def computeExpressionRaw(self, trace_collection):
self.variable_trace = trace_collection.getVariableCurrentTrace(
variable=self.variable
)
replacement = self.variable_trace.getReplacementNode(self)
if replacement is not None:
trace_collection.signalChange(
"new_expression",
self.source_ref,
"Value propagated for '%s' from '%s'."
% (
self.variable.getName(),
replacement.getSourceReference().getAsString(),
),
)
# Need to compute the replacement still.
return replacement.computeExpressionRaw(trace_collection)
# If we cannot be sure if the value is set, then we need the fallback,
# otherwise we could remove it simply.
if self.variable_trace.mustHaveValue():
trace_collection.signalChange(
"new_expression",
self.source_ref,
"Name '%s' must be in locals dict." % self.variable.getName(),
)
result = ExpressionLocalsVariableRef(
locals_scope=self.locals_scope,
variable_name=self.variable.getName(),
source_ref=self.source_ref,
)
# Need to compute the replacement still.
return result.computeExpressionRaw(trace_collection)
else:
trace_collection.onExceptionRaiseExit(BaseException)
branch_fallback = TraceCollectionBranch(
parent=trace_collection, name="fallback node usage"
)
branch_fallback.computeBranch(self.subnode_fallback)
trace_collection.mergeBranches(branch_fallback, None)
# if we can be sure if doesn't have a value set, go to the fallback directly.
if self.variable_trace.mustNotHaveValue():
return (
self.subnode_fallback,
"new_expression",
"Name '%s' cannot be in locals dict." % self.variable.getName(),
)
else:
return self, None, None
def computeStatement(self, trace_collection):
outer_trace_collection = trace_collection
trace_collection = TraceCollectionBranch(
parent = trace_collection,
name = "loop"
)
loop_body, break_collections = self.computeLoopBody(trace_collection)
# Consider trailing "continue" statements, these have no effect, so we
# can remove them.
if loop_body is not None:
assert loop_body.isStatementsSequence()
statements = loop_body.getStatements()
assert statements # Cannot be empty
# If the last statement is a "continue" statement, it can simply
# be discarded.
last_statement = statements[-1]
if last_statement.isStatementLoopContinue():
if len(statements) == 1:
self.setLoopBody(None)
loop_body = None
else:
last_statement.replaceWith(None)
trace_collection.signalChange(
"new_statements",
last_statement.getSourceReference(),
"""\
Removed useless terminal 'continue' as last statement of loop."""
)
if break_collections:
outer_trace_collection.mergeMultipleBranches(break_collections)
# Consider leading "break" statements, they should be the only, and
# should lead to removing the whole loop statement. Trailing "break"
# statements could also be handled, but that would need to consider if
# there are other "break" statements too. Numbering loop exits is
# nothing we have yet.
if loop_body is not None:
assert loop_body.isStatementsSequence()
statements = loop_body.getStatements()
assert statements # Cannot be empty
if len(statements) == 1 and statements[-1].isStatementLoopBreak():
return None, "new_statements", """\
Removed useless loop with immediate 'break' statement."""
# Also consider the threading intermission. TODO: We ought to make it
# explicit, so we can see it potentially disrupting and changing the
# global variables. It may also raise.
outer_trace_collection.onExceptionRaiseExit(BaseException)
return self, None, None
def computeStatement(self, trace_collection):
outer_trace_collection = trace_collection
trace_collection = TraceCollectionBranch(parent=trace_collection,
name="loop")
loop_body, break_collections = self.computeLoopBody(trace_collection)
# Consider trailing "continue" statements, these have no effect, so we
# can remove them.
if loop_body is not None:
assert loop_body.isStatementsSequence()
statements = loop_body.getStatements()
assert statements # Cannot be empty
# If the last statement is a "continue" statement, it can simply
# be discarded.
last_statement = statements[-1]
if last_statement.isStatementLoopContinue():
if len(statements) == 1:
self.subnode_body.finalize()
self.setLoopBody(None)
loop_body = None
else:
last_statement.parent.replaceChild(last_statement, None)
last_statement.finalize()
trace_collection.signalChange(
"new_statements", last_statement.getSourceReference(), """\
Removed useless terminal 'continue' as last statement of loop.""")
if break_collections:
outer_trace_collection.mergeMultipleBranches(break_collections)
# Consider leading "break" statements, they should be the only, and
# should lead to removing the whole loop statement. Trailing "break"
# statements could also be handled, but that would need to consider if
# there are other "break" statements too. Numbering loop exits is
# nothing we have yet.
if loop_body is not None:
assert loop_body.isStatementsSequence()
statements = loop_body.getStatements()
assert statements # Cannot be empty
if len(statements) == 1 and statements[-1].isStatementLoopBreak():
return None, "new_statements", """\
Removed useless loop with immediate 'break' statement."""
