ifelse_transformer.py 14.7 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
#   Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import copy
from collections import defaultdict

from paddle.fluid import unique_name
19
from paddle.jit.dy2static.static_analysis import AstNodeWrapper
20
from paddle.jit.dy2static.utils import (
21
    FOR_ITER_INDEX_PREFIX,
22 23
    FOR_ITER_ITERATOR_PREFIX,
    FOR_ITER_TARGET_PREFIX,
24
    FOR_ITER_TUPLE_INDEX_PREFIX,
25
    FOR_ITER_TUPLE_PREFIX,
26 27 28
    FOR_ITER_VAR_LEN_PREFIX,
    FOR_ITER_VAR_NAME_PREFIX,
    FOR_ITER_ZIP_TO_LIST_PREFIX,
29
    FunctionNameLivenessAnalysis,
30
    GetterSetterHelper,
31 32 33
    ast_to_source_code,
    create_funcDef_node,
    create_get_args_node,
34
    create_name_str,
35 36
    create_nonlocal_stmt_nodes,
    create_set_args_node,
37
)
38

39 40 41 42 43 44 45 46
# gast is a generic AST to represent Python2 and Python3's Abstract Syntax Tree(AST).
# It provides a compatibility layer between the AST of various Python versions,
# as produced by ast.parse from the standard ast module.
# See details in https://github.com/serge-sans-paille/gast/
from paddle.utils import gast

from .base_transformer import BaseTransformer

47 48
__all__ = ['IfElseTransformer']

49 50
TRUE_FUNC_PREFIX = 'true_fn'
FALSE_FUNC_PREFIX = 'false_fn'
51 52 53
GET_ARGS_FUNC_PREFIX = 'get_args'
SET_ARGS_FUNC_PREFIX = 'set_args'
ARGS_NAME = '__args'
54 55


56
class IfElseTransformer(BaseTransformer):
57 58 59 60 61
    """
    Transform if/else statement of Dygraph into Static Graph.
    """

    def __init__(self, wrapper_root):
62 63 64 65
        assert isinstance(wrapper_root, AstNodeWrapper), (
            "Type of input node should be AstNodeWrapper, but received %s ."
            % type(wrapper_root)
        )
66
        self.root = wrapper_root.node
67
        FunctionNameLivenessAnalysis(
68 69
            self.root
        )  # name analysis of current ast tree.
70 71 72 73 74 75 76 77 78

    def transform(self):
        """
        Main function to transform AST.
        """
        self.visit(self.root)

    def visit_If(self, node):
        self.generic_visit(node)
79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103
        (
            true_func_node,
            false_func_node,
            get_args_node,
            set_args_node,
            return_name_ids,
            push_pop_ids,
        ) = transform_if_else(node, self.root)

        new_node = create_convert_ifelse_node(
            return_name_ids,
            push_pop_ids,
            node.test,
            true_func_node,
            false_func_node,
            get_args_node,
            set_args_node,
        )

        return [
            get_args_node,
            set_args_node,
            true_func_node,
            false_func_node,
        ] + [new_node]
104 105 106 107 108 109 110

    def visit_Call(self, node):
        # Remove `numpy()` statement, like `Tensor.numpy()[i]` -> `Tensor[i]`
        if isinstance(node.func, gast.Attribute):
            attribute = node.func
            if attribute.attr == 'numpy':
                node = attribute.value
111
        self.generic_visit(node)
112 113
        return node

114 115 116 117
    def visit_IfExp(self, node):
        """
        Transformation with `true_fn(x) if Tensor > 0 else false_fn(x)`
        """
118
        self.generic_visit(node)
119

120 121 122
        new_node = create_convert_ifelse_node(
            None, None, node.test, node.body, node.orelse, None, None, True
        )
123 124 125 126 127
        # Note: A blank line will be added separately if transform gast.Expr
        # into source code. Using gast.Expr.value instead to avoid syntax error
        # in python.
        if isinstance(new_node, gast.Expr):
            new_node = new_node.value
128

