def transform_try_finally_stmt(builder: IRBuilder,
try_body: GenFunc,
finally_body: GenFunc) -> None:
"""Generalized try/finally handling that takes functions to gen the bodies.
The point of this is to also be able to support with."""
# Finally is a big pain, because there are so many ways that
# exits can occur. We emit 10+ basic blocks for every finally!
err_handler, main_entry, return_entry, finally_block = (
BasicBlock(), BasicBlock(), BasicBlock(), BasicBlock())
# Compile the body of the try
ret_reg = try_finally_try(
builder, err_handler, return_entry, main_entry, try_body)
# Set up the entry blocks for the finally statement
old_exc = try_finally_entry_blocks(
builder, err_handler, return_entry, main_entry, finally_block, ret_reg)
# Compile the body of the finally
cleanup_block, finally_control = try_finally_body(
builder, finally_block, finally_body, ret_reg, old_exc)
# Resolve the control flow out of the finally block
out_block = try_finally_resolve_control(
builder, cleanup_block, finally_control, old_exc, ret_reg)
builder.activate_block(out_block)
def try_finally_body(
builder: IRBuilder,
finally_block: BasicBlock,
finally_body: GenFunc,
ret_reg: Optional[Value],
old_exc: Value) -> Tuple[BasicBlock, FinallyNonlocalControl]:
cleanup_block = BasicBlock()
# Compile the finally block with the nonlocal control flow overridden to restore exc_info
builder.builder.push_error_handler(cleanup_block)
finally_control = FinallyNonlocalControl(
builder.nonlocal_control[-1], ret_reg, old_exc)
builder.nonlocal_control.append(finally_control)
builder.activate_block(finally_block)
finally_body()
builder.nonlocal_control.pop()
return cleanup_block, finally_control
def translate_next_call(builder: IRBuilder, expr: CallExpr,
callee: RefExpr) -> Optional[Value]:
# Special case for calling next() on a generator expression, an
# idiom that shows up some in mypy.
#
# For example, next(x for x in l if x.id == 12, None) will
# generate code that searches l for an element where x.id == 12
# and produce the first such object, or None if no such element
# exists.
if not (expr.arg_kinds in ([ARG_POS], [ARG_POS, ARG_POS])
and isinstance(expr.args[0], GeneratorExpr)):
return None
gen = expr.args[0]
retval = builder.alloc_temp(builder.node_type(expr))
default_val = None
if len(expr.args) > 1:
default_val = builder.accept(expr.args[1])
exit_block = BasicBlock()
def gen_inner_stmts() -> None:
# next takes the first element of the generator, so if
# something gets produced, we are done.
builder.assign(retval, builder.accept(gen.left_expr),
gen.left_expr.line)
builder.goto(exit_block)
loop_params = list(zip(gen.indices, gen.sequences, gen.condlists))
builder.comprehension_helper(loop_params, gen_inner_stmts, gen.line)
# Now we need the case for when nothing got hit. If there was
# a default value, we produce it, and otherwise we raise
# StopIteration.
if default_val:
builder.assign(retval, default_val, gen.left_expr.line)
builder.goto(exit_block)
else:
builder.add(
RaiseStandardError(RaiseStandardError.STOP_ITERATION, None,
expr.line))
builder.add(Unreachable())
builder.activate_block(exit_block)
return retval
def gen_glue_ne_method(builder: IRBuilder, cls: ClassIR, line: int) -> FuncIR:
"""Generate a __ne__ method from a __eq__ method. """
builder.enter()
rt_args = (RuntimeArg("self", RInstance(cls)), RuntimeArg("rhs", object_rprimitive))
# The environment operates on Vars, so we make some up
fake_vars = [(Var(arg.name), arg.type) for arg in rt_args]
args = [
builder.read(
builder.environment.add_local_reg(
var, type, is_arg=True
),
line
)
for var, type in fake_vars
] # type: List[Value]
builder.ret_types[-1] = object_rprimitive
# If __eq__ returns NotImplemented, then __ne__ should also
not_implemented_block, regular_block = BasicBlock(), BasicBlock()
eqval = builder.add(MethodCall(args[0], '__eq__', [args[1]], line))
not_implemented = builder.primitive_op(not_implemented_op, [], line)
builder.add(Branch(
builder.binary_op(eqval, not_implemented, 'is', line),
not_implemented_block,
regular_block,
Branch.BOOL_EXPR))
builder.activate_block(regular_block)
retval = builder.coerce(
builder.unary_op(eqval, 'not', line), object_rprimitive, line
)
builder.add(Return(retval))
builder.activate_block(not_implemented_block)
builder.add(Return(not_implemented))
blocks, env, ret_type, _ = builder.leave()
return FuncIR(
FuncDecl('__ne__', cls.name, builder.module_name,
FuncSignature(rt_args, ret_type)),
blocks, env)
def setup_non_ext_dict(builder: IRBuilder,
cdef: ClassDef,
metaclass: Value,
bases: Value) -> Value:
"""
Initialize the class dictionary for a non-extension class. This class dictionary
is passed to the metaclass constructor.