# Also consider the threading intermission. TODO: We ought to make it
# explicit, so we can see it potentially disrupting and changing the
# global variables. It may also raise.
outer_trace_collection.onExceptionRaiseExit(BaseException)
return self, None, None
def computeExpressionRaw(self, trace_collection):
# TODO: Use dictionary tracings for locals dict and then cut
# to no branch variant if possible.
possible = trace_collection.onLocalsDictGet(self.variable_name)
if possible is not True:
branch_fallback = TraceCollectionBranch(parent=trace_collection,
name="fallback node usage")
branch_fallback.computeBranch(self.subnode_fallback)
trace_collection.mergeBranches(branch_fallback, None)
if possible is False:
return self.subnode_fallback, "new_expression", "Name '%s' cannot be in locals dict." % self.variable_name
else:
return self, None, None
def computeExpressionRaw(self, trace_collection):
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
trace_collection.onExpression(
expression = self.getCondition()
)
condition = self.getCondition()
condition_may_raise = condition.mayRaiseException(BaseException)
if condition_may_raise:
trace_collection.onExceptionRaiseExit(
BaseException
)
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if condition.willRaiseException(BaseException):
return condition, "new_raise", """\
Conditional expression already raises implicitly in condition, removing \
branches."""
if not condition_may_raise and condition.mayRaiseExceptionBool(BaseException):
trace_collection.onExceptionRaiseExit(
BaseException
)
# Decide this based on truth value of condition.
truth_value = condition.getTruthValue()
# TODO: We now know that condition evaluates to true for the yes branch
# and to not true for no branch, the branch should know that.
yes_branch = self.getExpressionYes()
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if truth_value is not False:
branch_yes_collection = TraceCollectionBranch(
parent = trace_collection,
name = "conditional expression yes branch"
)
branch_yes_collection.computeBranch(
branch = yes_branch
)
# May have just gone away, so fetch it again.
yes_branch = self.getExpressionYes()
# If it's aborting, it doesn't contribute to merging.
if yes_branch.willRaiseException(BaseException):
branch_yes_collection = None
else:
branch_yes_collection = None
no_branch = self.getExpressionNo()
# Continue to execute for yes branch.
if truth_value is not True:
branch_no_collection = TraceCollectionBranch(
parent = trace_collection,
name = "conditional expression no branch"
)
branch_no_collection.computeBranch(
branch = no_branch
)
# May have just gone away, so fetch it again.
no_branch = self.getExpressionNo()
# If it's aborting, it doesn't contribute to merging.
if no_branch.willRaiseException(BaseException):
branch_no_collection = None
else:
branch_no_collection = None
# Merge into parent execution.
self.merge_traces = trace_collection.mergeBranches(
branch_yes_collection,
branch_no_collection
)
if truth_value is True:
return (
wrapExpressionWithNodeSideEffects(
new_node = self.getExpressionYes(),
old_node = condition
),
"new_expression",
"Conditional expression predicted to yes case"
)
elif truth_value is False:
return (
wrapExpressionWithNodeSideEffects(
new_node = self.getExpressionNo(),
old_node = condition
),
"new_expression",
"Conditional expression predicted to no case"
)
else:
return self, None, None
def computeStatement(self, trace_collection):
# This is rather complex stuff, pylint: disable=too-many-branches,too-many-statements
trace_collection.onExpression(
expression = self.getCondition()
)
condition = self.getCondition()
condition_may_raise = condition.mayRaiseException(BaseException)
if condition_may_raise:
trace_collection.onExceptionRaiseExit(
BaseException
)
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if condition.willRaiseException(BaseException):
result = makeStatementExpressionOnlyReplacementNode(
expression = condition,
node = self
)
return result, "new_raise", """\
Conditional statements already raises implicitly in condition, removing \
branches."""
if not condition_may_raise and condition.mayRaiseExceptionBool(BaseException):
trace_collection.onExceptionRaiseExit(
BaseException
)
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
truth_value = condition.getTruthValue()
# TODO: We now know that condition evaluates to true for the yes branch
# and to not true for no branch, the branch collection should know that.
yes_branch = self.getBranchYes()
no_branch = self.getBranchNo()
# Handle branches that became empty behind our back.
if yes_branch is not None:
if not yes_branch.getStatements():
yes_branch = None
if no_branch is not None:
if not no_branch.getStatements():
no_branch = None
# Consider to not remove branches that we know won't be taken.
if yes_branch is not None and truth_value is False:
trace_collection.signalChange(
tags = "new_statements",
source_ref = yes_branch.source_ref,
message = "Removed conditional branch not taken due to false condition value."
)
self.setBranchYes(None)
yes_branch = None
if no_branch is not None and truth_value is True:
trace_collection.signalChange(
tags = "new_statements",
source_ref = no_branch.source_ref,
message = "Removed 'else' branch not taken due to true condition value."
)
self.setBranchNo(None)
no_branch = None
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if yes_branch is not None:
branch_yes_collection = TraceCollectionBranch(
parent = trace_collection,
name = "conditional yes branch",
)
branch_yes_collection.computeBranch(
branch = yes_branch
)
# May have just gone away, so fetch it again.
yes_branch = self.getBranchYes()
# If it's aborting, it doesn't contribute to merging.
if yes_branch is None or yes_branch.isStatementAborting():
branch_yes_collection = None
else:
branch_yes_collection = None
# Continue to execute for yes branch.
if no_branch is not None:
branch_no_collection = TraceCollectionBranch(
parent = trace_collection,
name = "conditional no branch"
)
branch_no_collection.computeBranch(
branch = no_branch
)
# May have just gone away, so fetch it again.
no_branch = self.getBranchNo()
# If it's aborting, it doesn't contribute to merging.
if no_branch is None or no_branch.isStatementAborting():
branch_no_collection = None
else:
branch_no_collection = None
# Merge into parent execution.
self.merge_traces = trace_collection.mergeBranches(
branch_yes_collection,
branch_no_collection
)
# Both branches may have become empty, which case, the statement needs
# not remain.
if yes_branch is None and no_branch is None:
# Need to keep the boolean check.
if truth_value is None:
condition = ExpressionBuiltinBool(
value = condition,
source_ref = condition.getSourceReference()
)
if condition.mayHaveSideEffects():
# With both branches eliminated, the condition remains as a side
# effect.
result = makeStatementExpressionOnlyReplacementNode(
expression = condition,
node = self
)
return result, "new_statements", """\
Both branches have no effect, reduced to evaluate condition."""
else:
return None, "new_statements", """\
Removed conditional statement without effect."""