129 130
        return new_node

131

132
class NameVisitor(gast.NodeVisitor):
133 134 135
    def __init__(self, after_node=None, end_node=None):
        # The start node (exclusive) of the visitor
        self.after_node = after_node
136 137
        # The terminate node of the visitor.
        self.end_node = end_node
138 139 140 141
        # Dict to store the names and ctxs of vars.
        self.name_ids = defaultdict(list)
        # List of current visited nodes
        self.ancestor_nodes = []
142 143
        # True when in range (after_node, end_node).
        self._in_range = after_node is None
144
        self._candidate_ctxs = (gast.Store, gast.Load, gast.Param)
145
        self._def_func_names = set()
146 147 148

    def visit(self, node):
        """Visit a node."""
149 150 151 152 153
        if self.after_node is not None and node == self.after_node:
            self._in_range = True
            return
        if node == self.end_node:
            self._in_range = False
154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183
            return

        self.ancestor_nodes.append(node)
        method = 'visit_' + node.__class__.__name__
        visitor = getattr(self, method, self.generic_visit)
        ret = visitor(node)
        self.ancestor_nodes.pop()

        return ret

    def visit_If(self, node):
        """
        For nested `if/else`, the created vars are not always visible for parent node.
        In addition, the vars created in `if.body` are not visible for `if.orelse`.

        Case 1:
            x = 1
            if m > 1:
                res = new_tensor
            res = res + 1   # Error, `res` is not visible here.

        Case 2:
            if x_tensor > 0:
                res = new_tensor
            else:
                res = res + 1   # Error, `res` is not visible here.

        In above two cases, we should consider to manage the scope of vars to parsing
        the arguments and returned vars correctly.
        """
184
        if not self._in_range or not self.end_node:
185
            self.generic_visit(node)
186
            return
187
        else:
188 189 190
            before_if_name_ids = copy.deepcopy(self.name_ids)
            body_name_ids = self._visit_child(node.body)
            # If traversal process stops early in `if.body`, return the currently seen name_ids.
191
            if not self._in_range:
192 193 194 195
                self._update_name_ids(before_if_name_ids)
            else:
                else_name_ids = self._visit_child(node.orelse)
                # If traversal process stops early in `if.orelse`, return the currently seen name_ids.
196
                if not self._in_range:
197 198 199 200
                    self._update_name_ids(before_if_name_ids)
                else:
                    # Blocks the vars in `if.body` and only inserts the vars both created in 'if/else' branch
                    # into name_ids.
201
                    new_name_ids = self._find_new_name_ids(
202 203
                        body_name_ids, else_name_ids
                    )
204 205 206 207
                    for new_name_id in new_name_ids:
                        before_if_name_ids[new_name_id].append(gast.Store())

                    self.name_ids = before_if_name_ids
208 209

    def visit_Attribute(self, node):
210
        if not self._in_range or not self._is_call_func_name_node(node):
211 212 213
            self.generic_visit(node)

    def visit_Name(self, node):
214 215 216
        if not self._in_range:
            self.generic_visit(node)
            return
217
        blacklist = {'True', 'False', 'None'}
218 219
        if node.id in blacklist:
            return
220 221
        if node.id in self._def_func_names:
            return
222 223 224 225 226
        if not self._is_call_func_name_node(node):
            if isinstance(node.ctx, self._candidate_ctxs):
                self.name_ids[node.id].append(node.ctx)

    def visit_Assign(self, node):
227 228 229
        if not self._in_range:
            self.generic_visit(node)
            return
230 231 232 233
        # Visit `value` firstly.
        node._fields = ('value', 'targets')
        self.generic_visit(node)

234
    def visit_FunctionDef(self, node):
235 236 237
        # NOTE: We skip to visit names of get_args and set_args, because they contains
        # nonlocal statement such as 'nonlocal x, self' where 'self' should not be
        # parsed as returned value in contron flow.
238 239 240 241
        if (
            GET_ARGS_FUNC_PREFIX in node.name
            or SET_ARGS_FUNC_PREFIX in node.name
        ):
242 243
            return

