Re: [gcc] Enable DW_OP_VAL_EXPRESSION support in dwarf module

[Jason Merrill]

On 10/21/2016 04:30 AM, Jiong Wang wrote:
All DW_OP_* of the expression are grouped together inside the PARALLEL,
and those operations which don't have RTL mapping are wrapped by
UNSPEC.  The parsing algorithm is simply something like:
  foreach elem inside PARALLEL
    if (UNSPEC)
      {
        dw_op_code = INTVAL (XVECEXP (elem, 0, 0));
        oprnd1 = INTVAL (XVECEXP (elem, 0, 1));
        oprnd2 = INTVAL (XVECEXP (elem, 0, 2));
      }
    else
      call standard RTL parser.

Any comments on the approach?

If you're going to use UNSPEC, why not put the DWARF operator in the 
second operand?

Jason