On 5/9/2017 4:26 PM, Jiri Olsa wrote:
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
Sorry, I misunderstood that this comment and the next comment had the
same meaning.
In the previous version, I used the switch/case to convert from X86_BR
to PERF_BR. I got a comment from community that it'd better use a lookup
table for conversion.
Since each bit in type represents a X86_BR type so I use a mask (0x1) to
filter the bit. Yes, it looks I can also directly set 0x1 to mask.
I write the code "mask = ~(~0 << 1)" according to my coding habits. If
you think I should change the code to "mask = 0x1", that's OK :)
+
+ 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
Sorry, what's the meaning of ook? Does it mean "OK"?
Thanks
Jin Yao
