#! /usr/bin/perl
#
# Generate Valgrind's module dependence graph in 'dot' format.
#
# You can run it from anywhere(?) in a Valgrind source tree, but the two
# most interesting places are:
# - the root, to get the entire module dependence graph.
# - coregrind/, to get the core's module dependence graph.
#
# It sends a dot-format graph to stdout.  You can use dot (part of the
# "GraphViz" package) to generated a PostScript graphs like this:
#
#   dot -Tps foo.dot -o foo.ps
#
# Caveats:
# - It's not a proper parser.  If you have a #include that is commented out,
#   it will think it's there.  We see that particularly in m_demangle.
# - It only looks in C files, not in header files, so it will miss any
#   extra dependencies this causes.  Fortunately we don't have many like
#   that.

use warnings;
use strict;

#----------------------------------------------------------------------------
# Global variables
#----------------------------------------------------------------------------

# The dependence graph is a set of src-->dst pairs, stored in a double-hash:
#
#   hash(src, hash(dst, dst_realname))
#
# Each of 'src' and 'dst' are node names.  'src' is always a module name,
# eg. 'm_main' or 'memcheck'.  The destination is sometimes a module name,
# and sometimes a header file.  Because Dot can't handle certain characters
# in its node names, when 'dst' represents a header file it's a transformed
# version of the header file name, eg. 'INT_memcheck_h' or 'EXT_sys_mman_h'.
# The 'dst_realname' holds the original name, eg.  '"memcheck.h"' or
# "<sys/mman.h>".  We use 'dst' for the node name in the graph, but label it
# with 'dst_realname' and that's what gets seen.  (Although we use "" for
# 'dst_realname' when it would be the same as 'dst'.)
my $deps = {};

# Directories to skip.  These are the defaults, they can be augmented
# using command-line options.
my %dirs_to_skip = ( auxprogs => 1, hp2ps => 1, tests => 1 );

# Command-line variables -- things we should show.  Default is yes.
my $show_tools   = 1;
my $show_headers = 1;
my $show_libc    = 1;

# Modules to hide.
my %hide;

# List of all tools.
my @tools = ( "addrcheck", "cachegrind", "helgrind",
              "lackey", "massif", "memcheck", "none" );

my $usage = <<END
usage: gen-mdg [options]

  options:
    --headers=no|yes    show headers, ie. show module-to-module deps only
    --hide=<a>,<b>,...  hide module(s) named <a>, <b>, ...
END
;

#----------------------------------------------------------------------------
# Subroutines
#----------------------------------------------------------------------------

sub process_cmd_line()
{
   for my $arg (@ARGV) { 

        # --headers=yes|no
        if ($arg =~ /^--headers=(yes|no)$/) {
            $show_headers = 1 if ($1 eq "yes");
            $show_headers = 0 if ($1 eq "no");

        # --hide=<a>,<b>,...
        } elsif ($arg =~ /^--hide=(.*)$/) {
            my @hiders = split(/,/, $1);
            foreach my $h (@hiders) {
                $hide{$h} = 1;
            }

        } else {
            die $usage;
        }
    }

    if (!$show_tools) {
        foreach my $tool (@tools) {
            $dirs_to_skip{$tool} = 1;
        }
    }
}

# Convert a header filename into a node name acceptable by dot.
sub clean_nodename($)
{
    my ($s) = @_;
    $s =~ s/"([^"]+)"/INT_$1/;  # "foo.h" --> foo.h
    $s =~ s/<([^>]+)>/EXT_$1/;  # <foo.h> --> foo.h
    $s =~ s/\./_/g;  # foo.h     --> foo_h
    $s =~ s/-/_/g;   # foo-bar.h --> foo_bar_h
    $s =~ s/\//_/g;  # bar/foo_h --> bar_foo_h
    return $s;
}

# Convert a header filename into a node label acceptable by dot.
sub clean_nodelabel($)
{
    my ($s) = @_;
    $s =~ s/"/\\"/g;    # "foo.h" --> \"foo.h\"
    return $s;
}

