compiled_module.py

# Copyright 2023 Nod Labs, Inc
# Portions Copyright 2022 The IREE Authors
#
# Licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

from typing import Any, Callable, Dict, Generator, List, Optional, Tuple, Union

import enum
import inspect
import logging
from pathlib import Path
import re
import weakref
import sys

from torch.export import ExportedProgram

from . import builtins

from ..support.ir_imports import (
    Context,
    Location,
    MLIRError,
    Module,
    Operation,
    PassManager,
    StringAttr,
)
from ..support.logging import aot_logger as logger
from ..transforms.general.custom_op_expansion import ExpandCustomOpsPass

from .support.procedural import (
    GlobalsDef,
    ProcedureTrace,
    current_ir_trace,
)

from .support.procedural.exported_program import import_exported_program

from .support.ir_utils import (
    ModuleBuilder,
    ModuleBuilderOptions,
)


__all__ = [
    "CompiledModule",
]

################################################################################
# Data structures
################################################################################


class ImportPhase(enum.IntEnum):
    # Imports to torch dialect IR.
    TORCH_IR = 0

    # Performs custom op expansion and post processing for known custom ops.
    CUSTOM_OP_EXPANSION = 1

    # Compiles to valid MLIR that IREE can ingest as an input with the
    # input-type of torch.
    IMPORT = CUSTOM_OP_EXPANSION

    # Runs the IREE input pipeline to compile to internal form.
    IREE_INTERNAL = 2

    # The full import pipeline (this is an alias for another enum value).
    FULL = IREE_INTERNAL

    @staticmethod
    def parse(spec: Union[str, None, "ImportPhase"]) -> "ImportPhase":
        if spec is None:
            return ImportPhase.IMPORT
        if isinstance(spec, ImportPhase):
            return spec
        spec = spec.upper().replace("-", "_")
        if spec not in ImportPhase.__members__:
            raise ValueError(
                f"For import_phase= argument, expected one of: "
                f"{', '.join(ImportPhase.__members__.keys())}"
            )
        return ImportPhase[spec]

    def __str__(self):
        return self.name


class PyOnlyDef:
    """Exportable that does not export but can be resolved in Python."""

    __slots__ = ["py_value"]

    def __init__(self, py_value):
        self.py_value = py_value

    def __str__(self):
        return str(self.py_value)

    def __repr__(self):
        return repr(self.py_value)

    def __call__(self, *args, **kwargs):
        return self.py_value(*args, **kwargs)


class ExportProcDef:
    __slots__ = [
        "callable",
        "export_name",
        "signature",
        "file_line_loc",
    ]

    def __init__(
        self,
        export_name: str,
        callable: Callable,
        *,
        signature,
        file_line_loc: Optional[Tuple[str, int]] = None,
    ):
        self.export_name = export_name
        self.callable = callable
        self.signature = signature
        self.file_line_loc = file_line_loc

    def copy(self) -> "ExportProcDef":
        return ExportProcDef(self.export_name, self.callable, signature=self.signature)

    def __repr__(self):
        return f"<def {self.export_name}({self.signature})>"


class ExportedProgramDef:
    def __init__(
        self,
        ep: ExportedProgram,
        *,
        export_name: Optional[str] = None,
        public: bool = False,
    ):
        self.export_name = export_name
        self.exported_program = ep
        self.public = public

    def copy(self) -> "ExportedProgramDef":
        return ExportedProgramDef(
            self.exported_program, export_name=self.export_name, public=self.public
        )

    def __repr__(self):
        return f"<exported_program {self.exported_program}>"


Exportable = Union[ExportProcDef, ExportedProgramDef, PyOnlyDef, GlobalsDef]


class CompiledModuleClassInfo:
    __slots__ = [
        "all_exports",
        "ir_module_name",
        "options",
    ]

    def __init__(self, *, ir_module_name: str, options: ModuleBuilderOptions):
        self.ir_module_name = ir_module_name
        self.all_exports: Dict[str, Exportable] = dict()
        self.options = options

    def add_export(self, key: str, value: Exportable):
        if key in self.all_exports:
            raise TypeError(f"Cannot export attribute more than once: {key}")
        self.all_exports[key] = value

