Merge r77 from upstream tcmalloc to the local chromium branch....

third_party/tcmalloc/chromium/src/pprof

 #! /usr/bin/env perl
 
 # Copyright (c) 1998-2007, Google Inc.
 # All rights reserved.
 # 
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 # 
 #     * Redistributions of source code must retain the above copyright
@@ skipping 74 matching lines @@
   ## ConfigureObjTools may add architecture-specific entries:
   #"nm_pdb" => "nm-pdb",       # for reading windows (PDB-format) executables
   #"addr2line_pdb" => "addr2line-pdb",                                # ditto
   #"otool" => "otool",         # equivalent of objdump on OS X
 );
 my $DOT = "dot";          # leave non-absolute, since it may be in /usr/local
 my $GV = "gv";
 my $PS2PDF = "ps2pdf";
 # These are used for dynamic profiles
 my $WGET = "wget";
-my $WGET_FLAGS = "--no-http-keep-alive";   # only supported by some wgets
 my $CURL = "curl";
 
 # These are the web pages that servers need to support for dynamic profiles
 my $HEAP_PAGE = "/pprof/heap";
 my $PROFILE_PAGE = "/pprof/profile";   # must support cgi-param "?seconds=#"
 my $PMUPROFILE_PAGE = "/pprof/pmuprofile(?:\\?.*)?"; # must support cgi-param
                                                 # ?seconds=#&event=x&period=n
 my $GROWTH_PAGE = "/pprof/growth";
 my $CONTENTION_PAGE = "/pprof/contention";
 my $WALL_PAGE = "/pprof/wall(?:\\?.*)?";  # accepts options like namefilter
 my $FILTEREDPROFILE_PAGE = "/pprof/filteredprofile(?:\\?.*)?";
 my $SYMBOL_PAGE = "/pprof/symbol";     # must support symbol lookup via POST
 my $PROGRAM_NAME_PAGE = "/pprof/cmdline";
 
 # default binary name
 my $UNKNOWN_BINARY = "(unknown)";
 
 # There is a pervasive dependency on the length (in hex characters,
 # i.e., nibbles) of an address, distinguishing between 32-bit and
 # 64-bit profiles.  To err on the safe size, default to 64-bit here:
 my $address_length = 16;
 
 # A list of paths to search for shared object files
 my @prefix_list = ();
 
-# Special routine name that should not have any symbols.
-# Used as separator to parse "addr2line -i" output.
-my $sep_symbol = '_fini';
-my $sep_address = undef;
-
 ##### Argument parsing #####
 
 sub usage_string {
   return <<EOF;
 Usage:
 pprof [options] <program> <profiles>
    <profiles> is a space separated list of profile names.
 pprof [options] <symbolized-profiles>
    <symbolized-profiles> is a list of profile files where each file contains
    the necessary symbol mappings  as well as profile data (likely generated
@@ skipping 367 matching lines @@
   if ($main::use_symbol_page) {
     unless (IsProfileURL($main::pfile_args[0])) {
       error("The first profile should be a remote form to use $SYMBOL_PAGE\n");
     }
     CheckSymbolPage();
     $main::prog = FetchProgramName();
   } elsif (!$main::use_symbolized_profile) {  # may not need objtools!
     ConfigureObjTools($main::prog)
   }
 
-  # Check what flags our commandline utilities support
-  if (open(TFILE, "$WGET $WGET_FLAGS -V 2>&1 |")) {
-    my @lines = <TFILE>;
-    if (grep(/unrecognized/, @lines) > 0) {
-      # grep found 'unrecognized' token from WGET, clear WGET flags
-      $WGET_FLAGS = "";
-    }
-    close(TFILE);
-  }
-  # TODO(csilvers): check all the other binaries and objtools to see
-  # if they are installed and what flags they support, and store that
-  # in a data structure here, rather than scattering these tests about.
-  # Then, ideally, rewrite code to use wget OR curl OR GET or ...
-
   # Break the opt_list_prefix into the prefix_list array
   @prefix_list = split (',', $main::opt_lib_prefix);
 
   # Remove trailing / from the prefixes, in the list to prevent
   # searching things like /my/path//lib/mylib.so
   foreach (@prefix_list) {
     s|/+$||;
   }
 }
 
@@ skipping 428 matching lines @@
   my $prog = shift;
 
