[Bug fortran/89451] New: [9 Regression] FAIL: gfortran.dg/pr79315.f90 -O (internal compiler error)

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89451

            Bug ID: 89451
           Summary: [9 Regression] FAIL: gfortran.dg/pr79315.f90   -O
                    (internal compiler error)
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: janus at gcc dot gnu.org
  Target Milestone: ---

Building today's trunk on x86_64-linux-gnu (Ubuntu 18.10), I see the following
failure in the gfortran testsuite:

FAIL: gfortran.dg/pr79315.f90   -O  (internal compiler error)
FAIL: gfortran.dg/pr79315.f90   -O  (test for excess errors)


The backtrace for the ICE looks like this:

$ gfortran-9 pr79315.f90 -Ofast -ftree-parallelize-loops=4
during GIMPLE pass: ifcvt
pr79315.f90:37:0:

   37 |         do i = its, ite
      | 
internal compiler error: in gimple_duplicate_bb, at tree-cfg.c:6255
0x5b4a92 gimple_duplicate_bb
        /home/janus/github/gcc/trunk/gcc/tree-cfg.c:6255
0x7845f2 duplicate_block(basic_block_def*, edge_def*, basic_block_def*,
copy_bb_data*)
        /home/janus/github/gcc/trunk/gcc/cfghooks.c:1085
0x785774 copy_bbs(basic_block_def**, unsigned int, basic_block_def**,
edge_def**, unsigned int, edge_def**, loop*, basic_block_def*, bool)
        /home/janus/github/gcc/trunk/gcc/cfghooks.c:1353
0x790d6f duplicate_loop_to_header_edge(loop*, edge_def*, unsigned int,
simple_bitmap_def*, edge_def*, vec<edge_def*, va_heap, vl_ptr>*, int)
        /home/janus/github/gcc/trunk/gcc/cfgloopmanip.c:1296
0xc54768 gimple_duplicate_loop_to_header_edge(loop*, edge_def*, unsigned int,
simple_bitmap_def*, edge_def*, vec<edge_def*, va_heap, vl_ptr>*, int)
        /home/janus/github/gcc/trunk/gcc/tree-ssa-loop-manip.c:921
0x793e1c loop_version(loop*, void*, basic_block_def**, profile_probability,
profile_probability, profile_probability, profile_probability, bool)
        /home/janus/github/gcc/trunk/gcc/cfgloopmanip.c:1696
0xb90eb9 version_loop_for_if_conversion
        /home/janus/github/gcc/trunk/gcc/tree-if-conv.c:2746
0xb978a7 tree_if_conversion(loop*, vec<gimple*, va_heap, vl_ptr>*)
        /home/janus/github/gcc/trunk/gcc/tree-if-conv.c:3033
0xb98929 execute
        /home/janus/github/gcc/trunk/gcc/tree-if-conv.c:3150