def handle_prologue(self, func_name, *operands):
"""Handles the prologue of the function definition in IR.
"""
self.memory_offset = 0
# Allocate memory for both the defined variables and the formal parameters.
# Symbol table will have entry for all of them.
for symtab_entry in self.ir.local_symbol_table.values():
if 'memory' in symtab_entry:
symtab_entry['memory'].offset = self.memory_offset
symtab_entry['memory'].size = MEMORY_WIDTH
symtab_entry['memory'].base = 0
self.memory_offset += MEMORY_WIDTH
elif symtab_entry.get('dimensions'):
if 'memory' not in symtab_entry:
symtab_entry['memory'] = Memory()
symtab_entry['memory'].offset = self.memory_offset
total_size = 1
for dimension in symtab_entry['dimensions']:
total_size *= dimension
symtab_entry['memory'].size = total_size * MEMORY_WIDTH
symtab_entry['memory'].base = 0
self.memory_offset += total_size * MEMORY_WIDTH
self.create_stack()
def handle_load(self, label, result, *operands):
"""Handles the load instruction of IR.
"""
register = result
if isinstance(operands[0], Immediate) and isinstance(operands[1], Memory):
memory = Memory(
base=operands[1].base,
offset=operands[1].offset + (operands[0].value * MEMORY_WIDTH))
elif isinstance(operands[0], Register):
# This happens only in case of arrays
memory = Memory(base=operands[1], offset=operands[0])
elif isinstance(operands[0], Memory):
memory = operands[0]
if memory.offset == None:
memory.offset = self.memory_offset
self.memory_offset += MEMORY_WIDTH
mov = MOV(register, memory)
self.add_instruction(label, mov)
def allocate_global_memory(global_symbol_table):
"""Allocate memory for global datastructures.
Args:
global_symbol_table: Dictionary containing the global symbol table whose
keys are symbol names and values are symbol table data like memory
object for this symbol and type.
"""
memory_offset = 0
for symbol, symtab_entry in global_symbol_table.iteritems():
if symtab_entry.get('type') == 'function_name' or (
symbol in ['InputNum', 'OutputNum', 'OutputNewLine']):
# These symbols are function names, don't do anything for them here.
continue
elif symtab_entry.get('dimensions', None) != None:
# This entry is an array
if 'memory' not in symtab_entry:
symtab_entry['memory'] = Memory()
symtab_entry['memory'].offset = memory_offset
total_size = 1
for dimension in symtab_entry['dimensions']:
total_size *= dimension
symtab_entry['memory'].size = total_size * MEMORY_WIDTH
symtab_entry['memory'].base = 'rip'
memory_offset += total_size * MEMORY_WIDTH
else:
# This entry is a regular integer.
if 'memory' not in symtab_entry:
symtab_entry['memory'] = Memory()
symtab_entry['memory'].offset = memory_offset
symtab_entry['memory'].size = MEMORY_WIDTH
symtab_entry['memory'].base = 'rip'
memory_offset += MEMORY_WIDTH
return memory_offset
def handle_store(self, label, result, *operands):
"""Handles the store instruction of IR.
"""
if isinstance(operands[1], Immediate) and isinstance(operands[2], Memory):
memory = Memory(
base=operands[2].base,
offset=operands[2].offset + (operands[1].value * MEMORY_WIDTH))
elif isinstance(operands[1], Register):
memory = Memory()
memory.base = operands[2]
memory.offset = operands[1]
elif isinstance(operands[1], Memory):
memory = operands[1]
memory.offset = self.memory_offset
self.memory_offset += MEMORY_WIDTH
if isinstance(operands[0], Memory) or (isinstance(operands[0], Register)
and isinstance(operands[0].color, Memory)):
# Take the set difference
free_registers = (REGISTERS_COLOR_SET -
set(self.instruction_live_registers[label].keys()))
if free_registers:
# Create a dummy register for this color
register = Register()
# pop and add back since sets don't support indexing
register.color = free_registers.pop()
free_registers.add(register.color)
mov1 = MOV(register, operands[0])
self.add_instruction(label, mov1)
mov2 = MOV(memory, register)
self.add_instruction(label, mov2)
else:
# We don't have any free registers :(
# We can't do much, randomly pick a register, push it to the stack,
# do the memory move from the source to this register and then use
# this register to move the source to the destination and then
# pop back our register.
# NOTE: We pick %rax for this temporary operation
# Create a dummy register for %rax
register = Register()
register.color = 0
push = PUSH(register)
self.add_instruction(label, push)
mov1 = MOV(register, operands[0])
self.add_instruction(label, mov1)
mov2 = MOV(memory, register)
self.add_instruction(label, mov2)
pop = POP(register)
self.add_instruction(label, pop)
else:
register = operands[0]
mov = MOV(memory, register)
self.add_instruction(label, mov)
