[Bug tree-optimization/50727] New: ICE with segfault in flow_bb_inside_loop_p

["mgretton at sourceware dot org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50727

             Bug #: 50727
           Summary: ICE with segfault in flow_bb_inside_loop_p
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: mgretton@sourceware.org
                CC: irar@il.ibm.com
            Target: arm-none-eabi


Created attachment 25496
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25496
Test case

The attached test case causes an ICE when compiled as follows:

$ arm-none-eabi-gcc -O3 -mfpu=neon -mcpu=cortex-a9 -ftree-vectorize test.c
test.c: In function 'f0a':
test.c:5:1: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

$ gdb --args  /work/builds/install/libexec/gcc/arm-none-eabi/4.7.0/cc1 -quiet
-v -D__USES_INITFINI__ test.c -quiet -dumpbase test.c -mfpu=neon
-mcpu=cortex-a9 -mfloat-abi=softfp -auxbase test -O3 -version -ftree-vectorize
-o /tmp/ccaMl5b6.s

Gives the following backtrace:

#0  flow_bb_inside_loop_p (loop=0x7ffff7ebff68, bb=0x0) at
/work/local-checkouts/gcc-fsf/gcc/cfgloop.c:776
#1  0x00000000009f053f in vect_is_simple_use (operand=0x7ffff75fc910,
loop_vinfo=<value optimised out>, bb_vinfo=0x0, def_stmt=0x7fffffffd438,
def=0x7fffffffd440, dt=0x7fffffffd44c)
    at /work/local-checkouts/gcc-fsf/gcc/tree-vect-stmts.c:5611
#2  0x00000000009fa2ac in process_use (stmt=0x7ffff75f4630, use=0x7ffff75fc910,
loop_vinfo=0x14ed400, live_p=<value optimised out>,
relevant=vect_used_in_scope, worklist=<value optimised out>)
    at /work/local-checkouts/gcc-fsf/gcc/tree-vect-stmts.c:368
#3  0x00000000009fadb7 in vect_mark_stmts_to_be_vectorized
(loop_vinfo=0x14ed400) at
/work/local-checkouts/gcc-fsf/gcc/tree-vect-stmts.c:674
#4  0x0000000000a0cb61 in vect_analyze_loop_2 (loop=0x7ffff7ebff68) at
/work/local-checkouts/gcc-fsf/gcc/tree-vect-loop.c:1504
#5  vect_analyze_loop (loop=0x7ffff7ebff68) at
/work/local-checkouts/gcc-fsf/gcc/tree-vect-loop.c:1650
#6  0x0000000000a19ece in vectorize_loops () at
/work/local-checkouts/gcc-fsf/gcc/tree-vectorizer.c:203
#7  0x00000000007d81a9 in execute_one_pass (pass=0x129f780) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2064
#8  0x00000000007d8525 in execute_pass_list (pass=0x129f780) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2119
#9  0x00000000007d8537 in execute_pass_list (pass=0x129f5a0) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2120
#10 0x00000000007d8537 in execute_pass_list (pass=0x129eca0) at
/work/local-checkouts/gcc-fsf/gcc/passes.c:2120
#11 0x00000000008df618 in tree_rest_of_compilation (fndecl=0x7ffff7569600) at
/work/local-checkouts/gcc-fsf/gcc/tree-optimize.c:420
#12 0x00000000005c0e5e in cgraph_expand_function (node=0x7ffff7590000) at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:1805
#13 0x00000000005c445a in cgraph_expand_all_functions () at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:1864
#14 cgraph_optimize () at /work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:2141
#15 0x00000000005c497a in cgraph_finalize_compilation_unit () at
/work/local-checkouts/gcc-fsf/gcc/cgraphunit.c:1312
#16 0x00000000004a6e48 in c_write_global_declarations () at
/work/local-checkouts/gcc-fsf/gcc/c-decl.c:9936
#17 0x000000000087c61a in compile_file (argc=18, argv=0x7fffffffd8e8) at
/work/local-checkouts/gcc-fsf/gcc/toplev.c:581
#18 do_compile (argc=18, argv=0x7fffffffd8e8) at
/work/local-checkouts/gcc-fsf/gcc/toplev.c:1925
#19 toplev_main (argc=18, argv=0x7fffffffd8e8) at
/work/local-checkouts/gcc-fsf/gcc/toplev.c:2001
#20 0x00007ffff7874c4d in __libc_start_main () from /lib/libc.so.6
#21 0x0000000000496de9 in _start ()

The ICE happens at the same place as in PR50635 - however still occurs (in rev
179965) in a compiler with a fix for that PR.