modelverse/kernel/modelverse_jit/jit.py

import modelverse_kernel.primitives as primitive_functions
import modelverse_jit.tree_ir as tree_ir

KWARGS_PARAMETER_NAME = "kwargs"
"""The name of the kwargs parameter in jitted functions."""

def get_parameter_names(compiled_function):
    """Gets the given compiled function's parameter names."""
    if hasattr(compiled_function, '__code__'):
        return compiled_function.__code__.co_varnames[
            :compiled_function.__code__.co_argcount]
    elif hasattr(compiled_function, '__init__'):
        return get_parameter_names(compiled_function.__init__)[1:]
    else:
        raise ValueError("'compiled_function' must be a function or a type.")

def apply_intrinsic(intrinsic_function, named_args):
    """Applies the given intrinsic to the given sequence of named arguments."""
    param_names = get_parameter_names(intrinsic_function)
    if tuple(param_names) == tuple([n for n, _ in named_args]):
        # Perfect match. Yay!
        return intrinsic_function(**dict(named_args))
    else:
        # We'll have to store the arguments into locals to preserve
        # the order of evaluation.
        stored_args = [(name, tree_ir.StoreLocalInstruction(None, arg)) for name, arg in named_args]
        arg_value_dict = dict([(name, arg.create_load()) for name, arg in stored_args])
        store_instructions = [instruction for _, instruction in stored_args]
        return tree_ir.CompoundInstruction(
            tree_ir.create_block(*store_instructions),
            intrinsic_function(**arg_value_dict))

class JitCompilationFailedException(Exception):
    """A type of exception that is raised when the jit fails to compile a function."""
    pass

class ModelverseJit(object):
    """A high-level interface to the modelverse JIT compiler."""

    def __init__(self, max_instructions=None, compiled_function_lookup=None):
        self.todo_entry_points = set()
        self.no_jit_entry_points = set()
        self.jitted_entry_points = {}
        self.jitted_parameters = {}
        self.jit_globals = {
            'PrimitiveFinished' : primitive_functions.PrimitiveFinished
        }
        self.jit_count = 0
        self.max_instructions = 30 if max_instructions is None else max_instructions
        self.compiled_function_lookup = compiled_function_lookup
        # jit_intrinsics is a function name -> intrinsic map.
        self.jit_intrinsics = {}
        self.compilation_dependencies = {}
        self.jit_enabled = True

    def set_jit_enabled(self, is_enabled=True):
        """Enables or disables the JIT."""
        self.jit_enabled = is_enabled

    def mark_entry_point(self, body_id):
        """Marks the node with the given identifier as a function entry point."""
        if body_id not in self.no_jit_entry_points and body_id not in self.jitted_entry_points:
            self.todo_entry_points.add(body_id)

    def is_entry_point(self, body_id):
        """Tells if the node with the given identifier is a function entry point."""
        return body_id in self.todo_entry_points or \
               body_id in self.no_jit_entry_points or \
               body_id in self.jitted_entry_points

    def is_jittable_entry_point(self, body_id):
        """Tells if the node with the given identifier is a function entry point that
           has not been marked as non-jittable. This only returns `True` if the JIT
           is enabled and the function entry point has been marked jittable, or if
           the function has already been compiled."""
        return ((self.jit_enabled and body_id in self.todo_entry_points) or
                self.has_compiled(body_id))

    def has_compiled(self, body_id):
        """Tests if the function belonging to the given body node has been compiled yet."""
        return body_id in self.jitted_entry_points

    def get_compiled_name(self, body_id):
        """Gets the name of the compiled version of the given body node in the JIT
           global state."""
        return self.jitted_entry_points[body_id]

    def mark_no_jit(self, body_id):
        """Informs the JIT that the node with the given identifier is a function entry
           point that must never be jitted."""
        self.no_jit_entry_points.add(body_id)
        if body_id in self.todo_entry_points:
            self.todo_entry_points.remove(body_id)

    def generate_function_name(self, suggested_name=None):
        """Generates a new function name or picks the suggested name if it is still
           available."""
        if suggested_name is not None and suggested_name not in self.jit_globals:
            self.jit_count += 1
            return suggested_name
        else:
            function_name = 'jit_func%d' % self.jit_count
            self.jit_count += 1
            return function_name

