Re: [PATCH V3 05/17] perf machine: Remove the indent in resolve_lbr_callchain_sample

[Arnaldo Carvalho de Melo]

Em Fri, Mar 13, 2020 at 11:33:07AM -0700, kan.liang@xxxxxxxxxxxxxxx escreveu:
> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> 
> The indent is unnecessary in resolve_lbr_callchain_sample.
> Removing it will make the following patch simpler.
> 
> Current code path for resolve_lbr_callchain_sample()
> 
>         /* LBR only affects the user callchain */
>         if (i != chain_nr) {
>                 body of the function
>                 ....
>                 return 1;
>         }
> 
>         return 0;
> 
> With the patch,
> 
>         /* LBR only affects the user callchain */
>         if (i == chain_nr)
>                 return 0;
> 
>         body of the function
>         ...
>         return 1;
> 
> No functional changes.

Thanks for doing this,

-  Arnaldo
 
> Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> ---
>  tools/perf/util/machine.c | 123 +++++++++++++++++++-------------------
>  1 file changed, 63 insertions(+), 60 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index fd14f1489802..9021e5b6a2a9 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2177,6 +2177,12 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
>  	int chain_nr = min(max_stack, (int)chain->nr), i;
>  	u8 cpumode = PERF_RECORD_MISC_USER;
>  	u64 ip, branch_from = 0;
> +	struct branch_stack *lbr_stack;
> +	struct branch_entry *entries;
> +	int lbr_nr, j, k;
> +	bool branch;
> +	struct branch_flags *flags;
> +	int mix_chain_nr;
>  
>  	for (i = 0; i < chain_nr; i++) {
>  		if (chain->ips[i] == PERF_CONTEXT_USER)
> @@ -2184,71 +2190,68 @@ static int resolve_lbr_callchain_sample(struct thread *thread,
>  	}
>  
>  	/* LBR only affects the user callchain */
> -	if (i != chain_nr) {
> -		struct branch_stack *lbr_stack = sample->branch_stack;
> -		struct branch_entry *entries = perf_sample__branch_entries(sample);
> -		int lbr_nr = lbr_stack->nr, j, k;
> -		bool branch;
> -		struct branch_flags *flags;
> -		/*
> -		 * LBR callstack can only get user call chain.
> -		 * The mix_chain_nr is kernel call chain
> -		 * number plus LBR user call chain number.
> -		 * i is kernel call chain number,
> -		 * 1 is PERF_CONTEXT_USER,
> -		 * lbr_nr + 1 is the user call chain number.
> -		 * For details, please refer to the comments
> -		 * in callchain__printf
> -		 */
> -		int mix_chain_nr = i + 1 + lbr_nr + 1;
> -
> -		for (j = 0; j < mix_chain_nr; j++) {
> -			int err;
> -			branch = false;
> -			flags = NULL;
> +	if (i == chain_nr)
> +		return 0;
>  
> -			if (callchain_param.order == ORDER_CALLEE) {
> -				if (j < i + 1)
> -					ip = chain->ips[j];
> -				else if (j > i + 1) {
> -					k = j - i - 2;
> -					ip = entries[k].from;
> -					branch = true;
> -					flags = &entries[k].flags;
> -				} else {
> -					ip = entries[0].to;
> -					branch = true;
> -					flags = &entries[0].flags;
> -					branch_from = entries[0].from;
> -				}
> +	lbr_stack = sample->branch_stack;
> +	entries = perf_sample__branch_entries(sample);
> +	lbr_nr = lbr_stack->nr;
> +	/*
> +	 * LBR callstack can only get user call chain.
> +	 * The mix_chain_nr is kernel call chain
> +	 * number plus LBR user call chain number.
> +	 * i is kernel call chain number,
> +	 * 1 is PERF_CONTEXT_USER,
> +	 * lbr_nr + 1 is the user call chain number.
> +	 * For details, please refer to the comments
> +	 * in callchain__printf
> +	 */
> +	mix_chain_nr = i + 1 + lbr_nr + 1;
> +
> +	for (j = 0; j < mix_chain_nr; j++) {
> +		int err;
> +
> +		branch = false;
> +		flags = NULL;
> +
> +		if (callchain_param.order == ORDER_CALLEE) {
> +			if (j < i + 1)
> +				ip = chain->ips[j];
> +			else if (j > i + 1) {
> +				k = j - i - 2;
> +				ip = entries[k].from;
> +				branch = true;
> +				flags = &entries[k].flags;
>  			} else {
> -				if (j < lbr_nr) {
> -					k = lbr_nr - j - 1;
> -					ip = entries[k].from;
> -					branch = true;
> -					flags = &entries[k].flags;
> -				}
> -				else if (j > lbr_nr)
> -					ip = chain->ips[i + 1 - (j - lbr_nr)];
> -				else {
> -					ip = entries[0].to;
> -					branch = true;
> -					flags = &entries[0].flags;
> -					branch_from = entries[0].from;
> -				}
> +				ip = entries[0].to;
> +				branch = true;
> +				flags = &entries[0].flags;
> +				branch_from = entries[0].from;
> +			}
> +		} else {
> +			if (j < lbr_nr) {
> +				k = lbr_nr - j - 1;
> +				ip = entries[k].from;
> +				branch = true;
> +				flags = &entries[k].flags;
> +			} else if (j > lbr_nr)
> +				ip = chain->ips[i + 1 - (j - lbr_nr)];
> +			else {
> +				ip = entries[0].to;
> +				branch = true;
> +				flags = &entries[0].flags;
> +				branch_from = entries[0].from;
>  			}
> -
> -			err = add_callchain_ip(thread, cursor, parent,
> -					       root_al, &cpumode, ip,
> -					       branch, flags, NULL,
> -					       branch_from);
> -			if (err)
> -				return (err < 0) ? err : 0;
>  		}
> -		return 1;
> -	}
>  
> -	return 0;
> +		err = add_callchain_ip(thread, cursor, parent,
> +				       root_al, &cpumode, ip,
> +				       branch, flags, NULL,
> +				       branch_from);
> +		if (err)
> +			return (err < 0) ? err : 0;
> +	}
> +	return 1;
>  }
>  
>  static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
> -- 
> 2.17.1
> 

-- 

- Arnaldo