   $SYMBOL_PAGE =~ m,[^/]+$,;    # matches everything after the last slash
   my $symbol_marker = $&;
 
   print '--- ', $symbol_marker, "\n";
   if (defined($prog)) {
     print 'binary=', $prog, "\n";
   }
   while (my ($pc, $name) = each(%{$symbols})) {
-    my $sep = ' ';
-    print '0x', $pc;
-    # We have a list of function names, which include the inlined
-    # calls.  They are separated (and terminated) by --, which is
-    # illegal in function names.
-    for (my $j = 2; $j <= $#{$name}; $j += 3) {
-      print $sep, $name->[$j];
-      $sep = '--';
-    }
-    print "\n";
+    my $fullname = $name->[2];
+    print '0x', $pc, ' ', $fullname, "\n";
   }
   print '---', "\n";
 
-  $PROFILE_PAGE =~ m,[^/]+$,;    # matches everything after the last slash
-  my $profile_marker = $&;
-  print '--- ', $profile_marker, "\n";
   if (defined($main::collected_profile)) {
     # if used with remote fetch, simply dump the collected profile to output.
     open(SRC, "<$main::collected_profile");
     while (<SRC>) {
       print $_;
     }
-    close(SRC);
   } else {
     # dump a cpu-format profile to standard out
+    $PROFILE_PAGE =~ m,[^/]+$,;    # matches everything after the last slash
+    my $profile_marker = $&;
+    print '--- ', $profile_marker, "\n";
     PrintProfileData($profile);
   }
 }
 
 # Print text output
 sub PrintText {
   my $symbols = shift;
   my $flat = shift;
   my $cumulative = shift;
   my $total = shift;
@@ skipping 81 matching lines @@
                                     $start_addr, $end_addr, $total);
           last;
         }
         $addr = AddressInc($addr);
       }
     }
   }
 }
 
 # Return reference to array of tuples of the form:
-#       [start_address, filename, linenumber, instruction, limit_address]
+#       [address, filename, linenumber, instruction]
 # E.g.,
-#       ["0x806c43d", "/foo/bar.cc", 131, "ret", "0x806c440"]
+#       ["0x806c43d", "/foo/bar.cc", 131, "ret"]
 sub Disassemble {
   my $prog = shift;
   my $offset = shift;
   my $start_addr = shift;
   my $end_addr = shift;
 
   my $objdump = $obj_tool_map{"objdump"};
   my $cmd = sprintf("$objdump -C -d -l --no-show-raw-insn " .
                     "--start-address=0x$start_addr " .
                     "--stop-address=0x$end_addr $prog");
   open(OBJDUMP, "$cmd |") || error("$objdump: $!\n");
   my @result = ();
   my $filename = "";
   my $linenumber = -1;
-  my $last = ["", "", "", ""];
   while (<OBJDUMP>) {
     s/\r//g;         # turn windows-looking lines into unix-looking lines
     chop;
     if (m|\s*([^:\s]+):(\d+)\s*$|) {
       # Location line of the form:
       #   <filename>:<linenumber>
       $filename = $1;
       $linenumber = $2;
     } elsif (m/^ +([0-9a-f]+):\s*(.*)/) {
       # Disassembly line -- zero-extend address to full length
       my $addr = HexExtend($1);
       my $k = AddressAdd($addr, $offset);
-      $last->[4] = $k;   # Store ending address for previous instruction
-      $last = [$k, $filename, $linenumber, $2, $end_addr];
-      push(@result, $last);
+      push(@result, [$k, $filename, $linenumber, $2]);
     }
   }
   close(OBJDUMP);
   return @result;
 }
 
 # The input file should contain lines of the form /proc/maps-like
 # output (same format as expected from the profiles) or that looks
 # like hex addresses (like "0xDEADBEEF").  We will parse all
 # /proc/maps output, and for all the hex addresses, we will output
@@ skipping 155 matching lines @@
   # Assign all samples to the range $firstline,$lastline,
   # Hack 4: If an instruction does not occur in the range, its samples
   # are moved to the next instruction that occurs in the range.
   my $samples1 = {};
   my $samples2 = {};
   my $running1 = 0;     # Unassigned flat counts
   my $running2 = 0;     # Unassigned cumulative counts
   my $total1 = 0;       # Total flat counts
   my $total2 = 0;       # Total cumulative counts
   foreach my $e (@instructions) {
-    # Add up counts for all address that fall inside this instruction
-    my $c1 = 0;
-    my $c2 = 0;
-    for (my $a = $e->[0]; $a lt $e->[4]; $a = AddressInc($a)) {
-      $c1 += GetEntry($flat, $a);
-      $c2 += GetEntry($cumulative, $a);
-    }
+    my $c1 = GetEntry($flat, $e->[0]);
+    my $c2 = GetEntry($cumulative, $e->[0]);
     $running1 += $c1;
     $running2 += $c2;
     $total1 += $c1;
     $total2 += $c2;
     my $file = $e->[1];
     my $line = $e->[2];
     if (($file eq $filename) &&
         ($line >= $firstline) &&
         ($line <= $lastline)) {
       # Assign all accumulated samples to this line
@@ skipping 90 matching lines @@
 
