def visit_IF(self, node):
expr_ = (yield ToVisit(node.children[0]))
then_ = (yield ToVisit(node.children[1]))
else_ = (yield ToVisit(node.children[2])) if len(node.children) == 3 else self.NOP
if self.O_LEVEL >= 1:
if chk.is_null(then_, else_):
src.api.errmsg.warning_empty_if(node.lineno)
yield self.NOP
return
block_accessed = chk.is_block_accessed(then_) or chk.is_block_accessed(else_)
if not block_accessed and chk.is_number(expr_): # constant condition
if expr_.value: # always true (then_)
yield then_
else: # always false (else_)
yield else_
return
if chk.is_null(else_) and len(node.children) == 3:
node.children.pop() # remove empty else
yield node
return
for i in range(len(node.children)):
node.children[i] = (expr_, then_, else_)[i]
yield node
def append(self, *args):
for arg in args:
if check.is_null(arg):
continue
assert isinstance(arg, Symbol), f"Invalid argument '{arg}'"
if arg.token == 'BLOCK':
self.append(*arg.children)
else:
self.children.append(arg)
def visit_BLOCK(self, node):
warning_emitted = False
i = 0
while i < len(node):
sentence = node[i]
if chk.is_ender(sentence):
j = i + 1
while j < len(node):
if chk.is_LABEL(node[j]):
break
if node[j].token == 'FUNCDECL':
j += 1
continue
if node[j].token == 'SENTENCE' \
and node[j].is_sentinel: # "Sentinel" instructions can be freely removed
node.pop(j)
continue
if node[j].token == 'ASM':
break # User's ASM must always be left there
if not warning_emitted and self.O_LEVEL > 0:
warning_emitted = True
errmsg.warning_unreachable_code(lineno=node[j].lineno,
fname=node[j].filename)
if self.O_LEVEL < 2:
break
node.pop(j)
i += 1
if self.O_LEVEL >= 1 and chk.is_null(node):
yield self.NOP
return
yield (yield self.generic_visit(node))
def __init__(self, *nodes):
super().__init__(*(x for x in nodes if not check.is_null(x)))