    def register_compiled(self, body_id, compiled_function, function_name=None):
        """Registers a compiled entry point with the JIT."""
        # Get the function's name.
        function_name = self.generate_function_name(function_name)
        # Map the body id to the given parameter list.
        self.jitted_entry_points[body_id] = function_name
        self.jit_globals[function_name] = compiled_function
        if body_id in self.todo_entry_points:
            self.todo_entry_points.remove(body_id)

    def lookup_compiled_function(self, name):
        """Looks up a compiled function by name. Returns a matching function,
           or None if no function was found."""
        if name in self.jit_globals:
            return self.jit_globals[name]
        elif self.compiled_function_lookup is not None:
            return self.compiled_function_lookup(name)
        else:
            return None

    def get_intrinsic(self, name):
        """Tries to find an intrinsic version of the function with the
           given name."""
        if name in self.jit_intrinsics:
            return self.jit_intrinsics[name]
        else:
            return None

    def register_intrinsic(self, name, intrinsic_function):
        """Registers the given intrisic with the JIT. This will make the JIT replace calls to
           the function with the given entry point by an application of the specified function."""
        self.jit_intrinsics[name] = intrinsic_function

    def register_binary_intrinsic(self, name, operator):
        """Registers an intrinsic with the JIT that represents the given binary operation."""
        self.register_intrinsic(name, lambda a, b: tree_ir.CreateNodeWithValueInstruction(
            tree_ir.BinaryInstruction(
                tree_ir.ReadValueInstruction(a),
                operator,
                tree_ir.ReadValueInstruction(b))))

    def register_unary_intrinsic(self, name, operator):
        """Registers an intrinsic with the JIT that represents the given unary operation."""
        self.register_intrinsic(name, lambda a: tree_ir.CreateNodeWithValueInstruction(
            tree_ir.UnaryInstruction(
                operator,
                tree_ir.ReadValueInstruction(a))))

    def jit_parameters(self, body_id):
        """Acquires the parameter list for the given body id node."""
        if body_id not in self.jitted_parameters:
            signature_id, = yield [("RRD", [body_id, "body"])]
            signature_id = signature_id[0]
            param_set_id, = yield [("RD", [signature_id, "params"])]
            if param_set_id is None:
                self.jitted_parameters[body_id] = ([], [])
            else:
                param_name_ids, = yield [("RDK", [param_set_id])]
                param_names = yield [("RV", [n]) for n in param_name_ids]
                param_vars = yield [("RD", [param_set_id, k]) for k in param_names]
                self.jitted_parameters[body_id] = (param_vars, param_names)

        raise primitive_functions.PrimitiveFinished(self.jitted_parameters[body_id])

    def jit_compile(self, user_root, body_id, suggested_name=None):
        """Tries to jit the function defined by the given entry point id and parameter list."""
        # The comment below makes pylint shut up about our (hopefully benign) use of exec here.
        # pylint: disable=I0011,W0122

        if body_id in self.jitted_entry_points:
            # We have already compiled this function.
            raise primitive_functions.PrimitiveFinished(
                self.jit_globals[self.jitted_entry_points[body_id]])
        elif body_id in self.no_jit_entry_points:
            # We're not allowed to jit this function or have tried and failed before.
            raise JitCompilationFailedException(
                'Cannot jit function %s at %d because it is marked non-jittable.' % (
                    '' if suggested_name is None else "'" + suggested_name + "'",
                    body_id))

        # Generate a name for the function we're about to analyze, and pretend that
        # it already exists. (we need to do this for recursive functions)
        function_name = self.generate_function_name(suggested_name)
        self.jitted_entry_points[body_id] = function_name
        self.jit_globals[function_name] = None

        try:
            gen = self.jit_parameters(body_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            parameter_ids, parameter_list = ex.result

        param_dict = dict(zip(parameter_ids, parameter_list))
        body_param_dict = dict(zip(parameter_ids, [p + "_ptr" for p in parameter_list]))
        dependencies = set([body_id])
        self.compilation_dependencies[body_id] = dependencies
        try:
            gen = AnalysisState(
                self, body_id, user_root, body_param_dict,
                self.max_instructions).analyze(body_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            del self.compilation_dependencies[body_id]
            constructed_body = ex.result
        except JitCompilationFailedException as ex:
            del self.compilation_dependencies[body_id]
            for dep in dependencies:
                self.mark_no_jit(dep)
                if dep in self.jitted_entry_points:
                    del self.jitted_entry_points[dep]
            raise JitCompilationFailedException(
                "%s (function '%s' at %d)" % (ex.message, function_name, body_id))