   # Disassemble all instructions
   my @instructions = Disassemble($prog, $offset, $start_addr, $end_addr);
 
   # Make array of counts per instruction
   my @flat_count = ();
   my @cum_count = ();
   my $flat_total = 0;
   my $cum_total = 0;
   foreach my $e (@instructions) {
-    # Add up counts for all address that fall inside this instruction
-    my $c1 = 0;
-    my $c2 = 0;
-    for (my $a = $e->[0]; $a lt $e->[4]; $a = AddressInc($a)) {
-      $c1 += GetEntry($flat, $a);
-      $c2 += GetEntry($cumulative, $a);
-    }
+    my $c1 = GetEntry($flat, $e->[0]);
+    my $c2 = GetEntry($cumulative, $e->[0]);
     push(@flat_count, $c1);
     push(@cum_count, $c2);
     $flat_total += $c1;
     $cum_total += $c2;
   }
 
   # Print header with total counts
   printf("ROUTINE ====================== %s\n" .
          "%6s %6s %s (flat, cumulative) %.1f%% of total\n",
          ShortFunctionName($routine),
@@ skipping 207 matching lines @@
                 $style,
                );
   }
 
   # Get edges and counts per edge
   my %edge = ();
   my $n;
   foreach my $k (keys(%{$raw})) {
     # TODO: omit low %age edges
     $n = $raw->{$k};
-    my @translated = TranslateStack($symbols, $k);
-    for (my $i = 1; $i <= $#translated; $i++) {
-      my $src = $translated[$i];
-      my $dst = $translated[$i-1];
+    my @addrs = split(/\n/, $k);
+    for (my $i = 1; $i <= $#addrs; $i++) {
+      my $src = OutputKey($symbols, $addrs[$i]);
+      my $dst = OutputKey($symbols, $addrs[$i-1]);
       #next if ($src eq $dst);  # Avoid self-edges?
       if (exists($node{$src}) && exists($node{$dst})) {
         my $edge_label = "$src\001$dst";
         if (!exists($edge{$edge_label})) {
           $edge{$edge_label} = 0;
         }
         $edge{$edge_label} += $n;
       }
     }
   }
 
   # Print edges
   foreach my $e (keys(%edge)) {
     my @x = split(/\001/, $e);
     $n = $edge{$e};
 
     if (abs($n) > $edgelimit) {
       # Compute line width based on edge count
       my $fraction = abs($local_total ? (3 * ($n / $local_total)) : 0);
       if ($fraction > 1) { $fraction = 1; }
       my $w = $fraction * 2;
       #if ($w < 1) { $w = 1; }
 
       # Dot sometimes segfaults if given edge weights that are too large, so
       # we cap the weights at a large value
       my $edgeweight = abs($n) ** 0.7;
       if ($edgeweight > 100000) { $edgeweight = 100000; }
       $edgeweight = int($edgeweight);
 
-      my $style = sprintf("setlinewidth(%f)", $w);
-      if ($x[1] =~ m/\(inline\)/) {
-        $style .= ",dashed";
-      }
-
       # Use a slightly squashed function of the edge count as the weight
-      printf DOT ("N%s -> N%s [label=%s, weight=%d, style=\"%s\"];\n",
+      printf DOT ("N%s -> N%s [label=%s, weight=%d, " .
+                  "style=\"setlinewidth(%f)\"];\n",
                   $node{$x[0]},
                   $node{$x[1]},
                   Unparse($n),
                   $edgeweight,
-                  $style);
+                  $w);
     }
   }
 
   print DOT ("}\n");
 
   close(DOT);
   return 1;
 }
 
-# Translate a stack of addresses into a stack of symbols
-sub TranslateStack {
+# Generate the key under which a given address should be counted
+# based on the user-specified output granularity.
+sub OutputKey {
   my $symbols = shift;
-  my $k = shift;
+  my $a = shift;
 
