[Bug rtl-optimization/57320] New: Shrink-wrapping breaks graph dumping

["steven at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57320

            Bug ID: 57320
           Summary: Shrink-wrapping breaks graph dumping
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: steven at gcc dot gnu.org

Compiling gcc.target/i386/pad-10.c with:

$ ./xgcc -B. -O2 -fomit-frame-pointer -march=atom pad-10.c \
 -fdump-rtl-pro_and_epilogue-graph

gives:

pad-10.c: In function 'foo2':
pad-10.c:19:1: internal compiler error: in pre_and_rev_post_order_compute, at
cfganal.c:869
 }
 ^
0x61dbaa pre_and_rev_post_order_compute(int*, int*, bool)
        ../../trunk/gcc/cfganal.c:869
0xd28d21 draw_cfg_nodes_no_loops
        ../../trunk/gcc/graph.c:183
0xd28d21 draw_cfg_nodes
        ../../trunk/gcc/graph.c:265
0xd28d21 print_graph_cfg(char const*, function*)
        ../../trunk/gcc/graph.c:306


This happens because shrink-wrapping leaves unreachable blocks
in the CFG.  For a more detailed analysis see:
http://gcc.gnu.org/ml/gcc-patches/2013-05/msg01016.html