Support `config` cell clauses (#6717)

src/V3LinkCells.cpp

@@ -96,7 +96,11 @@ 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;
+    std::vector<std::string> m_liblistDefault;
+    // Library lists for specific cells
+    std::unordered_map<std::string, std::vector<std::string>> m_liblistCell;
+    // Use list for specific cells (libname, cellname)
+    std::unordered_map<std::string, std::vector<std::pair<std::string, std::string>>> m_uselistCell;
 };
 
 class LinkConfigsVisitor final : public VNVisitor {
@@ -119,23 +123,31 @@ class LinkConfigsVisitor final : public VNVisitor {
         VL_DO_DANGLING(pushDeletep(nodep->unlinkFrBack()), nodep);
     }
 
-    void visit(AstConfigCell* nodep) override {
-        nodep->v3warn(E_UNSUPPORTED, "Unsupported: config cell");
-        iterateChildren(nodep);
-    }
     void visit(AstConfigRule* nodep) override {
         if (!nodep->cellp()) {
             for (AstNode* usep = nodep->usep(); usep; usep = usep->nextp()) {
-                m_state.m_liblist.push_back(usep->name());
+                m_state.m_liblistDefault.push_back(usep->name());
+            }
+        } else if (nodep->isCell()) {
+            string cellName = nodep->cellp()->name();
+            if (VN_IS(nodep->usep(),ParseRef)) {
+                m_state.m_liblistCell[cellName] = std::vector<std::string>{};
+                for (AstParseRef* usep = VN_AS(nodep->usep(), ParseRef); usep; usep = VN_AS(usep->nextp(), ParseRef)) {
+                    m_state.m_liblistCell[cellName].push_back(usep->name());
+                }
+            } else {
+                m_state.m_uselistCell[cellName] = std::vector<std::pair<std::string, std::string>>{};
+                for (AstConfigUse* usep = VN_AS(nodep->usep(), ConfigUse); usep; usep = VN_AS(usep->nextp(), ConfigUse)) {
+                    m_state.m_uselistCell[cellName].push_back(std::pair<std::string, std::string>{usep->libname(), usep->cellname()});
+                }
             }
         } else {
-            nodep->v3warn(E_UNSUPPORTED, "Unsupported: config cell rule");
+            if (VN_IS(nodep->usep(),ParseRef)) {
+                nodep->v3warn(E_UNSUPPORTED, "Unsupported: config inst liblist rule");
+            } else {
+                nodep->v3warn(E_UNSUPPORTED, "Unsupported: config inst use rule");
+            }
         }
-        iterateChildren(nodep);
-    }
-    void visit(AstConfigUse* nodep) override {
-        nodep->v3warn(E_UNSUPPORTED, "Unsupported: config use");
-        iterateChildren(nodep);
     }
 
     void visit(AstNode* nodep) override { iterateChildren(nodep); }
@@ -206,9 +218,26 @@ 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
-        // First search IEEE config library list
         AstNodeModule* foundp;
-        for (auto const& l : m_state.m_liblist) {
+        string fullName = libname + "." + modName;
+        // First search cell-specific use list
+        const auto itCellUseList = m_state.m_uselistCell.find(fullName);
+        if (itCellUseList != m_state.m_uselistCell.end()) {
+            for (auto const& u : itCellUseList->second) {
+                foundp = findModuleLibSym(u.second, u.first);
+                if (foundp) return foundp;
+            }
+        }
+        // Then search cell-specific library list
+        const auto itCellLibList = m_state.m_liblistCell.find(fullName);
+        if (itCellLibList != m_state.m_liblistCell.end()) {
+            for (auto const& l : itCellLibList->second) {
+                foundp = findModuleLibSym(modName, l);
+                if (foundp) return foundp;
+            }
+        }
+        // Then search IEEE config default liblist
+        for (auto const& l : m_state.m_liblistDefault) {
             foundp = findModuleLibSym(modName, l);
             if (foundp) return foundp;
         }

test_regress/t/t_config_hier.out

@@ -1,47 +1,11 @@
-%Error-UNSUPPORTED: t/t_config_hier.v:36:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_hier.v:36:3: Unsupported: config inst use 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
+%Error-UNSUPPORTED: t/t_config_hier.v:41:3: Unsupported: config inst use rule
-   36 |   instance t.u_1 use work.cfg2 :config;
-      |                  ^~~
-%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
+%Error-UNSUPPORTED: t/t_config_hier.v:62:3: Unsupported: config inst use rule
-   41 |   instance t.u_1 use cfg2 :config;
-      |                  ^~~
-%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
-   46 |   cell work.m1 use work.cfg2 :config;
-      |        ^~~~
-%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 cell rule
-   51 |   cell m1 use cfg2 :config;
-      |   ^~~~
-%Error-UNSUPPORTED: t/t_config_hier.v:51:8: Unsupported: config cell
-   51 |   cell m1 use cfg2 :config;
-      |        ^~
-%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 cell rule
-   56 |   cell work.m1 use work.cfg2;   
-      |   ^~~~
-%Error-UNSUPPORTED: t/t_config_hier.v:56:8: Unsupported: config cell
-   56 |   cell work.m1 use work.cfg2;   
-      |        ^~~~
-%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 cell rule
    62 |   instance u_bb use work.c2_bb;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_hier.v:62:17: Unsupported: config use
-   62 |   instance u_bb use work.c2_bb;
-      |                 ^~~
 %Error: Exiting due to

test_regress/t/t_config_liblist.out

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

test_regress/t/t_config_liblist.py

@@ -0,0 +1,24 @@
+#!/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_liblist.v