-  my @addrs = split(/\n/, $k);
-  my @result = ();
-  for (my $i = 0; $i <= $#addrs; $i++) {
-    my $a = $addrs[$i];
-
-    # Skip large addresses since they sometimes show up as fake entries on RH9
-    if (length($a) > 8 && $a gt "7fffffffffffffff") {
-      next;
-    }
-
-    if ($main::opt_disasm || $main::opt_list) {
-      # We want just the address for the key
-      push(@result, $a);
-      next;
-    }
-
-    my $symlist = $symbols->{$a};
-    if (!defined($symlist)) {
-      $symlist = [$a, "", $a];
-    }
-
-    # We can have a sequence of symbols for a particular entry
-    # (more than one symbol in the case of inlining).  Callers
-    # come before callees in symlist, so walk backwards since
-    # the translated stack should contain callees before callers.
-    for (my $j = $#{$symlist}; $j >= 2; $j -= 3) {
-      my $func = $symlist->[$j-2];
-      my $fileline = $symlist->[$j-1];
-      my $fullfunc = $symlist->[$j];
-      if ($j > 2) {
-        $func = "$func (inline)";
-      }
-      if ($main::opt_addresses) {
-        push(@result, "$a $func $fileline");
-      } elsif ($main::opt_lines) {
-        if ($func eq '??' && $fileline eq '??:0') {
-          push(@result, "$a");
-        } else {
-          push(@result, "$func $fileline");
-        }
-      } elsif ($main::opt_functions) {
-        if ($func eq '??') {
-          push(@result, "$a");
-        } else {
-          push(@result, $func);
-        }
-      } elsif ($main::opt_files) {
-        if ($fileline eq '??:0' || $fileline eq '') {
-          push(@result, "$a");
-        } else {
-          my $f = $fileline;
-          $f =~ s/:\d+$//;
-          push(@result, $f);
-        }
-      } else {
-        push(@result, $a);
-        last;  # Do not print inlined info
-      }
-    }
+  # Skip large addresses since they sometimes show up as fake entries on RH9
+  if (length($a) > 8) {
+    if ($a gt "7fffffffffffffff") { return ''; }
   }
 
-  # print join(",", @addrs), " => ", join(",", @result), "\n";
-  return @result;
+  # Extract symbolic info for address
+  my $func = $a;
+  my $fullfunc = $a;
+  my $fileline = "";
+  if (exists($symbols->{$a})) {
+    $func = $symbols->{$a}->[0];
+    $fullfunc = $symbols->{$a}->[2];
+    $fileline = $symbols->{$a}->[1];
+  }
+
+  if ($main::opt_disasm || $main::opt_list) {
+    return $a;   # We want just the address for the key
+  } elsif ($main::opt_addresses) {
+    return "$a $func $fileline";
+  } elsif ($main::opt_lines) {
+    return "$func $fileline";
+  } elsif ($main::opt_functions) {
+    return $func;
+  } elsif ($main::opt_files) {
+    my $f = ($fileline eq '') ? $a : $fileline;
+    $f =~ s/:\d+$//;
+    return $f;
+  } else {
+    return $a;
+  }
 }
 
 # Generate percent string for a number and a total
 sub Percent {
   my $num = shift;
   my $tot = shift;
   if ($tot != 0) {
     return sprintf("%.1f%%", $num * 100.0 / $tot);
   } else {
     return ($num == 0) ? "nan" : (($num > 0) ? "+inf" : "-inf");
@@ skipping 257 matching lines @@
   return $result;
 }
 
 # Reduce profile to granularity given by user
 sub ReduceProfile {
   my $symbols = shift;
   my $profile = shift;
   my $result = {};
   foreach my $k (keys(%{$profile})) {
     my $count = $profile->{$k};
-    my @translated = TranslateStack($symbols, $k);
+    my @addrs = split(/\n/, $k);
     my @path = ();
     my %seen = ();
     $seen{''} = 1;      # So that empty keys are skipped
-    foreach my $e (@translated) {
+    foreach my $a (@addrs) {
       # To avoid double-counting due to recursion, skip a stack-trace
       # entry if it has already been seen
-      if (!$seen{$e}) {
-        $seen{$e} = 1;
-        push(@path, $e);
+      my $key = OutputKey($symbols, $a);
+      if (!$seen{$key}) {
+        $seen{$key} = 1;
+        push(@path, $key);
       }
     }
     my $reduced_path = join("\n", @path);
     AddEntry($result, $reduced_path, $count);
   }
   return $result;
 }
 
