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Date:   Tue, 23 Feb 2021 16:49:56 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Martin =?utf-8?B?TGnFoWth?= <mliska@suse.cz>
Cc:     linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH] perf annotate: add --demangle and --demangle-kernel
Message-ID: <YDVcZJscuKIgShsm@kernel.org>
References: <deb2af9e-25dd-ac72-29f4-ab90c2b24237@suse.cz>
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Em Mon, Feb 22, 2021 at 09:29:22AM +0100, Martin Liška escreveu:
> Perf annotate supports --symbol but it's impossible to filter
> a C++ symbol. With --no-demangle one can filter easily by
> mangled function name.
> 
> Signed-off-by: Martin Liška <mliska@suse.cz>
> ---
>  tools/perf/Documentation/perf-annotate.txt | 7 +++++++
>  tools/perf/builtin-annotate.c              | 4 ++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/tools/perf/Documentation/perf-annotate.txt b/tools/perf/Documentation/perf-annotate.txt
> index 1b5042f134a8..80c1be5d566c 100644
> --- a/tools/perf/Documentation/perf-annotate.txt
> +++ b/tools/perf/Documentation/perf-annotate.txt
> @@ -124,6 +124,13 @@ OPTIONS
>  --group::
>  	Show event group information together
> +--demangle::
> +	Demangle symbol names to human readable form. It's enabled by default,
> +	disable with --no-demangle.
> +
> +--demangle-kernel::
> +	Demangle kernel symbol names to human readable form (for C++ kernels).
> +
>  --percent-type::
>  	Set annotation percent type from following choices:
>  	  global-period, local-period, global-hits, local-hits
> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> index a23ba6bb99b6..ef70a17b9b5b 100644
> --- a/tools/perf/builtin-annotate.c
> +++ b/tools/perf/builtin-annotate.c
> @@ -538,6 +538,10 @@ int cmd_annotate(int argc, const char **argv)
>  		    "Strip first N entries of source file path name in programs (with --prefix)"),
>  	OPT_STRING(0, "objdump", &annotate.opts.objdump_path, "path",
>  		   "objdump binary to use for disassembly and annotations"),
> +	OPT_BOOLEAN(0, "demangle", &symbol_conf.demangle,
> +		    "Disable symbol demangling"),

Nope, this _enables_ demangling, i.e.:

	perf annotate --demangle

Asks for symbol demangling, while:

	perf annotate --no-demangle

As you correctly wrote in your commit message and on the
--demangle-kernel case, enables demangling.

Please consider making this configurable (if not already) via
~/.perfconfig, 'perf config', sure in a followup patch.

Thanks,

- Arnaldo

> +	OPT_BOOLEAN(0, "demangle-kernel", &symbol_conf.demangle_kernel,
> +		    "Enable kernel symbol demangling"),
>  	OPT_BOOLEAN(0, "group", &symbol_conf.event_group,
>  		    "Show event group information together"),
>  	OPT_BOOLEAN(0, "show-total-period", &symbol_conf.show_total_period,
> -- 
> 2.30.1
> 

-- 

- Arnaldo