        # Write a prologue and prepend it to the generated function body.
        prologue_statements = []
        for (key, val) in param_dict.items():
            arg_ptr = tree_ir.StoreLocalInstruction(
                body_param_dict[key],
                tree_ir.CreateNodeInstruction())
            prologue_statements.append(arg_ptr)
            prologue_statements.append(
                tree_ir.CreateDictionaryEdgeInstruction(
                    arg_ptr.create_load(),
                    tree_ir.LiteralInstruction('value'),
                    tree_ir.LoadLocalInstruction(val)))

        constructed_body = tree_ir.create_block(
            *(prologue_statements + [constructed_body]))

        # Wrap the IR in a function definition, give it a unique name.
        constructed_function = tree_ir.DefineFunctionInstruction(
            function_name,
            parameter_list + ['**' + KWARGS_PARAMETER_NAME],
            constructed_body.simplify())
        # Convert the function definition to Python code, and compile it.
        exec(str(constructed_function), self.jit_globals)
        # Extract the compiled function from the JIT global state.
        compiled_function = self.jit_globals[function_name]

        print(constructed_function)
        raise primitive_functions.PrimitiveFinished(compiled_function)

class AnalysisState(object):
    """The state of a bytecode analysis call graph."""
    def __init__(self, jit, body_id, user_root, local_mapping, max_instructions=None):
        self.analyzed_instructions = set()
        self.function_vars = set()
        self.local_vars = set()
        self.body_id = body_id
        self.max_instructions = max_instructions
        self.user_root = user_root
        self.jit = jit
        self.local_mapping = local_mapping

    def get_local_name(self, local_id):
        """Gets the name for a local with the given id."""
        if local_id not in self.local_mapping:
            self.local_mapping[local_id] = 'local%d' % local_id
        return self.local_mapping[local_id]

    def register_local_var(self, local_id):
        """Registers the given variable node id as a local."""
        if local_id in self.function_vars:
            raise JitCompilationFailedException(
                "Local is used as target of function call.")
        self.local_vars.add(local_id)

    def register_function_var(self, local_id):
        """Registers the given variable node id as a function."""
        if local_id in self.local_vars:
            raise JitCompilationFailedException(
                "Local is used as target of function call.")
        self.function_vars.add(local_id)

    def retrieve_user_root(self):
        """Creates an instruction that stores the user_root variable
           in a local."""
        return tree_ir.StoreLocalInstruction(
            'user_root',
            tree_ir.LoadIndexInstruction(
                tree_ir.LoadLocalInstruction(KWARGS_PARAMETER_NAME),
                tree_ir.LiteralInstruction('user_root')))

    def analyze(self, instruction_id):
        """Tries to build an intermediate representation from the instruction with the
        given id."""
        # Check the analyzed_instructions set for instruction_id to avoid
        # infinite loops.
        if instruction_id in self.analyzed_instructions:
            raise JitCompilationFailedException('Cannot jit non-tree instruction graph.')
        elif (self.max_instructions is not None and
              len(self.analyzed_instructions) > self.max_instructions):
            raise JitCompilationFailedException('Maximum number of instructions exceeded.')

        self.analyzed_instructions.add(instruction_id)
        instruction_val, = yield [("RV", [instruction_id])]
        instruction_val = instruction_val["value"]
        if instruction_val in self.instruction_analyzers:
            try:
                gen = self.instruction_analyzers[instruction_val](self, instruction_id)
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except StopIteration:
                raise Exception(
                    "Instruction analyzer (for '%s') finished without returning a value!" %
                    (instruction_val))
            except primitive_functions.PrimitiveFinished as outer_e:
                # Check if the instruction has a 'next' instruction.
                next_instr, = yield [("RD", [instruction_id, "next"])]
                if next_instr is None:
                    raise outer_e
                else:
                    gen = self.analyze(next_instr)
                    try:
                        inp = None
                        while True:
                            inp = yield gen.send(inp)
                    except primitive_functions.PrimitiveFinished as inner_e:
                        raise primitive_functions.PrimitiveFinished(
                            tree_ir.CompoundInstruction(
                                outer_e.result,
                                inner_e.result))
        else:
            raise JitCompilationFailedException(
                "Unknown instruction type: '%s'" % (instruction_val))

