Demonstrating the bug.

The hipe_bug.S file was generated using the new SSA-based compiler.

Erlang/OTP 21 [erts-10.0] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe]

Eshell V10.0  (abort with ^G)
1> c(hipe_bug, [from_asm,native]), hipe_bug:run().
** exception error: {badmap,{cons,{arg,0},nil}}
     in function  hipe_bug:dig_out_fc/1
2> c(hipe_bug, [from_asm]), hipe_bug:run().
{cons,{arg,0},nil}
3>

The problem seems to be in the following instruction:

    {get_map_elements,{f,5},
                      {x,0},
                      {list,[{literal,{x,1}},{x,0},{literal,{x,0}},{x,1}]}}.

Note that the source register for the map ({x,0}) is also one of the destinations.
BEAM has no problem with this, as it executes the instruction atomically.