forked from M-Labs/artiq
328 lines
13 KiB
Python
328 lines
13 KiB
Python
"""
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:class:`IODelayEstimator` calculates the amount of time
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elapsed from the point of view of the RTIO core for
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every function.
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"""
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from pythonparser import ast, algorithm, diagnostic
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from .. import types, iodelay, builtins, asttyped
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class _UnknownDelay(Exception):
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pass
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class _IndeterminateDelay(Exception):
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def __init__(self, cause):
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self.cause = cause
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class IODelayEstimator(algorithm.Visitor):
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def __init__(self, engine, ref_period):
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self.engine = engine
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self.ref_period = ref_period
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self.changed = False
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self.current_delay = iodelay.Const(0)
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self.current_args = None
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self.current_goto = None
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self.current_return = None
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def evaluate(self, node, abort, context):
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if isinstance(node, asttyped.NumT):
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return iodelay.Const(node.n)
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elif isinstance(node, asttyped.CoerceT):
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return self.evaluate(node.value, abort, context)
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elif isinstance(node, asttyped.NameT):
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if self.current_args is None:
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note = diagnostic.Diagnostic("note",
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"this variable is not an argument", {},
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node.loc)
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abort([note])
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elif node.id in [arg.arg for arg in self.current_args.args]:
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return iodelay.Var(node.id)
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else:
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notes = [
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diagnostic.Diagnostic("note",
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"this variable is not an argument of the innermost function", {},
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node.loc),
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diagnostic.Diagnostic("note",
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"only these arguments are in scope of analysis", {},
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self.current_args.loc)
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]
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abort(notes)
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elif isinstance(node, asttyped.BinOpT):
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lhs = self.evaluate(node.left, abort, context)
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rhs = self.evaluate(node.right, abort, context)
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if isinstance(node.op, ast.Add):
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return lhs + rhs
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elif isinstance(node.op, ast.Sub):
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return lhs - rhs
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elif isinstance(node.op, ast.Mult):
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return lhs * rhs
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elif isinstance(node.op, ast.Div):
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return lhs / rhs
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elif isinstance(node.op, ast.FloorDiv):
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return lhs // rhs
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else:
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note = diagnostic.Diagnostic("note",
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"this operator is not supported {context}",
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{"context": context},
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node.op.loc)
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abort([note])
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else:
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note = diagnostic.Diagnostic("note",
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"this expression is not supported {context}",
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{"context": context},
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node.loc)
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abort([note])
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def abort(self, message, loc, notes=[]):
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diag = diagnostic.Diagnostic("error", message, {}, loc, notes=notes)
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raise _IndeterminateDelay(diag)
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def visit_fixpoint(self, node):
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while True:
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self.changed = False
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self.visit(node)
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if not self.changed:
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return
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def visit_ModuleT(self, node):
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try:
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for stmt in node.body:
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try:
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self.visit(stmt)
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except _UnknownDelay:
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pass # more luck next time?
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except _IndeterminateDelay:
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pass # we don't care; module-level code is never interleaved
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def visit_function(self, args, body, typ, loc):
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old_args, self.current_args = self.current_args, args
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old_return, self.current_return = self.current_return, None
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old_delay, self.current_delay = self.current_delay, iodelay.Const(0)
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try:
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self.visit(body)
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if not iodelay.is_zero(self.current_delay) and self.current_return is not None:
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self.abort("only return statement at the end of the function "
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"can be interleaved", self.current_return.loc)
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delay = types.TFixedDelay(self.current_delay.fold())
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except _IndeterminateDelay as error:
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delay = types.TIndeterminateDelay(error.cause)
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self.current_delay = old_delay
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self.current_return = old_return
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self.current_args = old_args
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if types.is_indeterminate_delay(delay) and types.is_indeterminate_delay(typ.delay):
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# Both delays indeterminate; no point in unifying since that will
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# replace the lazy and more specific error with an eager and more generic
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# error (unification error of delay(?) with delay(?), which is useless).
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return
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try:
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old_delay = typ.delay.find()
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typ.delay.unify(delay)
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if typ.delay.find() != old_delay:
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self.changed = True
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except types.UnificationError as e:
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printer = types.TypePrinter()
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diag = diagnostic.Diagnostic("fatal",
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"delay {delaya} was inferred for this function, but its delay is already "
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"constrained externally to {delayb}",
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{"delaya": printer.name(delay), "delayb": printer.name(typ.delay)},
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loc)
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self.engine.process(diag)
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def visit_FunctionDefT(self, node):
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self.visit(node.args.defaults)
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self.visit(node.args.kw_defaults)
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# We can only handle return in tail position.
