gh-134584: Decref elimination for float ops in the JIT (GH-134588)

This PR adds a PyJitRef API to the JIT's optimizer that mimics the _PyStackRef API. This allows it to track references and their stack lifetimes properly. Thus opening up the doorway to refcount elimination in the JIT.

Python/executor_cases.c.h

@@ -1063,6 +1063,87 @@
             break;
         }
 
+        case _BINARY_OP_MULTIPLY_FLOAT__NO_DECREF_INPUTS: {
+            _PyStackRef right;
+            _PyStackRef left;
+            _PyStackRef res;
+            right = stack_pointer[-1];
+            left = stack_pointer[-2];
+            PyObject *left_o = PyStackRef_AsPyObjectBorrow(left);
+            PyObject *right_o = PyStackRef_AsPyObjectBorrow(right);
+            assert(PyFloat_CheckExact(left_o));
+            assert(PyFloat_CheckExact(right_o));
+            STAT_INC(BINARY_OP, hit);
+            double dres =
+            ((PyFloatObject *)left_o)->ob_fval *
+            ((PyFloatObject *)right_o)->ob_fval;
+            res = PyStackRef_FromPyObjectSteal(PyFloat_FromDouble(dres));
+            if (PyStackRef_IsNull(res)) {
+                stack_pointer[-2] = res;
+                stack_pointer += -1;
+                assert(WITHIN_STACK_BOUNDS());
+                JUMP_TO_ERROR();
+            }
+            stack_pointer[-2] = res;
+            stack_pointer += -1;
+            assert(WITHIN_STACK_BOUNDS());
+            break;
+        }
+
+        case _BINARY_OP_ADD_FLOAT__NO_DECREF_INPUTS: {
+            _PyStackRef right;
+            _PyStackRef left;
+            _PyStackRef res;
+            right = stack_pointer[-1];
+            left = stack_pointer[-2];
+            PyObject *left_o = PyStackRef_AsPyObjectBorrow(left);
+            PyObject *right_o = PyStackRef_AsPyObjectBorrow(right);
+            assert(PyFloat_CheckExact(left_o));
+            assert(PyFloat_CheckExact(right_o));
+            STAT_INC(BINARY_OP, hit);
+            double dres =
+            ((PyFloatObject *)left_o)->ob_fval +
+            ((PyFloatObject *)right_o)->ob_fval;
+            res = PyStackRef_FromPyObjectSteal(PyFloat_FromDouble(dres));
+            if (PyStackRef_IsNull(res)) {
+                stack_pointer[-2] = res;
+                stack_pointer += -1;
+                assert(WITHIN_STACK_BOUNDS());
+                JUMP_TO_ERROR();
+            }
+            stack_pointer[-2] = res;
+            stack_pointer += -1;
+            assert(WITHIN_STACK_BOUNDS());
+            break;
+        }
+
+        case _BINARY_OP_SUBTRACT_FLOAT__NO_DECREF_INPUTS: {
+            _PyStackRef right;
+            _PyStackRef left;
+            _PyStackRef res;
+            right = stack_pointer[-1];
+            left = stack_pointer[-2];
+            PyObject *left_o = PyStackRef_AsPyObjectBorrow(left);
+            PyObject *right_o = PyStackRef_AsPyObjectBorrow(right);
+            assert(PyFloat_CheckExact(left_o));
+            assert(PyFloat_CheckExact(right_o));
+            STAT_INC(BINARY_OP, hit);
+            double dres =
+            ((PyFloatObject *)left_o)->ob_fval -
+            ((PyFloatObject *)right_o)->ob_fval;
+            res = PyStackRef_FromPyObjectSteal(PyFloat_FromDouble(dres));
+            if (PyStackRef_IsNull(res)) {
+                stack_pointer[-2] = res;
+                stack_pointer += -1;
+                assert(WITHIN_STACK_BOUNDS());
+                JUMP_TO_ERROR();
+            }
+            stack_pointer[-2] = res;
+            stack_pointer += -1;
+            assert(WITHIN_STACK_BOUNDS());
+            break;
+        }
+
         case _BINARY_OP_ADD_UNICODE: {
             _PyStackRef right;
             _PyStackRef left;