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authorRasmus Villemoes <rv@rasmusvillemoes.dk>2016-12-06 19:53:38 +0700
committerJunio C Hamano <gitster@pobox.com>2016-12-07 15:44:31 -0800
commit1127b3ced55b97229c55ff0c7585b284e3551a9e (patch)
tree670aac6ae5864183d3b8672a2cdf563309f258e4 /shallow.c
parent381aa8e73070646933520e1133a81ab4ba383891 (diff)
downloadgit-1127b3ced55b97229c55ff0c7585b284e3551a9e.tar.gz
shallow.c: bit manipulation tweaks
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@rasmusvillemoes.dk> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'shallow.c')
-rw-r--r--shallow.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/shallow.c b/shallow.c
index 4c4486ad67..2bf25552f0 100644
--- a/shallow.c
+++ b/shallow.c
@@ -389,7 +389,7 @@ 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;
@@ -401,7 +401,7 @@ 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;
@@ -575,11 +575,11 @@ 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]++;
}