Support named event locals (#5422)

Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>

src/V3Fork.cpp

@@ -173,6 +173,12 @@ public:
                                     new AstVarRef{varp->fileline(), varp, VAccess::READ}};
                 initsp = AstNode::addNext(initsp, initAsgnp);
             }
+
+            if (AstBasicDType* const dtypep = VN_CAST(varp->dtypep()->skipRefp(), BasicDType)) {
+                v3Global.setAssignsEvents();
+                if (dtypep->isEvent()) continue;
+            }
+
             if (varp->direction().isWritable()) {
                 AstMemberSel* const memberselp = new AstMemberSel{
                     varp->fileline(),
@@ -416,7 +422,12 @@ class DynScopeVisitor final : public VNVisitor {
         ForkDynScopeFrame* const framep = frameOf(nodep->varp());
         if (!framep) return;
         if (needsDynScope(nodep)) {
-            if (m_afterTimingControl && nodep->varp()->isWritable()
+            bool isEvent = false;
+            if (AstBasicDType* const dtypep = VN_CAST(nodep->dtypep()->skipRefp(), BasicDType)) {
+                v3Global.setAssignsEvents();
+                isEvent = dtypep->isEvent();
+            }
+            if (!isEvent && m_afterTimingControl && nodep->varp()->isWritable()
                 && nodep->access().isWriteOrRW()) {
                 // The output variable may not exist after a delay, so we can't just write to it
                 nodep->v3warn(

src/V3Timing.cpp

@@ -925,12 +925,6 @@ class TimingControlVisitor final : public VNVisitor {
         // Do not allow waiting on local named events, as they get enqueued for clearing, but can
         // go out of scope before that happens
         if (!nodep->sensesp()) nodep->v3warn(E_UNSUPPORTED, "Unsupported: no sense equation (@*)");
-        if (nodep->sensesp()->exists([](const AstNodeVarRef* refp) {
-                AstBasicDType* const dtypep = refp->dtypep()->skipRefp()->basicp();
-                return dtypep && dtypep->isEvent() && refp->varp()->isFuncLocal();
-            })) {
-            nodep->v3warn(E_UNSUPPORTED, "Unsupported: waiting on local event variables");
-        }
         FileLine* const flp = nodep->fileline();
         // Relink child statements after the event control
         if (nodep->stmtsp()) nodep->addNextHere(nodep->stmtsp()->unlinkFrBackWithNext());

test_regress/t/t_timing_localevent.pl

@@ -2,7 +2,7 @@
 if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
 # DESCRIPTION: Verilator: Verilog Test driver/expect definition
 #
-# Copyright 2022 by Antmicro Ltd. This program is free software; you
+# Copyright 2024 by Wilson Snyder. This program is free software; you
 # can redistribute it and/or modify it under the terms of either the GNU
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
@@ -10,10 +10,12 @@ if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); di
 
 scenarios(linter => 1);
 
-lint(
-    verilator_flags2 => ["--timing"],
-    fails => 1,
-    expect_filename => $Self->{golden_filename},
+compile(
+    verilator_flags2 => ["--exe --main --timing"],
+    );
+
+execute(
+    check_finished => 1,
     );
 
 ok(1);

test_regress/t/t_timing_localevent.v

@@ -0,0 +1,39 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2024 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+    class Foo;
+        task sleep;
+            event e;
+            fork
+                @e;
+                #1 ->e;
+            join
+        endtask
+        task trigger_later1(event e);
+            fork #2 ->e; join_none
+        endtask
+        task trigger_later2(ref event e);
+            fork #3 ->e; join_none
+        endtask
+        task test;
+            for (int i = 0; i < 10; i++) begin
+                event e1, e2;
+                trigger_later1(e1);
+                trigger_later2(e2);
+                sleep;
+                @e1; @e2;
+            end
+        endtask
+    endclass
+
+    initial begin
+        Foo foo = new;
+        foo.test;
+        $write("*-* All Finished *-*\n");
+        $finish;
+    end
+endmodule

test_regress/t/t_timing_localevent_unsup.out

@@ -1,6 +0,0 @@
-%Error-UNSUPPORTED: t/t_timing_localevent_unsup.v:12:17: Unsupported: waiting on local event variables
-                                                       : ... note: In instance 't::Sleeper'
-   12 |                 @e;
-      |                 ^
-                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
-%Error: Exiting due to

test_regress/t/t_timing_localevent_unsup.v

@@ -1,24 +0,0 @@
-// DESCRIPTION: Verilator: Verilog Test module
-//
-// This file ONLY is placed under the Creative Commons Public Domain, for
-// any use, without warranty, 2022 by Antmicro Ltd.
-// SPDX-License-Identifier: CC0-1.0
-
-module t;
-    class Sleeper;
-        task sleep;
-            event e;
-            fork
-                @e;
-                #1 ->e;
-            join;
-        endtask
-    endclass
-
-    initial begin
-        Sleeper sleeper = new;
-        sleeper.sleep;
-        $write("*-* All Finished *-*\n");
-        $finish;
-    end
-endmodule

test_regress/t/t_uvm_pkg_todo.vh

@@ -20256,9 +20256,7 @@ virtual class uvm_sequence_base extends uvm_sequence_item;
     if (is_rel_default != wait_rel_default)
       uvm_report_fatal("RELMSM",
         "is_relevant() was implemented without defining wait_for_relevant()", UVM_NONE);
-//TODO issue #4495 - unsupported local event - may want to model the larger context where is used - might be case where edit upstream?
-//TODO  %Error-UNSUPPORTED: t/t_uvm_pkg_todo.vh:20247:5: Unsupported: waiting on local event variables
-//TODO    @e;
+    @e;
   endtask
   task lock(uvm_sequencer_base sequencer = null);
     if (sequencer == null)