linux-kernel - Re: [PATCH 6/9] tracing: recordmcount.pl Exit early if no work to do

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Message-Id: <1256674842.26028.439.camel@gandalf.stny.rr.com>
Date:	Tue, 27 Oct 2009 16:20:42 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Li Hong <lihong.hi@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/9] tracing: recordmcount.pl Exit early if no work to
 do

On Tue, 2009-10-27 at 15:02 +0800, Li Hong wrote:
> >From 1589563d8113db41fa77dd657459b563dcecd389 Mon Sep 17 00:00:00 2001
> From: Li Hong <lihong.hi@...il.com>
> Date: Tue, 27 Oct 2009 13:13:37 +0800
> Subject: [PATCH] tracing: recordmcount.pl Exit early if no work to do
> 
> Also keep the global symbols and use it to check if no work to do, exit
> early.

How many files does this fall out of?  This looks like added complexity
for no real gain.

-- Steve

> 
> Signed-off-by: Li Hong <lihong.hi@...il.com>
> 
> diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> index a6585b6..d750da8 100755
> --- a/scripts/recordmcount.pl
> +++ b/scripts/recordmcount.pl
> @@ -91,7 +91,7 @@
>  #
>  # Here are the steps we take:
>  #
> -# 1) Record all the local symbols by using 'nm'
> +# 1) Record all the global, local and weak symbols by using 'nm'
>  # 2) Use objdump to find all the call site offsets and sections for
>  #    mcount.
>  # 3) Compile the list into its own object.
> @@ -143,12 +143,15 @@ $mv = "mv" if ((length $mv) == 0);
>  #print STDERR "running: $P '$arch' '$objdump' '$objcopy' '$cc' '$ld' " .
>  #    "'$nm' '$rm' '$mv' '$inputfile'\n";
>  
> +my %globals;		# List of global functions
>  my %locals;		# List of local (static) functions
>  my %weak;		# List of weak functions
>  my %convert;		# List of local functions used that needs conversion
>  
>  my $type;
> -my $nm_regex;		# Find the local functions (return function)
> +my $global_regex;	# Match a global function (return function)
> +my $local_regex;	# Match a local function (return function)
> +my $weak_regex; 	# Match a weak function (return function)
>  my $section_regex;	# Find the start of a section
>  my $function_regex;	# Find the name of a function
>  			#    (return offset and func name)
> @@ -190,7 +193,9 @@ if ($arch eq "x86") {
>  # We base the defaults off of i386, the other archs may
>  # feel free to change them in the below if statements.
>  #
> -$nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
> +$global_regex = "^[0-9a-fA-F]+\\s+T\\s+(\\S+)";
> +$local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\S+)";
> +$weak_regex = "^[0-9a-fA-F]+\\s+([wW])\\s+(\\S+)";
>  $section_regex = "Disassembly of section\\s+(\\S+):";
>  $function_regex = "^([0-9a-fA-F]+)\\s+<(.*?)>:";
>  $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount\$";
> @@ -239,7 +244,8 @@ if ($arch eq "x86_64") {
>      $cc .= " -m32";
>  
>  } elsif ($arch eq "powerpc") {
> -    $nm_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
> +    $global_regex = "^[0-9a-fA-F]+\\s+T\\s+(\\.?\\S+)";
> +    $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
>      $function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?.*?)>:";
>      $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
>  
> @@ -314,19 +320,24 @@ my $mcount_o = $dirname . "/.tmp_mc_" . $prefix . ".o";
>  check_objcopy();
>  
>  #
> -# Step 1: find all the local (static functions) and weak symbols.
> -#        't' is local, 'w/W' is weak (we never use a weak function)
> +# Step 1: find all the global and local (static functions) and weak symbols.
> +#        'T' is global 't' is local, 'w/W' is weak
>  #
>  open (IN, "$nm $inputfile|") || die "error running $nm";
>  while (<IN>) {
> -    if (/$nm_regex/) {
> +    if (/$global_regex/) {
> +        $globals{$1} = 1;
> +    } elsif (/$local_regex/) {
>  	$locals{$1} = 1;
> -    } elsif (/^[0-9a-fA-F]+\s+([wW])\s+(\S+)/) {
> +    } elsif (/$weak_regex/) {
>  	$weak{$2} = $1;
>      }
>  }
>  close(IN);
>  
> +# Exit early if no work to do 
> +exit(0) unless (%globals or (%locals and $can_use_local)); 
> +
>  my @offsets;		# Array of offsets of mcount callers
>  my $ref_func;		# reference function to use for offsets
>  my $offset = 0;		# offset of ref_func to section beginning

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