244 245 246
        if not self._in_range:
            self.generic_visit(node)
            return
247
        self._def_func_names.add(node.name)
248 249 250 251 252 253 254
        if not self.end_node:
            self.generic_visit(node)
        else:
            before_name_ids = copy.deepcopy(self.name_ids)
            self.name_ids = defaultdict(list)
            self.generic_visit(node)

255
            if not self._in_range:
256 257 258 259
                self._update_name_ids(before_name_ids)
            else:
                self.name_ids = before_name_ids

260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277
    def _visit_child(self, node):
        self.name_ids = defaultdict(list)
        if isinstance(node, list):
            for item in node:
                if isinstance(item, gast.AST):
                    self.visit(item)
        elif isinstance(node, gast.AST):
            self.visit(node)

        return copy.deepcopy(self.name_ids)

    def _find_new_name_ids(self, body_name_ids, else_name_ids):
        def is_required_ctx(ctxs, required_ctx):
            for ctx in ctxs:
                if isinstance(ctx, required_ctx):
                    return True
            return False

278
        candidate_name_ids = set(body_name_ids.keys()) & set(
279 280
            else_name_ids.keys()
        )
281 282 283
        store_ctx = gast.Store
        new_name_ids = set()
        for name_id in candidate_name_ids:
284 285 286
            if is_required_ctx(
                body_name_ids[name_id], store_ctx
            ) and is_required_ctx(else_name_ids[name_id], store_ctx):
287 288 289 290 291
                new_name_ids.add(name_id)

        return new_name_ids

    def _is_call_func_name_node(self, node):
292
        white_func_names = set(['append', 'extend'])
293 294 295 296
        if len(self.ancestor_nodes) > 1:
            assert self.ancestor_nodes[-1] == node
            parent_node = self.ancestor_nodes[-2]
            if isinstance(parent_node, gast.Call) and parent_node.func == node:
297
                # e.g: var_list.append(elem), var_list is also a name_id.
298 299 300 301
                should_skip = (
                    isinstance(node, gast.Attribute)
                    and node.attr in white_func_names
                )
302 303
                if not should_skip:
                    return True
304 305
        return False

306
    def _update_name_ids(self, new_name_ids):
307
        for name_id, ctxs in new_name_ids.items():
308 309
            self.name_ids[name_id] = ctxs + self.name_ids[name_id]

310

311 312 313 314
def _valid_nonlocal_names(return_name_ids, nonlocal_names):
    """
    All var in return_name_ids should be in nonlocal_names.
    Moreover, we will always put return_name_ids in front of nonlocal_names.
315

316 317 318 319 320 321 322 323 324 325 326 327
    For Example:

        return_name_ids: [x, y]
        nonlocal_names : [a, y, b, x]

    Return:
        nonlocal_names : [x, y, a, b]
    """
    assert isinstance(return_name_ids, list)
    for name in return_name_ids:
        if name not in nonlocal_names:
            raise ValueError(
328 329 330 331
                "Required returned var '{}' must be in 'nonlocal' statement '', but not found.".format(
                    name
                )
            )
332 333 334 335 336
        nonlocal_names.remove(name)

    return return_name_ids + nonlocal_names


337 338 339 340
def transform_if_else(node, root):
    """
    Transform ast.If into control flow statement of Paddle static graph.
    """
341

342
    # TODO(liym27): Consider variable like `self.a` modified in if/else node.
343
    return_name_ids = sorted(list(node.pd_scope.modified_vars()))
344
    push_pop_ids = sorted(list(node.pd_scope.variadic_length_vars()))
345
    nonlocal_names = list(return_name_ids)
346 347 348 349 350
    nonlocal_names.sort()
    # NOTE: All var in return_name_ids should be in nonlocal_names.
    nonlocal_names = _valid_nonlocal_names(return_name_ids, nonlocal_names)

