From 3bf001835431ef83c1e4d33f259723cccb039db6 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sat, 12 Sep 2026 14:36:45 -0400
Subject: [PATCH] Optimize away __Vconfigure if empty function

---
 src/V3EmitCHeaders.cpp               |  4 +++-
 src/V3EmitCImp.cpp                   |  6 +++---
 src/V3EmitCSyms.cpp                  | 20 +++++++++++---------
 test_regress/t/t_protect_ids_key.out |  1 -
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/src/V3EmitCHeaders.cpp b/src/V3EmitCHeaders.cpp
index a071e4a0b..08e8d6a0c 100644
--- a/src/V3EmitCHeaders.cpp
+++ b/src/V3EmitCHeaders.cpp
@@ -209,7 +209,9 @@ class EmitCHeader final : public EmitCConstInit {
 
         if (!VN_IS(modp, Class)) {
             decorateFirst(first, section);
-            puts("void " + protect("__Vconfigure") + "(bool first);\n");
+            if (v3Global.opt.coverage()) {
+                puts("void " + protect("__Vconfigure") + "(bool first);\n");
+            }
         } else {
             decorateFirst(first, section);
             const std::string name = V3OutFormatter::quoteNameControls(
diff --git a/src/V3EmitCImp.cpp b/src/V3EmitCImp.cpp
index 0f968d486..e56677f7d 100644
--- a/src/V3EmitCImp.cpp
+++ b/src/V3EmitCImp.cpp
@@ -163,12 +163,12 @@ class EmitCImp final : public EmitCFunc {
                              "(" + modName + "* vlSelf, bool first);");
         }
 
-        puts("\nvoid " + modName + "::" + protect("__Vconfigure") + "(bool first) {\n");
-        puts("(void)first;  // Prevent unused variable warning\n");
         if (v3Global.opt.coverage()) {
+            puts("\nvoid " + modName + "::" + protect("__Vconfigure") + "(bool first) {\n");
+            puts("(void)first;  // Prevent unused variable warning\n");
             puts(modName + "__" + protect("_configure_coverage") + "(this, first);\n");
+            puts("}\n");
         }
-        puts("}\n");
     }
     void emitCoverageImp() {
         // Rather than putting out VL_COVER_INSERT calls directly, we do it via this
diff --git a/src/V3EmitCSyms.cpp b/src/V3EmitCSyms.cpp
index bf20e0f71..6490a911c 100644
--- a/src/V3EmitCSyms.cpp
+++ b/src/V3EmitCSyms.cpp
@@ -1277,15 +1277,17 @@ std::vector<std::string> EmitCSyms::getSymCtorStmts() {
         add(stmt);
     }
 
-    add("// Setup each module's pointer back to symbol table (for public functions)");
-    for (const ScopeModPair& i : m_scopes) {
-        const AstScope* const scopep = i.first;
-        AstNodeModule* const modp = i.second;
-        // first is used by AstCoverDecl's call to __vlCoverInsert
-        const bool first = !modp->user1();
-        modp->user1(true);
-        add(VIdProtect::protectIf(scopep->nameDotless(), scopep->protect()) + "."
-            + protect("__Vconfigure") + "(" + (first ? "true" : "false") + ");");
+    if (v3Global.opt.coverage()) {
+        add("// Setup each module's pointer back to symbol table (for public functions)");
+        for (const ScopeModPair& i : m_scopes) {
+            const AstScope* const scopep = i.first;
+            AstNodeModule* const modp = i.second;
+            // first is used by AstCoverDecl's call to __vlCoverInsert
+            const bool first = !modp->user1();
+            modp->user1(true);
+            add(VIdProtect::protectIf(scopep->nameDotless(), scopep->protect()) + "."
+                + protect("__Vconfigure") + "(" + (first ? "true" : "false") + ");");
+        }
     }
 
     // Every scope has the same construction shape, so all fold into one table with no
diff --git a/test_regress/t/t_protect_ids_key.out b/test_regress/t/t_protect_ids_key.out
index ef4f013ca..6417d1d28 100644
--- a/test_regress/t/t_protect_ids_key.out
+++ b/test_regress/t/t_protect_ids_key.out
@@ -12,7 +12,6 @@
   <map from="PStVCQ" to="__PVT__secret_r"/>
   <map from="PSfqS0" to="__PVT__t__DOT__secret_inst"/>
   <map from="PSScAO" to="__VactTriggered"/>
-  <map from="PSx9Nt" to="__Vconfigure"/>
   <map from="PSrjMj" to="__Vdly__secret_cyc"/>
   <map from="PS4o5S" to="__Vdpiexp_dpix_a_func_TOP__t__DOT__secret_inst"/>
   <map from="PStVA8" to="__Vdpiexp_dpix_a_task_TOP__t__DOT__secret_inst"/>