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if isinstance(node.body[-1], ast.Return):
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body = node.body[:-1]
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else:
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body = node.body
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self.visit_function(node.args, body, node.signature_type.find(), node.loc)
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visit_QuotedFunctionDefT = visit_FunctionDefT
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def visit_LambdaT(self, node):
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self.visit_function(node.args, node.body, node.type.find(), node.loc)
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def get_iterable_length(self, node, context):
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def abort(notes):
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self.abort("for statement cannot be interleaved because "
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"iteration count is indeterminate",
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node.loc, notes)
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def evaluate(node):
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return self.evaluate(node, abort, context)
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if isinstance(node, asttyped.CallT) and types.is_builtin(node.func.type, "range"):
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range_min, range_max, range_step = iodelay.Const(0), None, iodelay.Const(1)
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if len(node.args) == 3:
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range_min, range_max, range_step = map(evaluate, node.args)
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elif len(node.args) == 2:
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range_min, range_max = map(evaluate, node.args)
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elif len(node.args) == 1:
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range_max, = map(evaluate, node.args)
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return (range_max - range_min) // range_step
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else:
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note = diagnostic.Diagnostic("note",
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"this value is not a constant range literal", {},
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node.loc)
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abort([note])
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def visit_ForT(self, node):
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self.visit(node.iter)
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old_goto, self.current_goto = self.current_goto, None
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old_delay, self.current_delay = self.current_delay, iodelay.Const(0)
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self.visit(node.body)
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if iodelay.is_zero(self.current_delay):
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self.current_delay = old_delay
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else:
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if self.current_goto is not None:
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self.abort("loop iteration count is indeterminate because of control flow",
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self.current_goto.loc)
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context = "in an iterable used in a for loop that is being interleaved"
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node.trip_count = self.get_iterable_length(node.iter, context).fold()
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node.trip_interval = self.current_delay.fold()
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self.current_delay = old_delay + node.trip_interval * node.trip_count
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self.current_goto = old_goto
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self.visit(node.orelse)
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def visit_goto(self, node):
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self.current_goto = node
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visit_Break = visit_goto
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visit_Continue = visit_goto
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def visit_control_flow(self, kind, node):
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old_delay, self.current_delay = self.current_delay, iodelay.Const(0)
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self.generic_visit(node)
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if not iodelay.is_zero(self.current_delay):
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self.abort("{} cannot be interleaved".format(kind), node.loc)
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self.current_delay = old_delay
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visit_If = lambda self, node: self.visit_control_flow("if statement", node)
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visit_IfExpT = lambda self, node: self.visit_control_flow("if expression", node)
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visit_Try = lambda self, node: self.visit_control_flow("try statement", node)
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def visit_While(self, node):
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old_goto, self.current_goto = self.current_goto, None
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self.visit_control_flow("while statement", node)
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self.current_goto = old_goto
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def visit_Return(self, node):
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self.current_return = node
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def visit_With(self, node):
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self.visit(node.items)
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context_expr = node.items[0].context_expr
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if len(node.items) == 1 and types.is_builtin(context_expr.type, "interleave"):
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try:
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delays = []
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for stmt in node.body:
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old_delay, self.current_delay = self.current_delay, iodelay.Const(0)
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self.visit(stmt)
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delays.append(self.current_delay)
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self.current_delay = old_delay
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if any(delays):
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self.current_delay += iodelay.Max(delays)
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except _IndeterminateDelay as error:
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# Interleave failures inside `with` statements are hard failures,
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# since there's no chance that the code will never actually execute
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# inside a `with` statement after all.
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note = diagnostic.Diagnostic("note",
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"while interleaving this 'with interleave:' statement", {},
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node.loc)
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error.cause.notes += [note]
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self.engine.process(error.cause)
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flow_stmt = None
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if self.current_goto is not None:
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flow_stmt = self.current_goto
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elif self.current_return is not None:
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flow_stmt = self.current_return
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if flow_stmt is not None:
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note = diagnostic.Diagnostic("note",
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"this '{kind}' statement transfers control out of "
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"the 'with interleave:' statement",
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{"kind": flow_stmt.keyword_loc.source()},
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flow_stmt.loc)
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diag = diagnostic.Diagnostic("error",
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"cannot interleave this 'with interleave:' statement", {},
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node.keyword_loc.join(node.colon_loc), notes=[note])
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self.engine.process(diag)
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elif len(node.items) == 1 and types.is_builtin(context_expr.type, "sequential"):
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self.visit(node.body)
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else:
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self.abort("with statement cannot be interleaved", node.loc)
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def visit_CallT(self, node):
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typ = node.func.type.find()
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def abort(notes):
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self.abort("call cannot be interleaved because "
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"an argument cannot be statically evaluated",
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node.loc, notes)
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if types.is_builtin(typ, "delay"):
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value = self.evaluate(node.args[0], abort=abort,
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context="as an argument for delay()")
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call_delay = iodelay.SToMU(value, ref_period=self.ref_period)
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elif types.is_builtin(typ, "delay_mu"):
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value = self.evaluate(node.args[0], abort=abort,
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context="as an argument for delay_mu()")
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call_delay = value
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elif not types.is_builtin(typ):
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if types.is_function(typ) or types.is_rpc(typ):
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offset = 0
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elif types.is_method(typ):
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offset = 1
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typ = types.get_method_function(typ)
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else:
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assert False
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if types.is_rpc(typ):
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call_delay = iodelay.Const(0)
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else:
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delay = typ.find().delay.find()
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if types.is_var(delay):
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raise _UnknownDelay()
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elif delay.is_indeterminate():
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note = diagnostic.Diagnostic("note",
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"function called here", {},
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node.loc)
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cause = delay.cause
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cause = diagnostic.Diagnostic(cause.level, cause.reason, cause.arguments,
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cause.location, cause.highlights,
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cause.notes + [note])
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raise _IndeterminateDelay(cause)
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elif delay.is_fixed():
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args = {}
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for kw_node in node.keywords:
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args[kw_node.arg] = kw_node.value
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for arg_name, arg_node in zip(list(typ.args)[offset:], node.args):
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args[arg_name] = arg_node
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free_vars = delay.duration.free_vars()
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node.arg_exprs = {
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arg: self.evaluate(args[arg], abort=abort,
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context="in the expression for argument '{}' "
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"that affects I/O delay".format(arg))
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for arg in free_vars
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}
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call_delay = delay.duration.fold(node.arg_exprs)
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else:
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assert False
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else:
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call_delay = iodelay.Const(0)
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self.current_delay += call_delay
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node.iodelay = call_delay
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