    def analyze_all(self, instruction_ids):
        """Tries to compile a list of IR trees from the given list of instruction ids."""
        results = []
        for inst in instruction_ids:
            gen = self.analyze(inst)
            try:
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except primitive_functions.PrimitiveFinished as ex:
                results.append(ex.result)

        raise primitive_functions.PrimitiveFinished(results)

    def analyze_return(self, instruction_id):
        """Tries to analyze the given 'return' instruction."""
        retval_id, = yield [("RD", [instruction_id, 'value'])]
        if retval_id is None:
            raise primitive_functions.PrimitiveFinished(
                tree_ir.ReturnInstruction(
                    tree_ir.EmptyInstruction()))
        else:
            gen = self.analyze(retval_id)
            try:
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except primitive_functions.PrimitiveFinished as ex:
                raise primitive_functions.PrimitiveFinished(
                    tree_ir.ReturnInstruction(ex.result))

    def analyze_if(self, instruction_id):
        """Tries to analyze the given 'if' instruction."""
        cond, true, false = yield [
            ("RD", [instruction_id, "cond"]),
            ("RD", [instruction_id, "then"]),
            ("RD", [instruction_id, "else"])]

        try:
            gen = self.analyze_all(
                [cond, true]
                if false is None
                else [cond, true, false])
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            if false is None:
                cond_r, true_r = ex.result
                false_r = tree_ir.EmptyInstruction()
            else:
                cond_r, true_r, false_r = ex.result
            raise primitive_functions.PrimitiveFinished(
                tree_ir.SelectInstruction(
                    tree_ir.ReadValueInstruction(cond_r),
                    true_r,
                    false_r))

    def analyze_while(self, instruction_id):
        """Tries to analyze the given 'while' instruction."""
        cond, body = yield [
            ("RD", [instruction_id, "cond"]),
            ("RD", [instruction_id, "body"])]

        try:
            gen = self.analyze_all([cond, body])
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            cond_r, body_r = ex.result
            raise primitive_functions.PrimitiveFinished(
                tree_ir.LoopInstruction(
                    tree_ir.CompoundInstruction(
                        tree_ir.SelectInstruction(
                            tree_ir.ReadValueInstruction(cond_r),
                            tree_ir.EmptyInstruction(),
                            tree_ir.BreakInstruction()),
                        body_r)))

    def analyze_constant(self, instruction_id):
        """Tries to analyze the given 'constant' (literal) instruction."""
        node_id, = yield [("RD", [instruction_id, "node"])]
        raise primitive_functions.PrimitiveFinished(
            tree_ir.LiteralInstruction(node_id))

    def analyze_output(self, instruction_id):
        """Tries to analyze the given 'output' instruction."""
        # The plan is to basically generate this tree:
        #
        # value = <some tree>
        # last_output, last_output_link, new_last_output = \
        #                 yield [("RD", [user_root, "last_output"]),
        #                        ("RDE", [user_root, "last_output"]),
        #                        ("CN", []),
        #                       ]
        # _, _, _, _ = \
        #                 yield [("CD", [last_output, "value", value]),
        #                        ("CD", [last_output, "next", new_last_output]),
        #                        ("CD", [user_root, "last_output", new_last_output]),
        #                        ("DE", [last_output_link])
        #                       ]
        # yield None

        value_id, = yield [("RD", [instruction_id, "value"])]
        try:
            gen = self.analyze(value_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            value_local = tree_ir.StoreLocalInstruction('value', ex.result)

        store_user_root = self.retrieve_user_root()
        last_output = tree_ir.StoreLocalInstruction(
            'last_output',
            tree_ir.ReadDictionaryValueInstruction(
                store_user_root.create_load(),
                tree_ir.LiteralInstruction('last_output')))

        last_output_link = tree_ir.StoreLocalInstruction(
            'last_output_link',
            tree_ir.ReadDictionaryEdgeInstruction(
                store_user_root.create_load(),
                tree_ir.LiteralInstruction('last_output')))

        new_last_output = tree_ir.StoreLocalInstruction(
            'new_last_output',
            tree_ir.CreateNodeInstruction())

