Added LLVM implementation of bubble sort (#693)

Author: prex03

pydatastructs/graphs/_backend/cpp/Algorithms.hpp

@@ -14,8 +14,8 @@ static PyObject* breadth_first_search_adjacency_list(PyObject* self, PyObject* a
     PyObject* operation;
     PyObject* varargs = nullptr;
     PyObject* kwargs_dict = nullptr;
-
     static const char* kwlist[] = {"graph", "source_node", "operation", "args", "kwargs", nullptr};
+
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O!sO|OO", const_cast<char**>(kwlist),
                                      &AdjacencyListGraphType, &graph_obj,
                                      &source_name, &operation,
@@ -24,54 +24,58 @@ static PyObject* breadth_first_search_adjacency_list(PyObject* self, PyObject* a
     }
 
     AdjacencyListGraph* cpp_graph = reinterpret_cast<AdjacencyListGraph*>(graph_obj);
-
     auto it = cpp_graph->node_map.find(source_name);
     AdjacencyListGraphNode* start_node = it->second;
-
     std::unordered_set<std::string> visited;
     std::queue<AdjacencyListGraphNode*> q;
-
     q.push(start_node);
     visited.insert(start_node->name);
 
     while (!q.empty()) {
-    AdjacencyListGraphNode* node = q.front();
-    q.pop();
+        AdjacencyListGraphNode* node = q.front();
+        q.pop();
 
-    for (const auto& [adj_name, adj_obj] : node->adjacent) {
-        if (visited.count(adj_name)) continue;
-        if (get_type_tag(adj_obj) != NodeType_::AdjacencyListGraphNode) continue;
+        for (const auto& [adj_name, adj_obj] : node->adjacent) {
+            if (visited.count(adj_name)) continue;
+            if (get_type_tag(adj_obj) != NodeType_::AdjacencyListGraphNode) continue;
 
-        AdjacencyListGraphNode* adj_node = reinterpret_cast<AdjacencyListGraphNode*>(adj_obj);
+            AdjacencyListGraphNode* adj_node = reinterpret_cast<AdjacencyListGraphNode*>(adj_obj);
 
-        PyObject* base_args = PyTuple_Pack(2,
-                                           reinterpret_cast<PyObject*>(node),
-                                           reinterpret_cast<PyObject*>(adj_node));
-        if (!base_args)
-            return nullptr;
+            PyObject* node_pyobj = reinterpret_cast<PyObject*>(node);
+            PyObject* adj_node_pyobj = reinterpret_cast<PyObject*>(adj_node);
 
-        PyObject* final_args;
-        if (varargs && PyTuple_Check(varargs)) {
-            final_args = PySequence_Concat(base_args, varargs);
-            Py_DECREF(base_args);
+            PyObject* final_args;
+
+            if (varargs && PyTuple_Check(varargs)) {
+                Py_ssize_t varargs_size = PyTuple_Size(varargs);
+                if (varargs_size == 1) {
+                    PyObject* extra_arg = PyTuple_GetItem(varargs, 0);
+                    final_args = PyTuple_Pack(3, node_pyobj, adj_node_pyobj, extra_arg);
+                } else {
+                    PyObject* base_args = PyTuple_Pack(2, node_pyobj, adj_node_pyobj);
+                    if (!base_args)
+                        return nullptr;
+                    final_args = PySequence_Concat(base_args, varargs);
+                    Py_DECREF(base_args);
+                }
+            } else {
+                final_args = PyTuple_Pack(2, node_pyobj, adj_node_pyobj);
+            }
             if (!final_args)
                 return nullptr;
-        } else {
-            final_args = base_args;
-        }
-
-        PyObject* result = PyObject_Call(operation, final_args, kwargs_dict);
-        Py_DECREF(final_args);
 
-        if (!result)
-            return nullptr;
+            PyObject* result = PyObject_Call(operation, final_args, kwargs_dict);
+            Py_DECREF(final_args);
 
-        Py_DECREF(result);
+            if (!result)
+                return nullptr;
 
