[Bug rtl-optimization/59020] New: [4.9 Regression] internal compiler error: in maybe_add_or_update_dep_1, at sched-deps.c:933

["Joost.VandeVondele at mat dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59020

            Bug ID: 59020
           Summary: [4.9 Regression] internal compiler error: in
                    maybe_add_or_update_dep_1, at sched-deps.c:933
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Joost.VandeVondele at mat dot ethz.ch

Created attachment 31172
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31172&action=edit
reduced testcase.

The attached testcase compiled with current trunk fails as

gfortran  -c -O2 -march=native -fmodulo-sched -ffast-math -ffree-form
-fno-inline  bug.f90

bug.f90:98:0: internal compiler error: in maybe_add_or_update_dep_1, at
sched-deps.c:933
   END SUBROUTINE write_forces
 ^
0xf3e498 maybe_add_or_update_dep_1
    ../../gcc/gcc/sched-deps.c:933
0xf3e498 maybe_add_or_update_dep_1
    ../../gcc/gcc/sched-deps.c:928
0xf3e5fc haifa_note_dep
    ../../gcc/gcc/sched-deps.c:1866
0xf35e52 note_dep
    ../../gcc/gcc/sched-deps.c:1901
0xf35e52 add_dependence_1
    ../../gcc/gcc/sched-deps.c:4175
0xf389d1 add_dependence(rtx_def*, rtx_def*, reg_note)
    ../../gcc/gcc/sched-deps.c:1557
0xf3c0f5 chain_to_prev_insn
    ../../gcc/gcc/sched-deps.c:1693
0xf3c0f5 deps_analyze_insn(deps_desc*, rtx_def*)
    ../../gcc/gcc/sched-deps.c:3697
0xf3c6f2 sched_analyze(deps_desc*, rtx_def*, rtx_def*)
    ../../gcc/gcc/sched-deps.c:3739
0x9b1dd5 compute_block_dependences
    ../../gcc/gcc/sched-rgn.c:2721
0x9b1dd5 sched_rgn_compute_dependencies(int)
    ../../gcc/gcc/sched-rgn.c:3234
0x9b4621 schedule_region

This is a recent failure introduced between r204343 and r204377