diff --git a/CMakeLists.txt b/CMakeLists.txt
index efffad5..acfdb88 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -113,8 +113,8 @@ set(QIREE_RUNTIME_OUTPUT_DIRECTORY
 enable_language(C) # Needed for LLVM
 find_package(LLVM REQUIRED)
 if((LLVM_VERSION VERSION_LESS 14)
-  OR (LLVM_VERSION VERSION_GREATER_EQUAL 20))
-  message(WARNING "QIR-EE is only tested with LLVM 14-19: found version ${LLVM_VERSION}")
+  OR (LLVM_VERSION VERSION_GREATER_EQUAL 21))
+  message(WARNING "QIR-EE is only tested with LLVM 14-20: found version ${LLVM_VERSION}")
 endif()
 
 if(QIREE_USE_QSIM)
diff --git a/app/qir-qsim.cc b/app/qir-qsim.cc
index 57368d0..f9f5dd5 100644
--- a/app/qir-qsim.cc
+++ b/app/qir-qsim.cc
@@ -3,7 +3,7 @@
 // See the top-level COPYRIGHT file for details.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //---------------------------------------------------------------------------//
-//! \file qir-xacc/qir-xacc.cc
+//! \file qir-qsim/qir-qsim.cc
 //---------------------------------------------------------------------------//
 #include <cstdlib>
 #include <iostream>
@@ -13,8 +13,8 @@
 #include "qiree/Executor.hh"
 #include "qiree/Module.hh"
 #include "qiree/ResultDistribution.hh"
-#include "qirqsim/QsimDefaultRuntime.hh"
 #include "qirqsim/QsimQuantum.hh"
+#include "qirqsim/QsimRuntime.hh"
 
 using namespace std::string_view_literals;
 
@@ -30,7 +30,7 @@ void run(std::string const& filename, int num_shots)
 
     // Set up qsim
     QsimQuantum sim(std::cout, 0);
-    QsimDefaultRuntime rt(std::cout, sim);
+    QsimRuntime rt(std::cout, sim);
     ResultDistribution distribution;
 
     // Run several time = shots (default 1)
diff --git a/src/qiree/CMakeLists.txt b/src/qiree/CMakeLists.txt
index 88ad986..5dbe211 100644
--- a/src/qiree/CMakeLists.txt
+++ b/src/qiree/CMakeLists.txt
@@ -19,6 +19,7 @@ qiree_add_library(qiree
   Module.cc
   Executor.cc
   ResultDistribution.cc
+  SingleResultRuntime.cc
   QuantumNotImpl.cc
 )
 target_compile_features(qiree PUBLIC cxx_std_17)
diff --git a/src/qiree/QuantumInterface.hh b/src/qiree/QuantumInterface.hh
index ae2e69b..0de15cf 100644
--- a/src/qiree/QuantumInterface.hh
+++ b/src/qiree/QuantumInterface.hh
@@ -61,7 +61,7 @@ class QuantumInterface
     virtual Result measure(Array, Array) = 0;  //!< body
     virtual Result mresetz(Qubit) = 0;  //!< body
     virtual void mz(Qubit, Result) = 0;  //!< body
-    virtual QState read_result(Result) = 0;  //!< body
+    virtual QState read_result(Result) const = 0;  //!< body
 
     //@}
     //@{
diff --git a/src/qiree/QuantumNotImpl.cc b/src/qiree/QuantumNotImpl.cc
index 7b28840..94fccd2 100644
--- a/src/qiree/QuantumNotImpl.cc
+++ b/src/qiree/QuantumNotImpl.cc
@@ -28,7 +28,7 @@ void QuantumNotImpl::mz(Qubit, Result)
 {
     QIREE_NOT_IMPLEMENTED("quantum instruction 'mz.body'");
 }
-QState QuantumNotImpl::read_result(Result)
+QState QuantumNotImpl::read_result(Result) const
 {
     QIREE_NOT_IMPLEMENTED("quantum instruction 'read_result.body'");
 }
diff --git a/src/qiree/QuantumNotImpl.hh b/src/qiree/QuantumNotImpl.hh
index b6a93cd..2e1633c 100644
--- a/src/qiree/QuantumNotImpl.hh
+++ b/src/qiree/QuantumNotImpl.hh
@@ -25,7 +25,7 @@ class QuantumNotImpl : virtual public QuantumInterface
     Result measure(Array, Array) override;
     Result mresetz(Qubit) override;
     void mz(Qubit, Result) override;
-    QState read_result(Result) override;
+    QState read_result(Result) const override;
 
