def visit_bool_literal(self, node, target, *args):
if target == ir.EXPR:
return ir.Const(int(node.value), args[0])
else:
if node.value:
return ir.Jump(args[0])
else:
return ir.Jump(args[1])
def add_block_to_trace(self, trace, in_block):
# add block to trace. As a side-effect, tidy up last jump to
# enforce condition that each cjump must be followed by its
# false label
block = copy.copy(in_block) # avoid modifying block used by caller
target = block[0].name
if trace != []:
lastjump = trace[-1]
if isinstance(lastjump, ir.Jump):
if lastjump.dest == target:
# remove jumps to the next stm
del trace[-1]
else:
assert (isinstance(lastjump, ir.CJump))
if lastjump.falseDest == target:
# no change required
pass
elif lastjump.trueDest == target:
trace[-1] = self.flip_cjump(lastjump)
else:
# insert extra label and jump to make it work
jump = ir.Jump(lastjump.falseDest, lastjump.node)
newFalse = self.symbols.newLabel()
label = ir.Label(newFalse, lastjump.node)
lastjump.falseDest = newFalse
trace += [label, jump]
trace += block
def basic_blocks(self, tree, startLabel, endLabel):
# divides tree into a list of basic blocks
# we assume it has a Seq() at the top, and no other seqs or eseqs
assert (isinstance(tree, ir.Seq))
tree.children.append(ir.Label(endLabel, tree.node))
blocks = []
label = startLabel
inBlock = 0
block = []
for stm in tree.children:
if isinstance(stm, ir.Label):
if block == []:
block.append(stm)
else:
# close existing block, create a new one
if not self.is_jump(block[-1]):
# append a jump to current label
block.append(ir.Jump(stm.name, stm.node))
blocks.append(block)
block = [stm]
else:
if block == []:
# manufacture a label if first stm is not a label
block.append(ir.Label(label, tree.node))
label = self.symbols.newLabel()
block.append(stm)
if self.is_jump(stm):
blocks.append(block)
block = []
return blocks
def visit_while_statement(self, node, *args):
lbl_start = self.get_id()
lbl_body = self.get_id()
lbl_end = self.get_id()
return [
ir.Label(lbl_start),
self.visit(node.condition, ir.COND, lbl_body, lbl_end),
ir.Label(lbl_body),
list(map(self.visit, node.stmt)),
ir.Jump(lbl_start),
ir.Label(lbl_end),
]
def visit_if_statement(self, node, *args):
lbl_then = self.get_id()
lbl_else = self.get_id()
lbl_end = self.get_id()
return [
self.visit(node.condition, ir.COND, lbl_then, lbl_else),
ir.Label(lbl_then),
list(map(self.visit, node.stmt_then)),
ir.Jump(lbl_end),
ir.Label(lbl_else),
list(map(self.visit, node.stmt_else)),
ir.Label(lbl_end),
]
def visit_bin_op(self, node, target, *args):
if node.op in ['+', '-', '*', '%'] or (node.op == '<'
and target == ir.EXPR):
assert target == ir.EXPR
lhs = self.get_id()
rhs = self.get_id()
arg1, arg2 = self.reorder_for_bin_op(node.left, node.right, lhs,
rhs)
return [
arg1,
arg2,
ir.BinOp(node.op, lhs, rhs, args[0]),
]
if node.op == '<':
assert target == ir.COND
lhs = self.get_id()
rhs = self.get_id()
arg1, arg2 = self.reorder_for_bin_op(node.left, node.right, lhs,
rhs)
return [
arg1,
arg2,
ir.CJumpLess(lhs, rhs, args[0], args[1]),
]
if node.op == '&&':
if target == ir.COND:
lbl_second_arg = self.get_id()
return [
self.visit(node.left, ir.COND, lbl_second_arg, args[1]),
ir.Label(lbl_second_arg),
self.visit(node.right, ir.COND, args[0], args[1]),
]
else:
lbl_second_arg = self.get_id()
lbl_false = self.get_id()
lbl_true = self.get_id()
lbl_end = self.get_id()
return [
self.visit(node.left, ir.COND, lbl_second_arg, lbl_false),
ir.Label(lbl_second_arg),
self.visit(node.right, ir.COND, lbl_true, lbl_false),
ir.Label(lbl_true),
ir.Const(1, args[0]),
ir.Jump(lbl_end),
ir.Label(lbl_false),
ir.Const(0, args[0]),
ir.Label(lbl_end),
]
if node.op == '||':
if target == ir.COND:
lbl_second_arg = self.get_id()
return [
self.visit(node.left, ir.COND, args[0], lbl_second_arg),
ir.Label(lbl_second_arg),
self.visit(node.right, ir.COND, args[0], args[1]),
]
else:
lbl_second_arg = self.get_id()
lbl_false = self.get_id()
lbl_true = self.get_id()
lbl_end = self.get_id()
return [
self.visit(node.left, ir.COND, lbl_true, lbl_second_arg),
ir.Label(lbl_second_arg),
self.visit(node.right, ir.COND, lbl_true, lbl_false),
ir.Label(lbl_false),
ir.Const(0, args[0]),
ir.Jump(lbl_end),
ir.Label(lbl_true),
ir.Const(1, args[0]),
ir.Label(lbl_end),
]
assert False
def jump(self, dest):
return ir.Jump(dest, self.fakeNode)