opt_expr: consume_x to require/imply !keepdc

diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc
index 60221f32d0b1886d5eadf00a10cfe084b65a570e..9a8bc0869661e4782e81a40ae9e6d2becfaaa823 100644 (file)
--- a/passes/opt/opt_expr.cc
+++ b/passes/opt/opt_expr.cc
@@ -543,13 +543,13 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
                                }
                        }
 
-                       if (detect_const_and && (found_zero || found_inv || (!keepdc && found_undef && consume_x))) {
+                       if (detect_const_and && (found_zero || found_inv || (found_undef && consume_x))) {
                                cover("opt.opt_expr.const_and");
                                replace_cell(assign_map, module, cell, "const_and", ID::Y, RTLIL::State::S0);
                                goto next_cell;
                        }
 
-                       if (detect_const_or && (found_one || found_inv || (!keepdc && found_undef && consume_x))) {
+                       if (detect_const_or && (found_one || found_inv || (found_undef && consume_x))) {
                                cover("opt.opt_expr.const_or");
                                replace_cell(assign_map, module, cell, "const_or", ID::Y, RTLIL::State::S1);
                                goto next_cell;
@@ -1149,7 +1149,7 @@ skip_fine_alu:
                        goto next_cell;
                }
 
-               if (!keepdc && consume_x)
+               if (consume_x)
                {
                        bool identity_wrt_a = false;
                        bool identity_wrt_b = false;
@@ -2041,11 +2041,12 @@ struct OptExprPass : public Pass {
                        do {
                                do {
                                        did_something = false;
-                                       replace_const_cells(design, module, false, mux_undef, mux_bool, do_fine, keepdc, clkinv);
+                                       replace_const_cells(design, module, false /* consume_x */, mux_undef, mux_bool, do_fine, keepdc, clkinv);
                                        if (did_something)
                                                design->scratchpad_set_bool("opt.did_something", true);
                                } while (did_something);
-                               replace_const_cells(design, module, true, mux_undef, mux_bool, do_fine, keepdc, clkinv);
+                               if (!keepdc)
+                                   replace_const_cells(design, module, true /* consume_x */, mux_undef, mux_bool, do_fine, keepdc, clkinv);
                                if (did_something)
                                        design->scratchpad_set_bool("opt.did_something", true);
                        } while (did_something);