def ConvertShortCircuitIf(if_stmt: c_ast.If, parent: c_ast.Node, id_gen: common.UniqueId):
cond = if_stmt.cond
if isinstance(cond, c_ast.UnaryOp) and cond.op == "!":
# for a not not just swap the branches
if_stmt.cond = cond.expr
if_stmt.iffalse, if_stmt.iftrue = if_stmt.iftrue, if_stmt.iffalse
ConvertShortCircuitIf(if_stmt, parent, id_gen)
return
if not isinstance(cond, c_ast.BinaryOp):
return
if cond.op != "&&" and cond.op != "||":
return
labelnext = id_gen.next("branch")
if cond.op == "&&":
if_stmt2 = c_ast.If(cond.left, c_ast.Goto(labelnext), if_stmt.iffalse)
else:
assert cond.op == "||"
if_stmt2 = c_ast.If(cond.left, if_stmt.iftrue, c_ast.Goto(labelnext))
if_stmt.cond = cond.right
stmts = common.GetStatementList(parent)
# this is easy to fix but basically guaranteed after running IfTransform
assert stmts, parent
pos = stmts.index(if_stmt)
stmts[pos:pos + 1] = [if_stmt2, c_ast.Label(labelnext, c_ast.EmptyStatement()), if_stmt]
ConvertShortCircuitIf(if_stmt2, parent, id_gen)
ConvertShortCircuitIf(if_stmt, parent, id_gen)
def ConvertWhileLoop(ast, id_gen: common.UniqueId):
def IsWhileLoop(node, _):
return isinstance(node, (c_ast.DoWhile, c_ast.While))
candidates = common.FindMatchingNodesPostOrder(ast, ast, IsWhileLoop)
for node, parent in candidates:
loop_label = id_gen.next("while")
test_label = loop_label + "_cond"
exit_label = loop_label + "_exit"
conditional = c_ast.If(node.cond, c_ast.Goto(loop_label), None)
block = [c_ast.Label(loop_label, c_ast.EmptyStatement()), node.stmt,
c_ast.Label(test_label, c_ast.EmptyStatement()), conditional,
c_ast.Label(exit_label, c_ast.EmptyStatement())]
if isinstance(node, c_ast.While):
block = [c_ast.Goto(test_label)] + block
common.ReplaceBreakAndContinue(node.stmt, node, test_label, exit_label)
common.ReplaceNode(parent, node, c_ast.Compound(block))
def ConvertForLoop(ast, id_gen: common.UniqueId):
candidates = common.FindMatchingNodesPostOrder(
ast, ast, lambda n, _: isinstance(n, c_ast.For))
for node, parent in candidates:
loop_label = id_gen.next("for")
next_label = loop_label + "_next"
test_label = loop_label + "_cond"
exit_label = loop_label + "_exit"
goto = c_ast.Goto(loop_label)
conditional = c_ast.If(node.cond, goto, None) if node.cond else goto
block = ExtractForInitStatements(node.init) + [
c_ast.Goto(test_label),
c_ast.Label(loop_label, c_ast.EmptyStatement()), node.stmt,
c_ast.Label(next_label, c_ast.EmptyStatement()),
node.next if node.next else c_ast.EmptyStatement(),
c_ast.Label(test_label, c_ast.EmptyStatement()), conditional,
c_ast.Label(exit_label, c_ast.EmptyStatement())
]
common.ReplaceBreakAndContinue(node.stmt, node, next_label, exit_label)
common.ReplaceNode(parent, node, c_ast.Compound(block))
def ConvertToGotos(if_stmt: c_ast.If, parent, id_gen: common.UniqueId):
if (isinstance(if_stmt.iftrue, c_ast.Goto) and
isinstance(if_stmt.iffalse, c_ast.Goto) and
not isinstance(if_stmt.cond, c_ast.ExprList)):
return
label = id_gen.next("if")
labeltrue = label + "_true"
labelfalse = label + "_false"
labelend = label + "_end"
emptytrue = common.IsEmpty(if_stmt.iftrue) or isinstance(if_stmt.iftrue, c_ast.Goto)
emptyfalse = common.IsEmpty(if_stmt.iffalse) or isinstance(if_stmt.iffalse, c_ast.Goto)
seq: List[c_ast.Node] = []
# TODO: this should be done in EliminateExpressionLists(
if isinstance(if_stmt.cond, c_ast.ExprList):
exprs = if_stmt.cond.exprs
if_stmt.cond = exprs.pop(-1)
seq += exprs
seq.append(if_stmt)
if not emptytrue:
seq += [c_ast.Label(labeltrue, c_ast.EmptyStatement()), if_stmt.iftrue]
if not emptyfalse:
seq.append(c_ast.Goto(labelend))
