write_verilog: write RTLIL::Sa aka - as Verilog ?.

Currently, the only ways (determined by grepping for regex \bSa\b) to
end up with RTLIL::Sa in a netlist is by reading a Verilog constant
with ? in it as a part of case, or by running certain FSM passes.
Both of these cases should be round-tripped back to ? in Verilog.

diff --git a/backends/verilog/verilog_backend.cc b/backends/verilog/verilog_backend.cc
index 6288502a549bd6efd445e5a5cb310f95bbda950b..1c68288ce74e3db8fec9e857cf83fa28b065b102 100644 (file)
--- a/backends/verilog/verilog_backend.cc
+++ b/backends/verilog/verilog_backend.cc
@@ -222,7 +222,7 @@ void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int o
                                case RTLIL::S1: bin_digits.push_back('1'); break;
                                case RTLIL::Sx: bin_digits.push_back('x'); break;
                                case RTLIL::Sz: bin_digits.push_back('z'); break;
-                               case RTLIL::Sa: bin_digits.push_back('z'); break;
+                               case RTLIL::Sa: bin_digits.push_back('?'); break;
                                case RTLIL::Sm: log_error("Found marker state in final netlist.");
                                }
                        }
@@ -251,6 +251,12 @@ void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int o
                                        hex_digits.push_back('z');
                                        continue;
                                }
+                               if (bit_3 == '?' || bit_2 == '?' || bit_1 == '?' || bit_0 == '?') {
+                                       if (bit_3 != '?' || bit_2 != '?' || bit_1 != '?' || bit_0 != '?')
+                                               goto dump_bin;
+                                       hex_digits.push_back('?');
+                                       continue;
+                               }
                                int val = 8*(bit_3 - '0') + 4*(bit_2 - '0') + 2*(bit_1 - '0') + (bit_0 - '0');
                                hex_digits.push_back(val < 10 ? '0' + val : 'a' + val - 10);
                        }
@@ -270,7 +276,7 @@ void dump_const(std::ostream &f, const RTLIL::Const &data, int width = -1, int o
                                case RTLIL::S1: f << stringf("1"); break;
                                case RTLIL::Sx: f << stringf("x"); break;
                                case RTLIL::Sz: f << stringf("z"); break;
-                               case RTLIL::Sa: f << stringf("z"); break;
+                               case RTLIL::Sa: f << stringf("?"); break;
                                case RTLIL::Sm: log_error("Found marker state in final netlist.");
                                }
                        }