# Note: Checking the condition late, so that the surviving branch got
# processed already. Returning without doing that, will corrupt the SSA
# results. TODO: Could pretend the other branch didn't exist to save
# complexity the merging of processing.
if truth_value is not None:
if truth_value is True:
choice = "true"
new_statement = self.getBranchYes()
else:
choice = "false"
new_statement = self.getBranchNo()
new_statement = wrapStatementWithSideEffects(
new_node = new_statement,
old_node = condition,
allow_none = True # surviving branch may empty
)
return new_statement, "new_statements", """\
Condition for branch was predicted to be always %s.""" % choice
# If there is no "yes" branch, remove that. Maybe a bad idea though.
if yes_branch is None:
# Would be eliminated already, if there wasn't any "no" branch
# either.
assert no_branch is not None
from .OperatorNodes import ExpressionOperationNOT
new_statement = StatementConditional(
condition = ExpressionOperationNOT(
operand = condition,
source_ref = condition.getSourceReference()
),
yes_branch = no_branch,
no_branch = None,
source_ref = self.getSourceReference()
)
return new_statement, "new_statements", """\
Empty 'yes' branch for conditional statement treated with inverted condition check."""
return self, None, None
def computeExpressionRaw(self, trace_collection):
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
trace_collection.onExpression(
expression = self.getLeft()
)
left = self.getLeft()
left_may_raise = left.mayRaiseException(BaseException)
if left_may_raise:
trace_collection.onExceptionRaiseExit(
BaseException
)
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if left.willRaiseException(BaseException):
return left, "new_raise", """\
Conditional %s statements already raises implicitly in condition, removing \
branches.""" % self.conditional_kind
if not left_may_raise and left.mayRaiseExceptionBool(BaseException):
trace_collection.onExceptionRaiseExit(
BaseException
)
# Decide this based on truth value of condition.
truth_value = left.getTruthValue()
truth_value_use_left = self.conditional_kind == "or"
truth_value_use_right = not truth_value_use_left
right = self.getRight()
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if truth_value is not truth_value_use_left:
# TODO: We now know that left evaluates and we should tell the
# branch that.
branch_yes_collection = TraceCollectionBranch(
parent = trace_collection,
name = "boolean %s right branch" % self.conditional_kind
)
branch_yes_collection.computeBranch(
branch = right
)
# May have just gone away, so fetch it again.
right = self.getRight()
# If it's aborting, it doesn't contribute to merging.
if right.willRaiseException(BaseException):
branch_yes_collection = None
else:
branch_yes_collection = None
if branch_yes_collection:
# Merge into parent execution.
self.merge_traces = trace_collection.mergeBranches(
branch_yes_collection,
None
)
else:
self.merge_traces = None
if truth_value is truth_value_use_left:
return (
left,
"new_expression",
"Conditional '%s' expression predicted to left value." % self.conditional_kind
)
elif truth_value is truth_value_use_right:
return (
wrapExpressionWithNodeSideEffects(
new_node = right,
old_node = left
),
"new_expression",
"Conditional '%s' expression predicted right value." % self.conditional_kind
)
else:
return self, None, None
def computeStatement(self, trace_collection):
# This node has many children to handle, pylint: disable=R0912,R0914
tried = self.getBlockTry()
except_handler = self.getBlockExceptHandler()
break_handler = self.getBlockBreakHandler()
continue_handler = self.getBlockContinueHandler()
return_handler = self.getBlockReturnHandler()
# The tried block must be considered as a branch, if it is not empty
# already.
collection_start = TraceCollectionBranch(parent=trace_collection,
name="try start")
abort_context = trace_collection.makeAbortStackContext(
catch_breaks=break_handler is not None,
catch_continues=continue_handler is not None,
catch_returns=return_handler is not None,
catch_exceptions=True,
)
with abort_context:
# As a branch point for the many types of handlers.
result = tried.computeStatementsSequence(
trace_collection=trace_collection)
# We might be done entirely already.
if result is None:
return None, "new_statements", "Removed now empty try statement."
# Might be changed.
if result is not tried:
self.setBlockTry(result)
tried = result
break_collections = trace_collection.getLoopBreakCollections()
continue_collections = trace_collection.getLoopContinueCollections(
)
return_collections = trace_collection.getFunctionReturnCollections(
)
exception_collections = trace_collection.getExceptionRaiseCollections(
)
tried_may_raise = tried.mayRaiseException(BaseException)