# $module is the module to which the C/asm file $f belongs.
sub scan_C_or_asm_file($$)
{
    my ($module, $f) = @_;

    # Skip if this is a module we want to hide
    if ($hide{$module}) {
        return;
    }
    
    # Get any existing dependencies for this module, initialise if none
    my $module_deps = $deps->{$module};
    if (not defined $module_deps) {
        $module_deps = {};
    }
    
    # Scan the C/asm file
    open(CFILE, "< $f") || die "File $f not openable\n";
    while (my $line = <CFILE>) {
        if ($line =~ /#include\s+(("|<)[^">]+("|>))/) {
            # Right!  We've found a #include line.
            my $include_string = $1;
            my $target;
            my $realname;
            if ($include_string =~ /"pub_(core|tool)_([A-Za-z]+).h"/) {
                # If #include string is "pub_core_foo.h" or "pub_tool_foo.h", 
                # the target module is "m_foo".
                #
                # Nb: assuming the "foo" part does not contains underscores!
                $target   = "m_$2";
                $realname = "";

                # But don't show hidden modules
                if ($hide{$target}) {
                    $target = "";
                }

            } elsif ($show_headers) {
                # Otherwise use the #include string as-is for the target.
                # Note that "#include pub_core_foo_asm.h" falls into this
                # category.  We don't consider that part of the m_foo module
                # because the *_asm.h only define some constants.
                $target   = clean_nodename($include_string);
                $realname = clean_nodelabel($include_string);

            } else {
                # Don't record anything
                $target   = "";
                $realname = "";
            }

            # Maybe record dependency (unless it's circular)
            if ($target ne "" and $target ne $module) {
                $module_deps->{$target} = $realname;
            }
        }
    }
    close(CFILE);

    # Store the updated dependencies.
    $deps->{$module} = $module_deps;
}

sub process_dir($);      # forward declarations required because of recursion
sub process_dir($)
{
    my ($parentd) = @_;

    # Go through each file/dir in the directory.
    my @fs = <*>;
    foreach my $f (@fs) {
        if (-d $f) {
            # Directory -- recursively process unless we want to skip it.
            if (not exists $dirs_to_skip{$f}) {
                chdir $f or die;
                process_dir($f);
                chdir ".." or die;
            }

        } elsif (-f $f) {
            if ($f =~ /\w+\.[cS]$/) {
                # If this is a .c/.S file in coregrind/, it's a module in its
                # own right, eg. coregrind/m_redir.c --> module name of
                # "m_redir".
                #
                # Otherwise, it belongs to the module whose name is that of
                # the parent directory, eg. coregrind/m_debuginfo/symtab.c
                # --> module name of "m_debuginfo".
                my $module;
                if ($parentd eq "coregrind") {
                    $module = $f;
                    $module =~ s/(\w+).[cS]$/$1/;     # foo.c --> foo
                } else {
                    $module = $parentd;
                }
                # Now the module/f pair is either:
                #   -    like this:  (m_redir, m_redir.c)
                #   - or like this:  (m_debuginfo, symtab.c)
                scan_C_or_asm_file($module, $f);
            }

        } else {
            die "$f is not a dir nor a file\n";
        }
    }
}

sub print_graph()
{
    my %printed_realnames;

    print("digraph G {\n");
    while (my ($src, $dst_hash) = each %$deps) {
        while (my ($dst, $dst_realname) = each %$dst_hash) {

            # If the dstnode has a realname, print just the dstnode with that
            # realname, and record it in %printed_realnames so we don't print
            # it again.
            if ($dst_realname ne "") {
                if (not defined $printed_realnames{$dst}) {
                    print("  $dst [label=\"$dst_realname\"]\n");
                    $printed_realnames{$dst} = 1;
                }
            }
            
            # Print the src-->dst edge.
            print("  $src -> $dst\n");
        }
    }
    print("}\n");
}

#----------------------------------------------------------------------------
# main
#----------------------------------------------------------------------------
process_cmd_line();

my $start_dir = `basename \`pwd\``;
chop($start_dir);           # trim newline
process_dir($start_dir);

print_graph();