[Bug gas/12049] Unnecessary relaxation

[amodra at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=12049

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
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             Status|NEW                         |ASSIGNED
                 CC|                            |amodra at gmail dot com
         AssignedTo|unassigned at sources dot   |amodra at gmail dot com
                   |redhat.com                  |

--- Comment #17 from Alan Modra <amodra at gmail dot com> 2010-10-23 11:58:22 
UTC ---
Nice testcase!  The comment in my fix below explains how relax_frag went wrong.
 I'll apply this later, probably tomorrow sometime.

Index: gas/write.c
===================================================================
RCS file: /cvs/src/src/gas/write.c,v
retrieving revision 1.134
diff -u -p -r1.134 write.c
--- gas/write.c    19 Oct 2010 12:14:23 -0000    1.134
+++ gas/write.c    23 Oct 2010 11:55:01 -0000
@@ -2163,6 +2163,13 @@ relax_frag (segT segment, fragS *fragP, 
       if (stretch < 0
           || sym_frag->region == fragP->region)
         target += stretch;
+      /* If we get here we know we have a forward branch.  This
+         relax pass may have stretched previous instructions so
+         far that omitting STRETCH would make the branch
+         negative.  Don't allow this in case the negative reach is
+         large enough to require a larger branch instruction.  */
+      else if (target < address)
+        target = fragP->fr_next->fr_address + stretch;
     }
     }

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