# Exception handling is useless if no exception is to be raised.
# TODO: signal the change.
if not tried_may_raise:
if except_handler is not None:
self.setBlockExceptHandler(None)
except_handler = None
# If tried may raise, even empty exception handler has a meaning to
# ignore that exception.
if tried_may_raise:
collection_exception_handling = TraceCollectionBranch(
parent=collection_start, name="except handler")
if not exception_collections:
for statement in tried.getStatements():
if statement.mayRaiseException(BaseException):
assert False, statement.asXmlText()
assert False
collection_exception_handling.mergeMultipleBranches(
exception_collections)
if except_handler is not None:
result = except_handler.computeStatementsSequence(
trace_collection=collection_exception_handling)
# Might be changed.
if result is not except_handler:
self.setBlockExceptHandler(result)
except_handler = result
if break_handler is not None:
if not tried.mayBreak():
self.setBlockBreakHandler(None)
break_handler = None
if break_handler is not None:
collection_break = TraceCollectionBranch(parent=collection_start,
name="break handler")
collection_break.mergeMultipleBranches(break_collections)
result = break_handler.computeStatementsSequence(
trace_collection=collection_break)
# Might be changed.
if result is not break_handler:
self.setBlockBreakHandler(result)
break_handler = result
if continue_handler is not None:
if not tried.mayContinue():
self.setBlockContinueHandler(None)
continue_handler = None
if continue_handler is not None:
collection_continue = TraceCollectionBranch(
parent=collection_start, name="continue handler")
collection_continue.mergeMultipleBranches(continue_collections)
result = continue_handler.computeStatementsSequence(
trace_collection=collection_continue)
# Might be changed.
if result is not continue_handler:
self.setBlockContinueHandler(result)
continue_handler = result
if return_handler is not None:
if not tried.mayReturn():
self.setBlockReturnHandler(None)
return_handler = None
if return_handler is not None:
collection_return = TraceCollectionBranch(parent=collection_start,
name="return handler")
collection_return.mergeMultipleBranches(return_collections)
result = return_handler.computeStatementsSequence(
trace_collection=collection_return)
# Might be changed.
if result is not return_handler:
self.setBlockReturnHandler(result)
return_handler = result
if return_handler is not None:
if return_handler.getStatements()[0].isStatementReturn() and \
return_handler.getStatements()[0].getExpression().isExpressionReturnedValueRef():
self.setBlockReturnHandler(None)
return_handler = None
# Merge exception handler only if it is used. Empty means it is not
# aborting, as it swallows the exception.
if tried_may_raise and (
except_handler is None or \
not except_handler.isStatementAborting()
):
trace_collection.mergeBranches(
collection_yes=collection_exception_handling,
collection_no=None)
# An empty exception handler means we have to swallow exception.
if not tried_may_raise and \
break_handler is None and \
continue_handler is None and \
return_handler is None:
return tried, "new_statements", "Removed all try handlers."
tried_statements = tried.getStatements()
pre_statements = []
while tried_statements:
tried_statement = tried_statements[0]
if tried_statement.mayRaiseException(BaseException):
break
if break_handler is not None and \
tried_statement.mayBreak():
break
if continue_handler is not None and \
tried_statement.mayContinue():
break
if return_handler is not None and \
tried_statement.mayReturn():
break
pre_statements.append(tried_statement)
tried_statements = list(tried_statements)
del tried_statements[0]
post_statements = []
if except_handler is not None and except_handler.isStatementAborting():
while tried_statements:
tried_statement = tried_statements[-1]
if tried_statement.mayRaiseException(BaseException):
break
if break_handler is not None and \
tried_statement.mayBreak():
break
if continue_handler is not None and \
tried_statement.mayContinue():
break
if return_handler is not None and \
tried_statement.mayReturn():
break
post_statements.insert(0, tried_statement)
tried_statements = list(tried_statements)
del tried_statements[-1]
if pre_statements or post_statements:
assert tried_statements # Should be dealt with already
tried.setStatements(tried_statements)
result = StatementsSequence(statements=pre_statements + [self] +
post_statements,
source_ref=self.getSourceReference())
def explain():
# TODO: We probably don't want to say this for re-formulation ones.
result = "Reduced scope of tried block."
if pre_statements:
result += " Leading statements at %s." % (','.join(
x.getSourceReference().getAsString() + '/' + str(x)
for x in pre_statements))
if post_statements:
result += " Trailing statements at %s." % (','.join(
x.getSourceReference().getAsString() + '/' + str(x)
for x in post_statements))
return result
return (result, "new_statements", explain)
return self, None, None
def computeExpressionRaw(self, trace_collection):
# This is rather complex stuff, pylint: disable=too-many-branches
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
condition = trace_collection.onExpression(
expression=self.subnode_condition)
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if condition.willRaiseException(BaseException):
return (
condition,
"new_raise",
"""\
Conditional expression already raises implicitly in condition, removing \
branches.""",
)
# Tell it we are evaluation it for boolean value only, it may demote
# itself possibly.
condition.computeExpressionBool(trace_collection)
condition = self.subnode_condition
# Decide this based on truth value of condition.
truth_value = condition.getTruthValue()
# TODO: We now know that condition evaluates to true for the yes branch
# and to not true for no branch, the branch should know that.
yes_branch = self.subnode_expression_yes
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if truth_value is not False:
branch_yes_collection = TraceCollectionBranch(
parent=trace_collection,
name="conditional expression yes branch")
branch_yes_collection.computeBranch(branch=yes_branch)
# May have just gone away, so fetch it again.
yes_branch = self.subnode_expression_yes
# If it's aborting, it doesn't contribute to merging.
if yes_branch.willRaiseException(BaseException):
branch_yes_collection = None
else:
branch_yes_collection = None
no_branch = self.subnode_expression_no
# Continue to execute for yes branch.
if truth_value is not True:
branch_no_collection = TraceCollectionBranch(
parent=trace_collection,
name="conditional expression no branch")
branch_no_collection.computeBranch(branch=no_branch)
# May have just gone away, so fetch it again.
no_branch = self.subnode_expression_no
# If it's aborting, it doesn't contribute to merging.
if no_branch.willRaiseException(BaseException):
branch_no_collection = None
else:
branch_no_collection = None
if truth_value is True:
trace_collection.replaceBranch(branch_yes_collection)
elif truth_value is False:
trace_collection.replaceBranch(branch_no_collection)
else:
# Merge into parent execution.
trace_collection.mergeBranches(branch_yes_collection,
branch_no_collection)
if truth_value is True:
return (
wrapExpressionWithNodeSideEffects(
new_node=self.subnode_expression_yes, old_node=condition),
"new_expression",
"Conditional expression predicted to yes case.",
)
elif truth_value is False:
return (
wrapExpressionWithNodeSideEffects(
new_node=self.subnode_expression_no, old_node=condition),
"new_expression",
"Conditional expression predicted to no case.",
)
else:
return self, None, None
def computeStatement(self, trace_collection):
# This node has many children to handle, pylint: disable=I0021,too-many-branches,too-many-locals,too-many-statements
tried = self.getBlockTry()
except_handler = self.getBlockExceptHandler()
break_handler = self.getBlockBreakHandler()
continue_handler = self.getBlockContinueHandler()
return_handler = self.getBlockReturnHandler()
# The tried block must be considered as a branch, if it is not empty
# already.
collection_start = TraceCollectionBranch(parent=trace_collection,
name="try start")
abort_context = trace_collection.makeAbortStackContext(
catch_breaks=break_handler is not None,
catch_continues=continue_handler is not None,
catch_returns=return_handler is not None,
catch_exceptions=True,
)
with abort_context:
# As a branch point for the many types of handlers.
result = tried.computeStatementsSequence(
trace_collection=trace_collection)
# We might be done entirely already.
if result is None:
return None, "new_statements", "Removed now empty try statement."
# Might be changed.
if result is not tried:
self.setBlockTry(result)
tried = result
break_collections = trace_collection.getLoopBreakCollections()
continue_collections = trace_collection.getLoopContinueCollections(
)
return_collections = trace_collection.getFunctionReturnCollections(
)
exception_collections = trace_collection.getExceptionRaiseCollections(
)
tried_may_raise = tried.mayRaiseException(BaseException)
# Exception handling is useless if no exception is to be raised.
if not tried_may_raise:
if except_handler is not None:
except_handler.finalize()
self.setBlockExceptHandler(None)
trace_collection.signalChange(
tags="new_statements",
message="Removed useless exception handler.",
source_ref=except_handler.source_ref,
)
except_handler = None
# If tried may raise, even empty exception handler has a meaning to
# ignore that exception.
if tried_may_raise:
collection_exception_handling = TraceCollectionBranch(
parent=collection_start, name="except handler")
# When no exception exits are there, this is a problem, we just
# found an inconsistency that is a bug.
if not exception_collections:
for statement in tried.getStatements():
if statement.mayRaiseException(BaseException):
raise NuitkaOptimizationError(
"This statement does raise but didn't annotate an exception exit.",
statement,
)
raise NuitkaOptimizationError(
"Falsely assuming tried block may raise, but no statement says so.",
tried,
)
collection_exception_handling.mergeMultipleBranches(
exception_collections)
if except_handler is not None:
result = except_handler.computeStatementsSequence(
trace_collection=collection_exception_handling)
# Might be changed.
if result is not except_handler:
self.setBlockExceptHandler(result)
except_handler = result
if break_handler is not None:
if not tried.mayBreak():
break_handler.finalize()
self.setBlockBreakHandler(None)
break_handler = None
if break_handler is not None:
collection_break = TraceCollectionBranch(parent=collection_start,
name="break handler")
collection_break.mergeMultipleBranches(break_collections)
result = break_handler.computeStatementsSequence(
trace_collection=collection_break)
# Might be changed.
if result is not break_handler:
self.setBlockBreakHandler(result)
break_handler = result
if continue_handler is not None:
if not tried.mayContinue():
continue_handler.finalize()
self.setBlockContinueHandler(None)
continue_handler = None
if continue_handler is not None:
collection_continue = TraceCollectionBranch(
parent=collection_start, name="continue handler")
collection_continue.mergeMultipleBranches(continue_collections)
result = continue_handler.computeStatementsSequence(
trace_collection=collection_continue)
# Might be changed.
if result is not continue_handler:
self.setBlockContinueHandler(result)
continue_handler = result
if return_handler is not None:
if not tried.mayReturn():
return_handler.finalize()
self.setBlockReturnHandler(None)
return_handler = None
if return_handler is not None:
collection_return = TraceCollectionBranch(parent=collection_start,
name="return handler")
collection_return.mergeMultipleBranches(return_collections)
result = return_handler.computeStatementsSequence(
trace_collection=collection_return)
# Might be changed.
if result is not return_handler:
self.setBlockReturnHandler(result)
return_handler = result
# Check for trivial return handlers that immediately return, they can
# just be removed.
if return_handler is not None:
if (return_handler.getStatements()[0].isStatementReturn()
and return_handler.getStatements()
[0].getExpression().isExpressionReturnedValueRef()):
return_handler.finalize()
self.setBlockReturnHandler(None)
return_handler = None
# Merge exception handler only if it is used. Empty means it is not
# aborting, as it swallows the exception.
if tried_may_raise and (except_handler is None
or not except_handler.isStatementAborting()):
trace_collection.mergeBranches(
collection_yes=collection_exception_handling,
collection_no=None)
# An empty exception handler means we have to swallow exception.
if ((not tried_may_raise or
(except_handler is not None and
except_handler.getStatements()[0].isStatementReraiseException()))
and break_handler is None and continue_handler is None
and return_handler is None):
return tried, "new_statements", "Removed useless try, all handlers removed."
