[Bug lto/79587] ICE in streamer_write_gcov_count_stream, at data-streamer-out.c:343 while building Python 3.6.0 with PGO and LTO

["trippels at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79587

Markus Trippelsdorf <trippels at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-02-18
                 CC|                            |trippels at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Confirmed. Also happens on trunk:

(gdb) p work
$1 = -1099511627775
(gdb) p ob
$2 = (output_block *) 0x1e2a970
(gdb) p *ob
$3 = {
  section_type = LTO_section_function_body,
  decl_state = 0x1e2a550,
  main_stream = 0x1e2a620,
  string_stream = 0x1e2a6a0,
  cfg_stream = 0x1e2a740,
  string_hash_table = 0x1e2a770,
  symbol = 0x7ffff6f24450,
  current_file = 0x1eb0e80
"/home/markus/tmp/Python-3.6.0/Modules/_decimal/libmpdec/crt.c",
  current_line = 159,
  current_col = 24,
  current_sysp = false,
  writer_cache = 0x1e2a6d0,
  obstack = {
    chunk_size = 65536,
    chunk = 0x1f30ff0,
    object_base = 0x1f312e0 '\257' <repeats 40 times>,
    next_free = 0x1f312e0 '\257' <repeats 40 times>,
    chunk_limit = 0x1f40ff0 "",
    temp = {
      i = 0,
      p = 0x0
    },
    alignment_mask = 15,
    chunkfun = {
      plain = 0x13aeaf0 <mempool_obstack_chunk_alloc(unsigned long)>,
      extra = 0x13aeaf0 <mempool_obstack_chunk_alloc(unsigned long)>
    },
    freefun = {
      plain = 0x13aebd0 <mempool_obstack_chunk_free(void*)>,
      extra = 0x13aebd0 <mempool_obstack_chunk_free(void*)>
    },
    extra_arg = 0x0,
    use_extra_arg = 0,
    maybe_empty_object = 0,
    alloc_failed = 0
  }
}
(gdb) cont
Continuing.
/home/markus/tmp/Python-3.6.0/Modules/_decimal/libmpdec/crt.c: In function
‘crt3’:
/home/markus/tmp/Python-3.6.0/Modules/_decimal/libmpdec/crt.c:177:1: internal
compiler error: in streamer_write_gcov_count_stream, at data-streamer-out.c:343
 }
 ^
0x1273565 streamer_write_gcov_count_stream(lto_output_stream*, long)
        /home/markus/gcc/gcc/data-streamer-out.c:343
0x1273565 streamer_write_gcov_count(output_block*, long)
        /home/markus/gcc/gcc/data-streamer-out.c:228
0xe39e8d stream_out_histogram_value(output_block*, histogram_value_t*)
        /home/markus/gcc/gcc/value-prof.c:368
0x12a7170 output_gimple_stmt
        /home/markus/gcc/gcc/gimple-streamer-out.c:195
0x12a7170 output_bb(output_block*, basic_block_def*, function*)
        /home/markus/gcc/gcc/gimple-streamer-out.c:225
0xa0a5a5 output_function
        /home/markus/gcc/gcc/lto-streamer-out.c:2128
0xa0a5a5 lto_output()
        /home/markus/gcc/gcc/lto-streamer-out.c:2343
0xa78f4e write_lto
        /home/markus/gcc/gcc/passes.c:2578
0xa7cd56 ipa_write_summaries_1
        /home/markus/gcc/gcc/passes.c:2642
0xa7cd56 ipa_write_summaries()
        /home/markus/gcc/gcc/passes.c:2702
0x7432e9 ipa_passes
        /home/markus/gcc/gcc/cgraphunit.c:2368
0x7432e9 symbol_table::compile()
        /home/markus/gcc/gcc/cgraphunit.c:2462
0x745b94 symbol_table::compile()
        /home/markus/gcc/gcc/cgraphunit.c:2624
0x745b94 symbol_table::finalize_compilation_unit()
        /home/markus/gcc/gcc/cgraphunit.c:2621