Fix forced assignments that override non-continuous assignments (#4183) (#4192)

Only assign forced value on release if it was forced in the first place.

src/V3Force.cpp

@@ -253,16 +253,33 @@ class ForceConvertVisitor final : public VNVisitor {
         resetRdp->rhsp()->foreach([this](AstNodeVarRef* refp) {
             if (refp->access() != VAccess::WRITE) return;
             AstVarScope* const vscp = refp->varScopep();
-            AstVarScope* const newVscp
-                = vscp->varp()->isContinuously() ? vscp : getForceComponents(vscp).m_valVscp;
-            AstVarRef* const newpRefp = new AstVarRef{refp->fileline(), newVscp, VAccess::READ};
+            FileLine* const flp = new FileLine{refp->fileline()};
+            AstVarRef* const newpRefp = new AstVarRef{refp->fileline(), vscp, VAccess::READ};
             newpRefp->user2(1);  // Don't replace this read ref with the read signal
-            refp->replaceWith(newpRefp);
+            if (vscp->varp()->isContinuously()) {
+                refp->replaceWith(newpRefp);
+            } else if (isRangedDType(vscp)) {
+                refp->replaceWith(new AstOr{
+                    flp,
+                    new AstAnd{
+                        flp, new AstVarRef{flp, getForceComponents(vscp).m_enVscp, VAccess::READ},
+                        new AstVarRef{flp, getForceComponents(vscp).m_valVscp, VAccess::READ}},
+                    new AstAnd{
+                        flp,
+                        new AstNot{flp, new AstVarRef{flp, getForceComponents(vscp).m_enVscp,
+                                                      VAccess::READ}},
+                        newpRefp}});
+            } else {
+                refp->replaceWith(new AstCond{
+                    flp, new AstVarRef{flp, getForceComponents(vscp).m_enVscp, VAccess::READ},
+                    new AstVarRef{flp, getForceComponents(vscp).m_valVscp, VAccess::READ},
+                    newpRefp});
+            }
             VL_DO_DANGLING(refp->deleteTree(), refp);
         });
 
-        resetEnp->addNext(resetRdp);
-        relinker.relink(resetEnp);
+        resetRdp->addNext(resetEnp);
+        relinker.relink(resetRdp);
     }
 
     void visit(AstVarScope* nodep) override {

test_regress/t/t_clocked_release_combo.pl

@@ -0,0 +1,21 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2023 by Antmicro Ltd. 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
+
+scenarios(simulator => 1);
+
+compile(
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;

test_regress/t/t_clocked_release_combo.v

@@ -0,0 +1,51 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Antmicro Ltd.
+// SPDX-License-Identifier: CC0-1.0
+
+// verilator lint_off MULTIDRIVEN
+module t (/*AUTOARG*/
+  // Inputs
+  clk
+  );
+  input clk;
+
+  logic [31:0] lhs1, lhs2, rhs;
+  logic cond = 0;
+
+  always_comb lhs1 = rhs;
+  assign lhs2 = rhs;
+
+  always @(posedge clk) rhs = '1;
+
+  always @(negedge clk) begin
+    if (cond) begin
+      force lhs1 = 'hdeadbeef;
+      force lhs2 = 'hfeedface;
+    end
+    else begin
+      release lhs1;
+      release lhs2;
+    end
+  end
+
+  int cyc = 0;
+  always @(posedge clk) begin
+    cyc <= cyc + 1;
+    if (cyc == 0) cond <= 1;
+    if (cyc == 3) cond <= 0;
+    if (cyc > 1 && cyc < 4) begin
+        if (lhs1 != 'hdeadbeef) $stop;
+        if (lhs2 != 'hfeedface) $stop;
+    end
+    if (cyc > 4 && cyc < 8) begin
+        if (lhs1 != '1) $stop;
+        if (lhs2 != '1) $stop;
+    end
+    if (cyc >= 8) begin
+        $write("*-* All Finished *-*\n");
+        $finish;
+    end
+  end
+endmodule