Support `config` default liblist (#6714)

src/V3LinkCells.cpp

@@ -95,6 +95,8 @@ void LinkCellsGraph::loopsMessageCb(V3GraphVertex* vertexp, V3EdgeFuncP edgeFunc
 struct LinkCellsState final {
     // Set of possible top module names from command line and configs
     std::unordered_set<std::string> m_topModuleNames;
+    // Default library lists to search
+    std::vector<std::string> m_liblist;
 };
 
 class LinkConfigsVisitor final : public VNVisitor {
@@ -114,6 +116,7 @@ class LinkConfigsVisitor final : public VNVisitor {
         }
         // We don't do iterateChildren here because we want to skip designp
         iterateAndNextNull(nodep->itemsp());
+        VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
     }
 
     void visit(AstConfigCell* nodep) override {
@@ -121,7 +124,14 @@ class LinkConfigsVisitor final : public VNVisitor {
         iterateChildren(nodep);
     }
     void visit(AstConfigRule* nodep) override {
-        nodep->v3warn(E_UNSUPPORTED, "Unsupported: config rule");
+        if (!nodep->cellp()) {
+            for (AstNode* usep = nodep->usep(); usep;
+                usep = usep->nextp()) {
+                m_state.m_liblist.push_back(usep->name());
+            }
+        } else {
+            nodep->v3warn(E_UNSUPPORTED, "Unsupported: config cell rule");
+        }
         iterateChildren(nodep);
     }
     void visit(AstConfigUse* nodep) override {
@@ -197,11 +207,16 @@ class LinkCellsVisitor final : public VNVisitor {
     }
     AstNodeModule* findModuleSym(const string& modName, const string& libname) {
         // Given module and library to start search in, resolve using config library choices
-        // TODO support IEEE config library search order
+        // First search IEEE config library list
-        // First search local library
+        AstNodeModule* foundp;
-        AstNodeModule* foundp = findModuleLibSym(modName, libname);
+        for (auto const& l : m_state.m_liblist) {
+                foundp = findModuleLibSym(modName, l);
+                if (foundp) return foundp;
+        }
+        // Then search local library
+        foundp = findModuleLibSym(modName, libname);
         if (foundp) return foundp;
-        // THen search global
+        // Then search global
         foundp = findModuleLibSym(modName, "__GLOBAL");
         return foundp;
     }

test_regress/t/t_config_default.out

@@ -0,0 +1,5 @@
+*-* All Finished *-*
+liba:m1 %m=t.u_1 %l=liba.m1
+liba:m3 %m=t.u_1.u_13 %l=liba.m3
+liba:m3 %m=t.u_2.u_23 %l=liba.m3
+libb:m2 %m=t.u_2 %l=libb.m2

test_regress/t/t_config_default.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile(verilator_flags2=[
+    '--binary', '--top cfg1', '--work liba', 't/t_config_work__liba.v', '--work libb', 't/t_config_work__libb.v'
+])
+
+test.execute()
+
+# Sort so that 'initial' scheduling order is not relevant
+test.files_identical_sorted(test.run_log_filename, test.golden_filename, is_logfile=True)
+
+test.passes()

test_regress/t/t_config_default.v

@@ -0,0 +1,18 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+  // Test config allows selecting two different libraries for these instances
+  m1 u_1();
+  m2 u_2();
+  final $write("*-* All Finished *-*\n");
+endmodule
+
+config cfg1;
+    design t;
+    // resolve liba, then libb
+    default liblist liba libb ;
+endconfig

test_regress/t/t_config_hier.out

@@ -1,17 +1,17 @@
-%Error-UNSUPPORTED: t/t_config_hier.v:36:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_hier.v:36:3: Unsupported: config cell rule
    36 |   instance t.u_1 use work.cfg2 :config;
       |   ^~~~~~~~
                     ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
 %Error-UNSUPPORTED: t/t_config_hier.v:36:18: Unsupported: config use
    36 |   instance t.u_1 use work.cfg2 :config;
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_hier.v:41:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_hier.v:41:3: Unsupported: config cell rule
    41 |   instance t.u_1 use cfg2 :config;
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_hier.v:41:18: Unsupported: config use
    41 |   instance t.u_1 use cfg2 :config;
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_hier.v:46:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_hier.v:46:3: Unsupported: config cell rule
    46 |   cell work.m1 use work.cfg2 :config;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_hier.v:46:8: Unsupported: config cell
@@ -20,7 +20,7 @@
 %Error-UNSUPPORTED: t/t_config_hier.v:46:16: Unsupported: config use
    46 |   cell work.m1 use work.cfg2 :config;
       |                ^~~
-%Error-UNSUPPORTED: t/t_config_hier.v:51:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_hier.v:51:3: Unsupported: config cell rule
    51 |   cell m1 use cfg2 :config;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_hier.v:51:8: Unsupported: config cell
@@ -29,7 +29,7 @@
 %Error-UNSUPPORTED: t/t_config_hier.v:51:11: Unsupported: config use
    51 |   cell m1 use cfg2 :config;
       |           ^~~
-%Error-UNSUPPORTED: t/t_config_hier.v:56:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_hier.v:56:3: Unsupported: config cell rule
    56 |   cell work.m1 use work.cfg2;   
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_hier.v:56:8: Unsupported: config cell
@@ -38,7 +38,7 @@
 %Error-UNSUPPORTED: t/t_config_hier.v:56:16: Unsupported: config use
    56 |   cell work.m1 use work.cfg2;   
       |                ^~~
-%Error-UNSUPPORTED: t/t_config_hier.v:62:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_hier.v:62:3: Unsupported: config cell rule
    62 |   instance u_bb use work.c2_bb;
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_hier.v:62:17: Unsupported: config use