     //@}
     //@{
diff --git a/src/qiree/RecordedResult.hh b/src/qiree/RecordedResult.hh
index 78320ad..5822cb7 100644
--- a/src/qiree/RecordedResult.hh
+++ b/src/qiree/RecordedResult.hh
@@ -37,7 +37,7 @@ class RecordedResult
     RecordedResult() = default;
 
     // Construct with size and optional label
-    RecordedResult(std::size_t count, OptionalCString label);
+    inline RecordedResult(std::size_t count, OptionalCString label);
 
     explicit RecordedResult(std::size_t count) : RecordedResult{count, nullptr}
     {
diff --git a/src/qiree/SingleResultRuntime.cc b/src/qiree/SingleResultRuntime.cc
new file mode 100644
index 0000000..0912b8f
--- /dev/null
+++ b/src/qiree/SingleResultRuntime.cc
@@ -0,0 +1,37 @@
+//----------------------------------*-C++-*----------------------------------//
+// Copyright 2025 UT-Battelle, LLC, and other QIR-EE developers.
+// See the top-level COPYRIGHT file for details.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//---------------------------------------------------------------------------//
+//! \file qiree/SingleResultRuntime.cc
+//---------------------------------------------------------------------------//
+#include "SingleResultRuntime.hh"
+
+#include "QuantumInterface.hh"
+
+namespace qiree
+{
+//---------------------------------------------------------------------------//
+//! Mark the following N results as being part of an array named tag
+void SingleResultRuntime::array_record_output(size_type size,
+                                              OptionalCString tag)
+{
+    result_ = RecordedResult(size, tag);
+}
+
+//! Mark the following N results as being part of a tuple named tag
+void SingleResultRuntime::tuple_record_output(size_type size,
+                                              OptionalCString tag)
+{
+    result_ = RecordedResult(size, tag);
+}
+
+//! Save one result
+void SingleResultRuntime::result_record_output(Result result,
+                                               OptionalCString tag)
+{
+    result_.push_back(sim_->read_result(result), tag);
+}
+
+//---------------------------------------------------------------------------//
+}  // namespace qiree
diff --git a/src/qiree/SingleResultRuntime.hh b/src/qiree/SingleResultRuntime.hh
new file mode 100644
index 0000000..c0cc039
--- /dev/null
+++ b/src/qiree/SingleResultRuntime.hh
@@ -0,0 +1,46 @@
+//----------------------------------*-C++-*----------------------------------//
+// Copyright 2025 UT-Battelle, LLC, and other QIR-EE developers.
+// See the top-level COPYRIGHT file for details.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//---------------------------------------------------------------------------//
+//! \file qiree/SingleResultRuntime.hh
+//---------------------------------------------------------------------------//
+#pragma once
+
+#include "RecordedResult.hh"
+#include "RuntimeInterface.hh"
+#include "qiree/Assert.hh"
+
+namespace qiree
+{
+class QuantumInterface;
+//---------------------------------------------------------------------------//
+/*!
+ * Interface class for recording a single shot per execution.
+ */
+class SingleResultRuntime : public RuntimeInterface
+{
+  public:
+    // Mark the following N results as being part of an array named tag
+    void array_record_output(size_type size, OptionalCString tag) final;
+
+    // Mark the following N results as being part of a tuple named tag
+    void tuple_record_output(size_type size, OptionalCString tag) final;
+
+    // Save one result
+    void result_record_output(Result result, OptionalCString tag) final;
+
+    //! Access the saved results
+    RecordedResult const& result() const { return result_; }
+
+  protected:
+    // This class should only be constructed from a daughter
+    explicit SingleResultRuntime(QuantumInterface const& sim) : sim_{&sim} {}
+
+  private:
+    QuantumInterface const* sim_;
+    RecordedResult result_;
+};
+
+//---------------------------------------------------------------------------//
+}  // namespace qiree
diff --git a/src/qirqsim/CMakeLists.txt b/src/qirqsim/CMakeLists.txt
index 0d81dec..1b28bda 100644
--- a/src/qirqsim/CMakeLists.txt
+++ b/src/qirqsim/CMakeLists.txt
@@ -7,7 +7,7 @@
 # Adding qsim as a library to qiree
 qiree_add_library(qirqsim
   QsimQuantum.cc
-  QsimDefaultRuntime.cc
+  QsimRuntime.cc
 )
 
