[Bug tree-optimization/71462] [7 Regression] gcc ICE at -O3 on valid code on x86_64-linux-gnu with “seg fault”

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71462

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
#4  0x0000000001035c30 in find_uses_to_rename (changed_bbs=0x26e1748, 
    use_blocks=0x281d750, need_phis=0x2792450, use_flags=1)
    at /space/rguenther/src/svn/trunk/gcc/tree-ssa-loop-manip.c:476
476                                   need_phis, use_flags);
(gdb) l
471       bitmap_iterator bi;
472
473       if (changed_bbs)
474         EXECUTE_IF_SET_IN_BITMAP (changed_bbs, 0, index, bi)
475           find_uses_to_rename_bb (BASIC_BLOCK_FOR_FN (cfun, index),
use_blocks,
476                                   need_phis, use_flags);

hits a block in the bitmap that was removed.  This bitmap is filled
by unloop called in unloop_loops and after that we remove paths
that may cause such blocks to become removed...

It's probably easiest to robustify the above code instead.