test_regress/t/t_config_rules.out

@@ -1,56 +1,50 @@
-%Error-UNSUPPORTED: t/t_config_rules.v:28:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:33:3: Unsupported: config cell rule
-   28 |   default liblist;   
-      |   ^~~~~~~
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_config_rules.v:29:3: Unsupported: config rule
-   29 |   default liblist liba libb;
-      |   ^~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:33:3: Unsupported: config rule
    33 |   instance t.m20 liblist;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:34:3: Unsupported: config rule
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error-UNSUPPORTED: t/t_config_rules.v:34:3: Unsupported: config cell rule
    34 |   instance t.m21 liblist libc;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:35:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:35:3: Unsupported: config cell rule
    35 |   instance t.m22 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:36:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:36:3: Unsupported: config cell rule
    36 |   instance t.m23 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:37:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:37:3: Unsupported: config cell rule
    37 |   instance t.m24 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:40:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:40:3: Unsupported: config cell rule
    40 |   instance t.m30 use cell_identifier;
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:40:18: Unsupported: config use
    40 |   instance t.m30 use cell_identifier;
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_rules.v:41:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:41:3: Unsupported: config cell rule
    41 |   instance t.m31 use lib_id.cell_id;
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:41:18: Unsupported: config use
    41 |   instance t.m31 use lib_id.cell_id;
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_rules.v:42:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:42:3: Unsupported: config cell rule
    42 |   instance t.m32 use #();
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:42:18: Unsupported: config use
    42 |   instance t.m32 use #();
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_rules.v:45:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:45:3: Unsupported: config cell rule
    45 |   cell m40 liblist libc libd;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:45:8: Unsupported: config cell
    45 |   cell m40 liblist libc libd;
       |        ^~~
-%Error-UNSUPPORTED: t/t_config_rules.v:46:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:46:3: Unsupported: config cell rule
    46 |   cell work.m41 liblist libc libd;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:46:8: Unsupported: config cell
    46 |   cell work.m41 liblist libc libd;
       |        ^~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:47:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:47:3: Unsupported: config cell rule
    47 |   cell m42 use m42alt;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:47:8: Unsupported: config cell
@@ -59,7 +53,7 @@
 %Error-UNSUPPORTED: t/t_config_rules.v:47:12: Unsupported: config use
    47 |   cell m42 use m42alt;
       |            ^~~
-%Error-UNSUPPORTED: t/t_config_rules.v:48:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_rules.v:48:3: Unsupported: config cell rule
    48 |   cell work.m43 use work.m43alt;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_rules.v:48:8: Unsupported: config cell

test_regress/t/t_config_unsup.out

@@ -1,56 +1,50 @@
-%Error-UNSUPPORTED: t/t_config_unsup.v:28:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:32:3: Unsupported: config cell rule
-   28 |   default liblist;   
-      |   ^~~~~~~
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_config_unsup.v:29:3: Unsupported: config rule
-   29 |   default liblist liba libb;
-      |   ^~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:32:3: Unsupported: config rule
    32 |   instance t.m20 liblist;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:33:3: Unsupported: config rule
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error-UNSUPPORTED: t/t_config_unsup.v:33:3: Unsupported: config cell rule
    33 |   instance t.m21 liblist libc;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:34:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:34:3: Unsupported: config cell rule
    34 |   instance t.m22 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:35:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:35:3: Unsupported: config cell rule
    35 |   instance t.m23 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:36:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:36:3: Unsupported: config cell rule
    36 |   instance t.m24 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:39:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:39:3: Unsupported: config cell rule
    39 |   instance t.m30 use cell_identifier;
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:39:18: Unsupported: config use
    39 |   instance t.m30 use cell_identifier;
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:40:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:40:3: Unsupported: config cell rule
    40 |   instance t.m31 use lib_id.cell_id;
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:40:18: Unsupported: config use
    40 |   instance t.m31 use lib_id.cell_id;
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:41:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:41:3: Unsupported: config cell rule
    41 |   instance t.m32 use #();
       |   ^~~~~~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:41:18: Unsupported: config use
    41 |   instance t.m32 use #();
       |                  ^~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:44:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:44:3: Unsupported: config cell rule
    44 |   cell m40 liblist libc libd;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:44:8: Unsupported: config cell
    44 |   cell m40 liblist libc libd;
       |        ^~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:45:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:45:3: Unsupported: config cell rule
    45 |   cell work.m41 liblist libc libd;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:45:8: Unsupported: config cell
    45 |   cell work.m41 liblist libc libd;
       |        ^~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:46:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:46:3: Unsupported: config cell rule
    46 |   cell m42 use m42alt;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:46:8: Unsupported: config cell
@@ -59,7 +53,7 @@
 %Error-UNSUPPORTED: t/t_config_unsup.v:46:12: Unsupported: config use
    46 |   cell m42 use m42alt;
       |            ^~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:47:3: Unsupported: config rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:47:3: Unsupported: config cell rule
    47 |   cell work.m43 use work.m43alt;
       |   ^~~~
 %Error-UNSUPPORTED: t/t_config_unsup.v:47:8: Unsupported: config cell