On Thu, Jul 13, 2017 at 08:04:14PM +0800, Jin Yao wrote:
> +#define X86_BR_TYPE_MAP_MAX 16
> +
> +static int
> +common_branch_type(int type)
> +{
> + int i, mask;
> + const int branch_map[X86_BR_TYPE_MAP_MAX] = {
> + PERF_BR_CALL, /* X86_BR_CALL */
> + PERF_BR_RET, /* X86_BR_RET */
> + PERF_BR_SYSCALL, /* X86_BR_SYSCALL */
> + PERF_BR_SYSRET, /* X86_BR_SYSRET */
> + PERF_BR_UNKNOWN, /* X86_BR_INT */
> + PERF_BR_UNKNOWN, /* X86_BR_IRET */
> + PERF_BR_COND, /* X86_BR_JCC */
> + PERF_BR_UNCOND, /* X86_BR_JMP */
> + PERF_BR_UNKNOWN, /* X86_BR_IRQ */
> + PERF_BR_IND_CALL, /* X86_BR_IND_CALL */
> + PERF_BR_UNKNOWN, /* X86_BR_ABORT */
> + PERF_BR_UNKNOWN, /* X86_BR_IN_TX */
> + PERF_BR_UNKNOWN, /* X86_BR_NO_TX */
> + PERF_BR_CALL, /* X86_BR_ZERO_CALL */
> + PERF_BR_UNKNOWN, /* X86_BR_CALL_STACK */
> + PERF_BR_IND, /* X86_BR_IND_JMP */
> + };
> +
> + type >>= 2; /* skip X86_BR_USER and X86_BR_KERNEL */
> + mask = ~(~0 << 1);
OCC worthy means of writing: 1
> +
> + for (i = 0; i < X86_BR_TYPE_MAP_MAX; i++) {
> + if (type & mask)
> + return branch_map[i];
> +
> + type >>= 1;
> + }
That is some of the more confused code I've seen in a while :/
if (type)
return branch_map[__ffs(type)];
is what you meant to write, no?
> +
> + return PERF_BR_UNKNOWN;
> +}
