[Bug lto/81847] ICE with LTO enabled

["v at vsamko dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81847

--- Comment #4 from Valentine <v at vsamko dot com> ---
Created attachment 42002
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42002&action=edit
code to reproduce ICE

I reduced (thanks to suggestions above and CReduce) this to the attached
example.

g++ -w -flto -O3  -c gccbug.ii -o gccbug.ii.o

g++ -flto -O3 -Wl,-r gccbug.ii.o -o gccbug.ii.merged.o -nostdlib -Wl,-r
-flto-partition=one

Second command crashes with 

lto1: internal compiler error: in add_symbol_to_partition_1, at
lto/lto-partition.c:203
0x1317e97 add_symbol_to_partition_1
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:203
0x1317723 add_references_to_partition
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:93
0x1317b8e add_symbol_to_partition_1
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:176
0x1317723 add_references_to_partition
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:93
0x1317b8e add_symbol_to_partition_1
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:176
0x1317cab add_symbol_to_partition_1
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:163
0x1318e63 lto_balanced_map(int, int)
        ../../gcc-7.1.0/gcc/lto/lto-partition.c:550
0x1312b8d do_whole_program_analysis
        ../../gcc-7.1.0/gcc/lto/lto.c:3123
0x1312b8d lto_main()
        ../../gcc-7.1.0/gcc/lto/lto.c:3320
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