    @property
    def export_procs(self) -> Generator[Tuple[str, ExportProcDef], None, None]:
        return filter(
            lambda kv_tuple: isinstance(kv_tuple[1], ExportProcDef),
            self.all_exports.items(),
        )  # type: ignore

    @property
    def exported_programs(
        self,
    ) -> Generator[Tuple[str, ExportedProgramDef], None, None]:
        return filter(
            lambda kv_tuple: isinstance(kv_tuple[1], ExportedProgramDef),
            self.all_exports.items(),
        )  # type: ignore

    @property
    def py_only_defs(self) -> Generator[Tuple[str, PyOnlyDef], None, None]:
        return filter(
            lambda kv_tuple: isinstance(kv_tuple[1], PyOnlyDef),
            self.all_exports.items(),
        )  # type: ignore

    @property
    def globals_defs(self) -> Generator[Tuple[str, GlobalsDef], None, None]:
        return filter(
            lambda kv_tuple: isinstance(kv_tuple[1], GlobalsDef),
            self.all_exports.items(),
        )  # type: ignore

    def def_attribute(self, key, value):
        # Some decorators, the only thing we do is convert them to PyOnlyDef.
        # Do that first so the generic descriptor code below handles them.
        if isinstance(value, builtins.jittable):
            value = PyOnlyDef(value)

        # Promote a torch ExportedProgram to an ExportedProgramDef.
        if isinstance(value, ExportedProgram):
            value = ExportedProgramDef(
                value, export_name=key, public=not key.startswith("_")
            )

        # Detect our own descriptors.
        if isinstance(value, GlobalsDef):
            logging.debug("DEFINE GLOBALS: %s = %r", key, value)
            self.add_export(key, value)
            return value
        if isinstance(value, ExportProcDef):
            value = value.copy()
            if value.export_name is None:
                value.export_name = key
            self.add_export(key, value)
            return value
        if isinstance(value, PyOnlyDef):
            logging.debug("DEFINE PY_ONLY: %s = %r", key, value)
            self.add_export(key, value)
            return value
        if isinstance(value, ExportedProgramDef):
            if value.export_name is None:
                value = value.copy()
                value.export_name = key
            logging.debug("DEFINE EXPORTED_PROGRAM: %r", value.export_name)
            self.add_export(key, value)
            return value

        # Infer if it is an exported function.
        if callable(value) and inspect.isfunction(value):
            return self.def_export_proc(key, value)

        raise TypeError(
            f"cannot set arbitrary Python value '{key}' on "
            f"compiled module: {value!r}"
        )

    def def_export_proc(self, name, f) -> ExportProcDef:
        logging.debug("DEFINE EXPORT: %s = %r", name, f)
        # Get a reasonable location.
        file_line_loc = None
        try:
            sourcefile = inspect.getsourcefile(f)
            _, linenum = sourcelines = inspect.getsourcelines(f)
        except OSError:
            ...
        else:
            file_line_loc = (sourcefile or "<unnamed>", linenum)

        sig = inspect.signature(f)
        if len(sig.parameters) < 1:
            raise TypeError(
                f"export proc '{name}' is expected to have a 'self' parameter"
            )

        # By default, we discover signature details from default values
        # on the function. But we should also source from an annotation.
        input_sig = []
        parameter_list = list(sig.parameters.values())
        # TODO: Reconstitute a pytree so as to handle kwargs?
        # See: https://github.com/nod-ai/SHARK-Turbine/issues/128
        for param in parameter_list[1:]:
            if (
                param.kind != inspect.Parameter.POSITIONAL_ONLY
                and param.kind != inspect.Parameter.POSITIONAL_OR_KEYWORD
            ):
                raise TypeError(
                    f"exported functions only support positional parameters"
                )
            param_desc = param.default
            if param_desc is inspect.Parameter.empty:
                # TODO: Merge from a decorator?
                # See: https://github.com/nod-ai/SHARK-Turbine/issues/126
                raise TypeError(
                    f"export function {name} missing required default value annotation "
                    f"for '{param.name}'"
                )
            input_sig.append(param_desc)

        info = ExportProcDef(name, f, signature=input_sig, file_line_loc=file_line_loc)
        self.add_export(name, info)
        return info


class CompiledModuleInstanceInfo:
    """Info class for compiled module instances."""