"""
# Check if the metaclass defines a __prepare__ method, and if so, call it.
has_prepare = builder.primitive_op(py_hasattr_op,
[metaclass,
builder.load_static_unicode('__prepare__')], cdef.line)
non_ext_dict = builder.alloc_temp(dict_rprimitive)
true_block, false_block, exit_block, = BasicBlock(), BasicBlock(), BasicBlock()
builder.add_bool_branch(has_prepare, true_block, false_block)
builder.activate_block(true_block)
cls_name = builder.load_static_unicode(cdef.name)
prepare_meth = builder.py_get_attr(metaclass, '__prepare__', cdef.line)
prepare_dict = builder.py_call(prepare_meth, [cls_name, bases], cdef.line)
builder.assign(non_ext_dict, prepare_dict, cdef.line)
builder.goto(exit_block)
builder.activate_block(false_block)
builder.assign(non_ext_dict, builder.primitive_op(new_dict_op, [], cdef.line), cdef.line)
builder.goto(exit_block)
builder.activate_block(exit_block)
return non_ext_dict
def try_finally_resolve_control(builder: IRBuilder,
cleanup_block: BasicBlock,
finally_control: FinallyNonlocalControl,
old_exc: Value,
ret_reg: Optional[Value]) -> BasicBlock:
"""Resolve the control flow out of a finally block.
This means returning if there was a return, propagating
exceptions, break/continue (soon), or just continuing on.
"""
reraise, rest = BasicBlock(), BasicBlock()
builder.add(Branch(old_exc, rest, reraise, Branch.IS_ERROR))
# Reraise the exception if there was one
builder.activate_block(reraise)
builder.primitive_op(reraise_exception_op, [], NO_TRACEBACK_LINE_NO)
builder.add(Unreachable())
builder.builder.pop_error_handler()
# If there was a return, keep returning
if ret_reg:
builder.activate_block(rest)
return_block, rest = BasicBlock(), BasicBlock()
builder.add(Branch(ret_reg, rest, return_block, Branch.IS_ERROR))
builder.activate_block(return_block)
builder.nonlocal_control[-1].gen_return(builder, ret_reg, -1)
# TODO: handle break/continue
builder.activate_block(rest)
out_block = BasicBlock()
builder.goto(out_block)
# If there was an exception, restore again
builder.activate_block(cleanup_block)
finally_control.gen_cleanup(builder, -1)
builder.primitive_op(keep_propagating_op, [], NO_TRACEBACK_LINE_NO)
builder.add(Unreachable())
return out_block
def transform_assert_stmt(builder: IRBuilder, a: AssertStmt) -> None:
if builder.options.strip_asserts:
return
cond = builder.accept(a.expr)
ok_block, error_block = BasicBlock(), BasicBlock()
builder.add_bool_branch(cond, ok_block, error_block)
builder.activate_block(error_block)
if a.msg is None:
# Special case (for simpler generated code)
builder.add(RaiseStandardError(RaiseStandardError.ASSERTION_ERROR, None, a.line))
elif isinstance(a.msg, StrExpr):
# Another special case
builder.add(RaiseStandardError(RaiseStandardError.ASSERTION_ERROR, a.msg.value,
a.line))
else:
# The general case -- explicitly construct an exception instance
message = builder.accept(a.msg)
exc_type = builder.load_module_attr_by_fullname('builtins.AssertionError', a.line)
exc = builder.py_call(exc_type, [message], a.line)
builder.primitive_op(raise_exception_op, [exc], a.line)
builder.add(Unreachable())
builder.activate_block(ok_block)
def transform_if_stmt(builder: IRBuilder, stmt: IfStmt) -> None:
if_body, next = BasicBlock(), BasicBlock()
else_body = BasicBlock() if stmt.else_body else next
# If statements are normalized
assert len(stmt.expr) == 1
builder.process_conditional(stmt.expr[0], if_body, else_body)
builder.activate_block(if_body)
builder.accept(stmt.body[0])
builder.goto(next)
if stmt.else_body:
builder.activate_block(else_body)
builder.accept(stmt.else_body)
builder.goto(next)
builder.activate_block(next)
def transform_while_stmt(builder: IRBuilder, s: WhileStmt) -> None:
body, next, top, else_block = BasicBlock(), BasicBlock(), BasicBlock(), BasicBlock()
normal_loop_exit = else_block if s.else_body is not None else next
builder.push_loop_stack(top, next)
# Split block so that we get a handle to the top of the loop.
builder.goto_and_activate(top)
builder.process_conditional(s.expr, body, normal_loop_exit)
builder.activate_block(body)
builder.accept(s.body)
