Messages in this thread | | | Subject | Re: [PATCH v8 2/7] perf/x86/intel: Record branch type | From | "Jin, Yao" <> | Date | Thu, 13 Jul 2017 23:15:14 +0800 |
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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; >>> +} >
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