The following patch fixes

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55153

The reason for the crash was in moving prefetch after return insn.  That 
is because there was no dependency from prefetch to the return as the 
prefetch did not generate any pending memory or register and 
MOVE_BARRIER from the return insn generates dependencies only for 
pending memory or register insns.  More info is in a comment for the 
added code.

The patch was successfully bootstrapped and tested on x86/x86-64.

Committed as rev. 195211.

2013-01-15  Vladimir Makarov  <vmakarov@redhat.com>

         PR rtl-optimization/pr55153
         * sched-deps.c (sched_analyze_2): Add pending reads for prefetch.

2013-01-15  Vladimir Makarov <vmakarov@redhat.com>

         PR rtl-optimization/pr55153
         * gcc.dg/pr55153.c: New.