        result = tree_ir.create_block(
            value_local,
            store_user_root,
            last_output,
            last_output_link,
            new_last_output,
            tree_ir.CreateDictionaryEdgeInstruction(
                last_output.create_load(),
                tree_ir.LiteralInstruction('value'),
                value_local.create_load()),
            tree_ir.CreateDictionaryEdgeInstruction(
                last_output.create_load(),
                tree_ir.LiteralInstruction('next'),
                new_last_output.create_load()),
            tree_ir.CreateDictionaryEdgeInstruction(
                store_user_root.create_load(),
                tree_ir.LiteralInstruction('last_output'),
                new_last_output.create_load()),
            tree_ir.DeleteEdgeInstruction(last_output_link.create_load()),
            tree_ir.NopInstruction())

        raise primitive_functions.PrimitiveFinished(result)

    def analyze_input(self, _):
        """Tries to analyze the given 'input' instruction."""
        # The plan is to generate this tree:
        #
        #     value = None
        #     while True:
        #         if value is None:
        #             yield None # nop
        #         else:
        #             break
        #
        #         _input = yield [("RD", [user_root, "input"])]
        #         value = yield [("RD", [_input, "value"])]
        #
        #     _next = yield [("RD", [_input, "next"])]
        #     yield [("CD", [user_root, "input", _next])]
        #     yield [("DN", [_input])]

        user_root = self.retrieve_user_root()
        _input = tree_ir.StoreLocalInstruction(
            '_input',
            tree_ir.ReadDictionaryValueInstruction(
                user_root.create_load(),
                tree_ir.LiteralInstruction('input')))

        value = tree_ir.StoreLocalInstruction(
            'value',
            tree_ir.ReadDictionaryValueInstruction(
                _input.create_load(),
                tree_ir.LiteralInstruction('value')))

        raise primitive_functions.PrimitiveFinished(
            tree_ir.CompoundInstruction(
                tree_ir.create_block(
                    user_root,
                    value.create_store(tree_ir.LiteralInstruction(None)),
                    tree_ir.LoopInstruction(
                        tree_ir.create_block(
                            tree_ir.SelectInstruction(
                                tree_ir.BinaryInstruction(
                                    value.create_load(),
                                    'is',
                                    tree_ir.LiteralInstruction(None)),
                                tree_ir.NopInstruction(),
                                tree_ir.BreakInstruction()),
                            _input,
                            value)),
                    tree_ir.CreateDictionaryEdgeInstruction(
                        user_root.create_load(),
                        tree_ir.LiteralInstruction('input'),
                        tree_ir.ReadDictionaryValueInstruction(
                            _input.create_load(),
                            tree_ir.LiteralInstruction('next'))),
                    tree_ir.DeleteNodeInstruction(_input.create_load())),
                value.create_load()))

    def analyze_resolve(self, instruction_id):
        """Tries to analyze the given 'resolve' instruction."""
        var_id, = yield [("RD", [instruction_id, "var"])]
        var_name, = yield [("RV", [var_id])]

        # To resolve a variable, we'll do something along the
        # lines of:
        #
        #     if 'local_var' in locals():
        #         tmp = local_var
        #     else:
        #         _globals, = yield [("RD", [user_root, "globals"])]
        #         global_var, = yield [("RD", [_globals, var_name])]
        #
        #         if global_var is None:
        #             raise Exception("Runtime error: global '%s' not found" % (var_name))
        #
        #         tmp = global_var

        name = self.get_local_name(var_id)

        if var_name is None:
            raise primitive_functions.PrimitiveFinished(
                tree_ir.LoadLocalInstruction(name))

        user_root = self.retrieve_user_root()
        global_var = tree_ir.StoreLocalInstruction(
            'global_var',
            tree_ir.ReadDictionaryValueInstruction(
                tree_ir.ReadDictionaryValueInstruction(
                    user_root.create_load(),
                    tree_ir.LiteralInstruction('globals')),
                tree_ir.LiteralInstruction(var_name)))

        err_block = tree_ir.SelectInstruction(
            tree_ir.BinaryInstruction(
                global_var.create_load(),
                'is',
                tree_ir.LiteralInstruction(None)),
            tree_ir.RaiseInstruction(
                tree_ir.CallInstruction(
                    tree_ir.LoadGlobalInstruction('Exception'),
                    [tree_ir.LiteralInstruction(
                        "Runtime error: global '%s' not found" % var_name)
                    ])),
            tree_ir.EmptyInstruction())

        raise primitive_functions.PrimitiveFinished(
            tree_ir.SelectInstruction(
                tree_ir.LocalExistsInstruction(name),
                tree_ir.LoadLocalInstruction(name),
                tree_ir.CompoundInstruction(
                    tree_ir.create_block(
                        user_root,
                        global_var,
                        err_block),
                    global_var.create_load())))

    def analyze_declare(self, instruction_id):
        """Tries to analyze the given 'declare' function."""
        var_id, = yield [("RD", [instruction_id, "var"])]

        self.register_local_var(var_id)

        name = self.get_local_name(var_id)