-# Does the specified symbol array match the regexp?
-sub SymbolMatches {
-  my $sym = shift;
-  my $re = shift;
-  if (defined($sym)) {
-    for (my $i = 0; $i < $#{$sym}; $i += 3) {
-      if ($sym->[$i] =~ m/$re/ || $sym->[$i+1] =~ m/$re/) {
-        return 1;
-      }
-    }
-  }
-  return 0;
-}
-
 # Focus only on paths involving specified regexps
 sub FocusProfile {
   my $symbols = shift;
   my $profile = shift;
   my $focus = shift;
   my $result = {};
   foreach my $k (keys(%{$profile})) {
     my $count = $profile->{$k};
     my @addrs = split(/\n/, $k);
     foreach my $a (@addrs) {
       # Reply if it matches either the address/shortname/fileline
-      if (($a =~ m/$focus/) || SymbolMatches($symbols->{$a}, $focus)) {
+      if (($a =~ m/$focus/) ||
+          (exists($symbols->{$a}) &&
+           (($symbols->{$a}->[0] =~ m/$focus/) ||
+            ($symbols->{$a}->[1] =~ m/$focus/)))) {
         AddEntry($result, $k, $count);
         last;
       }
     }
   }
   return $result;
 }
 
 # Focus only on paths not involving specified regexps
 sub IgnoreProfile {
   my $symbols = shift;
   my $profile = shift;
   my $ignore = shift;
   my $result = {};
   foreach my $k (keys(%{$profile})) {
     my $count = $profile->{$k};
     my @addrs = split(/\n/, $k);
     my $matched = 0;
     foreach my $a (@addrs) {
       # Reply if it matches either the address/shortname/fileline
-      if (($a =~ m/$ignore/) || SymbolMatches($symbols->{$a}, $ignore)) {
+      if (($a =~ m/$ignore/) ||
+          (exists($symbols->{$a}) &&
+           (($symbols->{$a}->[0] =~ m/$ignore/) ||
+            ($symbols->{$a}->[1] =~ m/$ignore/)))) {
         $matched = 1;
         last;
       }
     }
     if (!$matched) {
       AddEntry($result, $k, $count);
     }
   }
   return $result;
 }
@@ skipping 139 matching lines @@
   my @lines = <TFILE>;
   my $result = grep(/^--- *$symbol_marker/, @lines);
   close(TFILE);
   return $result > 0;
 }
 
 ##### Code to profile a server dynamically #####
 
 sub CheckSymbolPage {
   my $url = SymbolPageURL();
-  open(SYMBOL, "$WGET $WGET_FLAGS -qO- '$url' |");
+  open(SYMBOL, "$WGET -qO- '$url' |");
   my $line = <SYMBOL>;
   $line =~ s/\r//g;         # turn windows-looking lines into unix-looking lines
   close(SYMBOL);
   unless (defined($line)) {
     error("$url doesn't exist\n");
   }
 
   if ($line =~ /^num_symbols:\s+(\d+)$/) {
     if ($1 == 0) {
       error("Stripped binary. No symbols available.\n");
@@ skipping 24 matching lines @@
 
 # We fetch symbols from the first profile argument.
 sub SymbolPageURL {
   my ($host, $port, $path) = ParseProfileURL($main::pfile_args[0]);
   return "http://$host:$port$SYMBOL_PAGE";
 }
 
 sub FetchProgramName() {
   my ($host, $port, $path) = ParseProfileURL($main::pfile_args[0]);
   my $url = "http://$host:$port$PROGRAM_NAME_PAGE";
-  my $command_line = "$WGET $WGET_FLAGS -qO- '$url'";
+  my $command_line = "$WGET -qO- '$url'";
   open(CMDLINE, "$command_line |") or error($command_line);
   my $cmdline = <CMDLINE>;
   $cmdline =~ s/\r//g;   # turn windows-looking lines into unix-looking lines
   close(CMDLINE);
   error("Failed to get program name from $url\n") unless defined($cmdline);
   $cmdline =~ s/\x00.+//;  # Remove argv[1] and latters.
   $cmdline =~ s!\n!!g;  # Remove LFs.
   return $cmdline;
 }
 