tried_statements = tried.getStatements()
pre_statements = []
while tried_statements:
tried_statement = tried_statements[0]
if tried_statement.mayRaiseException(BaseException):
break
if break_handler is not None and tried_statement.mayBreak():
break
if continue_handler is not None and tried_statement.mayContinue():
break
if return_handler is not None and tried_statement.mayReturn():
break
pre_statements.append(tried_statement)
tried_statements = list(tried_statements)
del tried_statements[0]
post_statements = []
if except_handler is not None and except_handler.isStatementAborting():
while tried_statements:
tried_statement = tried_statements[-1]
if tried_statement.mayRaiseException(BaseException):
break
if break_handler is not None and tried_statement.mayBreak():
break
if continue_handler is not None and tried_statement.mayContinue(
):
break
if return_handler is not None and tried_statement.mayReturn():
break
post_statements.insert(0, tried_statement)
tried_statements = list(tried_statements)
del tried_statements[-1]
if pre_statements or post_statements:
assert tried_statements # Should be dealt with already
tried.setStatements(tried_statements)
result = StatementsSequence(
statements=pre_statements + [self] + post_statements,
source_ref=self.source_ref,
)
def explain():
# TODO: We probably don't want to say this for re-formulation ones.
result = "Reduced scope of tried block."
if pre_statements:
result += " Leading statements at %s." % (",".join(
x.getSourceReference().getAsString() + "/" + str(x)
for x in pre_statements))
if post_statements:
result += " Trailing statements at %s." % (",".join(
x.getSourceReference().getAsString() + "/" + str(x)
for x in post_statements))
return result
return (result, "new_statements", explain)
return self, None, None
def computeExpressionRaw(self, trace_collection):
# This is rather complex stuff, pylint: disable=too-many-branches
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
trace_collection.onExpression(expression=self.getCondition())
condition = self.getCondition()
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if condition.willRaiseException(BaseException):
return (
condition,
"new_raise",
"""\
Conditional expression already raises implicitly in condition, removing \
branches.""",
)
# Tell it we are evaluation it for boolean value only, it may demote
# itself possibly.
condition.computeExpressionBool(trace_collection)
condition = self.getCondition()
# Decide this based on truth value of condition.
truth_value = condition.getTruthValue()
# TODO: We now know that condition evaluates to true for the yes branch
# and to not true for no branch, the branch should know that.
yes_branch = self.getExpressionYes()
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if truth_value is not False:
branch_yes_collection = TraceCollectionBranch(
parent=trace_collection, name="conditional expression yes branch"
)
branch_yes_collection.computeBranch(branch=yes_branch)
# May have just gone away, so fetch it again.
yes_branch = self.getExpressionYes()
# If it's aborting, it doesn't contribute to merging.
if yes_branch.willRaiseException(BaseException):
branch_yes_collection = None
else:
branch_yes_collection = None
no_branch = self.getExpressionNo()
# Continue to execute for yes branch.
if truth_value is not True:
branch_no_collection = TraceCollectionBranch(
parent=trace_collection, name="conditional expression no branch"
)
branch_no_collection.computeBranch(branch=no_branch)
# May have just gone away, so fetch it again.
no_branch = self.getExpressionNo()
# If it's aborting, it doesn't contribute to merging.
if no_branch.willRaiseException(BaseException):
branch_no_collection = None
else:
branch_no_collection = None
if truth_value is True:
trace_collection.replaceBranch(branch_yes_collection)
elif truth_value is False:
trace_collection.replaceBranch(branch_no_collection)
else:
# Merge into parent execution.
trace_collection.mergeBranches(branch_yes_collection, branch_no_collection)
if truth_value is True:
return (
wrapExpressionWithNodeSideEffects(
new_node=self.getExpressionYes(), old_node=condition
),
"new_expression",
"Conditional expression predicted to yes case.",
)
elif truth_value is False:
return (
wrapExpressionWithNodeSideEffects(
new_node=self.getExpressionNo(), old_node=condition
),
"new_expression",
"Conditional expression predicted to no case.",
)
else:
return self, None, None
def computeStatement(self, trace_collection):
# This is rather complex stuff, pylint: disable=too-many-branches,too-many-statements
trace_collection.onExpression(expression=self.getCondition())
condition = self.getCondition()
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if condition.willRaiseException(BaseException):
result = makeStatementExpressionOnlyReplacementNode(
expression=condition, node=self
)
return (
result,
"new_raise",
"""\
Conditional statements already raises implicitly in condition, removing \
branches.""",
)
# Tell it we are evaluation it for boolean value only, it may demote
# itself possibly.
condition.computeExpressionBool(trace_collection)
condition = self.getCondition()
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
truth_value = condition.getTruthValue()
# TODO: We now know that condition evaluates to true for the yes branch
# and to not true for no branch, the branch collection should know that.
yes_branch = self.getBranchYes()
no_branch = self.getBranchNo()
# Handle branches that became empty behind our back.
if yes_branch is not None:
if not yes_branch.getStatements():
yes_branch.finalize()
yes_branch = None
self.setBranchYes(None)
if no_branch is not None:
if not no_branch.getStatements():
no_branch.finalize()
no_branch = None
self.setBranchNo(None)
# Consider to not remove branches that we know won't be taken.
if yes_branch is not None and truth_value is False:
trace_collection.signalChange(
tags="new_statements",
source_ref=yes_branch.source_ref,
message="Removed conditional branch not taken due to false condition value.",
)
yes_branch.finalize()
self.setBranchYes(None)
yes_branch = None
if no_branch is not None and truth_value is True:
trace_collection.signalChange(
tags="new_statements",
source_ref=no_branch.source_ref,
message="Removed 'else' branch not taken due to true condition value.",
)
no_branch.finalize()
self.setBranchNo(None)
no_branch = None
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if yes_branch is not None:
branch_yes_collection = TraceCollectionBranch(
parent=trace_collection, name="conditional yes branch"
)
branch_yes_collection.computeBranch(branch=yes_branch)
