[util] Add diffsize.pl utility for generating diffs of object sizes

This is useful when comparing size optimizations.

Signed-off-by: Marty Connor <mdc@etherboot.org>

src/util/diffsize.pl

@@ -0,0 +1,101 @@
+#!/usr/bin/perl -w
+# usage:
+# [somebody@somewhere ~/gpxe/src]$ ./util/diffsize.pl [<old rev> [<new rev>]]
+# by default <old rev> is HEAD and <new rev> is the working tree
+
+use strict;
+
+-d "bin" or die "Please run me in the gPXE src directory\n";
+mkdir ".sizes";
+
+my($oldrev, $newrev);
+my($oldname, $newname);
+
+if (@ARGV) {
+  $oldname = shift;
+} else {
+  $oldname = "HEAD";
+}
+
+if (@ARGV) {
+  $newname = shift;
+} else {
+  $newrev = "tree" . time();
+}
+
+$oldrev = `git rev-parse $oldname`;
+chomp $oldrev;
+
+unless (defined $newrev) {
+  $newrev = `git rev-parse $newname`;
+  chomp $newrev;
+}
+
+sub calc_sizes($$) {
+  my($name, $rev) = @_;
+  my $output;
+  my $lastrev;
+  my $stashed = 0;
+  my $res = 0;
+
+  return if -e ".sizes/$rev.sizes";
+
+  if (defined $name) {
+    $output = `git stash`;
+    $stashed = 1 unless $output =~ /No local changes to save/;
+    $lastrev = `git name-rev --name-only HEAD`;
+    system("git checkout $name >/dev/null"); $res ||= $?;
+  }
+
+  system("make -j4 bin/gpxe.lkrn >/dev/null"); $res ||= $?;
+  system("make bin/gpxe.lkrn.sizes > .sizes/$rev.sizes"); $res ||= $?;
+
+  if (defined $name) {
+    system("git checkout $lastrev >/dev/null"); $res ||= $?;
+    system("git stash pop >/dev/null") if $stashed; $res ||= $?;
+  }
+
+  if ($res) {
+    unlink(".sizes/$rev.sizes");
+    die "Error making sizes file\n";
+  }
+}
+
+our %Sizes;
+
+sub save_sizes($$) {
+  my($id, $rev) = @_;
+  my $file = ".sizes/$rev.sizes";
+
+  open SIZES, $file or die "opening $file: $!\n";
+  while (<SIZES>) {
+    my($text, $data, $bss, $total, $hex, $name) = split;
+    $name =~ s|bin/||; $name =~ s|\.o$||;
+
+    # Skip the header and totals lines
+    next if $total =~ /[a-z]/ or $name =~ /TOTALS/;
+
+    # Skip files named with dash, due to old Makefile bug
+    next if $name =~ /-/;
+
+    $Sizes{$name} = {old => 0, new => 0} unless exists $Sizes{$name};
+    $Sizes{$name}{$id} = $total;
+  }
+}
+
+calc_sizes($oldname, $oldrev);
+calc_sizes($newname, $newrev);
+
+save_sizes('old', $oldrev);
+save_sizes('new', $newrev);
+
+my $total = 0;
+
+for (sort keys %Sizes) {
+  my $diff = $Sizes{$_}{new} - $Sizes{$_}{old};
+  if (abs($diff) >= 16) {
+    printf "%12s %+d\n", substr($_, 0, 12), $Sizes{$_}{new} - $Sizes{$_}{old};
+  }
+  $total += $diff;
+}
+printf "      TOTAL: %+d\n", $total;