@@ skipping 85 matching lines @@
   my $symbols = {};
   foreach my $pc (@pcs) {
     my $fullname;
     # For 64 bits binaries, symbols are extracted with 8 leading zeroes.
     # Then /symbol reads the long symbols in as uint64, and outputs
     # the result with a "0x%08llx" format which get rid of the zeroes.
     # By removing all the leading zeroes in both $pc and the symbols from
     # /symbol, the symbols match and are retrievable from the map.
     my $shortpc = $pc;
     $shortpc =~ s/^0*//;
-    # Each line may have a list of names, which includes the function
-    # and also other functions it has inlined.  They are separated
-    # (in PrintSymbolizedFile), by --, which is illegal in function names.
-    my $fullnames;
     if (defined($symbol_map->{$shortpc})) {
-      $fullnames = $symbol_map->{$shortpc};
+      $fullname = $symbol_map->{$shortpc};
     } else {
-      $fullnames = "0x" . $pc;  # Just use addresses
+      $fullname = "0x" . $pc;  # Just use addresses
     }
-    my $sym = [];
-    $symbols->{$pc} = $sym;
-    foreach my $fullname (split("--", $fullnames)) {
-      my $name = ShortFunctionName($fullname);
-      push(@{$sym}, $name, "?", $fullname);
-    }
+    my $name = ShortFunctionName($fullname);
+    $symbols->{$pc} = [$name, "?", $fullname];
   }
   return $symbols;
 }
 
 sub BaseName {
   my $file_name = shift;
   $file_name =~ s!^.*/!!;  # Remove directory name
   return $file_name;
 }
 
@@ skipping 54 matching lines @@
       mkdir($profile_dir)
           || die("Unable to create profile directory $profile_dir: $!\n");
     }
     my $tmp_profile = "$profile_dir/.tmp.$profile_file";
     my $real_profile = "$profile_dir/$profile_file";
 
     if ($fetch_name_only > 0) {
       return $real_profile;
     }
 
-    my $cmd = "$WGET $WGET_FLAGS $wget_timeout -q -O $tmp_profile '$url'";
+    my $cmd = "$WGET $wget_timeout -q -O $tmp_profile '$url'";
     if (($path =~ m/$PROFILE_PAGE/) || ($path =~ m/$PMUPROFILE_PAGE/)){
       print STDERR "Gathering CPU profile from $url for $main::opt_seconds seconds to\n  ${real_profile}\n";
       if ($encourage_patience) {
         print STDERR "Be patient...\n";
       }
     } else {
       print STDERR "Fetching $path profile from $host:$port to\n  ${real_profile}\n";
     }
 
     (system($cmd) == 0) || error("Failed to get profile: $cmd: $!\n");
@@ skipping 304 matching lines @@
         error("$fname: stack trace depth >= 2**32\n");
       }
       if ($slots->get($i) == 0 && $slots->get($i+1) == 0) {
         # End of profile data marker
         $i += 2 * $d;
         last;
       }
 
       # Make key out of the stack entries
       my @k = ();
-      for (my $j = 0; $j < $d; $j++) {
+      for (my $j = $d; $j--; ) {
         my $pclo = $slots->get($i++);
         my $pchi = $slots->get($i++);
         if ($pclo == -1 || $pchi == -1) {
           error("$fname: Unexpected EOF when reading stack of depth $d\n");
         }
-
-        # Subtract one from caller pc so we map back to call instr.
-        # However, don't do this if we're reading a symbolized profile
-        # file, in which case the subtract-one was done when the file
-        # was written.
-        if ($j > 0 && !$main::use_symbolized_profile) {
-          if ($pclo == 0) {
-            $pchi--;
-            $pclo = 0xffffffff;
-          } else {
-            $pclo--;
-          }
-        }
-
         my $pc = sprintf("%08x%08x", $pchi, $pclo);
         $pcs->{$pc} = 1;
         push @k, $pc;
       }
       AddEntry($profile, (join "\n", @k), $n);
     }
   }
 
   # Parse map
   my $map = '';
@@ skipping 738 matching lines @@
   return $symbols;
 }
 
 # Map list of PC values to symbols for a given image
 sub MapToSymbols {
   my $image = shift;
   my $offset = shift;
   my $pclist = shift;
   my $symbols = shift;
 
-  my $debug = 0;
-
   # Ignore empty binaries
   if ($#{$pclist} < 0) { return; }
 
-  # Figure out the addr2line command to use
-  my $addr2line = $obj_tool_map{"addr2line"};
-  my $cmd = "$addr2line -f -C -e $image";
-  if (exists $obj_tool_map{"addr2line_pdb"}) {
-    $addr2line = $obj_tool_map{"addr2line_pdb"};
-    $cmd = "$addr2line --demangle -f -C -e $image";
+  my $got_symbols = MapSymbolsWithNM($image, $offset, $pclist, $symbols);
+  if ($main::opt_interactive ||
+      $main::opt_addresses   ||
+      $main::opt_lines       ||
+      $main::opt_files       ||
+      $main::opt_list        ||
+      $main::opt_callgrind   ||
+      !$got_symbols) {
+    GetLineNumbers($image, $offset, $pclist, $symbols);
   }
+}
 