    # TODO(dev): Need a better way to deal this.
351 352
    # LoopTransformer will create some special vars, which is not visiable by users. so we can sure it's safe to remove them.
    filter_names = [
353 354 355 356 357 358 359 360 361
        ARGS_NAME,
        FOR_ITER_INDEX_PREFIX,
        FOR_ITER_TUPLE_PREFIX,
        FOR_ITER_TARGET_PREFIX,
        FOR_ITER_ITERATOR_PREFIX,
        FOR_ITER_TUPLE_INDEX_PREFIX,
        FOR_ITER_VAR_LEN_PREFIX,
        FOR_ITER_VAR_NAME_PREFIX,
        FOR_ITER_ZIP_TO_LIST_PREFIX,
362 363 364 365
    ]

    def remove_if(x):
        for name in filter_names:
366 367
            if x.startswith(name):
                return False
368 369 370 371
        return True

    nonlocal_names = list(filter(remove_if, nonlocal_names))
    return_name_ids = nonlocal_names
372

373
    nonlocal_stmt_node = create_nonlocal_stmt_nodes(nonlocal_names)
374

375 376 377 378 379 380 381 382 383
    empty_arg_node = gast.arguments(
        args=[],
        posonlyargs=[],
        vararg=None,
        kwonlyargs=[],
        kw_defaults=None,
        kwarg=None,
        defaults=[],
    )
384 385

    true_func_node = create_funcDef_node(
386
        nonlocal_stmt_node + node.body,
387
        name=unique_name.generate(TRUE_FUNC_PREFIX),
388
        input_args=empty_arg_node,
389 390
        return_name_ids=[],
    )
391
    false_func_node = create_funcDef_node(
392
        nonlocal_stmt_node + node.orelse,
393
        name=unique_name.generate(FALSE_FUNC_PREFIX),
394
        input_args=empty_arg_node,
395 396
        return_name_ids=[],
    )
397

398 399 400
    helper = GetterSetterHelper(None, None, nonlocal_names, push_pop_ids)
    get_args_node = create_get_args_node(helper.union())
    set_args_node = create_set_args_node(helper.union())
401

402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421
    return (
        true_func_node,
        false_func_node,
        get_args_node,
        set_args_node,
        return_name_ids,
        push_pop_ids,
    )


def create_convert_ifelse_node(
    return_name_ids,
    push_pop_ids,
    pred,
    true_func,
    false_func,
    get_args_func,
    set_args_func,
    is_if_expr=False,
):
422
    """
423
    Create `paddle.jit.dy2static.convert_ifelse(
424
            pred, true_fn, false_fn, get_args, set_args, return_name_ids)`
425
    to replace original `python if/else` statement.
426
    """
427 428 429 430 431 432 433 434
    if is_if_expr:
        true_func_source = "lambda : {}".format(ast_to_source_code(true_func))
        false_func_source = "lambda : {}".format(ast_to_source_code(false_func))
    else:
        true_func_source = true_func.name
        false_func_source = false_func.name

    convert_ifelse_layer = gast.parse(
435
        '_jst.IfElse('
436
        '{pred}, {true_fn}, {false_fn}, {get_args}, {set_args}, {return_name_ids}, push_pop_names={push_pop_ids})'.format(
437 438 439
            pred=ast_to_source_code(pred),
            true_fn=true_func_source,
            false_fn=false_func_source,
440 441 442
            get_args=get_args_func.name
            if not is_if_expr
            else 'lambda: None',  # TODO: better way to deal with this
443
            set_args=set_args_func.name
444 445
            if not is_if_expr
            else 'lambda args: None',
446
            return_name_ids=create_name_str(return_name_ids),
447 448 449
            push_pop_ids=create_name_str(push_pop_ids),
        )
    ).body[0]
450

451
    return convert_ifelse_layer