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paddlepaddle--paddle/python/paddle/jit/dy2static/transformers/loop_transformer.py
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2026-07-13 12:40:42 +08:00

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# 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.base import unique_name
from paddle.utils import gast
from ..utils import (
GetterSetterHelper,
ast_to_source_code,
)
from .base import (
BaseTransformer,
ForLoopTuplePreTransformer,
ForNodeVisitor,
)
from .utils import (
ARGS_NAME,
FOR_BODY_PREFIX,
FOR_CONDITION_PREFIX,
WHILE_BODY_PREFIX,
WHILE_CONDITION_PREFIX,
FunctionNameLivenessAnalysis,
create_get_args_node,
create_name_str,
create_nonlocal_stmt_nodes,
create_set_args_node,
get_attribute_full_name,
get_parent_mapping,
)
__all__ = []
def create_while_nodes(
condition_name,
body_name,
loop_var_names,
push_pop_names,
getter_name,
setter_name,
):
"""
Returns a list of gast.Node which represents the calling of Paddle
controlflow while_loop.
Usually, the list just contain 1 statement such as:
[a, b, c] = paddle.jit.dy2static.convert_while_loop(
condition_name, body_name, [a, b, c])
where a, b, c are in loop_var_names.
However, if loop_var_names contains property such as foo.x, we cannot
assign the property as output of convert_while_loop because Python
property is a kind of read-only attribute. To handle the case, we replace
the attributes which are output of convert_while_loop with generated
variables, then if we know the attribute is not read-only at runtime, we
assign the attribute. The created statements are like:
[a, b, __attribute_variable_1] = paddle.jit.dy2static.convert_while_loop(
condition_name, body_name, [a, b, foo.x])
if not isinstance(getattr(type(foo), x, None), property): foo.x = __attribute_variable_1
The number of above statements is not only 1, that's why the return type is
a list of gast.Node.
"""
# NOTE(liym27):
# It's better to parse the source code into an AST node than to customize an AST node
# including child nodes, because it is easy to mistake the ast node type when customizing the node.
#
# For example: loop_var_names = [a, b, foo.x], the type of `a` or `b` is gast.Name,
# but the type of `foo.x` gast.Attribute.
# We have to make loop_var_names and assign_loop_var_names with same order
# set doesn't have order so we convert it to list
loop_var_names = list(loop_var_names)
assign_loop_var_names = []
for name in loop_var_names:
assign_loop_var_names.append(name)
while_func_name = "_jst.While"
while_node_str = f"{while_func_name}({condition_name}, {body_name}, {getter_name}, {setter_name}, return_name_ids={create_name_str(loop_var_names)}, push_pop_names={create_name_str(push_pop_names)})"
while_node = gast.parse(while_node_str).body[0]
ret = [while_node]
return ret
class NameVisitor(gast.NodeVisitor):
'''
Analysis name liveness for loop transformer
'''
def __init__(self, root_node):
# Set of gast.Name or gast.Attribute for variables
self.current_seen_vars = set()
# List of gast.While/gast.For nodes
self.current_loop = []
# List of nodes that have scope of variables.
self.nodes_with_scope = []
self.blacklist_names = {"False", "True", "None"}
# Mapping from gast.While/gast.For to variable nodes
self.before_loop_body_vars = defaultdict(set)
# NOTE: Use ordered list as dict value
self.in_loop_vars = defaultdict(list)
# Mapping from gast.While/gast.For to variable nodes which is condition
# of loop or being modified during the loop
self.write_in_loop = defaultdict(set)
self.condition_vars = defaultdict(set)