-  # If "addr2line" isn't installed on the system at all, just use
-  # nm to get what info we can (function names, but not line numbers).
-  if (system("$addr2line --help >/dev/null 2>&1") != 0) {
-    MapSymbolsWithNM($image, $offset, $pclist, $symbols);
-    return;
-  }
+# The file $tmpfile_sym must already have been created before calling this.
+sub GetLineNumbersViaAddr2Line {
+  my $addr2line_command = shift;
+  my $pclist = shift;
+  my $symbols = shift;
 
-  # "addr2line -i" can produce a variable number of lines per input
-  # address, with no separator that allows us to tell when data for
-  # the next address starts.  So we find the address for a special
-  # symbol (_fini) and interleave this address between all real
-  # addresses passed to addr2line.  The name of this special symbol
-  # can then be used as a separator.
-  $sep_address = undef;  # May be filled in by MapSymbolsWithNM()
-  my $nm_symbols = {};
-  MapSymbolsWithNM($image, $offset, $pclist, $nm_symbols);
-  # TODO(csilvers): only add '-i' if addr2line supports it.
-  if (defined($sep_address)) {
-    # Only add " -i" to addr2line if the binary supports it.
-    # addr2line --help returns 0, but not if it sees an unknown flag first.
-    if (system("$cmd -i --help >/dev/null 2>&1") == 0) {
-      $cmd .= " -i";
-    } else {
-      $sep_address = undef;   # no need for sep_address if we don't support -i
-    }
-  }
-
-  # Make file with all PC values with intervening 'sep_address' so
-  # that we can reliably detect the end of inlined function list
-  open(ADDRESSES, ">$main::tmpfile_sym") || error("$main::tmpfile_sym: $!\n");
-  if ($debug) { print("---- $image ---\n"); }
-  for (my $i = 0; $i <= $#{$pclist}; $i++) {
-    # addr2line always reads hex addresses, and does not need '0x' prefix.
-    if ($debug) { printf("%s\n", $pclist->[$i]); }
-    printf ADDRESSES ("%s\n", AddressSub($pclist->[$i], $offset));
-    if (defined($sep_address)) {
-      printf ADDRESSES ("%s\n", $sep_address);
-    }
-  }
-  close(ADDRESSES);
-  if ($debug) {
-    print("----\n");
-    system("cat $main::tmpfile_sym");
-    print("----\n");
-    system("$cmd <$main::tmpfile_sym");
-    print("----\n");
-  }
-
-  open(SYMBOLS, "$cmd <$main::tmpfile_sym |") || error("$cmd: $!\n");
-  my $count = 0;   # Index in pclist
+  open(SYMBOLS, "$addr2line_command <$main::tmpfile_sym |")
+    || error("$addr2line_command: $!\n");
+  my $count = 0;
   while (<SYMBOLS>) {
-    # Read fullfunction and filelineinfo from next pair of lines
     s/\r?\n$//g;
     my $fullfunction = $_;
+
     $_ = <SYMBOLS>;
     s/\r?\n$//g;
     my $filelinenum = $_;
-
-    if (defined($sep_address) && $fullfunction eq $sep_symbol) {
-      # Terminating marker for data for this address
-      $count++;
-      next;
+    $filelinenum =~ s|\\|/|g;   # turn windows-style paths into unix-style paths
+    if (!$main::opt_list) {
+      $filelinenum =~ s|^.*/([^/]+:\d+)$|$1|;    # Remove directory name
     }
 
-    $filelinenum =~ s|\\|/|g; # turn windows-style paths into unix-style paths
+    my $pcstr = $pclist->[$count];
+    if (defined($symbols->{$pcstr})) {
+      # Override just the line-number portion.  The function name portion
+      # is less buggy when computed using nm instead of addr2line.  But
+      # don't override if addr2line is giving ??'s and nm didn't.  (This
+      # may be seen mostly/entirely on cygwin's addr2line/nm.)
+      if (($filelinenum ne "??:0") || ($symbols->{$pcstr}->[1] eq "?")) {
+        $symbols->{$pcstr}->[1] = $filelinenum;
+      }
+    } else {
+      my $function = ShortFunctionName($fullfunction);
+      $symbols->{$pcstr} = [$function, $filelinenum, $fullfunction];
+    }
+    $count++;
+  }
+  close(SYMBOLS);
+  return $count;
+}
 
