[Bug tree-optimization/51580] New: [4.7 regression] segfault during loop vectorization at -O3

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51580

             Bug #: 51580
           Summary: [4.7 regression] segfault during loop vectorization at
                    -O3
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: ebotca...@gcc.gnu.org
            Target: i[345]86-*-*


Created attachment 26110
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26110
Testcase to be gnatchop'ed

The problem was introduced yesterday.  Compile loop_optimization1.ads at -O3
for an x86 target and you'll get:

Program received signal SIGSEGV, Segmentation fault.
flow_bb_inside_loop_p (loop=0xf7ca1bb8, bb=0x0)
    at /home/eric/svn/gcc/gcc/cfgloop.c:776
776       source_loop = bb->loop_father;
(gdb) bt
#0  flow_bb_inside_loop_p (loop=0xf7ca1bb8, bb=0x0)
    at /home/eric/svn/gcc/gcc/cfgloop.c:776
#1  0x08b5a922 in vect_stmt_relevant_p (stmt=stmt@entry=0xf7c9c0c0,
    relevant=relevant@entry=0xffffcc4c, live_p=live_p@entry=0xffffcc47,
    loop_vinfo=<error reading variable: Unhandled dwarf expression opcode
0xfa>) at /home/eric/svn/gcc/gcc/tree-vect-stmts.c:260
#2  0x08b605c9 in vect_mark_stmts_to_be_vectorized (loop_vinfo=0x9cdc988)
    at /home/eric/svn/gcc/gcc/tree-vect-stmts.c:552
#3  0x08b7ad7d in vect_analyze_loop_2 (loop_vinfo=0x9cdc988)
    at /home/eric/svn/gcc/gcc/tree-vect-loop.c:1521
#4  vect_analyze_loop (loop=0xf7ca1bb8)
    at /home/eric/svn/gcc/gcc/tree-vect-loop.c:1667
#5  0x08b8cc08 in vectorize_loops ()
    at /home/eric/svn/gcc/gcc/tree-vectorizer.c:203

The testcase can be added to the testsuite as
  gnat.dg/specs/loop_optimization1.ads
  gnat.dg/specs/loop_optimization1_pkg.ad[sb]