Fixed a bug in adjoint kernel construction

instruction replacements (e.g. T->Tdg) were not reflected.

Add unit test for pyxasm adjoint.

Signed-off-by: Thien Nguyen <nguyentm@ornl.gov>

python/tests/test_kernel_jit.py

@@ -301,6 +301,31 @@ class TestSimpleKernelJIT(unittest.TestCase):
         print(q.counts())
         self.assertEqual(q.counts()['100'], 1024)
 
+    def test_adjoint_kernel(self):
+        @qjit
+        def test_kernel(q : qreg):
+            CX(q[0], q[1])
+            Rx(q[0], 1.234)
+            T(q[0])
+            X(q[0])
+
+        @qjit
+        def check_adjoint(q : qreg):
+            test_kernel.adjoint(q)
+        
+        q = qalloc(2)
+        comp = check_adjoint.extract_composite(q)
+        print(comp.toString())
+        self.assertEqual(comp.nInstructions(), 4)   
+        # Reverse
+        self.assertEqual(comp.getInstruction(0).name(), "X") 
+        # Check T -> Tdg
+        self.assertEqual(comp.getInstruction(1).name(), "Tdg") 
+        self.assertEqual(comp.getInstruction(2).name(), "Rx") 
+        # Check angle -> -angle
+        self.assertAlmostEqual((float)(comp.getInstruction(2).getParameter(0)), -1.234)
+        self.assertEqual(comp.getInstruction(3).name(), "CNOT") 
+
 
 if __name__ == '__main__':
   unittest.main()
\ No newline at end of file

runtime/kernel/quantum_kernel.hpp

@@ -108,7 +108,6 @@ public:
     }
 
     auto provider = qcor::__internal__::get_provider();
-    std::reverse(instructions.begin(), instructions.end());
     for (int i = 0; i < instructions.size(); i++) {
       auto inst = derived.parent_kernel->getInstruction(i);
       // Parametric gates:
@@ -127,8 +126,13 @@ public:
       }
     }
 
+    // We update/replace instructions in the derived.parent_kernel composite,
+    // hence collecting these new instructions and reversing the sequence.
+    auto new_instructions = derived.parent_kernel->getInstructions();
+    std::reverse(new_instructions.begin(), new_instructions.end());
+
     // add the instructions to the current parent kernel
-    parent_kernel->addInstructions(instructions);
+    parent_kernel->addInstructions(new_instructions);
 
     // no measures, so no execute
   }