#!/usr/local/bin/perl -w

use strict;        

my %ref;
my %def;
my %file;

sub read_object
{
 my $obj = shift;
 open(NM,"nm -p $obj|") || die "Cannot open nm $obj:$!";
 $def{$obj} = {}; 
 $file{$obj} = {};              
 my @refs = ();
 while (<NM>)
  {
   if (/\b([A-Z])\b\s*_?(.*)$/)
    {
     my ($kind,$name) = ($1,$2);
     $file{$obj}{$name} = $kind;
     if ($kind ne 'U')
      {
       $def{$obj}{$name} = $kind;
      }
     else
      {
       $ref{$name} = [] unless (exists $ref{$name});
       push(@{$ref{$name}},$obj);
       push(@refs,$name);
      }
    }
  }
 close(NM);
 return @refs;
}

warn "Scanning object files\n";
foreach my $obj (<*.o>,<../*.o>)
 {
  # next if $obj =~ /_f\.o$/;
  read_object($obj);
 }

warn "Analysing...\n";
if (@ARGV)
 {
  FILE:
  foreach my $file (@ARGV)
   {
    if (exists $file{$file})
     {
      foreach my $sym (keys %{$def{$file}})
       {                                 
        if (exists $ref{$sym})           
         {                               
          my @files = grep(!/_f\.o$/,@{$ref{$sym}});
          if (@files)                    
           {                             
            print "$file defines $sym for ",join(',',@files),"\n";
            next FILE;                   
           }                             
         }                               
       }                                 
      warn "No good reason for $file!\n";
     }
    else
     {             
      my %exc;
      my @sym = read_object($file);
      foreach my $sym (sort @sym)
       {
        next unless $sym =~ /^[TL]/;
        if (exists $ref{$sym})           
         {                               
          my @files = grep($_ ne $file,grep(!/_f\.o$/,@{$ref{$sym}}));
          if (@files)                    
           {                             
            print "$sym needed by ",join(',',@files),"\n";
           }                             
          else
           {
            @files = grep(/_f\.o$/,@{$ref{$sym}});
            if (@files)
             {
              warn "$sym only used in ",join(',',@files),"\n";
              if (@files == 1)
               {
                my $exc = $files[0];
                die "Strange $exc" unless $exc =~ s/_f\.o$/.nexc/;
                $exc{$exc} = [] unless exists  $exc{$exc};
                push(@{$exc{$exc}},$sym);
               }
             }
           }
         }                               
       }
      foreach my $exc (keys %exc)
       {
        open(EXC,">$exc") || die "Cannot open $exc:$!";
        print EXC join("\n",@{$exc{$exc}},'');
        close(EXC);
       }
     }
   }
 }