[Bug middle-end/69987] New: [6 Regression] internal compiler error: in verify_loop_structure, at cfgloop.c:1639

[Joost.VandeVondele at mat dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69987

            Bug ID: 69987
           Summary: [6 Regression]  internal compiler error: in
                    verify_loop_structure, at cfgloop.c:1639
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Joost.VandeVondele at mat dot ethz.ch
  Target Milestone: ---

an overnight regression on trunk, which I'll tr to reduce:

/data/vjoost/gnu/cp2k/cp2k/makefiles/../src/cp_lbfgs.F:242:0:

   SUBROUTINE mainlb(n, m, x, l, u, nbd, f, g, factr, pgtol, ws, wy, &

Error: loop verification on loop tree that needs fixup
/data/vjoost/gnu/cp2k/cp2k/makefiles/../src/cp_lbfgs.F:242:0: internal compiler
error: in verify_loop_structure, at cfgloop.c:1639
0x773ecc verify_loop_structure()
        ../../gcc/gcc/cfgloop.c:1639
0xd07b50 checking_verify_loop_structure
        ../../gcc/gcc/cfgloop.h:324
0xd07b50 tree_transform_and_unroll_loop(loop*, unsigned int, edge_def*,
tree_niter_desc*, void (*)(loop*, void*), void*)
        ../../gcc/gcc/tree-ssa-loop-manip.c:1362
0xd19205 loop_prefetch_arrays
        ../../gcc/gcc/tree-ssa-loop-prefetch.c:1908
0xd19205 tree_ssa_prefetch_arrays()
        ../../gcc/gcc/tree-ssa-loop-prefetch.c:1977
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make[2]: *** [cp_lbfgs.o] Error 1

First guess would be this is related to the fix of PR69740 (which was also
backported to the 5 branch).