From b70696fc0ac9a03d9dd8712e0d0fc0f2ce8465cc Mon Sep 17 00:00:00 2001
From: Artur Bieniek <abieniek@antmicro.com>
Date: Fri, 31 Jul 2026 03:39:21 +0200
Subject: [PATCH] Fix $finish continuing event loop (#7267) (#7950)

Fixes #7267,
---
 include/verilated.cpp                      |  3 +++
 include/verilated.h                        | 10 ++++++++
 src/V3SenExprBuilder.h                     | 13 +++++++++-
 test_regress/t/t_finish_stops_nonfinal2.py | 18 +++++++++++++
 test_regress/t/t_finish_stops_nonfinal2.v  | 30 ++++++++++++++++++++++
 5 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100755 test_regress/t/t_finish_stops_nonfinal2.py
 create mode 100644 test_regress/t/t_finish_stops_nonfinal2.v

diff --git a/include/verilated.cpp b/include/verilated.cpp
index 92de3fd29..540f8ee22 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -243,8 +243,11 @@ void vl_warn(const char* filename, int linenum, const char* hier, const char* ms
 // Wrapper to call certain functions via messages when multithreaded
 
 void VL_FINISH_MT(const char* filename, int linenum, const char* hier) VL_MT_SAFE {
+    VerilatedContext* const contextp = Verilated::threadContextp();
+    contextp->finishPendingInc();
     VerilatedThreadMsgQueue::post(VerilatedMsg{[=]() {  //
         vl_finish(filename, linenum, hier);
+        contextp->finishPendingDec();
     }});
 }
 
diff --git a/include/verilated.h b/include/verilated.h
index b3ce78068..b8fc95e76 100644
--- a/include/verilated.h
+++ b/include/verilated.h
@@ -445,6 +445,8 @@ protected:
     struct NonSerialized final {  // Non-serialized information
         // These are reloaded from on command-line settings, so do not need to persist
         // Fast path
+        // A worker queues $finish before the main thread callback can set m_gotFinish.
+        std::atomic<uint32_t> m_finishPending{0};  // Number of queued $finish callbacks
         bool m_executingFinal = false;  // Running generated final() code
         uint64_t m_profExecStart = 1;  // +prof+exec+start time
         uint32_t m_profExecWindow = 2;  // +prof+exec+window size
@@ -684,6 +686,14 @@ public:
 
     // METHODS - public but for internal use only
 
+    // Internal: Track $finish callbacks queued by worker threads
+    bool finishPending() const VL_MT_SAFE { return m_ns.m_finishPending.load() != 0; }
+    void finishPendingInc() VL_MT_SAFE { ++m_ns.m_finishPending; }
+    void finishPendingDec() VL_MT_SAFE {
+        const uint32_t previous = m_ns.m_finishPending.fetch_sub(1);
+        assert(previous > 0);
+    }
+
     // Internal: access to implementation class
     VerilatedContextImp* impp() VL_MT_SAFE { return reinterpret_cast<VerilatedContextImp*>(this); }
     const VerilatedContextImp* impp() const VL_MT_SAFE {
diff --git a/src/V3SenExprBuilder.h b/src/V3SenExprBuilder.h
index ac9abf196..a0271fcfd 100644
--- a/src/V3SenExprBuilder.h
+++ b/src/V3SenExprBuilder.h
@@ -290,7 +290,18 @@ private:
             AstCMethodHard* const callp
                 = new AstCMethodHard{flp, currp(), VCMethod::EVENT_IS_FIRED};
             callp->dtypeSetBit();
-            return {wrapExprWithNullCheck(flp, callp, baseClassRefp), false};
+            AstNodeExpr* const firedp = wrapExprWithNullCheck(flp, callp, baseClassRefp);
+            if (const AstVarRef* const refp = VN_CAST(senp, VarRef)) {
+                // The private NBA event must run so pending assignments finish settling.
+                if (refp->varScopep() == v3Global.rootp()->nbaEventp()) return {firedp, false};
+            }
+            // Do not trigger user named-event processes after $finish.
+            AstNodeExpr* const notFinishp
+                = new AstCExpr{flp,
+                               "VL_LIKELY(!vlSymsp->_vm_contextp__->gotFinish() && "
+                               "!vlSymsp->_vm_contextp__->finishPending())",
+                               1};
+            return {new AstLogAnd{flp, notFinishp, firedp}, false};
         }
         case VEdgeType::ET_TRUE:  //
             return {currp(), false};
diff --git a/test_regress/t/t_finish_stops_nonfinal2.py b/test_regress/t/t_finish_stops_nonfinal2.py
new file mode 100755
index 000000000..6fe7d000c
--- /dev/null
+++ b/test_regress/t/t_finish_stops_nonfinal2.py
@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# 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-FileCopyrightText: 2026 Wilson Snyder
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('simulator')
+
+test.compile(verilator_flags2=["--binary"])
+
+test.execute()
+
+test.passes()
diff --git a/test_regress/t/t_finish_stops_nonfinal2.v b/test_regress/t/t_finish_stops_nonfinal2.v
new file mode 100644
index 000000000..350311476
--- /dev/null
+++ b/test_regress/t/t_finish_stops_nonfinal2.v
@@ -0,0 +1,30 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain
+// SPDX-FileCopyrightText: 2026 Antmicro
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+  int cyc;
+  event e;
+
+  always @(e) begin
+    $display("e=%0d", e.triggered);
+    ->e;
+    cyc = cyc + 1;
+    if (cyc >= 10) begin
+      $display("Fin");
+      $finish;
+    end
+  end
+
+  initial begin
+    #1;
+    ->e;
+    #1;
+  end
+
+  final begin
+    if (cyc != 10) $stop;
+  end
+endmodule