if not emptyfalse:
seq += [c_ast.Label(labelfalse, c_ast.EmptyStatement()), if_stmt.iffalse]
seq.append(c_ast.Label(labelend, c_ast.EmptyStatement()))
if not isinstance(if_stmt.iftrue, c_ast.Goto):
if_stmt.iftrue = c_ast.Goto(labelend if emptytrue else labeltrue)
if not isinstance(if_stmt.iffalse, c_ast.Goto):
if_stmt.iffalse = c_ast.Goto(labelend if emptyfalse else labelfalse)
stmts = common.GetStatementList(parent)
if not stmts:
stmts = [if_stmt]
parent = common.ReplaceNode(parent, if_stmt, c_ast.Compound(stmts))
pos = stmts.index(if_stmt)
stmts[pos: pos + 1] = seq
def ReplaceBreakAndContinue(node, parent, test_label, exit_label):
""" Starting at `node` recursively replace
all `continue` statements with `goto test_label` and
all `break` statements with `goto exit_label`
"""
if isinstance(node, c_ast.Continue):
ReplaceNode(parent, node, c_ast.Goto(test_label))
return
if exit_label and isinstance(node, c_ast.Break):
ReplaceNode(parent, node, c_ast.Goto(exit_label))
return
if isinstance(node, (c_ast.While, c_ast.DoWhile, c_ast.For)):
# do not recurse into other loops
return
if isinstance(node, c_ast.Switch):
# `break`s inside switches have their own meaning but we still need to replace `continue`s
exit_label = None
for c in node:
ReplaceBreakAndContinue(c, node, test_label, exit_label)
def generic_visit(self, node):
for ci, (c_name, c) in enumerate(node.children()):
self.visit(c)
# If child is sliced, then mark this as well
if c.sliced:
node.sliced = True
# If adding an assignment, ensure that it is declared by adding lvalue
# to dependency list
# FIXME: Only need to declare this variable, not handle all its dependences
if isinstance(node, c_ast.Assignment):
self.id_visitor.new_visit(node.lvalue)
self.rvalues += self.id_visitor.IDs
"""
print "Adding to slice:"
print_node(node)
print "because child is in slice:"
print_node(c)
print
"""
# Always include Returns, change them to Goto end of function
if isinstance(c, c_ast.Return):
# Create a new compound node
insert_node = c_ast.Compound([])
"""
# If there is a return value, add statement for return_value = value
if c.expr:
ret_id = c_ast.ID("return_value")
ret_id.sliced = True
assignment = c_ast.Assignment("=", ret_id, c.expr)
assignment.sliced = True
insert_node.block_items.append(assignment)
"""
# Goto end of function
goto = c_ast.Goto(self.end_label)
goto.sliced = True
insert_node.block_items.append(goto)
insert_node.sliced = True
# Add compound node back to function
if isinstance(node, c_ast.Compound):
node.block_items[ci] = insert_node
elif isinstance(node, c_ast.If):
exec("node.%s = insert_node" % c_name)
elif isinstance(node, c_ast.Case):
node.stmts[ci - 1] = insert_node
else:
print_node(node)
node.show(nodenames=True, showcoord=True)
raise Exception(
"Unsupported parent node type %s. Please implement." %
(type(node)))
def generic_visit(self, node):
for ci, (c_name, c) in enumerate(node.children()):
# Return statement
if isinstance(c, c_ast.Return):
# Create a new compound node
insert_node = c_ast.Compound([])
# If there is a return value, add statement for return_value = value
if c.expr:
insert_node.block_items.append(c_ast.Assignment("=", c_ast.ID("return_value"), c.expr))
# Add goto to end of function block
insert_node.block_items.append(c_ast.Goto(self.goto_name))
# Replace original node with new node
replace_node(node, insert_node, ci, c_name)
# Non-return statement, continue visiting
else:
self.visit(c)
def do_jump(**kw):
#goto {loc}
# fmt_op returns an ID but Goto takes a bare string
return c_ast.Goto(kw['loc'].name)