GNU_STACK header is not present when linking with gc-sections.

[Sriraman Tallam <tmsriram at google dot com>]

Hi,

    This bug was noticed by Ian with gc-sections.

Reason :

In Sized_relobj::do_layout

 bool seen_gnu_stack = false;

 ...

 for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
   {
     if (!is_gc_pass_two)
       {
         ...
         // The .note.GNU-stack section is special.  It gives the
         // protection flags that this object file requires for the stack
         // in memory.
         if (strcmp(name, ".note.GNU-stack") == 0)
           {
             seen_gnu_stack = true;
             ...
           }
       }
   }

 ...

 if (!is_gc_pass_one)
   layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);


In the second pass of do_layout, seen_gnu_stack is always false.

The fix is to call layout_gnu_stack in the first pass of do_layout.
This should be ok as layout_gnu_stack just sets 2 flags to true in the
layout object.

This patch should fix that.

Index: object.cc
===================================================================
RCS file: /cvs/src/src/gold/object.cc,v
retrieving revision 1.117
diff -u -u -p -r1.117 object.cc
--- object.cc	8 Jan 2010 22:34:34 -0000	1.117
+++ object.cc	15 Jan 2010 00:34:15 -0000
@@ -1321,7 +1321,7 @@ Sized_relobj<size, big_endian>::do_layou
         }
     }

-  if (!is_gc_pass_one)
+  if (!is_gc_pass_two)
     layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);


Is this ok to submit ?

Thanks,
-Sriraman.