 #Link the qsim library to qiree and any other relevant libraries
diff --git a/src/qirqsim/QsimDefaultRuntime.hh b/src/qirqsim/QsimDefaultRuntime.hh
deleted file mode 100644
index f4e8e4d..0000000
--- a/src/qirqsim/QsimDefaultRuntime.hh
+++ /dev/null
@@ -1,76 +0,0 @@
-//----------------------------------*-C++-*----------------------------------//
-// Copyright 2024 UT-Battelle, LLC, and other QIR-EE developers.
-// See the top-level COPYRIGHT file for details.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//---------------------------------------------------------------------------//
-//! \file qirqsim/QsimDefaultRuntime.hh
-//---------------------------------------------------------------------------//
-#pragma once
-
-#include "QsimQuantum.hh"
-#include "qiree/RecordedResult.hh"
-
-namespace qiree
-{
-
-/*!
- * Print per-qubit measurement statistics.
- *
- * Example for three qubits:
- * \code
- * Measurement output:
- * -------------------
- * Number of shots: 1024
- * Number of qubits: 3
- * q0 {0: 542, 1: 482}
- * q1 {0: 521, 1: 503}
- * q2 {0: 0, 1: 1024}
- *
- * \endcode
- */
-
-class QsimDefaultRuntime final : virtual public RuntimeInterface
-{
-  public:
-    /*!
-     * Construct \c QsimDefaultRuntime.
-     */
-    QsimDefaultRuntime(std::ostream& output, QsimQuantum& sim)
-        : output_(output), sim_(sim)
-    {
-    }
-
-    //!@{
-    //! \name Runtime interface
-
-    // Initialize the execution environment, resetting qubits
-    void initialize(OptionalCString env) override;
-
-    //! Mark the following N results as being part of an array named tag
-    void array_record_output(size_type size, OptionalCString tag) final
-    {
-        result_ = RecordedResult(size, tag);
-    }
-
-    //! Mark the following N results as being part of a tuple named tag
-    void tuple_record_output(size_type size, OptionalCString tag) final
-    {
-        result_ = RecordedResult(size, tag);
-    }
-
-    //! Save one result
-    void result_record_output(Result result, OptionalCString tag) final
-    {
-        result_.push_back(sim_.get_result(result), tag);
-    }
-    //!@}
-
-    RecordedResult const& result() const { return result_; }
-
-  private:
-    std::ostream& output_;
-    QsimQuantum& sim_;
-    RecordedResult result_;
-};
-
-}  // namespace qiree
diff --git a/src/qirqsim/QsimQuantum.cc b/src/qirqsim/QsimQuantum.cc
index ebccbab..1962fa2 100644
--- a/src/qirqsim/QsimQuantum.cc
+++ b/src/qirqsim/QsimQuantum.cc
@@ -191,9 +191,11 @@ void QsimQuantum::mz(Qubit q, Result r)
  * \todo We could add assertions to check that we actually measured into the
  * given result.
  */
-QState QsimQuantum::read_result(Result r)
+QState QsimQuantum::read_result(Result r) const
 {
-    return this->get_result(r);
+    QIREE_EXPECT(r.value < results_.size());
+    auto result_bool = static_cast<bool>(results_[r.value]);
+    return static_cast<QState>(result_bool);
 }
 
 //---------------------------------------------------------------------------//
diff --git a/src/qirqsim/QsimQuantum.hh b/src/qirqsim/QsimQuantum.hh
index 7f2b2bb..44aebc5 100644
--- a/src/qirqsim/QsimQuantum.hh
+++ b/src/qirqsim/QsimQuantum.hh
@@ -41,8 +41,6 @@ class QsimQuantum final : virtual public QuantumNotImpl
     //! Number of classical result registers
     size_type num_results() const { return results_.size(); }
 
-    // Get the result from a classical register
-    inline QState get_result(Result r) const;
     //!@}
 
     //!@{
@@ -57,7 +55,7 @@ class QsimQuantum final : virtual public QuantumNotImpl
     void mz(Qubit, Result) final;
 
     // Read the value of a result.
-    QState read_result(Result) final;
+    QState read_result(Result) const final;
     //!@}
 
     //!@{
@@ -110,15 +108,4 @@ class QsimQuantum final : virtual public QuantumNotImpl
     void add_gate(Ts&&... args);
 };
 
-//---------------------------------------------------------------------------//
-/*!
- * Get the result from a classical register.
- */
-QState QsimQuantum::get_result(Result r) const
-{
-    QIREE_EXPECT(r.value < results_.size());
-    auto result_bool = static_cast<bool>(results_[r.value]);
-    return static_cast<QState>(result_bool);
-}
-
 }  // namespace qiree
diff --git a/src/qirqsim/QsimDefaultRuntime.cc b/src/qirqsim/QsimRuntime.cc
similarity index 64%
rename from src/qirqsim/QsimDefaultRuntime.cc
rename to src/qirqsim/QsimRuntime.cc
index 99fca6a..ce9e65b 100644
--- a/src/qirqsim/QsimDefaultRuntime.cc
+++ b/src/qirqsim/QsimRuntime.cc
@@ -3,21 +3,31 @@
 // See the top-level COPYRIGHT file for details.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //---------------------------------------------------------------------------//
-//! \file qirqsim/QsimDefaultRuntime.cc
+//! \file qirqsim/QsimRuntime.cc
 //---------------------------------------------------------------------------//
-#include "QsimDefaultRuntime.hh"
+#include "QsimRuntime.hh"
 
