From 19f72795424664f936c2a2becd3f10a89f143b47 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Fri, 15 Sep 2023 22:05:55 -0400
Subject: [PATCH] Fix false INFINITELOOP on forever..mailbox.get() (#4323).

---
 Changes                              |  1 +
 src/V3Const.cpp                      | 11 ++++++++-
 test_regress/t/t_lint_infinite.pl    | 23 ++++++++++++++++++
 test_regress/t/t_lint_infinite.v     | 36 ++++++++++++++++++++++++++++
 test_regress/t/t_lint_infinite_bad.v |  1 +
 test_regress/t/t_uvm_todo.pl         |  1 -
 6 files changed, 71 insertions(+), 2 deletions(-)
 create mode 100755 test_regress/t/t_lint_infinite.pl
 create mode 100644 test_regress/t/t_lint_infinite.v

diff --git a/Changes b/Changes
index dbdee17e6..2c8535966 100644
--- a/Changes
+++ b/Changes
@@ -19,6 +19,7 @@ Verilator 5.015 devel
 * Support no-parentheses calls to static methods (#4432). [Krzysztof Boroński]
 * Support 'let'.
 * Fix Windows filename format, etc (#3873) (#4421). [Anthony Donlon].
+* Fix false INFINITELOOP on forever..mailbox.get() (#4323). [Srinivasan Venkataramanan]
 * Fix data type of condition operation on class objects (#4345) (#4352). [Ryszard Rozak, Antmicro Ltd]
 * Fix ++/-- under statements (#4399). [Aleksander Kiryk, Antmicro Ltd]
 * Fix detection of mixed blocking and nonblocking assignment in nested assignments (#4404). [Ryszard Rozak, Antmicro Ltd]
diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index b76c8244b..696fceb5e 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -3204,8 +3204,17 @@ private:
         iterateChildren(nodep);
     }
 
-    void visit(AstFuncRef* nodep) override {
+    void visit(AstNodeCCall* nodep) override {
         iterateChildren(nodep);
+        m_hasJumpDelay = true;  // As don't analyze inside tasks for timing controls
+    }
+    void visit(AstNodeFTaskRef* nodep) override {
+        // Note excludes AstFuncRef as other visitor below
+        iterateChildren(nodep);
+        m_hasJumpDelay = true;  // As don't analyze inside tasks for timing controls
+    }
+    void visit(AstFuncRef* nodep) override {
+        visit(static_cast<AstNodeFTaskRef*>(nodep));
         if (m_params) {  // Only parameters force us to do constant function call propagation
             replaceWithSimulation(nodep);
         }
diff --git a/test_regress/t/t_lint_infinite.pl b/test_regress/t/t_lint_infinite.pl
new file mode 100755
index 000000000..3364f1ed7
--- /dev/null
+++ b/test_regress/t/t_lint_infinite.pl
@@ -0,0 +1,23 @@
+#!/usr/bin/env perl
+if (!$::Driver) { use FindBin; exec("$FindBin::Bin/bootstrap.pl", @ARGV, $0); die; }
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 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
+
+scenarios(simulator => 1);
+
+compile(
+    verilator_flags2 => ["--exe --main --timing"],
+    make_main => 0,
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_lint_infinite.v b/test_regress/t/t_lint_infinite.v
new file mode 100644
index 000000000..305cd1e2d
--- /dev/null
+++ b/test_regress/t/t_lint_infinite.v
@@ -0,0 +1,36 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2023 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+
+   mailbox #(int) mbox;
+
+   task main();
+      // See issue #4323; not an INFINITELOOP due to delay inside get()
+      forever begin
+         int i;
+         mbox.get(i);
+         $display("[%0t] Got %0d", $time, i);
+      end
+   endtask
+
+   initial begin
+      mbox = new (1);
+
+      #10;
+      fork
+         main();
+      join_none
+
+      #10;
+      mbox.put(10);
+      mbox.put(11);
+
+      #10;
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule
diff --git a/test_regress/t/t_lint_infinite_bad.v b/test_regress/t/t_lint_infinite_bad.v
index 4bf795db2..c3cc1cc1b 100644
--- a/test_regress/t/t_lint_infinite_bad.v
+++ b/test_regress/t/t_lint_infinite_bad.v
@@ -10,5 +10,6 @@ module t ();
       forever begin end
       // verilator lint_off UNSIGNED
       for (reg [31:0] i=0; i>=0; i=i+1) begin end
+      $display;  // So loop not eaten
    end
 endmodule
diff --git a/test_regress/t/t_uvm_todo.pl b/test_regress/t/t_uvm_todo.pl
index d45b6064f..b71e06d09 100755
--- a/test_regress/t/t_uvm_todo.pl
+++ b/test_regress/t/t_uvm_todo.pl
@@ -15,7 +15,6 @@ compile(
                  "-Wno-PKGNODECL -Wno-IMPLICITSTATIC -Wno-CONSTRAINTIGN -Wno-MISINDENT",
                  "-Wno-CASEINCOMPLETE -Wno-CASTCONST -Wno-SYMRSVDWORD -Wno-WIDTHEXPAND -Wno-WIDTHTRUNC",
                  "-Wno-REALCVT", # TODO note mostly related to $realtime - could suppress or fix upstream
-                 "-Wno-INFINITELOOP" , # TODO issue #4323, false warning
                  "-Wno-RANDC", # TODO issue #4349, add support
                  "-Wno-ZERODLY", # TODO issue #4494, add support
                  ],