        # The following logic declares a local:
        #
        #     if 'local_name' not in locals():
        #         local_name, = yield [("CN", [])]

        raise primitive_functions.PrimitiveFinished(
            tree_ir.SelectInstruction(
                tree_ir.LocalExistsInstruction(name),
                tree_ir.EmptyInstruction(),
                tree_ir.StoreLocalInstruction(
                    name,
                    tree_ir.CreateNodeInstruction())))

    def analyze_global(self, instruction_id):
        """Tries to analyze the given 'global' (declaration) instruction."""
        var_id, = yield [("RD", [instruction_id, "var"])]
        var_name, = yield [("RV", [var_id])]

        # To resolve a variable, we'll do something along the
        # lines of:
        #
        #     _globals, = yield [("RD", [user_root, "globals"])]
        #     global_var = yield [("RD", [_globals, var_name])]
        #
        #     if global_var is None:
        #         global_var, = yield [("CN", [])]
        #         yield [("CD", [_globals, var_name, global_var])]
        #
        #     tmp = global_var

        user_root = self.retrieve_user_root()
        _globals = tree_ir.StoreLocalInstruction(
            '_globals',
            tree_ir.ReadDictionaryValueInstruction(
                user_root.create_load(),
                tree_ir.LiteralInstruction('globals')))

        global_var = tree_ir.StoreLocalInstruction(
            'global_var',
            tree_ir.ReadDictionaryValueInstruction(
                _globals.create_load(),
                tree_ir.LiteralInstruction(var_name)))

        raise primitive_functions.PrimitiveFinished(
            tree_ir.CompoundInstruction(
                tree_ir.create_block(
                    user_root,
                    _globals,
                    global_var,
                    tree_ir.SelectInstruction(
                        tree_ir.BinaryInstruction(
                            global_var.create_load(),
                            'is',
                            tree_ir.LiteralInstruction(None)),
                        tree_ir.create_block(
                            global_var.create_store(
                                tree_ir.CreateNodeInstruction()),
                            tree_ir.CreateDictionaryEdgeInstruction(
                                _globals.create_load(),
                                tree_ir.LiteralInstruction(var_name),
                                global_var.create_load())),
                        tree_ir.EmptyInstruction())),
                global_var.create_load()))

    def analyze_assign(self, instruction_id):
        """Tries to analyze the given 'assign' instruction."""
        var_id, value_id = yield [("RD", [instruction_id, "var"]),
                                  ("RD", [instruction_id, "value"])]

        try:
            gen = self.analyze_all([var_id, value_id])
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            var_r, value_r = ex.result

        # Assignments work like this:
        #
        #     value_link = yield [("RDE", [variable, "value"])]
        #     _, _ =       yield [("CD", [variable, "value", value]),
        #                         ("DE", [value_link])]

        variable = tree_ir.StoreLocalInstruction('variable', var_r)
        value = tree_ir.StoreLocalInstruction('value', value_r)
        value_link = tree_ir.StoreLocalInstruction(
            'value_link',
            tree_ir.ReadDictionaryEdgeInstruction(
                variable.create_load(),
                tree_ir.LiteralInstruction('value')))

        raise primitive_functions.PrimitiveFinished(
            tree_ir.create_block(
                variable,
                value,
                value_link,
                tree_ir.CreateDictionaryEdgeInstruction(
                    variable.create_load(),
                    tree_ir.LiteralInstruction('value'),
                    value.create_load()),
                tree_ir.DeleteEdgeInstruction(
                    value_link.create_load())))

    def analyze_access(self, instruction_id):
        """Tries to analyze the given 'access' instruction."""
        var_id, = yield [("RD", [instruction_id, "var"])]

        try:
            gen = self.analyze(var_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            var_r = ex.result