 #include <iostream>
 
+#include "QsimQuantum.hh"
 #include "qiree/Assert.hh"
 
 namespace qiree
 {
+//---------------------------------------------------------------------------//
+/*!
+ * Construct with quantum reference to access classical registers.
+ */
+QsimRuntime::QsimRuntime(std::ostream& output, QsimQuantum const& sim)
+    : SingleResultRuntime{sim}, output_(output)
+{
+}
+
 //---------------------------------------------------------------------------//
 /*!
  * Initialize the execution environment, resetting qubits.
  */
-void QsimDefaultRuntime::initialize(OptionalCString env)
+void QsimRuntime::initialize(OptionalCString env)
 {
     if (env)
     {
diff --git a/src/qirqsim/QsimRuntime.hh b/src/qirqsim/QsimRuntime.hh
new file mode 100644
index 0000000..9bad27e
--- /dev/null
+++ b/src/qirqsim/QsimRuntime.hh
@@ -0,0 +1,37 @@
+//----------------------------------*-C++-*----------------------------------//
+// Copyright 2024 UT-Battelle, LLC, and other QIR-EE developers.
+// See the top-level COPYRIGHT file for details.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//---------------------------------------------------------------------------//
+//! \file qirqsim/QsimRuntime.hh
+//---------------------------------------------------------------------------//
+#pragma once
+
+#include "qiree/SingleResultRuntime.hh"
+
+namespace qiree
+{
+//---------------------------------------------------------------------------//
+class QsimQuantum;
+
+//---------------------------------------------------------------------------//
+
+class QsimRuntime final : virtual public SingleResultRuntime
+{
+  public:
+    // Construct with quantum reference to access classical registers
+    QsimRuntime(std::ostream& output, QsimQuantum const& sim);
+
+    //!@{
+    //! \name Runtime interface
+
+    // Initialize the execution environment, resetting qubits
+    void initialize(OptionalCString env) override;
+
+    //!@}
+
+  private:
+    std::ostream& output_;
+};
+
+}  // namespace qiree
diff --git a/src/qirxacc/XaccQuantum.cc b/src/qirxacc/XaccQuantum.cc
index 336ba9a..13e35c9 100644
--- a/src/qirxacc/XaccQuantum.cc
+++ b/src/qirxacc/XaccQuantum.cc
@@ -143,7 +143,7 @@ continue:                                         ; preds = %else, %then
  *
  *
  */
-QState XaccQuantum::read_result(Result r)
+QState XaccQuantum::read_result(Result r) const
 {
     QIREE_EXPECT(r.value < this->num_results());
 
diff --git a/src/qirxacc/XaccQuantum.hh b/src/qirxacc/XaccQuantum.hh
index 5a0c77c..0d8edca 100644
--- a/src/qirxacc/XaccQuantum.hh
+++ b/src/qirxacc/XaccQuantum.hh
@@ -70,7 +70,7 @@ class XaccQuantum final : virtual public QuantumNotImpl
     void mz(Qubit, Result) final;
 
     // Read the value of a result.
-    QState read_result(Result) final;
+    QState read_result(Result) const final;
     //!@}
 
     //!@{
diff --git a/test/qiree/QuantumTestImpl.cc b/test/qiree/QuantumTestImpl.cc
index a02a222..f8cc498 100644
--- a/test/qiree/QuantumTestImpl.cc
+++ b/test/qiree/QuantumTestImpl.cc
@@ -60,7 +60,7 @@ void QuantumTestImpl::mz(Qubit q, Result r)
 /*!
  * Read the value of a result.
  */
-QState QuantumTestImpl::read_result(Result r)
+QState QuantumTestImpl::read_result(Result r) const
 {
     EXPECT_LT(r.value, this->num_results_);
     tr_->commands << "read_result(" << r << ")\n";
diff --git a/test/qiree/QuantumTestImpl.hh b/test/qiree/QuantumTestImpl.hh
index f89732f..caadb1e 100644
--- a/test/qiree/QuantumTestImpl.hh
+++ b/test/qiree/QuantumTestImpl.hh
@@ -44,7 +44,7 @@ class QuantumTestImpl final : public QuantumInterface
     void mz(Qubit, Result) final;
 
