Fix reordering of function body inlined on RHS of <= NBA (#6780)

src/V3Split.cpp

@@ -340,11 +340,17 @@ protected:
 
     // We don't do AstLoop, due to the standard question of what is before vs. after
 
+    void visit(AstExprStmt* nodep) override {
+        VL_RESTORER(m_inDly);
+        m_inDly = false;
+        iterateChildren(nodep);
+    }
     void visit(AstAssignDly* nodep) override {
+        UINFO(4, "    ASSIGNDLY " << nodep);
+        iterate(nodep->rhsp());
         VL_RESTORER(m_inDly);
         m_inDly = true;
-        UINFO(4, "    ASSIGNDLY " << nodep);
-        iterateChildren(nodep);
+        iterate(nodep->lhsp());
     }
     void visit(AstVarRef* nodep) override {
         if (!m_stmtStackps.empty()) {

test_regress/t/t_alw_reorder_inlined_func.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt_all')
+
+test.compile(verilator_flags2=["--binary"])
+
+test.execute()
+
+test.passes()

test_regress/t/t_alw_reorder_inlined_func.v

@@ -0,0 +1,58 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+`define stop $stop
+`define check(got ,exp) do if ((got) !== (exp)) begin $write("%%Error: %s:%0d: $time=%0t got='h%x exp='h%x\n", `__FILE__,`__LINE__, $time, (got), (exp)); `stop; end while(0)
+
+module t;
+
+  logic clk = 0;
+  always #5 clk = ~clk;
+
+  int cyc = 0;
+  always @(posedge clk) cyc <= cyc + 1;
+
+  // Constant 1 set in initial block, but not known at compile time
+  logic enable = 1'b0;
+
+  int array [32];
+
+  function automatic int get(logic en, logic [4:0] idx);
+    if (en) begin // Always taken, but need the 'if' to show bug
+      int tmp;
+      idx = ~idx;
+      tmp = array[~idx];
+      return tmp;
+    end else begin
+      return 0;
+    end
+  endfunction
+
+  int q;
+  always @(posedge clk) begin
+    // Function inlined on RHS or NBA used to have its body reordered as if
+    // assignments in the body were NBAs themselves.
+    q <= cyc == 0 ? 0 : get(enable, 5'(cyc));
+  end
+
+  initial begin
+    enable = 1'b1;
+    for (int n = 0; n < 32; ++n) begin
+      array[n] = 100 + n;
+    end
+
+    repeat (100) begin
+      @(posedge clk);
+      #1;
+      $display("$08t %3d %3d", $time, cyc - 1, q);
+      `check(q, cyc == 1 ? 0 : 100 + (cyc - 1) % 32);
+    end
+
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+
+endmodule