self.in_condition = False
# Some names are types, we shouldn't record them as loop var names.
self.type_vars = set()
self.to_parent_mapping = get_parent_mapping(root_node)
self.visit(root_node)
def get_loop_var_names(self, node):
assert isinstance(node, (gast.While, gast.For)), (
"Input node is not gast loop node"
)
loop_var_names = set()
create_var_names = set()
read_context = {type(gast.Load()), type(gast.AugLoad())}
in_loop_vars_list = self.in_loop_vars[node]
# get dict `var_name_to_ctxs`
var_name_to_ctxs = defaultdict(list)
for var_node in in_loop_vars_list:
var_name_to_ctxs[self._var_node_to_name(var_node)].append(
var_node.ctx
)
in_loop_vars = set(in_loop_vars_list)
in_loop_vars = self._remove_unnecessary_vars(in_loop_vars, node)
in_loop_name_strs = self._var_nodes_to_names(in_loop_vars)
before_loop_body_vars = self.before_loop_body_vars[node]
before_loop_body_vars = self._remove_unnecessary_vars(
before_loop_body_vars, node
)
before_loop_name_strs = self._var_nodes_to_names(before_loop_body_vars)
after_loop_vars = (
self.current_seen_vars - before_loop_body_vars - in_loop_vars
)
after_loop_vars = self._remove_unnecessary_vars(after_loop_vars, node)
after_loop_name_strs = self._var_nodes_to_names(
after_loop_vars, read_context
)
condition_vars = self.condition_vars[node]
condition_names = self._var_nodes_to_names(condition_vars)
write_vars = self.write_in_loop[node]
write_names = self._var_nodes_to_names(write_vars)
for name in in_loop_name_strs:
if name in before_loop_name_strs:
# If a variable is used in loop and created before loop
# If this var is a basic variable and read-only and not
# condition var, it may not be loop_var else it should
# be in loop_var as input
if (name not in condition_names) and (name not in write_names):
continue
loop_var_names.add(name)
elif name in after_loop_name_strs:
# If a variable is created in the while loop and read after
# loop, it should be in loop_var and we should create it
# because name in after_loop_name must be initialized in loop
# So it is write-only, we don't have to filter read-only basic
# vars out
loop_var_names.add(name)
create_var_names.add(name)
else:
# If a variable is used and created in loop, but used before created,
# it should be in loop_var and we should create it.
# For example, `var_a` should be in loop_var and we should create it.
#
# res = 0
# for i, x in enumerate(x_array):
# if i > 2:
# x = func1(var_a)
# var_a = func2(x)
#
is_created = False
for ctx in var_name_to_ctxs[name]:
if isinstance(ctx, gast.Store):
is_created = True
if (
isinstance(var_name_to_ctxs[name][0], gast.Load)
and is_created
):
loop_var_names.add(name)
create_var_names.add(name)
return loop_var_names, create_var_names
def visit_Name(self, node):
if self._is_call_func_name_node(node):
self.generic_visit(node)
return
if node.id in self.blacklist_names:
self.generic_visit(node)
return
self.current_seen_vars.add(node)
write_context = {
type(gast.Store()),
type(gast.AugStore()),
type(gast.Del()),
}
for loop_node in self.current_loop:
self.in_loop_vars[loop_node].append(node)
if type(node.ctx) in write_context:
self.write_in_loop[loop_node].add(node)
if self.in_condition:
self.condition_vars[loop_node].add(node)
self.generic_visit(node)
def visit_FunctionDef(self, node):
self.nodes_with_scope.append(node)
self.blacklist_names.add(node.name)
# The variables in the function are not visible to the outside scope.
before_func_seen_vars = copy.copy(self.current_seen_vars)
self.generic_visit(node)
self.nodes_with_scope.pop()
# After exiting the scope of the node, variables in this scope
# should be removed from self.current_seen_vars.
if self.nodes_with_scope:
self.current_seen_vars = before_func_seen_vars
def visit(self, node):
method = 'visit_' + node.__class__.__name__
visitor = getattr(self, method, self.generic_visit)
ret = visitor(node)
return ret
def visit_Attribute(self, node):
if self._is_call_func_name_node(node):
return
attr_full_name = get_attribute_full_name(node)
# Class variables are not allowed to appear in the arguments list
# of defined function under class methods in Python.
"""
def class_func(self):
def while_loop_body(self.x, y) # `self.x` is illegal.