     // Read the value of a result.
-    QState read_result(Result) final;
+    QState read_result(Result) const final;
 
     //// Gates ////
 
diff --git a/test/qirqsim/QsimQuantum.test.cc b/test/qirqsim/QsimQuantum.test.cc
index 7d2a15a..a0435b7 100644
--- a/test/qirqsim/QsimQuantum.test.cc
+++ b/test/qirqsim/QsimQuantum.test.cc
@@ -11,7 +11,7 @@
 
 #include "qiree/Types.hh"
 #include "qiree_test.hh"
-#include "qirqsim/QsimDefaultRuntime.hh"
+#include "qirqsim/QsimRuntime.hh"
 
 namespace qiree
 {
@@ -43,7 +43,7 @@ TEST_F(QsimQuantumTest, sim_dynamicbv)
 
     // Create a simulator that will write to the string stream
     QsimQuantum qsim_sim{os, 0};
-    QsimDefaultRuntime qsim_rt{os, qsim_sim};
+    QsimRuntime qsim_rt{os, qsim_sim};
 
     // Call functions in the same sequence that dynamicbv.ll would
     qsim_sim.set_up([] {
@@ -67,8 +67,8 @@ TEST_F(QsimQuantumTest, sim_dynamicbv)
     qsim_rt.array_record_output(2, "");
     qsim_rt.result_record_output(R{0}, "");
     qsim_rt.result_record_output(R{1}, "");
-    EXPECT_EQ(QState::one, qsim_sim.get_result(R{0}));
-    EXPECT_EQ(QState::one, qsim_sim.get_result(R{1}));
+    EXPECT_EQ(QState::one, qsim_sim.read_result(R{0}));
+    EXPECT_EQ(QState::one, qsim_sim.read_result(R{1}));
 
     qsim_sim.h(Q{0});
     qsim_sim.x(Q{1});
@@ -80,8 +80,8 @@ TEST_F(QsimQuantumTest, sim_dynamicbv)
     qsim_rt.array_record_output(2, "");
     qsim_rt.result_record_output(R{0}, "");
     qsim_rt.result_record_output(R{1}, "");
-    EXPECT_EQ(QState::zero, qsim_sim.get_result(R{0}));
-    EXPECT_EQ(QState::zero, qsim_sim.get_result(R{1}));
+    EXPECT_EQ(QState::zero, qsim_sim.read_result(R{0}));
+    EXPECT_EQ(QState::zero, qsim_sim.read_result(R{1}));
 
     qsim_sim.h(Q{0});
     qsim_sim.x(Q{1});
@@ -95,8 +95,8 @@ TEST_F(QsimQuantumTest, sim_dynamicbv)
     qsim_rt.array_record_output(2, "");
     qsim_rt.result_record_output(R{0}, "");
     qsim_rt.result_record_output(R{1}, "");
-    EXPECT_EQ(QState::one, qsim_sim.get_result(R{0}));
-    EXPECT_EQ(QState::zero, qsim_sim.get_result(R{1}));
+    EXPECT_EQ(QState::one, qsim_sim.read_result(R{0}));
+    EXPECT_EQ(QState::zero, qsim_sim.read_result(R{1}));
 
     qsim_sim.tear_down();
 }
@@ -111,7 +111,7 @@ TEST_F(QsimQuantumTest, result_order)
 
     // Create a simulator that will write to the string stream
     QsimQuantum qis{os, 0};
-    QsimDefaultRuntime rt{os, qis};
+    QsimRuntime rt{os, qis};
 
     // Call functions in the same sequence that dynamicbv.ll would
     qis.set_up([] {
@@ -124,9 +124,9 @@ TEST_F(QsimQuantumTest, result_order)
     qis.mz(Q{1}, R{1});
     qis.mz(Q{2}, R{0});
     std::vector<bool> expected;
-    expected.push_back(static_cast<bool>(qis.get_result(R{2})));
-    expected.push_back(static_cast<bool>(qis.get_result(R{0})));
-    expected.push_back(static_cast<bool>(qis.get_result(R{1})));
+    expected.push_back(static_cast<bool>(qis.read_result(R{2})));
+    expected.push_back(static_cast<bool>(qis.read_result(R{0})));
+    expected.push_back(static_cast<bool>(qis.read_result(R{1})));
     // So the internal result "buffer" is now {true, false, true}
     rt.array_record_output(3, "array");
     rt.result_record_output(R{2}, "foo");  // pushes true