gecko/tools/trace-malloc/TraceMalloc.pm

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2012-05-21 04:12:37 -07:00
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
package TraceMalloc;
use strict;
# Read in the type inference file and construct a network that we can
# use to match stack prefixes to types.
sub init_type_inference($) {
my ($file) = @_;
$::Fingerprints = { };
open(TYPES, "<$file") || die "unable to open $::opt_types, $!";
TYPE: while (<TYPES>) {
next TYPE unless /<(.*)>/;
my $type = $1;
my $link = \%::Fingerprints;
FRAME: while (<TYPES>) {
chomp;
last FRAME if /^$/;
my $next = $link->{$_};
if (! $next) {
$next = $link->{$_} = {};
}
$link = $next;
}
$link->{'#type#'} = $type;
last TYPE if eof;
}
}
# Infer the type, trying to find the most specific type possible.
sub infer_type($) {
my ($stack) = @_;
my $link = \%::Fingerprints;
my $last;
my $type = 'void*';
FRAME: foreach my $frame (@$stack) {
last FRAME unless $link;
$frame =~ s/\[.*\]$//; # ignore exact addresses, as they'll drift
$last = $link;
#
# Remember this type, but keep going. We use the longest match
# we find, but substacks of longer matches will also match.
#
if ($last->{'#type#'}) {
$type = $last->{'#type#'};
}
$link = $link->{$frame};
if (! $link) {
CHILD: foreach my $child (keys %$last) {
next CHILD unless $child =~ /^~/;
$child =~ s/^~//;
if ($frame =~ $child) {
$link = $last->{'~' . $child};
last CHILD;
}
}
}
}
return $type;
}
#----------------------------------------------------------------------
#
# Read in the output a trace malloc's dump.
#
sub read {
my ($callback, $noslop) = @_;
OBJECT: while (<>) {
# e.g., 0x0832FBD0 <void*> (80)
next OBJECT unless /^0x(\S+) <(.*)> \((\d+)\)/;
my ($addr, $type, $size) = (hex $1, $2, $3);
my $object = { 'type' => $type, 'size' => $size };
# Record the object's slots
my @slots;
SLOT: while (<>) {
# e.g., 0x00000000
last SLOT unless /^\t0x(\S+)/;
my $value = hex $1;
# Ignore low bits, unless they've specified --noslop
$value &= ~0x7 unless $noslop;
$slots[$#slots + 1] = $value;
}
$object->{'slots'} = \@slots;
# Record the stack by which the object was allocated
my @stack;
while (/^(.*)\[(.*) \+0x(\S+)\]$/) {
# e.g., _dl_debug_message[/lib/ld-linux.so.2 +0x0000B858]
my ($func, $lib, $off) = ($1, $2, hex $3);
chomp;
$stack[$#stack + 1] = $_;
$_ = <>;
}
$object->{'stack'} = \@stack;
$object->{'type'} = infer_type(\@stack)
if $object->{'type'} eq 'void*';
&$callback($object) if $callback;
# Gotta check EOF explicitly...
last OBJECT if eof;
}
}
1;
__END__
=head1 NAME
TraceMalloc - Perl routines to deal with output from ``trace malloc''
and the Boehm GC
=head1 SYNOPSIS
use TraceMalloc;
TraceMalloc::init_type_inference("types.dat");
TraceMalloc::read(0);
=head1 DESCRIPTION
=head1 EXAMPLES
=cut