Remove an invalid check in DW_OP_piece processing.

[abidh]

Summary

When lldb is processing a location containing DW_OP_piece, the result is being
stored in the 'pieces' variable. The location is popped from the 'stack' variable.
So this check to see that 'stack' is not empty was invalid and caused the pieces
after the first to not get processed.

I am working on an architecture which has 16-bit and 8-bit registers. So this
problem was quite easy to see. But I was able to re-produce this issue on x86
too with long long variable and compiling woth -m32. It resulted in following
location list.
00000014 08048496 080484b5 (DW_OP_reg6 (esi); DW_OP_piece: 4; DW_OP_reg7 (edi); DW_OP_piece: 4)

and lldb was only showing the contents of first register when I evaluated the
variable as it does not process the 2nd piece due to this check.

[aprantl]

Thanks, yes, this check looks like it serves no purpose.

source/Expression/DWARFExpression.cpp

                             // pieces will be able to access this piece and add to it
                             if (pieces.AppendDataToHostBuffer(curr_piece) == 0)
                             {
                                 if (error_ptr)
                                     error_ptr->SetErrorString("failed to append piece data");
                                 return false;
                             }
                         }
-                        else if (!stack.empty())
+                        else
                         {
                             // If this is the second or later piece there should be a value on the stack
                             if (pieces.GetBuffer().GetByteSize() != op_piece_offset)
                             {
                                 if (error_ptr)
                                     error_ptr->SetErrorStringWithFormat ("DW_OP_piece for offset %" PRIu64 " but top of stack is of size %" PRIu64,
                                                                          op_piece_offset,
                                                                          pieces.GetBuffer().GetByteSize());