# May have just gone away, so fetch it again.
yes_branch = self.getBranchYes()
# If it's aborting, it doesn't contribute to merging.
if yes_branch is None or yes_branch.isStatementAborting():
branch_yes_collection = None
else:
branch_yes_collection = None
# Continue to execute for yes branch.
if no_branch is not None:
branch_no_collection = TraceCollectionBranch(
parent=trace_collection, name="conditional no branch"
)
branch_no_collection.computeBranch(branch=no_branch)
# May have just gone away, so fetch it again.
no_branch = self.getBranchNo()
# If it's aborting, it doesn't contribute to merging.
if no_branch is None or no_branch.isStatementAborting():
branch_no_collection = None
else:
branch_no_collection = None
if truth_value is True:
if branch_yes_collection is not None:
trace_collection.replaceBranch(branch_yes_collection)
elif truth_value is False:
if branch_no_collection is not None:
trace_collection.replaceBranch(branch_no_collection)
else:
trace_collection.mergeBranches(branch_yes_collection, branch_no_collection)
# Both branches may have become empty, which case, the statement needs
# not remain.
if yes_branch is None and no_branch is None:
# Need to keep the boolean check.
if truth_value is None:
condition = ExpressionBuiltinBool(
value=condition, source_ref=condition.getSourceReference()
)
if condition.mayHaveSideEffects():
# With both branches eliminated, the condition remains as a side
# effect.
result = makeStatementExpressionOnlyReplacementNode(
expression=condition, node=self
)
del self.parent
return (
result,
"new_statements",
"""\
Both branches have no effect, reduced to evaluate condition.""",
)
else:
self.finalize()
return (
None,
"new_statements",
"""\
Removed conditional statement without effect.""",
)
# Note: Checking the condition late, so that the surviving branch got
# processed already. Returning without doing that, will corrupt the SSA
# results. TODO: Could pretend the other branch didn't exist to save
# complexity the merging of processing.
if truth_value is not None:
if truth_value is True:
choice = "true"
new_statement = yes_branch
if no_branch is not None:
no_branch.finalize()
else:
choice = "false"
new_statement = no_branch
if yes_branch is not None:
yes_branch.finalize()
new_statement = wrapStatementWithSideEffects(
new_node=new_statement,
old_node=condition,
allow_none=True, # surviving branch may empty
)
del self.parent
return (
new_statement,
"new_statements",
"""\
Condition for branch statement was predicted to be always %s."""
% choice,
)
# If there is no "yes" branch, remove that. Maybe a bad idea though.
if yes_branch is None:
# Would be eliminated already, if there wasn't any "no" branch
# either.
assert no_branch is not None
new_statement = makeStatementConditional(
condition=ExpressionOperationNOT(
operand=condition, source_ref=condition.getSourceReference()
),
yes_branch=no_branch,
no_branch=None,
source_ref=self.getSourceReference(),
)
del self.parent
return (
new_statement,
"new_statements",
"""\
Empty 'yes' branch for conditional statement treated with inverted condition check.""",
)
return self, None, None
def computeExpressionRaw(self, trace_collection):
# Query the truth value after the expression is evaluated, once it is
# evaluated in onExpression, it is known.
trace_collection.onExpression(expression=self.getLeft())
left = self.getLeft()
# No need to look any further, if the condition raises, the branches do
# not matter at all.
if left.willRaiseException(BaseException):
return (
left,
"new_raise",
"""\
Conditional %s statements already raises implicitly in condition, removing \
branches."""
% self.conditional_kind,
)
if not left.mayRaiseException(BaseException) and left.mayRaiseExceptionBool(
BaseException
):
trace_collection.onExceptionRaiseExit(BaseException)
# Decide this based on truth value of condition.
truth_value = left.getTruthValue()
truth_value_use_left = self.conditional_kind == "or"
truth_value_use_right = not truth_value_use_left
right = self.getRight()
# Continue to execute for yes branch unless we know it's not going to be
# relevant.
if truth_value is not truth_value_use_left:
# TODO: We now know that left evaluates and we should tell the
# branch that.
branch_yes_collection = TraceCollectionBranch(
parent=trace_collection,
name="boolean %s right branch" % self.conditional_kind,
)
branch_yes_collection.computeBranch(branch=right)
# May have just gone away, so fetch it again.
right = self.getRight()
# If it's aborting, it doesn't contribute to merging.
if right.willRaiseException(BaseException):
branch_yes_collection = None
else:
branch_yes_collection = None
if branch_yes_collection:
# Merge into parent execution.
trace_collection.mergeBranches(branch_yes_collection, None)
if truth_value is truth_value_use_left:
return (
left,
"new_expression",
"Conditional '%s' expression predicted to left value."
% self.conditional_kind,
)
elif truth_value is truth_value_use_right:
return (
wrapExpressionWithNodeSideEffects(new_node=right, old_node=left),
"new_expression",
"Conditional '%s' expression predicted right value."
