From 5c6315a880b84e87f9fb12d6bab55aaa276a8da7 Mon Sep 17 00:00:00 2001
From: Nick Brereton <nbrereton@striketechnologies.com>
Date: Tue, 14 Jul 2026 18:52:26 -0400
Subject: [PATCH] V3EmitCSyms: drop redundant varTriggersStructExpansion guard,
 add VPI test

---
 src/V3EmitCSyms.cpp          | 23 ----------------------
 test_regress/t/t_vpi_var.cpp | 38 ++++++++++++++++++++++++++++++++++++
 test_regress/t/t_vpi_var.v   |  8 ++++++++
 3 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/src/V3EmitCSyms.cpp b/src/V3EmitCSyms.cpp
index 7a535df43..1631038e5 100644
--- a/src/V3EmitCSyms.cpp
+++ b/src/V3EmitCSyms.cpp
@@ -338,27 +338,6 @@ class EmitCSyms final : EmitCBaseVisitorConst {
         return stmt;
     }
 
-    // True if addUOrStructMemberVars()/addUnpackedArrayUOrStructMemberVars()
-    // would expand this var (residual path only).
-    static bool varTriggersStructExpansion(const AstVar* const varp) {
-        const AstNodeDType* const dtypep = varp->dtypeSkipRefp();
-        if (const AstNodeUOrStructDType* const sdtypep = VN_CAST(dtypep, NodeUOrStructDType)) {
-            return !sdtypep->packed();
-        }
-        if (VN_IS(dtypep, UnpackArrayDType)) {
-            const AstNodeDType* elemp = dtypep;
-            while (const AstUnpackArrayDType* const adtypep
-                   = VN_CAST(elemp->skipRefp(), UnpackArrayDType)) {
-                elemp = adtypep->subDTypep();
-            }
-            if (const AstNodeUOrStructDType* const sdtypep
-                = VN_CAST(elemp->skipRefp(), NodeUOrStructDType)) {
-                return !sdtypep->packed();
-            }
-        }
-        return false;
-    }
-
     // Computed once here so the forceable-eligibility check can't be
     // re-derived (and desynced) by the caller.
     enum class TableEntryKind : uint8_t { kTableRow, kForceableResidual, kPlainResidual };
@@ -379,8 +358,6 @@ class EmitCSyms final : EmitCBaseVisitorConst {
         const std::string vlEnumType = varp->vlEnumType();
         if (needsEmittedEntSize(vlEnumType))
             return TableEntryKind::kPlainResidual;  // struct/union whole
-        if (varTriggersStructExpansion(varp))
-            return TableEntryKind::kPlainResidual;  // member expansion
         // Params are often 'static constexpr' (offsetof is invalid on those);
         // string params also need a runtime .c_str().
         if (varp->isParam()) return TableEntryKind::kPlainResidual;
diff --git a/test_regress/t/t_vpi_var.cpp b/test_regress/t/t_vpi_var.cpp
index 7c0eac4f4..9d3e4c3a9 100644
--- a/test_regress/t/t_vpi_var.cpp
+++ b/test_regress/t/t_vpi_var.cpp
@@ -671,6 +671,44 @@ int _mon_check_unpacked_struct_members() {
         CHECK_RESULT(tmpValue.value.integer, 0xace0);
     }
 
+    // unpacked array of a packed struct (element is a plain vector, not vpiStructVar)
+    {
+        TestVpiHandle vh210 = VPI_HANDLE("packed_struct_array_signal");
+        CHECK_RESULT_NZ(vh210);
+        CHECK_RESULT(vpi_get(vpiType, vh210), vpiRegArray);
+        CHECK_RESULT(vpi_get(vpiSize, vh210), 2);
+
+        TestVpiHandle vh211 = vpi_handle_by_index(vh210, 0);
+        CHECK_RESULT_NZ(vh211);
+        CHECK_RESULT(vpi_get(vpiType, vh211), vpiReg);
+        CHECK_RESULT(vpi_get(vpiSize, vh211), 8);
+
+        s_vpi_value putValue;
+        putValue.format = vpiIntVal;
+        putValue.value.integer = 0x5a;
+        vpi_put_value(vh211, &putValue, NULL, vpiNoDelay);
+        vpi_get_value(vh211, &tmpValue);
+        CHECK_RESULT(tmpValue.value.integer, 0x5a);
+
+        TestVpiHandle vh212 = vpi_handle_by_index(vh210, 1);
+        CHECK_RESULT_NZ(vh212);
+        CHECK_RESULT(vpi_get(vpiType, vh212), vpiReg);
+        putValue.value.integer = 0x33;
+        vpi_put_value(vh212, &putValue, NULL, vpiNoDelay);
+        vpi_get_value(vh212, &tmpValue);
+        CHECK_RESULT(tmpValue.value.integer, 0x33);
+
+        vpi_get_value(vh211, &tmpValue);
+        CHECK_RESULT(tmpValue.value.integer, 0x5a);
+
+        TestVpiHandle vh213 = vpi_handle_by_name(
+            const_cast<PLI_BYTE8*>(TestSimulator::rooted("packed_struct_array_signal[1]")),
+            nullptr);
+        CHECK_RESULT_NZ(vh213);
+        vpi_get_value(vh213, &tmpValue);
+        CHECK_RESULT(tmpValue.value.integer, 0x33);
+    }
+
     // array of unpacked structs with unpacked-array members
     {
         TestVpiHandle vh170 = VPI_HANDLE("parent_struct_array");
diff --git a/test_regress/t/t_vpi_var.v b/test_regress/t/t_vpi_var.v
index ea66b0712..5efca1a67 100644
--- a/test_regress/t/t_vpi_var.v
+++ b/test_regress/t/t_vpi_var.v
@@ -89,6 +89,14 @@ extern "C" int mon_check();
   input wire unpacked_struct_t wire_struct_array_port [1:0] /*verilator public_flat_rw*/;
   unpacked_struct_t struct_array_signal [1:0] /*verilator public_flat_rw*/;
 
+  // Unpacked array of a packed (not unpacked) struct element
+  typedef struct packed {
+    logic [6:0] packed_member_a;
+    logic packed_member_b;
+  } packed_leaf_struct_t;
+
+  packed_leaf_struct_t packed_struct_array_signal [1:0] /*verilator public_flat_rw*/;
+
   typedef struct {
     logic [6:0] unsigned_member;
     logic signed [6:0] signed_member;