On 7/13/2017 11:06 PM, Jin, Yao wrote:
Sorry, please ignore my previous response.
On 7/13/2017 10:31 PM, Peter Zijlstra wrote:
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?
Now I understand what you suggest. Yes, that's right.
Do I need to update the patch?
Thanks
Jin Yao
Looks it should be:
if (type)
return branch_map[__ffs(type) - 1];
+
+ return PERF_BR_UNKNOWN;
+}
