On Mon, Apr 24, 2017 at 08:47:14AM +0800, Jin, Yao wrote:
>
>
> On 4/23/2017 9:55 PM, Jiri Olsa wrote:
> > On Thu, Apr 20, 2017 at 08:07:50PM +0800, Jin Yao wrote:
> >
> > SNIP
> >
> > > +#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_INT, /* X86_BR_INT */
> > > + PERF_BR_IRET, /* X86_BR_IRET */
> > > + PERF_BR_JCC, /* X86_BR_JCC */
> > > + PERF_BR_JMP, /* X86_BR_JMP */
> > > + PERF_BR_IRQ, /* X86_BR_IRQ */
> > > + PERF_BR_IND_CALL, /* X86_BR_IND_CALL */
> > > + PERF_BR_NONE, /* X86_BR_ABORT */
> > > + PERF_BR_NONE, /* X86_BR_IN_TX */
> > > + PERF_BR_NONE, /* X86_BR_NO_TX */
> > > + PERF_BR_CALL, /* X86_BR_ZERO_CALL */
> > > + PERF_BR_NONE, /* X86_BR_CALL_STACK */
> > > + PERF_BR_IND_JMP, /* X86_BR_IND_JMP */
> > > + };
> > > +
> > > + type >>= 2; /* skip X86_BR_USER and X86_BR_KERNEL */
> > > + mask = ~(~0 << 1);
> > is that a fancy way to get 1 into the mask? what do I miss?
you did not comment on this one
> >
> > > +
> > > + for (i = 0; i < X86_BR_TYPE_MAP_MAX; i++) {
> > > + if (type & mask)
> > > + return branch_map[i];
> > I wonder some bit search would be faster in here, but maybe not big deal
> >
> > jirka
>
> I just think the branch_map[] doesn't contain many entries (16 entries
> here), so maybe checking 1 bit one time should be acceptable. I just want to
> keep the code simple.
>
> But if the number of entries is more (e.g. 64), maybe it'd better check 2 or
> 4 bits one time.
ook
jirka