"""
# TODO: If do change the variable with `self.var`, need a better
# way to deal with this case.
if attr_full_name.startswith("self."):
return
self.current_seen_vars.add(node)
for loop_node in self.current_loop:
self.in_loop_vars[loop_node].append(node)
# sub-nodes are visited during get_attribute_full_name and we shouldn't
# visit again
def visit_For(self, node):
self.current_loop.append(node)
self.in_condition = True
self.visit(node.target)
self.visit(node.iter)
self.in_condition = False
self.before_loop_body_vars[node] = copy.copy(self.current_seen_vars)
self.generic_visit(node)
self.current_loop.pop()
def visit_While(self, node):
self.current_loop.append(node)
self.in_condition = True
self.visit(node.test)
self.in_condition = False
self.before_loop_body_vars[node] = copy.copy(self.current_seen_vars)
self.generic_visit(node)
self.current_loop.pop()
def visit_Call(self, node):
# Store type var names such as "isinstance(x, some_type_names)" and
# Remove them later
if isinstance(node.func, gast.Name) and node.func.id == 'isinstance':
type_node = node.args[1]
if isinstance(type_node, gast.Tuple):
for element in type_node.elts:
self.type_vars.add(ast_to_source_code(element).strip())
else:
self.type_vars.add(ast_to_source_code(type_node).strip())
self.generic_visit(node)
def _var_nodes_to_names(self, node_set, ctx_filter_set=None):
ret = set()
for node in node_set:
if ctx_filter_set is None or type(node.ctx) in ctx_filter_set:
ret.add(self._var_node_to_name(node))
return ret
def _var_node_to_name(self, node):
if isinstance(node, gast.Name):
return node.id
elif isinstance(node, gast.Attribute):
return get_attribute_full_name(node)
def _is_call_func_name_node(self, node):
parent_node = self._get_parent_node(node)
if isinstance(parent_node, gast.Call) and parent_node.func == node:
return True
return False
def _is_global_or_nonlocal(self, node):
return False
def _is_ancestor_node(self, ancestor_node, node):
parent_node = self._get_parent_node(node)
while parent_node is not None:
if parent_node == ancestor_node:
return True
parent_node = self._get_parent_node(parent_node)
return False
def _get_parent_node(self, node):
return self.to_parent_mapping.get(node)
def _remove_unnecessary_vars(self, loop_vars, loop_node):
"""
Remove unnecessary vars from before_loop_vars, after_loop_vars or in_loop_vars about loop_node.
1. Remove target vars of gast.For from before_loop_vars or after_loop_vars.
2. Remove vars only in gast.comprehension.
3. Remove vars that are type names, for example: "isinstance(x, var_type_name)"
:param loop_vars: before_loop_vars, after_loop_vars or in_loop_vars of loop_node.
:param loop_node: Current loop node.
"""
def filter_name_nodes_from(root_node, target_var_names):
"""
Filter children with gast.Name type from node.(inclusivly)
"""
name_nodes = set()
if isinstance(root_node, gast.Name):
if node.id in target_var_names:
name_nodes.add(root_node)
for child_node in gast.walk(root_node):
if isinstance(child_node, gast.Name):
if child_node.id in target_var_names:
name_nodes.add(child_node)
return name_nodes
vars_of_list_generator = set()
target_vars_of_for_node = set()
for name_node in loop_vars:
if not isinstance(name_node, gast.Name):
continue
parent_node = self._get_parent_node(name_node)
# NOTE: gast.For.target or gast.comprehension.target can be gast.Tuple.
# For examples:
# 1) `for i, j in enumerate(x)` has two target vars: i and j
# 2) `[x for x,y in array]` has two target vars: x and y
if isinstance(parent_node, gast.Tuple):
parent_node = self._get_parent_node(parent_node)
# 1. Get vars only in gast.comprehension.
# For examples:
# 1) [x for x,y in array] -> x, x, y
# 2) [f(x) for x in array] -> x
# 3) [func(x, y) for x in array] -> x, x
if isinstance(parent_node, gast.comprehension):
# 1.1 target vars in list/set comprehensions
target_node = parent_node.target
if isinstance(target_node, gast.Tuple):
target_vars = target_node.elts
else:
target_vars = [target_node]
vars_of_list_generator = vars_of_list_generator | set(
target_vars
)
# 1.2 vars from target vars used in elt_node
target_var_names = {var.id for var in target_vars}
comp_node = self._get_parent_node(parent_node)
elt_nodes = []
if isinstance(comp_node, gast.ListComp):
elt_nodes.append(comp_node.elt)
elif isinstance(comp_node, gast.DictComp):
elt_nodes.extend([comp_node.key, comp_node.value])
for node in elt_nodes:
vars_of_list_generator |= filter_name_nodes_from(
node, target_var_names
)
