Fix dead removing packages with only DPI.

src/V3Dead.cpp

@@ -329,8 +329,12 @@ class DeadVisitor final : public VNVisitor {
     void visit(AstNodeFTask* nodep) override {
         iterateChildren(nodep);
         checkAll(nodep);
-        if (!nodep->taskPublic() && !nodep->dpiExport() && !nodep->dpiImport())
+        if (nodep->taskPublic() || nodep->dpiExport() || nodep->dpiImport()) {
+            if (m_modp && !m_modp->dead() && !m_modp->verilatorLib())
+                m_modp->user1Inc();  // Keep container
+        } else {
             m_tasksp.push(nodep);
+        }
         if (nodep->classOrPackagep()) {
             if (m_elimCells) {
                 nodep->classOrPackagep(nullptr);

src/V3GraphAlg.cpp

@@ -40,7 +40,7 @@ VL_DEFINE_DEBUG_FUNCTIONS;
 // Changes user() and weight()
 
 class GraphRemoveRedundant final : GraphAlg<> {
-    const bool m_sumWeights;  ///< Sum, rather then maximize weights
+    const bool m_sumWeights;  // Sum, rather then maximize weights
 private:
     void main() {
         for (V3GraphVertex& vertex : m_graphp->vertices()) vertexIterate(&vertex);

test_regress/t/t_opt_dead.cpp

@@ -0,0 +1,10 @@
+// -*- mode: C++; c-file-style: "cc-mode" -*-
+//*************************************************************************
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
+// SPDX-License-Identifier: CC0-1.0
+//*************************************************************************
+
+#include "Vt_opt_dead__Dpi.h"
+
+void dpii_Keep() {}

test_regress/t/t_opt_dead.py

@@ -11,13 +11,16 @@ import vltest_bootstrap
 
 test.scenarios('simulator')
 
-test.compile()
+test.compile(verilator_flags2=[test.pli_filename])
 
 test.execute()
 
 # bug2227, Verilator unsupported, class dead
 # This is what we really want:
-#   test.file_grep_not(test.obj_dir + "/V"+test.name+"__Syms.h", r'dead')
-test.file_grep(test.obj_dir + "/V" + test.name + "__Syms.h", r'dead')
+#   test.file_grep_not(test.obj_dir + "/V"+test.name+"__Syms.h", r'Dead')
+#   test.file_grep_not(test.obj_dir + "/V" + test.name + "_classes.mk", r'Dead');
+test.file_grep(test.obj_dir + "/V" + test.name + "__Dpi.h", r'dpii_Keep')
+test.file_grep(test.obj_dir + "/V" + test.name + "__Dpi.h", r'dpix_Keep')
+test.file_grep(test.obj_dir + "/V" + test.name + "_Pkg_public_kpt.h", r'public_int_Keep')
 
 test.passes()

test_regress/t/t_opt_dead.v

@@ -4,26 +4,95 @@
 // SPDX-FileCopyrightText: 2020 Wilson Snyder
 // SPDX-License-Identifier: CC0-1.0
 
-class EmptyClass_Dead;
+// Tests look for magic string "Dead" not to exist; V3Dead should remove these
+
+class BaseClass_Dead;
 endclass
 
+class EmptyClass_Dead extends BaseClass_Dead;
+endclass
+
+package Pack_Dead;
+  typedef bit typedef_Dead;
+endpackage
+
 module Mod_Dead;
+  typedef class ModClass_Co_Dead;
   class ModClass_Dead;
-    int memberb_dead;
+    int m_b_Dead;
+    ModClass_Co_Dead m_co_dead;
+    task method_Dead;
+    endtask
+    static task method_static_Dead;
+    endtask
+  endclass
+  class ModClass_Co_Dead;
+    ModClass_Dead m_dead;  // Check that ModClass_Dead<->ModClass_Co_Dead link gets Deadified
   endclass
 endmodule
 
-//TODO dead check with class extends
+module Mod_Empty_Dead;
+endmodule
 
-module t;
+module Mod_Parent_Empty_Dead;
+  Mod_Empty_Dead sub ();
+endmodule
+
+interface If_Dead;
+  function void if_func_Dead;
+  endfunction
+  modport modport_Dead(import if_func_Dead);
+endinterface
+
+package Pkg_public_kpt;
+  parameter int public_int_Keep  /*verilator public_flat_rd*/ = 5;
+endpackage
+
+package Pkg_Keep;
+  import "DPI-C" function void dpii_Keep();
+
+  export "DPI-C" function dpix_Keep;
+  function void dpix_Keep;
+  endfunction
+endpackage
+
+module t (  /*AUTOARG*/);
+
+  typedef struct {int struct_member_Dead;} struct_Dead_t;
+  struct_Dead_t var_struct_Dead;
+
+  typedef int typedef_Dead1_t;
+  typedef typedef_Dead1_t typedef_Dead2_t;
+
+  function void func_Dead;
+  endfunction
 
   generate
     if (0) begin
-      Mod_Dead cell_dead ();
+      Mod_Dead cell_nogen_Dead ();
+      If_Dead if_nogen_Dead ();
     end
   endgenerate
 
+  Mod_Empty_Dead cell_empty_Dead ();
+  Mod_Parent_Empty_Dead cell_parent_empty_Dead ();
+
+  typedef_Dead1_t assigned_to_Dead1;
+  typedef_Dead2_t assigned_to_Dead2;
+  typedef_Dead2_t assigned_to_Dead3;
+  typedef_Dead2_t assigned_to_Dead4;
+  typedef_Dead2_t assigned_to_Dead5;
+  typedef_Dead2_t assigned_to_Dead6;
+
+  always_comb assigned_to_Dead6 = assigned_to_Dead5;
+  always_comb assigned_to_Dead5 = assigned_to_Dead4;
+  always_comb assigned_to_Dead4 = assigned_to_Dead3;
+  always_comb assigned_to_Dead3 = assigned_to_Dead2;
+  always_comb assigned_to_Dead2 = assigned_to_Dead1;
+
   initial begin
+    assigned_to_Dead1 = 1;
+    assigned_to_Dead1 = 2;
     $write("*-* All Finished *-*\n");
     $finish;
   end