    __slots__ = [
        "class_info",
        "module_builder",
        "shadow_dict",
        "current_import_phase",
    ]

    def __init__(
        self, class_info: CompiledModuleClassInfo, module_builder: ModuleBuilder
    ):
        self.class_info = class_info
        self.module_builder = module_builder
        # The shadow dict holds instance attributes. We stash them here and the
        # Program instance itself arbitrates access via getattr/setattr.
        self.shadow_dict: dict[str, Any] = dict()
        self.current_import_phase = ImportPhase.TORCH_IR


################################################################################
# Live reference accounting
################################################################################

_all_compiled_module_class_infos: weakref.WeakKeyDictionary[
    "CompiledModuleMeta", CompiledModuleClassInfo
] = weakref.WeakKeyDictionary()
_all_compiled_module_instance_infos: weakref.WeakKeyDictionary[
    "CompiledModule", CompiledModuleInstanceInfo
] = weakref.WeakKeyDictionary()


################################################################################
# CompiledModule and metaclass
################################################################################

# Gate that is set to True once metaclass setup is complete.
_metaclass_setup_complete = False


@property  # type: ignore
def _blackhole_instance_attribute(self):
    # We're not here.
    raise AttributeError


def _uncallable_public_export(*args, **kwargs):
    raise RuntimeError(f"Calls to exported functions not yet supported")


_COMPILED_MODULE_API_ATTRIBUTES = [
    "create_from_dict",
    "expand_custom_ops",
    "export_global",
    "get_class_info",
    "get_info",
    "get_module_builder",
    "get_mlir_module",
    "jittable",
    "run_import",
    "run_pass_pipeline",
    "save_mlir",
]


class CompiledModuleMeta(type):
    """Metaclass for all CompiledModule subclasses.

    Do not use directly.
    """

    # __new__ on a metaclass is called when a new subclass is constructed.
    # It is passed the dictionary of declared attributes and any keyword
    # arguments from the class declaration:
    #   class Foo(Bar, kwarg="you probably just learned this is possible"):
    def __new__(
        mcls,
        name: str,
        bases,
        dct,
        *,
        export_name: Optional[str] = None,
        options: Optional[ModuleBuilderOptions] = None,
    ):
        if not _metaclass_setup_complete:
            return type.__new__(mcls, name, bases, dct)

        ir_module_name = _derive_ir_module_name(name, export_name)
        logger.debug("Create new CompiledModule: %s", ir_module_name)
        info = CompiledModuleClassInfo(
            ir_module_name=ir_module_name, options=options or ModuleBuilderOptions()
        )

        # Process that attributes that were set as part of class definition.
        # Any attributes that we decide are part of the compiled module
        # are removed and appropriately transferred to the backing info
        # hierarchy.
        del_attr_keys = set()
        for key, value in dct.items():
            if key.startswith("__") and key.endswith("__"):
                continue
            del_attr_keys.add(key)
            info.def_attribute(key, value)

        for key in del_attr_keys:
            del dct[key]

        # The CompiledModule exports a number of its own API methods, which
        # we explicitly hide on subclasses and instances.
        for key in _COMPILED_MODULE_API_ATTRIBUTES:
            if key not in dct:
                dct[key] = _blackhole_instance_attribute

        # Inheriting methods, globals, and export from parent class.
        # Use case such as building a child-class to StatelessLlama.
        for base in bases:
            if base is CompiledModule:
                continue
            base_exports = _all_compiled_module_class_infos[base].all_exports
            for export_name in base_exports:
                if export_name in info.all_exports:
                    continue
                info.all_exports[export_name] = base_exports[export_name]

        # Finish construction.
        new_class = type.__new__(mcls, name, bases, dct)
        _all_compiled_module_class_infos[new_class] = info
        return new_class

    # Gets unresolved attributes on classes of this meta-class.
    def __getattr__(cls, key):
        # CompiledModule does not expose anything else.
        if cls is CompiledModule:
            raise AttributeError(f"CompiledModule.{key}")
        info = CompiledModule.get_class_info(cls)
        try:
            return info.all_exports[key]
        except KeyError:
            raise AttributeError


class CompiledModule(metaclass=CompiledModuleMeta):
    """Base class for all staged modules."""

