Report on misuses of shared symbols, and excessively large static symbols.

src/util/symcheck.pl

   };
 }
 
-# Build up requires and provides tables for global symbols
+# Build up requires, provides and shares symbol tables for global
+# symbols
+#
 my $globals = {};
 while ( ( my $object, my $symbols ) = each %$symtab ) {
   while ( ( my $symbol, my $info ) = each %$symbols ) {
     if ( $info->{global} ) {
-      my $category = ( ( $info->{type} eq 'U' ? "requires" : "provides" ) );
+      my $category = ( ( $info->{type} eq 'U' ? "requires" :
+			 ( $info->{type} eq 'C' ? "shares" : "provides" ) ) );
       $globals->{$symbol}->{$category}->{$object} = 1;
     }
   }
 while ( ( my $symbol, my $info ) = each %$globals ) {
   my @provides = keys %{$info->{provides}};
   my @requires = keys %{$info->{requires}};
+  my @shares = keys %{$info->{shares}};
+
+  if ( ( @provides == 0 ) && ( @shares == 1 ) ) {
+    # A symbol "shared" by just a single file is actually being
+    # provided by that file; it just doesn't have an initialiser.
+    @provides = @shares;
+    @shares = ();
+  }
 
-  if ( @provides == 0 ) {
-    # No object provides this symbol
+  if ( ( @requires > 0 ) && ( @provides == 0 ) ) {
+    # No object provides this symbol, but some objects require it.
     $problems->{$_}->{nonexistent}->{$symbol} = 1 foreach @requires;
-  } elsif ( @provides > 1 ) {
-    # Symbol defined in multiple objects
-    $problems->{$_}->{multiples}->{$symbol} = 1 foreach @provides;
   }
-  if ( @requires == 0 ) {
-    # Symbol not required
+
+  if ( ( @requires == 0 ) && ( @provides > 0 ) ) {
+    # No object requires this symbol, but some objects provide it.
     $problems->{$_}->{unused}->{$symbol} = 1 foreach @provides;
   }
+
+  if ( ( @shares > 0 ) && ( @requires > 0 ) ) {
+    # A shared symbol is being referenced from another object
+    $problems->{$_}->{shared}->{$symbol} = 1 foreach @requires;
+  }
+
+  if ( ( @shares > 0 ) && ( @provides > 0 ) ) {
+    # A shared symbol is being initialised by an object
+    $problems->{$_}->{shared}->{$symbol} = 1 foreach @provides;
+  }
+
+  if ( ( @shares > 0 ) && ! ( $symbol =~ /^_shared_/ ) ) {
+    # A shared symbol is not declared via __shared
+    $problems->{$_}->{shared}->{$symbol} = 1 foreach @shares;
+  }
+
+  if ( @provides > 1 ) {
+    # A non-shared symbol is defined in multiple objects
+    $problems->{$_}->{multiples}->{$symbol} = 1 foreach @provides;
+  }
+}
+
+# Check for excessively large local symbols
+#
+while ( ( my $object, my $symbols ) = each %$symtab ) {
+  while ( ( my $symbol, my $info ) = each %$symbols ) {
+    if ( ( ! $info->{global} ) &&
+	 ( $info->{type} ne 't' ) &&
+	 ( $info->{size} >= WARNING_SIZE ) ) {
+      $problems->{$object}->{large}->{$symbol} = 1;
+    }
+  }
 }
 
 # Print out error messages
   my @nonexistent = sort keys %{$problems->{$object}->{nonexistent}};
   my @multiples = sort keys %{$problems->{$object}->{multiples}};
   my @unused = sort keys %{$problems->{$object}->{unused}};
+  my @shared = sort keys %{$problems->{$object}->{shared}};
+  my @large = sort keys %{$problems->{$object}->{large}};
 
   print "WARN $object provides unused symbol $_\n" foreach @unused;
   $warnings += @unused;
+  print "WARN $object has large static symbol $_\n" foreach @large;
+  $warnings += @large;
   print "ERR  $object requires non-existent symbol $_\n" foreach @nonexistent;
   $errors += @nonexistent;
   foreach my $symbol ( @multiples ) {
 	." (also provided by @other_objects)\n";
   }
   $errors += @multiples;
+  print "ERR  $object misuses shared symbol $_\n" foreach @shared;
 }
 
 print "$errors error(s), $warnings warning(s)\n";