Mitch Bailey10/19/2020, 9:33 AM
31169 is as expected - input 'A' has a net assigned. However, 31170, 31171, and 34 other instances are missing connections to the buffer input 'A'. This appears to lead to a floating input in the final layout.
sky130_fd_sc_hd__buf_2 _31169_ ( .A(mem_la_wdata), .VGND(VGND), .VPWR(VPWR), .X(pcpi_rs2) ); sky130_fd_sc_hd__buf_2 _31170_ ( .VGND(VGND), .VPWR(VPWR), .X(trace_data) );34 sky130_fd_sc_hd__buf_2 _31171_ ( .VGND(VGND), .VPWR(VPWR), .X(trace_data) );
Ahmed Ghazy10/19/2020, 2:23 PM
Since the parameter ENABLE_TRACE is set to 0, those ports are expected to be floating. However, we were already forcing such undefined signals to be tied down to 0, but this was being done incorrectly after HI LO constant mapping. This has now been fixed in https://github.com/efabless/openlane/commit/0882565dd09d513c1965aa92ffdf21d8373f6c7d; thanks for noting this!
if (!ENABLE_TRACE) trace_data <= 'bx;
Mitch Bailey10/20/2020, 12:25 AM