% self.conditional_kind,
)
else:
return self, None, None
def computeStatement(self, trace_collection):
# This node has many children to handle, pylint: disable=R0912,R0914
tried = self.getBlockTry()
except_handler = self.getBlockExceptHandler()
break_handler = self.getBlockBreakHandler()
continue_handler = self.getBlockContinueHandler()
return_handler = self.getBlockReturnHandler()
# The tried block must be considered as a branch, if it is not empty
# already.
collection_start = TraceCollectionBranch(parent=trace_collection, name="try start")
abort_context = trace_collection.makeAbortStackContext(
catch_breaks=break_handler is not None,
catch_continues=continue_handler is not None,
catch_returns=return_handler is not None,
catch_exceptions=True,
)
with abort_context:
# As a branch point for the many types of handlers.
result = tried.computeStatementsSequence(trace_collection=trace_collection)
# We might be done entirely already.
if result is None:
return None, "new_statements", "Removed now empty try statement."
# Might be changed.
if result is not tried:
self.setBlockTry(result)
tried = result
break_collections = trace_collection.getLoopBreakCollections()
continue_collections = trace_collection.getLoopContinueCollections()
return_collections = trace_collection.getFunctionReturnCollections()
exception_collections = trace_collection.getExceptionRaiseCollections()
tried_may_raise = tried.mayRaiseException(BaseException)
# Exception handling is useless if no exception is to be raised.
# TODO: signal the change.
if not tried_may_raise:
if except_handler is not None:
self.setBlockExceptHandler(None)
except_handler = None
# If tried may raise, even empty exception handler has a meaning to
# ignore that exception.
if tried_may_raise:
collection_exception_handling = TraceCollectionBranch(parent=collection_start, name="except handler")
if not exception_collections:
for statement in tried.getStatements():
if statement.mayRaiseException(BaseException):
assert False, statement.asXmlText()
assert False
collection_exception_handling.mergeMultipleBranches(exception_collections)
if except_handler is not None:
result = except_handler.computeStatementsSequence(trace_collection=collection_exception_handling)
# Might be changed.
if result is not except_handler:
self.setBlockExceptHandler(result)
except_handler = result
if break_handler is not None:
if not tried.mayBreak():
self.setBlockBreakHandler(None)
break_handler = None
if break_handler is not None:
collection_break = TraceCollectionBranch(parent=collection_start, name="break handler")
collection_break.mergeMultipleBranches(break_collections)
result = break_handler.computeStatementsSequence(trace_collection=collection_break)
# Might be changed.
if result is not break_handler:
self.setBlockBreakHandler(result)
break_handler = result
if continue_handler is not None:
if not tried.mayContinue():
self.setBlockContinueHandler(None)
continue_handler = None
if continue_handler is not None:
collection_continue = TraceCollectionBranch(parent=collection_start, name="continue handler")
collection_continue.mergeMultipleBranches(continue_collections)
result = continue_handler.computeStatementsSequence(trace_collection=collection_continue)
# Might be changed.
if result is not continue_handler:
self.setBlockContinueHandler(result)
continue_handler = result
if return_handler is not None:
if not tried.mayReturn():
self.setBlockReturnHandler(None)
return_handler = None
if return_handler is not None:
collection_return = TraceCollectionBranch(parent=collection_start, name="return handler")
collection_return.mergeMultipleBranches(return_collections)
result = return_handler.computeStatementsSequence(trace_collection=collection_return)
# Might be changed.
if result is not return_handler:
self.setBlockReturnHandler(result)
return_handler = result
if return_handler is not None:
if (
return_handler.getStatements()[0].isStatementReturn()
and return_handler.getStatements()[0].getExpression().isExpressionReturnedValueRef()
):
self.setBlockReturnHandler(None)
return_handler = None
# Merge exception handler only if it is used. Empty means it is not
# aborting, as it swallows the exception.
if tried_may_raise and (except_handler is None or not except_handler.isStatementAborting()):
trace_collection.mergeBranches(collection_yes=collection_exception_handling, collection_no=None)
# An empty exception handler means we have to swallow exception.
if not tried_may_raise and break_handler is None and continue_handler is None and return_handler is None:
return tried, "new_statements", "Removed all try handlers."
tried_statements = tried.getStatements()
pre_statements = []
while tried_statements:
tried_statement = tried_statements[0]
if tried_statement.mayRaiseException(BaseException):
break
if break_handler is not None and tried_statement.mayBreak():
break
if continue_handler is not None and tried_statement.mayContinue():
break
if return_handler is not None and tried_statement.mayReturn():
break
pre_statements.append(tried_statement)
tried_statements = list(tried_statements)
del tried_statements[0]
post_statements = []
if except_handler is not None and except_handler.isStatementAborting():
while tried_statements:
tried_statement = tried_statements[-1]
if tried_statement.mayRaiseException(BaseException):
break
if break_handler is not None and tried_statement.mayBreak():
break
if continue_handler is not None and tried_statement.mayContinue():
break
if return_handler is not None and tried_statement.mayReturn():
break
post_statements.insert(0, tried_statement)
tried_statements = list(tried_statements)
del tried_statements[-1]
if pre_statements or post_statements:
assert tried_statements # Should be dealt with already
tried.setStatements(tried_statements)
result = StatementsSequence(
statements=pre_statements + [self] + post_statements, source_ref=self.getSourceReference()
)
def explain():
# TODO: We probably don't want to say this for re-formulation ones.
result = "Reduced scope of tried block."
if pre_statements:
result += " Leading statements at %s." % (
",".join(x.getSourceReference().getAsString() + "/" + str(x) for x in pre_statements)
)
if post_statements:
result += " Trailing statements at %s." % (
",".join(x.getSourceReference().getAsString() + "/" + str(x) for x in post_statements)
)
return result
return (result, "new_statements", explain)
return self, None, None