# 2. Get target vars or vars from target vars used in for-loop but the for-loop is
# 1) not the "loop_node" itself
# 2) not the ancestor of the "loop_node"
#
# For examples:
# for k in range(x): # if it's this "loop_node", i or j both should be target vars.
# # do something
#
# for i in range(a): # if it's this "loop_node", k or j should be in target vars but i should not.
# for j in range(a): # if it's this "loop_node", k should be in target_vars but i or j should not.
# x = i+j
elif isinstance(parent_node, gast.For):
if parent_node is loop_node:
continue
if self._is_ancestor_node(parent_node, loop_node):
continue
# 2.1 target vars in gast.For node.
target_node = parent_node.target
if isinstance(target_node, gast.Tuple):
target_vars = target_node.elts
else:
target_vars = [target_node]
target_vars_of_for_node = target_vars_of_for_node | set(
target_vars
)
# 2.2 vars from target vars used in for-loop
target_vars_name_strs = {var.id for var in target_vars_of_for_node}
for var in loop_vars:
if not isinstance(var, gast.Name):
continue
if (
var.id in target_vars_name_strs
and var not in self.condition_vars[loop_node]
):
target_vars_of_for_node.add(var)
removed_vars = target_vars_of_for_node | vars_of_list_generator
# 3. Remove var type names which are stored in self.type_vars
for var in loop_vars:
if ast_to_source_code(var).strip() in self.type_vars:
removed_vars.add(var)
return loop_vars - removed_vars
class LoopTransformer(BaseTransformer):
"""
This class transforms python while/for statement into Static Graph Ast
"""
def __init__(self, root):
self.root = root
FunctionNameLivenessAnalysis(self.root)
def transform(self):
ForLoopTuplePreTransformer(self.root).transform()
self.visit(self.root)
def visit_While(self, node):
self.generic_visit(node)
new_stmts = self.get_while_stmt_nodes(node)
return new_stmts
def visit_For(self, node):
self.generic_visit(node)
new_stmts = self.get_for_stmt_nodes(node)
return new_stmts
def replace_stmt_list(self, body_list):
if not isinstance(body_list, list):
return
i = 0
while i < len(body_list):
if isinstance(body_list[i], gast.While):
new_stmts = self.get_while_stmt_nodes(body_list[i])
body_list[i : i + 1] = new_stmts
i += len(new_stmts)
elif isinstance(body_list[i], gast.For):
new_stmts = self.get_for_stmt_nodes(body_list[i])
body_list[i : i + 1] = new_stmts
i += len(new_stmts)
else:
i += 1
def get_for_stmt_nodes(self, node):
# TODO: consider for - else in python
# 1. get key statements for different cases
# NOTE 1: three key statements:
# 1). init_stmts: list[node], prepare nodes of for loop, may not only one
# 2). cond_stmt: node, condition node to judge whether continue loop
# 3). body_stmts: list[node], updated loop body, sometimes we should change
# the original statement in body, not just append new statement
#
# NOTE 2: The following `for` statements will be transformed to `while` statements:
# 1). for x in range(*)
# 2). for x in iter_var
# 3). for i, x in enumerate(*)
current_for_node_parser = ForNodeVisitor(node)
stmts_tuple = current_for_node_parser.parse()
if stmts_tuple is None:
return [node]
init_stmts, cond_stmt, body_stmts = stmts_tuple
# 2. get original loop vars
loop_var_names, create_var_names = (
node.pd_scope.modified_vars(),
node.pd_scope.created_vars(),
)
push_pop_names = list(node.pd_scope.variadic_length_vars())
# TODO: Remove the bunch of code? We have the unique format `for A in B:`
# NOTE: in 'for x in var' or 'for i, x in enumerate(var)' cases,
# we need append new loop var & remove useless loop var
# 1. for x in var -> x is no need
# 2. for i, x in enumerate(var) -> x is no need
if current_for_node_parser.is_for_iter():
iter_var_name = current_for_node_parser.iter_var_name
iter_idx_name = current_for_node_parser.iter_idx_name
loop_var_names.add(iter_idx_name)
if current_for_node_parser.enum_idx_name is not None:
loop_var_names.add(current_for_node_parser.enum_idx_name)
# 3. prepare result statement list
new_stmts = []