        # Accessing a variable is pretty easy. It really just boils
        # down to reading the value corresponding to the 'value' key
        # of the variable.
        #
        #     value, = yield [("RD", [returnvalue, "value"])]

        raise primitive_functions.PrimitiveFinished(
            tree_ir.ReadDictionaryValueInstruction(
                var_r,
                tree_ir.LiteralInstruction('value')))

    def analyze_direct_call(self, callee_id, callee_name, first_parameter_id):
        """Tries to analyze a direct 'call' instruction."""
        self.register_function_var(callee_id)

        body_id, = yield [("RD", [callee_id, "body"])]

        # Make this function dependent on the callee.
        if body_id in self.jit.compilation_dependencies:
            self.jit.compilation_dependencies[body_id].add(self.body_id)

        # Figure out if the function might be an intrinsic.
        intrinsic = self.jit.get_intrinsic(callee_name)

        if intrinsic is None:
            compiled_func = self.jit.lookup_compiled_function(callee_name)
            if compiled_func is None:
                # Compile the callee.
                try:
                    gen = self.jit.jit_compile(self.user_root, body_id, callee_name)
                    inp = None
                    while True:
                        inp = yield gen.send(inp)
                except primitive_functions.PrimitiveFinished as ex:
                    pass
            else:
                self.jit.register_compiled(body_id, compiled_func, callee_name)

            # Get the callee's name.
            compiled_func_name = self.jit.get_compiled_name(body_id)

        # Analyze the argument dictionary.
        try:
            gen = self.analyze_arguments(first_parameter_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            named_args = ex.result

        if intrinsic is not None:
            raise primitive_functions.PrimitiveFinished(
                apply_intrinsic(intrinsic, named_args))
        else:
            raise primitive_functions.PrimitiveFinished(
                tree_ir.JitCallInstruction(
                    tree_ir.LoadGlobalInstruction(compiled_func_name),
                    named_args,
                    tree_ir.LoadLocalInstruction(KWARGS_PARAMETER_NAME)))

    def analyze_arguments(self, first_argument_id):
        """Analyzes the parameter-to-argument mapping started by the specified first argument
           node."""
        next_param = first_argument_id
        named_args = []
        while next_param is not None:
            param_name_id, = yield [("RD", [next_param, "name"])]
            param_name, = yield [("RV", [param_name_id])]
            param_val_id, = yield [("RD", [next_param, "value"])]
            try:
                gen = self.analyze(param_val_id)
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except primitive_functions.PrimitiveFinished as ex:
                named_args.append((param_name, ex.result))

            next_param, = yield [("RD", [next_param, "next_param"])]

        raise primitive_functions.PrimitiveFinished(named_args)

    def analyze_call(self, instruction_id):
        """Tries to analyze the given 'call' instruction."""
        func_id, first_param_id, = yield [("RD", [instruction_id, "func"]),
                                          ("RD", [instruction_id, "params"])]

        # Figure out what the 'func' instruction's type is.
        func_instruction_op, = yield [("RV", [func_id])]
        if func_instruction_op['value'] == 'access':
            # Calls to 'access(resolve(var))' instructions are translated to direct calls.
            access_value_id, = yield [("RD", [func_id, "var"])]
            access_value_op, = yield [("RV", [access_value_id])]
            if access_value_op['value'] == 'resolve':
                resolved_var_id, = yield [("RD", [access_value_id, "var"])]
                resolved_var_name, = yield [("RV", [resolved_var_id])]

                # Try to look the name up as a global.
                _globals, = yield [("RD", [self.user_root, "globals"])]
                global_var, = yield [("RD", [_globals, resolved_var_name])]
                global_val, = yield [("RD", [global_var, "value"])]

                if global_val is None:
                    raise JitCompilationFailedException(
                        "Cannot JIT function calls that target an unknown value.")
                else:
                    gen = self.analyze_direct_call(
                        global_val, resolved_var_name, first_param_id)
                    inp = None
                    while True:
                        inp = yield gen.send(inp)
                    # PrimitiveFinished exception will bubble up from here.

        raise JitCompilationFailedException("Cannot JIT indirect function calls yet.")


    instruction_analyzers = {
        'if' : analyze_if,
        'while' : analyze_while,
        'return' : analyze_return,
        'constant' : analyze_constant,
        'resolve' : analyze_resolve,
        'declare' : analyze_declare,
        'global' : analyze_global,
        'assign' : analyze_assign,
        'access' : analyze_access,
        'output' : analyze_output,
        'input' : analyze_input,
        'call' : analyze_call
    }