i is 'signed int' and gcc doesn't know that i is positive, gcc
generates code to compute the C99-mandated values of "i / 32" and "i %
32", which is a lot more complicated than simple a simple shifts/mask.
The only caller of paint_down actually passes an "unsigned int" value,
but the prototype of paint_down causes (completely well-defined)
conversion to signed int, and gcc has no way of knowing that the
converted value is non-negative. Just make the id parameter unsigned.
In update_refstatus, the change in generated code is much smaller,
presumably because gcc is smart enough to see that i starts as 0 and is
only incremented, so it is allowed (per the UD of signed overflow) to
assume that i is always non-negative. But let's just help less smart
compilers generate good code anyway.
Signed-off-by: Rasmus Villemoes <rv@xxxxxxxxxxxxxxxxxx>
---
shallow.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/shallow.c b/shallow.c
index 8b1c35d..5aec5a5 100644
--- a/shallow.c
+++ b/shallow.c
@@ -464,7 +464,7 @@ static uint32_t *paint_alloc(struct paint_info *info)
* all walked commits.
*/
static void paint_down(struct paint_info *info, const unsigned char *sha1,
- int id)
+ unsigned int id)
{
unsigned int i, nr;
struct commit_list *head = NULL;
@@ -476,7 +476,7 @@ static void paint_down(struct paint_info *info, const unsigned char *sha1,
if (!c)
return;
memset(bitmap, 0, bitmap_size);
- bitmap[id / 32] |= (1 << (id % 32));
+ bitmap[id / 32] |= (1U << (id % 32));
commit_list_insert(c, &head);
while (head) {
struct commit_list *p;
@@ -650,11 +650,11 @@ static int add_ref(const char *refname, const struct object_id *oid,
static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
{
- int i;
+ unsigned int i;
if (!ref_status)
return;
for (i = 0; i < nr; i++)
- if (bitmap[i / 32] & (1 << (i % 32)))
+ if (bitmap[i / 32] & (1U << (i % 32)))
ref_status[i]++;
}
--
2.1.4