def c_gen_code_get_array_pointer(self):
'''Creates code that will store the array a reference to the array in ebx
and the offset for the index in eax.'''
array_check_pass = manager.CodeGenManager.get_label('array_check_pass')
array_check_fail = manager.CodeGenManager.get_label('array_check_fail')
# Assume that we're doing an array read.
return [
self.array_expression.c_gen_code(),
common.check_null('eax'),
'push eax',
self.index.c_gen_code(),
'pop ebx ; restore the pointer to the array',
common.unwrap_primitive('eax', 'eax'),
'; check whether the index is out of bounds:',
common.get_array_length('ecx', 'ebx'),
common.unwrap_primitive('ecx', 'ecx'),
'cmp eax, ecx',
'jge {0}'.format(array_check_fail),
'cmp eax, 0',
'jl {0}'.format(array_check_fail),
'jmp {0}'.format(array_check_pass),
'{0}:'.format(array_check_fail),
'call __exception',
'{0}:'.format(array_check_pass),
'; calculate the offset into the array:',
'imul eax, 4',
'add eax, 12',
]
def c_gen_code(self):
import code_gen.access as access
result = self.right.c_gen_code()
# The left hand side is either an ASTArrayAccess, ASTFieldAccess or
# ASTIdentifiers.
if isinstance(self.left, ASTIdentifiers):
# For assignment expressions, we evaluate the left hand side first. If
# the left hand side is an ASTIdentifiers, the same ASTIdentifiers could
# be used on the right hand side in an assignment.
# Thus, we must store a reference to where the left hand side points
# before evaluating the right hand side.
if self.left.is_simple:
# If the left hand side is simple, it is either a method parameter,
# local variable or an instance field on the enclosing type. The
# location for all of these cannot be altered by the right hand side,
# so we can calculate the right hand side first.
return [
result,
access.set_simple_var(self.left.simple_decl, 'eax'),
]
else:
import code_gen.annotate_ids as annotate_ids
annotations = annotate_ids.annotate_identifier(self.left)
if len(annotations) == 0:
# If we do not have any annotations then the left hand side is a
# static field. This address cannot change.
return [
result,
access.set_simple_static_field(self.left, 'eax'),
]
else:
# _get_to_final provides code to store a pointer to the second last
# part of the identifier in $eax.
type_, code = access._get_to_final(self.left, annotations)
env = type_.definition.environment
final_part = str(self.left.parts[-1])
f, _ = env.lookup_field(final_part)
return [
code,
common.check_null('eax'),
'push eax ; save instance that we want to store a field on',
result,
'pop ebx ; instance to store a field on',
common.save_instance_field('ebx', f, 'eax'),
]
elif isinstance(self.left, ASTFieldAccess):
left_asm = self.left.left.c_gen_code()
left_t = self.left.left.expr_type
if left_t.is_array:
raise Exception('Trying to write to array field')
return [
'; FieldAccess assignment',
access.get_field_from_parts(
left_t, self.left.right, left_asm, get_addr=True),
'push eax ; Save field addr',
result,
'; RHS of assignment should be eax',
'pop ebx ; Pop addr of field',
'mov [ebx], eax ; Assign!'
]
elif isinstance(self.left, ASTArrayAccess):
array_soundness_pass = manager.CodeGenManager.get_label('array_soundness_pass')
soundness_asm = []
if not self.left.array_expression.expr_type.is_primitive:
soundness_asm = [
'push eax',
'push ebx',
'push ecx',
'; Get CIT of right side',
'mov ecx, [ecx]'
'; Get subtype col of right side',
'mov ecx, [ecx + 4]',
'; get subtype offset',
'mov ebx, [ebx + 4]',
'; index into subtype col',
'mov ecx, [ecx + ebx]',
'cmp ecx, 1 ; 1 means that RHS is a subtype of LHS',
'je {0}'.format(array_soundness_pass),
'call __exception',
'{0}:'.format(array_soundness_pass),
'pop ecx',
'pop ebx',
'pop eax',
]
# The result is calculated after the array index offset.
return [
self.left.c_gen_code_get_array_pointer(),
'push ebx ; save array pointer',
'push eax ; save array offset',
result,
'mov ecx, eax ; move result',
'pop eax ; restore array offset',
'pop ebx ; restore array pointer',
'; do array type soundness check',
soundness_asm,
'mov [ebx + eax], ecx',
'mov eax, ecx ; result should be in eax',
]
raise Exception('Programmer error: trying to assign to invalid AST')