    @classmethod
    def create_from_dict(
        cls: CompiledModuleMeta,
        name: str,
        dct: dict,
        *,
        export_name: Optional[str] = None,
        options: Optional[ModuleBuilderOptions] = None,
    ) -> CompiledModuleMeta:
        """Creates a CompiledModule subclass with an explicit dictionary of members.

        This is the unsugared form of:

        ```
        class Foo(CompiledModule, export_name="bar"):
          def member(): ...
        ```
        """
        return CompiledModuleMeta(
            name, (cls,), dct, export_name=export_name, options=options
        )

    @staticmethod
    def get_class_info(cls: CompiledModuleMeta) -> CompiledModuleClassInfo:
        return _all_compiled_module_class_infos[cls]

    @staticmethod
    def get_info(inst: "CompiledModule") -> CompiledModuleInstanceInfo:
        return _all_compiled_module_instance_infos[inst]

    @staticmethod
    def get_module_builder(inst: "CompiledModule") -> Operation:
        if not isinstance(inst, CompiledModule):
            raise ValueError(
                f"Expected a CompiledModule instance but got: {inst.__class__}"
            )
        info = CompiledModule.get_info(inst)
        return info.module_builder

    @staticmethod
    def get_mlir_module(inst: "CompiledModule") -> Operation:
        return CompiledModule.get_module_builder(inst).module_op

    @staticmethod
    def run_import(
        inst: "CompiledModule", import_to: Union[ImportPhase, str, None] = "import"
    ):
        import_to = ImportPhase.parse(import_to)
        info = CompiledModule.get_info(inst)
        for phase in [
            ImportPhase.TORCH_IR,
            ImportPhase.CUSTOM_OP_EXPANSION,
            ImportPhase.IREE_INTERNAL,
        ]:
            if phase > import_to:
                logger.debug("Stopped import at phase %s", info.current_import_phase)
                break
            if info.current_import_phase >= phase:
                continue
            logger.debug("Run import phase %s", phase)
            if phase == ImportPhase.TORCH_IR:
                # Starting phase. Do nothing.
                ...
            elif phase == ImportPhase.CUSTOM_OP_EXPANSION:
                CompiledModule.expand_custom_ops(inst)
            elif phase == ImportPhase.IREE_INTERNAL:
                CompiledModule.run_pass_pipeline(inst, "builtin.module(torch-to-iree)")
            else:
                assert False, f"Phase {phase} not handled in switch"
            info.current_import_phase = phase

    @staticmethod
    def expand_custom_ops(inst: "CompiledModule"):
        """Performs custom torch.operator expansion for known custom ops."""
        logger.debug("Expand known torch.operator custom ops")
        module_op = CompiledModule.get_mlir_module(inst)
        p = ExpandCustomOpsPass(module_op)
        p.run()

    @staticmethod
    def run_pass_pipeline(
        inst: "CompiledModule", pipeline: str, enable_ir_printing: bool = False
    ):
        """Runs an arbitrary pass pipeline against the current IR.

        Args:
          pipeline: The text format pass pipeline as supported by PassManager.parse.
          enable_ir_printing: Enables print-after-all to stderr.
        """
        logger.debug("Run pass pipeline: %s", pipeline)
        module_op = CompiledModule.get_mlir_module(inst)
        with module_op.context:
            pm = PassManager.parse(pipeline)
            if enable_ir_printing:
                module_op.context.enable_multithreading(False)
                pm.enable_ir_printing()
            try:
                pm.run(module_op)
            except MLIRError:
                # TODO: Better error handling.
                # See: https://github.com/nod-ai/SHARK-Turbine/issues/127
                print(module_op, file=sys.stderr)
                raise

    @staticmethod
    def save_mlir(inst: "CompiledModule", path: Union[Path, str]):
        """Saves a snapshot of the MLIR module in this CompiledModule to a file.

        This is a convenience wrapper around the facilities of the underlying
        API and does not expose all features.

