From 30546afdabad094eb504b9e0743846ecd62626ae Mon Sep 17 00:00:00 2001
From: Marlon James <marlon.james@garmin.com>
Date: Sat, 12 Dec 2020 05:11:08 -0800
Subject: [PATCH] Fix VPI range iterator null return (#2691)

* Test that range iterator exhausts after 1 dimension

* Separate range iterator from range object

Range iterators should return NULL after all ranges have been returned
---
 include/verilated_vpi.cpp       | 29 +++++++++++++++++++----------
 test_regress/t/t_vpi_memory.cpp |  3 +++
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/include/verilated_vpi.cpp b/include/verilated_vpi.cpp
index fe730dbfa..607a85610 100644
--- a/include/verilated_vpi.cpp
+++ b/include/verilated_vpi.cpp
@@ -167,7 +167,6 @@ public:
 
 class VerilatedVpioRange final : public VerilatedVpio {
     const VerilatedRange* m_range;
-    vlsint32_t m_iteration = 0;
 
 public:
     explicit VerilatedVpioRange(const VerilatedRange* range)
@@ -179,15 +178,25 @@ public:
     virtual vluint32_t type() const override { return vpiRange; }
     virtual vluint32_t size() const override { return m_range->elements(); }
     virtual const VerilatedRange* rangep() const override { return m_range; }
-    int iteration() const { return m_iteration; }
-    void iterationInc() { ++m_iteration; }
+};
+
+class VerilatedVpioRangeIter final : public VerilatedVpio {
+    // Only supports 1 dimension
+    const VerilatedRange* m_range;
+    bool m_done = false;
+
+public:
+    explicit VerilatedVpioRangeIter(const VerilatedRange* range)
+        : m_range{range} {}
+    virtual ~VerilatedVpioRangeIter() override = default;
+    static VerilatedVpioRangeIter* castp(vpiHandle h) {
+        return dynamic_cast<VerilatedVpioRangeIter*>(reinterpret_cast<VerilatedVpio*>(h));
+    }
+    virtual vluint32_t type() const override { return vpiIterator; }
     virtual vpiHandle dovpi_scan() override {
-        if (!iteration()) {
-            VerilatedVpioRange* nextp = new VerilatedVpioRange(*this);
-            nextp->iterationInc();
-            return ((nextp)->castVpiHandle());
-        }
-        return nullptr;  // End of list - only one deep
+        if (m_done) return nullptr;
+        m_done = true;
+        return ((new VerilatedVpioRange(m_range))->castVpiHandle());
     }
 };
 
@@ -1249,7 +1258,7 @@ vpiHandle vpi_iterate(PLI_INT32 type, vpiHandle object) {
                             VerilatedVpiError::strFromVpiMethod(type), vop->fullname(),
                             vop->varp()->dims());
         }
-        return ((new VerilatedVpioRange(vop->rangep()))->castVpiHandle());
+        return ((new VerilatedVpioRangeIter(vop->rangep()))->castVpiHandle());
     }
     case vpiReg: {
         VerilatedVpioScope* vop = VerilatedVpioScope::castp(object);
diff --git a/test_regress/t/t_vpi_memory.cpp b/test_regress/t/t_vpi_memory.cpp
index 6cfaebdaf..374a166e8 100644
--- a/test_regress/t/t_vpi_memory.cpp
+++ b/test_regress/t/t_vpi_memory.cpp
@@ -174,6 +174,9 @@ int _mon_check_memory() {
     CHECK_RESULT_NZ(side_h);
     vpi_get_value(side_h, &value);
     CHECK_RESULT(value.value.integer, 1);
+    // iterator should exhaust after 1 dimension
+    lcl_h = vpi_scan(iter_h);
+    CHECK_RESULT(lcl_h, 0);
 
     // check writing to vpiConstant
     vpi_put_value(side_h, &value, NULL, vpiNoDelay);