diff options
Diffstat (limited to 'backends')
| -rw-r--r-- | backends/cxxrtl/cxxrtl.cc | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/backends/cxxrtl/cxxrtl.cc b/backends/cxxrtl/cxxrtl.cc index 3cdc5ab6b..bb473cefb 100644 --- a/backends/cxxrtl/cxxrtl.cc +++ b/backends/cxxrtl/cxxrtl.cc @@ -1202,6 +1202,24 @@ struct CxxrtlWorker { f << indent << mangle(cell) << access << mangle_wire_name(conn.first) << " = "; dump_sigspec_rhs(conn.second); f << ";\n"; + if (getenv("CXXRTL_VOID_MY_WARRANTY")) { + // Until we have proper clock tree detection, this really awful hack that opportunistically + // propagates prev_* values for clocks can be used to estimate how much faster a design could + // be if only one clock edge was simulated by replacing: + // top.p_clk = value<1>{0u}; top.step(); + // top.p_clk = value<1>{1u}; top.step(); + // with: + // top.prev_p_clk = value<1>{0u}; top.p_clk = value<1>{1u}; top.step(); + // Don't rely on this; it will be removed without warning. + RTLIL::Module *cell_module = cell->module->design->module(cell->type); + if (cell_module != nullptr && cell_module->wire(conn.first) && conn.second.is_wire()) { + RTLIL::Wire *cell_module_wire = cell_module->wire(conn.first); + if (edge_wires[conn.second.as_wire()] && edge_wires[cell_module_wire]) { + f << indent << mangle(cell) << access << "prev_" << mangle(cell_module_wire) << " = "; + f << "prev_" << mangle(conn.second.as_wire()) << ";\n"; + } + } + } } else if (cell->input(conn.first)) { f << indent << mangle(cell) << access << mangle_wire_name(conn.first) << ".next = "; dump_sigspec_rhs(conn.second); |