# Add branch to the top at the end of the body.
builder.goto(top)
builder.pop_loop_stack()
if s.else_body is not None:
builder.activate_block(else_block)
builder.accept(s.else_body)
builder.goto(next)
builder.activate_block(next)
def transform_conditional_expr(builder: IRBuilder,
expr: ConditionalExpr) -> Value:
if_body, else_body, next = BasicBlock(), BasicBlock(), BasicBlock()
builder.process_conditional(expr.cond, if_body, else_body)
expr_type = builder.node_type(expr)
# Having actual Phi nodes would be really nice here!
target = builder.alloc_temp(expr_type)
builder.activate_block(if_body)
true_value = builder.accept(expr.if_expr)
true_value = builder.coerce(true_value, expr_type, expr.line)
builder.add(Assign(target, true_value))
builder.goto(next)
builder.activate_block(else_body)
false_value = builder.accept(expr.else_expr)
false_value = builder.coerce(false_value, expr_type, expr.line)
builder.add(Assign(target, false_value))
builder.goto(next)
builder.activate_block(next)
return target
def try_finally_entry_blocks(builder: IRBuilder,
err_handler: BasicBlock,
return_entry: BasicBlock,
main_entry: BasicBlock,
finally_block: BasicBlock,
ret_reg: Optional[Register]) -> Value:
old_exc = builder.alloc_temp(exc_rtuple)
# Entry block for non-exceptional flow
builder.activate_block(main_entry)
if ret_reg:
builder.add(
Assign(
ret_reg,
builder.add(LoadErrorValue(builder.ret_types[-1]))
)
)
builder.goto(return_entry)
builder.activate_block(return_entry)
builder.add(Assign(old_exc, builder.add(LoadErrorValue(exc_rtuple))))
builder.goto(finally_block)
# Entry block for errors
builder.activate_block(err_handler)
if ret_reg:
builder.add(
Assign(
ret_reg,
builder.add(LoadErrorValue(builder.ret_types[-1]))
)
)
builder.add(Assign(old_exc, builder.primitive_op(error_catch_op, [], -1)))
builder.goto(finally_block)
return old_exc
def transform_try_except(builder: IRBuilder,
body: GenFunc,
handlers: Sequence[
Tuple[Optional[Expression], Optional[Expression], GenFunc]],
else_body: Optional[GenFunc],
line: int) -> None:
"""Generalized try/except/else handling that takes functions to gen the bodies.
The point of this is to also be able to support with."""
assert handlers, "try needs except"
except_entry, exit_block, cleanup_block = BasicBlock(), BasicBlock(), BasicBlock()
double_except_block = BasicBlock()
# If there is an else block, jump there after the try, otherwise just leave
else_block = BasicBlock() if else_body else exit_block
# Compile the try block with an error handler
builder.builder.push_error_handler(except_entry)
builder.goto_and_activate(BasicBlock())
body()
builder.goto(else_block)
builder.builder.pop_error_handler()
# The error handler catches the error and then checks it
# against the except clauses. We compile the error handler
# itself with an error handler so that it can properly restore
# the *old* exc_info if an exception occurs.
# The exception chaining will be done automatically when the
# exception is raised, based on the exception in exc_info.
builder.builder.push_error_handler(double_except_block)
builder.activate_block(except_entry)
old_exc = builder.maybe_spill(builder.primitive_op(error_catch_op, [], line))
# Compile the except blocks with the nonlocal control flow overridden to clear exc_info
builder.nonlocal_control.append(
ExceptNonlocalControl(builder.nonlocal_control[-1], old_exc))
# Process the bodies
for type, var, handler_body in handlers:
next_block = None
if type:
next_block, body_block = BasicBlock(), BasicBlock()
matches = builder.primitive_op(
exc_matches_op, [builder.accept(type)], type.line
)
builder.add(Branch(matches, body_block, next_block, Branch.BOOL_EXPR))
builder.activate_block(body_block)
if var:
target = builder.get_assignment_target(var)
builder.assign(
target,
builder.primitive_op(get_exc_value_op, [], var.line),
var.line
)
handler_body()
builder.goto(cleanup_block)
if next_block:
builder.activate_block(next_block)
# Reraise the exception if needed
if next_block:
builder.primitive_op(reraise_exception_op, [], NO_TRACEBACK_LINE_NO)
builder.add(Unreachable())
builder.nonlocal_control.pop()
builder.builder.pop_error_handler()
# Cleanup for if we leave except through normal control flow:
# restore the saved exc_info information and continue propagating
# the exception if it exists.
builder.activate_block(cleanup_block)
builder.primitive_op(restore_exc_info_op, [builder.read(old_exc)], line)
builder.goto(exit_block)
# Cleanup for if we leave except through a raised exception:
# restore the saved exc_info information and continue propagating
# the exception.
builder.activate_block(double_except_block)
builder.primitive_op(restore_exc_info_op, [builder.read(old_exc)], line)
builder.primitive_op(keep_propagating_op, [], NO_TRACEBACK_LINE_NO)
builder.add(Unreachable())
# If present, compile the else body in the obvious way
if else_body:
builder.activate_block(else_block)
else_body()
builder.goto(exit_block)
builder.activate_block(exit_block)