http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46091
Summary: missed optimization: x86 bt/btc/bts instructions
Product: gcc
Version: 4.3.5
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: [email protected]
ReportedBy: [email protected]
The following code, at least when optimizing for space, should use x86
bt/btc/bts instructions.
#include <limits.h>
#include <stddef.h>
void set_bit(size_t* a, size_t b)
{
const unsigned c = sizeof(size_t) * CHAR_BIT;
a[b / c] |= (((size_t)1) << (b % c));
}
void clear_bit(size_t* a, size_t b)
{
const unsigned c = sizeof(size_t) * CHAR_BIT;
a[b / c] &= ~(((size_t)1) << (b % c));
}
int get_bit(size_t* a, size_t b)
{
const unsigned c = sizeof(size_t) * CHAR_BIT;
return !!(a[b / c] & (((size_t)1) << (b % c)));
}