-    my $pcstr = $pclist->[$count];
-    my $function = ShortFunctionName($fullfunction);
-    if ($fullfunction eq '??') {
-      # See if nm found a symbol
-      my $nms = $nm_symbols->{$pcstr};
-      if (defined($nms)) {
-        $function = $nms->[0];
-        $fullfunction = $nms->[2];
-      }
-    }
+sub GetLineNumbers {
+  my $image = shift;
+  my $offset = shift;
+  my $pclist = shift;
+  my $symbols = shift;
 
-    # Prepend to accumulated symbols for pcstr
-    # (so that caller comes before callee)
-    my $sym = $symbols->{$pcstr};
-    if (!defined($sym)) {
-      $sym = [];
-      $symbols->{$pcstr} = $sym;
-    }
-    unshift(@{$sym}, $function, $filelinenum, $fullfunction);
-    if ($debug) { printf("%s => [%s]\n", $pcstr, join(" ", @{$sym})); }
-    if (!defined($sep_address)) {
-      # Inlining is off, se this entry ends immediately
-      $count++;
+  # Make file with all PC values
+  open(ADDRESSES, ">$main::tmpfile_sym") || error("$main::tmpfile_sym: $!\n");
+  for (my $i = 0; $i <= $#{$pclist}; $i++) {
+    # addr2line always reads hex addresses, and does not need '0x' prefix.
+    printf ADDRESSES ("%s\n", AddressSub($pclist->[$i], $offset));
+  }
+  close(ADDRESSES);
+
+  # Pass to addr2line
+  my $addr2line = $obj_tool_map{"addr2line"};
+  my @addr2line_commands = ("$addr2line -f -C -e $image");
+  if (exists $obj_tool_map{"addr2line_pdb"}) {
+    my $addr2line_pdb = $obj_tool_map{"addr2line_pdb"};
+    push(@addr2line_commands, "$addr2line_pdb --demangle -f -C -e $image");
+  }
+  foreach my $addr2line_command (@addr2line_commands) {
+    if (GetLineNumbersViaAddr2Line("$addr2line_command", $pclist, $symbols)) {
+      last;
     }
   }
-  close(SYMBOLS);
 }
 
 # Use nm to map the list of referenced PCs to symbols.  Return true iff we
 # are able to read procedure information via nm.
 sub MapSymbolsWithNM {
   my $image = shift;
   my $offset = shift;
   my $pclist = shift;
   my $symbols = shift;
 
@@ skipping 29 matching lines @@
     }
     if ($mpc lt $symbol_table->{$fullname}->[1]) {
       $symbols->{$pc} = [$name, "?", $fullname];
     } else {
       my $pcstr = "0x" . $pc;
       $symbols->{$pc} = [$pcstr, "?", $pcstr];
     }
   }
   return 1;
 }
- 
+
 sub ShortFunctionName {
   my $function = shift;
   while ($function =~ s/\([^()]*\)(\s*const)?//g) { }   # Argument types
   while ($function =~ s/<[^<>]*>//g)  { }    # Remove template arguments
   $function =~ s/^.*\s+(\w+::)/$1/;          # Remove leading type
   return $function;
 }
 
 ##### Miscellaneous #####
 
@@ skipping 146 matching lines @@
       # got touched in the queue), and ignore the others.
       if ($start_val eq $last_start && $type =~ /t/i) {
         # We are the 'T' symbol at this address, replace previous symbol.
         $routine = $this_routine;
         next;
       } elsif ($start_val eq $last_start) {
         # We're not the 'T' symbol at this address, so ignore us.
         next;
       }
 
-      if ($this_routine eq $sep_symbol) {
-        $sep_address = HexExtend($start_val);
-      }
-
       # Tag this routine with the starting address in case the image
       # has multiple occurrences of this routine.  We use a syntax
       # that resembles template paramters that are automatically
       # stripped out by ShortFunctionName()
       $this_routine .= "<$start_val>";
 
       if (defined($routine) && $routine =~ m/$regexp/) {
         $symbol_table->{$routine} = [HexExtend($last_start),
                                      HexExtend($start_val)];
       }
@@ skipping 290 matching lines @@
   $error_count += AddressSubUnitTest($unit_test_data_8, $unit_test_data_16);
   $error_count += AddressIncUnitTest($unit_test_data_8, $unit_test_data_16);
   if ($error_count > 0) {
     print STDERR $error_count, " errors: FAILED\n";
   } else {
     print STDERR "PASS\n";
   }
   exit ($error_count);
 }