# Python can create variable in loop and use it out of loop, E.g.
#
# for x in range(10):
# y += x
# print(x) # x = 10
#
# We don't need to create static variable for them, because
# we do this in CreateUndefinedVarTransformer
# create non-local statement for body and cond.
nonlocal_names = list(loop_var_names | create_var_names)
nonlocal_names.sort()
# TODO(dev): Need a better way to deal this.
if ARGS_NAME in nonlocal_names:
nonlocal_names.remove(ARGS_NAME)
nonlocal_stmt_node = create_nonlocal_stmt_nodes(nonlocal_names)
# 4. append init statements
new_stmts.extend(init_stmts)
# 5. create & append condition function node
condition_func_node = gast.FunctionDef(
name=unique_name.generate(FOR_CONDITION_PREFIX),
args=gast.arguments(
args=[],
posonlyargs=[],
vararg=None,
kwonlyargs=[],
kw_defaults=None,
kwarg=None,
defaults=[],
),
body=[*nonlocal_stmt_node, gast.Return(value=cond_stmt)],
decorator_list=[],
returns=None,
type_comment=None,
type_params=[],
)
new_stmts.append(condition_func_node)
# 6. create & append loop body function node
# append return values for loop body
body_func_node = gast.FunctionDef(
name=unique_name.generate(FOR_BODY_PREFIX),
args=gast.arguments(
args=[],
posonlyargs=[],
vararg=None,
kwonlyargs=[],
kw_defaults=None,
kwarg=None,
defaults=[],
),
body=nonlocal_stmt_node + body_stmts,
decorator_list=[],
returns=None,
type_comment=None,
type_params=[],
)
new_stmts.append(body_func_node)
helper = GetterSetterHelper(None, None, nonlocal_names, push_pop_names)
get_args_node = create_get_args_node(helper.union())
set_args_node = create_set_args_node(helper.union())
# 7. create & append while loop node
while_loop_nodes = create_while_nodes(
condition_func_node.name,
body_func_node.name,
nonlocal_names,
push_pop_names,
get_args_node.name,
set_args_node.name,
)
new_stmts.extend([get_args_node, set_args_node])
new_stmts.extend(while_loop_nodes)
return new_stmts
def get_while_stmt_nodes(self, node):
loop_var_names, create_var_names = (
node.pd_scope.modified_vars(),
node.pd_scope.created_vars(),
)
push_pop_names = list(node.pd_scope.variadic_length_vars())
new_stmts = []
# create non-local statement for body and cond.
nonlocal_names = list(loop_var_names | create_var_names)
nonlocal_names.sort()
# TODO(dev): Need a better way to deal this.
if ARGS_NAME in nonlocal_names:
nonlocal_names.remove(ARGS_NAME)
nonlocal_stmt_node = create_nonlocal_stmt_nodes(nonlocal_names)
# Python can create variable in loop and use it out of loop, E.g.
#
# while x < 10:
# x += 1
# y = x
# z = y
#
# We don't need to create static variable for those variables, because
# we do this in CreateUndefinedVarTransformer
condition_func_node = gast.FunctionDef(
name=unique_name.generate(WHILE_CONDITION_PREFIX),
args=gast.arguments(
args=[],
posonlyargs=[],
vararg=None,
kwonlyargs=[],
kw_defaults=None,
kwarg=None,
defaults=[],
),
body=[*nonlocal_stmt_node, gast.Return(value=node.test)],
decorator_list=[],
returns=None,
type_comment=None,
type_params=[],
)
new_stmts.append(condition_func_node)
new_body = node.body
body_func_node = gast.FunctionDef(
name=unique_name.generate(WHILE_BODY_PREFIX),
args=gast.arguments(
args=[],
posonlyargs=[],
vararg=None,
kwonlyargs=[],
kw_defaults=None,
kwarg=None,
defaults=[],
),
body=nonlocal_stmt_node + new_body,
decorator_list=[],
returns=None,
type_comment=None,
type_params=[],
)
new_stmts.append(body_func_node)
helper = GetterSetterHelper(None, None, nonlocal_names, push_pop_names)
get_args_node = create_get_args_node(helper.union())
set_args_node = create_set_args_node(helper.union())
while_loop_nodes = create_while_nodes(
condition_func_node.name,
body_func_node.name,
nonlocal_names,
push_pop_names,
get_args_node.name,
set_args_node.name,
)
new_stmts.extend([get_args_node, set_args_node])
new_stmts.extend(while_loop_nodes)
return new_stmts