gameboy superoptimizer
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from math import log
from random import random
from typing import List, Optional, Tuple
from gbso.program.test_case import Output, TestCase, eq_on_testcase
from gbso.program.mutate import mutate_program
from gbso.program.program import Program
EPSILON = 0.00001
DEFAULT_NUM_ITERS = 1_000_000
DEFAULT_PROB_OPCODE = 0.25
DEFAULT_PROB_OPERAND = 0.25
DEFAULT_PROB_SWAP = 0.25
DEFAULT_PROB_INSN = 0.25
DEFAULT_PROB_INSN_UNUSED = 0.1
def cost(orig_prgm, test_cases, outputs, prgm) -> Tuple[int, bool]:
# Since each instruction executes in 4*k cycles (for some k), this can have
# the undesirable effect of performance improvements being weighted much
# higher than correctness. This hurts convergence pretty badly, so we scale
# by 1/4 to compensate.
perf = (prgm.perf() - orig_prgm.perf()) / 4.0
eq = 0
for test_case in test_cases:
eq += eq_on_testcase(orig_prgm, prgm, test_case, outputs)
return perf + eq, eq == 0
def optimize(
target_prgm: Program,
max_size: int,
test_cases: List[TestCase],
outputs: List[Output],
beta: int = 0.5, # How far away in cost you are allowed to search
init_prgm: Optional[Program] = None,
num_iters: int = DEFAULT_NUM_ITERS,
prob_opcode: float = DEFAULT_PROB_OPCODE,
prob_operand: float = DEFAULT_PROB_OPERAND,
prob_swap: float = DEFAULT_PROB_SWAP,
prob_insn: float = DEFAULT_PROB_INSN,
prob_insn_unused: float = DEFAULT_PROB_INSN_UNUSED,
) -> Program:
padded_prgm = (init_prgm or target_prgm).pad(max_size)
last_prgm = padded_prgm
last_cost, _last_eq = cost(target_prgm, test_cases, outputs, last_prgm)
best_prgm = target_prgm.pad(max_size)
best_cost = 0
num_candidates = 0
for _ in range(num_iters):
candidate_prgm = mutate_program(
last_prgm, prob_opcode, prob_operand, prob_swap, prob_insn, prob_insn_unused
)
candidate_cost, candidate_eq = cost(
target_prgm, test_cases, outputs, candidate_prgm
)
if candidate_cost < best_cost and candidate_eq:
best_prgm = candidate_prgm
best_cost = candidate_cost
num_candidates += 1
if candidate_cost < last_cost - log(random()) / beta:
last_prgm = candidate_prgm
last_cost = candidate_cost
print(f"Optimization complete. Total candidates: {num_candidates}")
return best_prgm