-        visited.insert(adj_name);
-        q.push(adj_node);
-    }
+            Py_DECREF(result);
+            visited.insert(adj_name);
+            q.push(adj_node);
+        }
     }
+
     if (PyErr_Occurred()) {
         return nullptr;
     }

pydatastructs/graphs/tests/test_algorithms.py

@@ -45,17 +45,17 @@ def bfs_tree(curr_node, next_node, parent):
             (parent[V3.name] == V2.name and parent[V2.name] == V1.name)
 
         if (ds=='List'):
-            parent2 = {}
+            parent = {}
             V9 = AdjacencyListGraphNode("9",0,backend = Backend.CPP)
             V10 = AdjacencyListGraphNode("10",0,backend = Backend.CPP)
             V11 = AdjacencyListGraphNode("11",0,backend = Backend.CPP)
             G2 = Graph(V9, V10, V11,implementation = 'adjacency_list', backend = Backend.CPP)
             assert G2.num_vertices()==3
             G2.add_edge("9", "10")
             G2.add_edge("10", "11")
-            breadth_first_search(G2, "9", bfs_tree, parent2, backend = Backend.CPP)
-            assert parent2[V10] == V9
-            assert parent2[V11] == V10
+            breadth_first_search(G2, "9", bfs_tree, parent, backend = Backend.CPP)
+            assert parent[V10] == V9
+            assert parent[V11] == V10
 
         if (ds == 'Matrix'):
             parent3 = {}

pydatastructs/linear_data_structures/_backend/cpp/algorithms/__init__.py

@@ -8,6 +8,8 @@ static PyMethodDef algorithms_PyMethodDef[] = {
      METH_VARARGS | METH_KEYWORDS, ""},
     {"bubble_sort", (PyCFunction) bubble_sort,
      METH_VARARGS | METH_KEYWORDS, ""},
+    {"bubble_sort_llvm",  (PyCFunction)bubble_sort_llvm,
+     METH_VARARGS | METH_KEYWORDS, ""},
     {"selection_sort", (PyCFunction) selection_sort,
      METH_VARARGS | METH_KEYWORDS, ""},
     {"insertion_sort", (PyCFunction) insertion_sort,