        Args:
          path: The file path to write to. If the extension is ".mlirbc", it
            will be written as bytecode.
        """
        path = Path(path)
        bytecode = path.suffix == ".mlirbc"
        module_op = CompiledModule.get_mlir_module(inst)
        with open(path, "wb") as f:
            if bytecode:
                module_op.write_bytecode(f)
            else:
                module_op.print(f, binary=True)

    jittable = staticmethod(builtins.jittable)

    def __getattr__(self, name):
        info = CompiledModule.get_info(self)
        try:
            return info.shadow_dict[name]
        except KeyError:
            raise AttributeError(f"Attribute {name} not defined")

    def __setattr__(self, name, value):
        info = CompiledModule.get_info(self)
        try:
            descriptor = info.shadow_dict[name]
        except KeyError:
            raise AttributeError(f"Attribute {name} cannot be set")
        current_ir_trace().handle_assignment(self, descriptor, value)

    def __new__(
        cls,
        *,
        context: Optional[Context] = None,
        module_op: Optional[Operation] = None,
        import_to: Union[ImportPhase, None, str] = "import",
    ):
        import_to = ImportPhase.parse(import_to)
        self = super().__new__(cls)
        class_info = CompiledModule.get_class_info(cls)
        if context and module_op:
            raise ValueError("Only one of context= or module_op= can be specified")
        if not context and not module_op:
            try:
                context = Context.current
            except ValueError:
                pass

        if not context:
            context = Context()

        if not module_op:
            with context:
                loc = Location.unknown(context=context)
                module = Module.create(loc)
                module_op = module.operation
                module_op.attributes["sym_name"] = StringAttr.get(
                    class_info.ir_module_name, context=context
                )
        module_builder = ModuleBuilder(module_op, options=class_info.options)
        info = CompiledModuleInstanceInfo(class_info, module_builder=module_builder)
        _all_compiled_module_instance_infos[self] = info

        # Instantiate globals
        for key, globals_def in info.class_info.globals_defs:
            info.shadow_dict[key] = globals_def.track(module_builder, key)

        # Make PyOnly defs visible.
        for key, py_def in info.class_info.py_only_defs:
            info.shadow_dict[key] = py_def.py_value

        # Instantiate exported programs.
        # TODO: This should be done in two phases along with export_procs
        # in order to enable dependence.
        for key, ep_def in info.class_info.exported_programs:
            info.shadow_dict[key] = import_exported_program(
                module_builder,
                ep_def.exported_program,
                symbol_name=ep_def.export_name or "main",
                symbol_visibility=None if ep_def.public else "private",
            )

        # Instantiate procs.
        # TODO: This should be done in two phases, first binding the symbols
        # and then defining them, enabling dependence.
        # See: https://github.com/nod-ai/SHARK-Turbine/issues/129
        for key, proc_def in info.class_info.export_procs:

            def do_export(proc_def: ExportProcDef):
                def invoke_with_self(*args, **kwargs):
                    return proc_def.callable(self, *args, **kwargs)

                logger.debug("Generating procedural function: %s", key)
                if proc_def.file_line_loc:
                    loc = Location.file(
                        proc_def.file_line_loc[0],
                        proc_def.file_line_loc[1],
                        col=0,
                        context=module_builder.context,
                    )
                else:
                    loc = Location.unknown(context=module_builder.context)
                trace = ProcedureTrace.define_func(
                    module_builder,
                    symbol_name=proc_def.export_name,
                    posargs=proc_def.signature,
                    kwargs={},  # TODO(#128): kwargs
                    loc=loc,
                )
                trace.trace_py_func(invoke_with_self)
                info.shadow_dict[key] = _uncallable_public_export

            do_export(proc_def)

        module_builder.finalize_construct()
        CompiledModule.run_import(self, import_to)
        return self


_metaclass_setup_complete = True

################################################################################
# Utilities
################################################################################


def _derive_ir_module_name(class_name: str, explicit_name: Optional[str]):
    """Returns an appropriate module export name given a class name and override.

    If an explicit_name is given, that is used as is. Otherwise, the class name
    is mangled by:
      * Removing and "Module" suffix.
      * Converting camel case to snake case.
    """
    if explicit_name:
        return explicit_name
    return _to_snake_case(_strip_suffix(class_name, "Module"))


def _to_snake_case(s: str) -> str:
    return re.sub(r"(?<!^)(?=[A-Z])", "_", s).lower()


def _strip_suffix(s: str, optional_suffix: str) -> str:
    if s.endswith(optional_suffix):
        return s[0 : len(s) - len(optional_suffix)]
    else:
        return s