def gen_for_stmt(info, node, method_obj):
output = []
# Initialize, if any.
if len(node[0].children) == 1:
if node[0][0].name == 'LocalVariableDeclaration':
output.extend(gen_local_variable_decl(info, node[0][0], method_obj))
else: # expression
output.extend(expression.gen_expr(info, node[0][0], method_obj))
loop_lbl = info.get_jump_label()
end_lbl = info.get_jump_label()
output.append(loop_lbl + ':')
# Generate cond, if any.
if len(node[1].children) == 1:
output.extend(expression.gen_expr(info, node[1][0], method_obj))
output.append('mov ebx, 0')
output.append('cmp eax, ebx')
output.append('je %s' % end_lbl) # If false, go to end.
# Generate body, if any.
if len(node[3].children) == 1:
output.extend(gen_stmt(info, node[3][0], method_obj))
# Generate update, if any.
if len(node[2].children) == 1:
output.extend(expression.gen_expr(info, node[2][0], method_obj))
output.append('jmp %s' % loop_lbl)
output.append(end_lbl + ':')
return output
def gen_static_field_decl(info, node):
assert node.name == 'FieldDeclaration'
output = []
# If there's no initializer, nothing needs to be done. Otherwise, generate
# the expression code and set it.
initializer = node[3]
if len(initializer.children) == 1:
output.extend(expression.gen_expr(info, initializer[0], None))
output.append('mov [%s], eax' % node.label)
return output
def gen_return_stmt(info, node, method_obj):
output = []
if len(node.children) != 0:
output.extend(expression.gen_expr(info, node[0], method_obj))
pass
else:
output.append("mov eax, %d" % 0xDEADBEEF)
output.append("jmp END~%s" % (method_obj.node.label))
return output
def gen_local_variable_decl(info, node, method_obj):
output = ["; gen_local_variable_decl"]
# Generate the initialization code.
output.extend(expression.gen_expr(info, node[2][0], method_obj))
# Get the offset.
offset = node.frame_offset * 4
output.append('mov ebx, %d' % offset)
# Calculate address and assign.
output.append('mov [ebp+ebx], eax')
return output
def gen_while_stmt(info, node, method_obj):
output = []
loop_lbl = info.get_jump_label()
end_lbl = info.get_jump_label()
output.append(loop_lbl + ':')
# Generate condition.
output.extend(expression.gen_expr(info, node[0], method_obj))
output.append('mov ebx, 0')
output.append('cmp eax, ebx')
output.append('je %s' % end_lbl) # If false, go to end.
# Loop body.
output.extend(gen_stmt(info, node[1], method_obj))
output.append('jmp %s' % loop_lbl)
output.append(end_lbl + ':')
return output
def gen_if_stmt(info, node, method_obj):
output = []
else_label = info.get_jump_label()
end_label = info.get_jump_label()
# Check condition.
output.extend(expression.gen_expr(info, node[0], method_obj))
output.append('mov ebx, 0')
output.append('cmp eax, ebx')
output.append('je %s' % else_label) # statement is false, jump to else
# True path.
output.extend(gen_stmt(info, node[1], method_obj))
output.append('jmp %s' % end_label)
# False path.
output.append(else_label + ':')
if len(node.children) == 3: # If there's an else condition, gen some code
output.extend(gen_stmt(info, node[2], method_obj))
output.append(end_label + ':')
return output
def gen_expr_stmt(info, node, method_obj):
output = []
output.extend(expression.gen_expr(info, node[0], method_obj))
return output
def gen_constructor(info, constructor_obj):
node = constructor_obj.node
assert node.name == 'ConstructorDeclaration'
# Preprocessing:
# Assign frame pointer offsets to each parameter and local variable
# declaration node.
param_start_index = len(node.find_child('Parameters').children) + 1
for decl in node.find_child('Parameters').children:
decl.frame_offset = param_start_index
param_start_index -= 1
local_var_start_index = -1
num_vars = 0
all_local_decls = list(node.select(['LocalVariableDeclaration']))
for decl in all_local_decls:
decl.frame_offset = local_var_start_index
local_var_start_index -= 1
num_vars += 1
output = []
# Preamble for constructor.
output.append(constructor_obj.node.label + ':')
# save ebp & esp
output.extend([
"push ebp",
"mov ebp, esp",
])
# make room for local vars in the stack
output.append("sub esp, %d" % (num_vars*4))
# Call superclass default constructor if this is not java.lang.Object.
if info.class_obj.name != 'java.lang.Object':
this_offset = (len(constructor_obj.params) * 4) + 8
output.append('mov eax, %d' % this_offset)
output.append('mov eax, [eax+ebp]')
output.append('push eax')
superclass = info.class_obj.extends.name
superclass_simple = superclass.split('.')[-1]
superclass_label = 'CONSTRUCTOR~%s.%s~' % (superclass, superclass_simple)
output.append('call %s' % superclass_label)
output.append('add esp, 4')
# Initialize instance fields.
for member in info.class_obj.declare:
if isinstance(member, class_hierarchy.Field) == False:
continue
field_obj = member
field_node = field_obj.node
if 'Static' not in field_obj.mods and \
len(field_node[3].children) == 1: # Initializer
# Evaluate initializer.
output.extend(expression.gen_expr(info, field_node[3][0], constructor_obj))
# Get the address of 'this'.
this_offset = (len(constructor_obj.params) * 4) + 8
output.append('mov ebx, ebp')
output.append('add ebx, %d' % this_offset)
output.append('mov ebx, [ebx]')
# Assign to field offset.
receiver_type = info.class_obj.name
field_name = field_obj.name
field_offset = info.get_field_offset_from_field_name(receiver_type, field_name)
field_offset += 12
output.append('mov [ebx+%d], eax' % field_offset)
body = node # ConstructorBody
if len(body.children) != 0:
output.extend(statement.gen_block(info, body[3], constructor_obj))
# restore ebp & esp
output.extend([
"END~%s:" % (constructor_obj.node.label),
"mov esp, ebp",
"pop ebp",
"ret"
])
return output
