From aa0ef554b3e18d5d08b1201bb397cadf75ac34a1 Mon Sep 17 00:00:00 2001
From: Ryszard Rozak <rrozak@antmicro.com>
Date: Fri, 21 Jul 2023 09:29:11 +0200
Subject: [PATCH] Fix order of evaluation of function calls in statements
 (#4375)

---
 src/V3Task.cpp                      |  8 +-----
 test_regress/t/t_func_call_order.pl | 21 +++++++++++++++
 test_regress/t/t_func_call_order.v  | 42 +++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 7 deletions(-)
 create mode 100755 test_regress/t/t_func_call_order.pl
 create mode 100644 test_regress/t/t_func_call_order.v

diff --git a/src/V3Task.cpp b/src/V3Task.cpp
index 163b5d37e..a37cc1c6e 100644
--- a/src/V3Task.cpp
+++ b/src/V3Task.cpp
@@ -350,7 +350,6 @@ private:
     // TYPES
     enum InsertMode : uint8_t {
         IM_BEFORE,  // Pointing at statement ref is in, insert before this
-        IM_AFTER,  // Pointing at last inserted stmt, insert after
         IM_WHILE_PRECOND  // Pointing to for loop, add to body end
     };
     using DpiCFuncs = std::map<const string, std::tuple<AstNodeFTask*, std::string, AstCFunc*>>;
@@ -1346,16 +1345,13 @@ private:
     AstNode* insertBeforeStmt(AstNode* nodep, AstNode* newp) {
         // Return node that must be visited, if any
         if (debug() >= 9) nodep->dumpTree("-  newstmt: ");
-        UASSERT_OBJ(m_insStmtp, nodep, "Function not underneath a statement");
+        UASSERT_OBJ(m_insStmtp, nodep, "Function call not underneath a statement");
         AstNode* visitp = nullptr;
         if (m_insMode == IM_BEFORE) {
             // Add the whole thing before insertAt
             UINFO(5, "     IM_Before  " << m_insStmtp << endl);
             if (debug() >= 9) newp->dumpTree("-  newfunc: ");
             m_insStmtp->addHereThisAsNext(newp);
-        } else if (m_insMode == IM_AFTER) {
-            UINFO(5, "     IM_After   " << m_insStmtp << endl);
-            m_insStmtp->addNextHere(newp);
         } else if (m_insMode == IM_WHILE_PRECOND) {
             UINFO(5, "     IM_While_Precond " << m_insStmtp << endl);
             AstWhile* const whilep = VN_AS(m_insStmtp, While);
@@ -1365,8 +1361,6 @@ private:
         } else {
             nodep->v3fatalSrc("Unknown InsertMode");
         }
-        m_insMode = IM_AFTER;
-        m_insStmtp = newp;
         return visitp;
     }
 
diff --git a/test_regress/t/t_func_call_order.pl b/test_regress/t/t_func_call_order.pl
new file mode 100755
index 000000000..aabcde63e
--- /dev/null
+++ b/test_regress/t/t_func_call_order.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 2020 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(
+    );
+
+execute(
+    check_finished => 1,
+    );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_func_call_order.v b/test_regress/t/t_func_call_order.v
new file mode 100644
index 000000000..7bba5a785
--- /dev/null
+++ b/test_regress/t/t_func_call_order.v
@@ -0,0 +1,42 @@
+// 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
+
+`define checkd(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got=%0d exp=%0d\n", `__FILE__,`__LINE__, (gotv), (expv)); $stop; end while(0);
+
+module t(/*AUTOARG*/);
+   int a;
+   function int assign5;
+      a = 5;
+      return 5;
+   endfunction
+   function int assign3;
+      a = 3;
+      return 3;
+   endfunction
+   function int incr;
+      a++;
+      return a;
+   endfunction
+   function int assign5_return_arg(int x);
+      a = 5;
+      return x;
+   endfunction
+   int i;
+
+   initial begin
+      a = 1;
+      i = assign5() + assign3() + incr();
+      `checkd(a, 4); `checkd(i, 12);
+
+      a = 1;
+      i = assign5_return_arg(assign3()+incr());
+      `checkd(a, 5); `checkd(i, 7);
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+endmodule