@@ -0,0 +1,19 @@
+// 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;
+    // Use libb's version of m3 for m1 and liba's version of m3 for m2
+    cell liba.m3 liblist libb;
+    cell libb.m3 use liba.m3;
+endconfig

test_regress/t/t_config_rules.out

@@ -1,65 +1,26 @@
-%Error-UNSUPPORTED: t/t_config_rules.v:33:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_rules.v:33:3: Unsupported: config inst use rule
    33 |   instance t.m20 liblist;   
       |   ^~~~~~~~
                     ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_config_rules.v:34:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_rules.v:34:3: Unsupported: config inst liblist rule
    34 |   instance t.m21 liblist libc;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:35:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_rules.v:35:3: Unsupported: config inst liblist rule
    35 |   instance t.m22 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:36:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_rules.v:36:3: Unsupported: config inst liblist rule
    36 |   instance t.m23 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:37:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_rules.v:37:3: Unsupported: config inst liblist rule
    37 |   instance t.m24 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:40:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_rules.v:40:3: Unsupported: config inst use rule
    40 |   instance t.m30 use cell_identifier;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:40:18: Unsupported: config use
+%Error-UNSUPPORTED: t/t_config_rules.v:41:3: Unsupported: config inst use rule
-   40 |   instance t.m30 use cell_identifier;
-      |                  ^~~
-%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
+%Error-UNSUPPORTED: t/t_config_rules.v:42:3: Unsupported: config inst use rule
-   41 |   instance t.m31 use lib_id.cell_id;
-      |                  ^~~
-%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 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 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 cell rule
-   47 |   cell m42 use m42alt;
-      |   ^~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:47:8: Unsupported: config cell
-   47 |   cell m42 use m42alt;
-      |        ^~~
-%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 cell rule
-   48 |   cell work.m43 use work.m43alt;
-      |   ^~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:48:8: Unsupported: config cell
-   48 |   cell work.m43 use work.m43alt;
-      |        ^~~~
-%Error-UNSUPPORTED: t/t_config_rules.v:48:17: Unsupported: config use
-   48 |   cell work.m43 use work.m43alt;
-      |                 ^~~
 %Error: Exiting due to

test_regress/t/t_config_unsup.out

@@ -1,65 +1,26 @@
-%Error-UNSUPPORTED: t/t_config_unsup.v:32:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:32:3: Unsupported: config inst use rule
    32 |   instance t.m20 liblist;   
       |   ^~~~~~~~
                     ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error-UNSUPPORTED: t/t_config_unsup.v:33:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:33:3: Unsupported: config inst liblist rule
    33 |   instance t.m21 liblist libc;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:34:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:34:3: Unsupported: config inst liblist rule
    34 |   instance t.m22 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:35:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:35:3: Unsupported: config inst liblist rule
    35 |   instance t.m23 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:36:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:36:3: Unsupported: config inst liblist rule
    36 |   instance t.m24 liblist libc libd;   
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:39:3: Unsupported: config cell rule
+%Error-UNSUPPORTED: t/t_config_unsup.v:39:3: Unsupported: config inst use rule
    39 |   instance t.m30 use cell_identifier;
       |   ^~~~~~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:39:18: Unsupported: config use
+%Error-UNSUPPORTED: t/t_config_unsup.v:40:3: Unsupported: config inst use rule
-   39 |   instance t.m30 use cell_identifier;
-      |                  ^~~
-%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
+%Error-UNSUPPORTED: t/t_config_unsup.v:41:3: Unsupported: config inst use rule
-   40 |   instance t.m31 use lib_id.cell_id;
-      |                  ^~~
-%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 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 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 cell rule
-   46 |   cell m42 use m42alt;
-      |   ^~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:46:8: Unsupported: config cell
-   46 |   cell m42 use m42alt;
-      |        ^~~
-%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 cell rule
-   47 |   cell work.m43 use work.m43alt;
-      |   ^~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:47:8: Unsupported: config cell
-   47 |   cell work.m43 use work.m43alt;
-      |        ^~~~
-%Error-UNSUPPORTED: t/t_config_unsup.v:47:17: Unsupported: config use
-   47 |   cell work.m43 use work.m43alt;
-      |                 ^~~
 %Error: Exiting due to