pydatastructs/linear_data_structures/_backend/cpp/algorithms/algorithms.cpp

@@ -0,0 +1,162 @@
+from llvmlite import ir, binding
+import atexit
+
+_SUPPORTED = {
+    "int32": (ir.IntType(32), 4),
+    "int64": (ir.IntType(64), 8),
+    "float32": (ir.FloatType(), 4),
+    "float64": (ir.DoubleType(), 8),
+}
+
+_engines = {}
+_target_machine = None
+_fn_ptr_cache = {}
+
+def _cleanup():
+    """Clean up LLVM resources on exit."""
+    global _engines, _target_machine, _fn_ptr_cache
+    _engines.clear()
+    _target_machine = None
+    _fn_ptr_cache.clear()
+
+atexit.register(_cleanup)
+
+def _ensure_target_machine():
+    global _target_machine
+    if _target_machine is not None:
+        return
+
+    try:
+        binding.initialize()
+        binding.initialize_native_target()
+        binding.initialize_native_asmprinter()
+
+        target = binding.Target.from_default_triple()
+        _target_machine = target.create_target_machine()
+    except Exception as e:
+        raise RuntimeError(f"Failed to initialize LLVM target machine: {e}")
+
+def get_bubble_sort_ptr(dtype: str) -> int:
+    """Get function pointer for bubble sort with specified dtype."""
+    dtype = dtype.lower().strip()
+    if dtype not in _SUPPORTED:
+        raise ValueError(f"Unsupported dtype '{dtype}'. Supported: {list(_SUPPORTED)}")
+
+    return _materialize(dtype)
+
+def _build_bubble_sort_ir(dtype: str) -> str:
+    if dtype not in _SUPPORTED:
+        raise ValueError(f"Unsupported dtype '{dtype}'. Supported: {list(_SUPPORTED)}")
+
+    T, _ = _SUPPORTED[dtype]
+    i32 = ir.IntType(32)
+    i64 = ir.IntType(64)
+
+    mod = ir.Module(name=f"bubble_sort_{dtype}_module")
+    fn_name = f"bubble_sort_{dtype}"
+
+    fn_ty = ir.FunctionType(ir.VoidType(), [T.as_pointer(), i32])
+    fn = ir.Function(mod, fn_ty, name=fn_name)
+
+    arr, n = fn.args
+    arr.name, n.name = "arr", "n"
+
+    b_entry = fn.append_basic_block("entry")
+    b_outer = fn.append_basic_block("outer")
+    b_inner_init = fn.append_basic_block("inner.init")
+    b_inner = fn.append_basic_block("inner")
+    b_body = fn.append_basic_block("body")
+    b_swap = fn.append_basic_block("swap")
+    b_inner_latch = fn.append_basic_block("inner.latch")
+    b_outer_latch = fn.append_basic_block("outer.latch")
+    b_exit = fn.append_basic_block("exit")
+
+    b = ir.IRBuilder(b_entry)
+
+    cond_trivial = b.icmp_signed("<=", n, ir.Constant(i32, 1))
+    b.cbranch(cond_trivial, b_exit, b_outer)
+
+    b.position_at_end(b_outer)
+    i_phi = b.phi(i32, name="i")
+    i_phi.add_incoming(ir.Constant(i32, 0), b_entry)
+
+    n1 = b.sub(n, ir.Constant(i32, 1), name="n_minus_1")
+    cond_outer = b.icmp_signed("<", i_phi, n1)
+    b.cbranch(cond_outer, b_inner_init, b_exit)
+
+    b.position_at_end(b_inner_init)
+
+    inner_limit = b.sub(n1, i_phi, name="inner_limit")
+    b.branch(b_inner)
+
+    b.position_at_end(b_inner)
+    j_phi = b.phi(i32, name="j")
+    j_phi.add_incoming(ir.Constant(i32, 0), b_inner_init)
+
+    cond_inner = b.icmp_signed("<", j_phi, inner_limit)
+    b.cbranch(cond_inner, b_body, b_outer_latch)
+
+    b.position_at_end(b_body)
+    j64 = b.sext(j_phi, i64)
+    jp1 = b.add(j_phi, ir.Constant(i32, 1))
+    jp1_64 = b.sext(jp1, i64)
+
+    ptr_j = b.gep(arr, [j64], inbounds=True)
+    ptr_jp1 = b.gep(arr, [jp1_64], inbounds=True)
+
+    val_j = b.load(ptr_j)
+    val_jp1 = b.load(ptr_jp1)
+
+    if isinstance(T, ir.IntType):
+        should_swap = b.icmp_signed(">", val_j, val_jp1)
+    else:
+        should_swap = b.fcmp_ordered(">", val_j, val_jp1)
+
+    b.cbranch(should_swap, b_swap, b_inner_latch)
+
+    b.position_at_end(b_swap)
+    b.store(val_jp1, ptr_j)
+    b.store(val_j, ptr_jp1)
+    b.branch(b_inner_latch)
+
+    b.position_at_end(b_inner_latch)
+    j_next = b.add(j_phi, ir.Constant(i32, 1))
+    j_phi.add_incoming(j_next, b_inner_latch)
+    b.branch(b_inner)
+
+    b.position_at_end(b_outer_latch)
+    i_next = b.add(i_phi, ir.Constant(i32, 1))
+    i_phi.add_incoming(i_next, b_outer_latch)
+    b.branch(b_outer)
+
+    b.position_at_end(b_exit)
+    b.ret_void()
+
+    return str(mod)
+
+def _materialize(dtype: str) -> int:
+    _ensure_target_machine()
+
+    if dtype in _fn_ptr_cache:
+        return _fn_ptr_cache[dtype]
+
+    try:
+        llvm_ir = _build_bubble_sort_ir(dtype)
+        mod = binding.parse_assembly(llvm_ir)
+        mod.verify()
+
+        engine = binding.create_mcjit_compiler(mod, _target_machine)
+        engine.finalize_object()
+        engine.run_static_constructors()
+
+        addr = engine.get_function_address(f"bubble_sort_{dtype}")
+        if not addr:
+            raise RuntimeError(f"Failed to get address for bubble_sort_{dtype}")
+
+        _fn_ptr_cache[dtype] = addr
+        _engines[dtype] = engine
+
+        return addr
+
+    except Exception as e:
+        raise RuntimeError(f"Failed to materialize function for dtype {dtype}: {e}")