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use std::ops::Mul;
use crate::{
llir_nodes::{BinaryOperation, Node},
minecraft_utils::{ScoreboardOperation, ScoreboardValue},
opt::{
global_opt::Commands,
optimize_commands::{OptimizeCommand, OptimizeCommandKind},
},
};
/// Optimizes basic arithmetic expressions with the shape
/// x OP constant OP constant ...
/// NOTE: This optimizer changes the runtime behavior!
/// An operation like `a * 2000 / 1000` can cause an overflow,
/// while the optimized version `a * 2` might not.
/// For this reason it is **very important** that this optimizer is
/// not toggled between release and debug mode.
pub fn simple_arithmetic_optimization(commands: &mut Commands) {
'functions: for function in commands.optimizer.iter_functions() {
for (node_id, node) in function {
if let Node::BinaryOperation(BinaryOperation {
id: target,
lhs: ScoreboardValue::Scoreboard(lhs_id),
rhs: ScoreboardValue::Static(value),
operation,
}) = node
{
if matches!(
operation,
ScoreboardOperation::Plus | ScoreboardOperation::Minus
) {
let mut subsequent_nodes = commands
.optimizer
.iter_at(&node_id)
.map(|(_, other_node)| {
if let Node::BinaryOperation(BinaryOperation {
id: new_target,
lhs: ScoreboardValue::Scoreboard(also_new_target),
rhs: ScoreboardValue::Static(new_value),
operation,
}) = other_node
{
if new_target == also_new_target
&& new_target == target
&& matches!(
operation,
ScoreboardOperation::Plus | ScoreboardOperation::Minus
)
{
return Some(match operation {
ScoreboardOperation::Plus => *new_value,
ScoreboardOperation::Minus => -new_value,
_ => unreachable!(),
});
}
}
None
})
.take_while(Option::is_some)
.map(Option::unwrap)
.peekable();
if subsequent_nodes.peek().is_some() {
let (optimized_value, len) =
optimize_additive(std::iter::once(*value).chain(subsequent_nodes));
for i in 0..((len - 1) as usize) {
commands.commands.push(OptimizeCommand::new(
(node_id.0, node_id.1 + i),
OptimizeCommandKind::Delete,
));
}
commands.commands.push(OptimizeCommand::new(
node_id,
OptimizeCommandKind::Replace(Node::BinaryOperation(BinaryOperation {
id: *target,
lhs: ScoreboardValue::Scoreboard(*lhs_id),
rhs: ScoreboardValue::Static(optimized_value),
operation: *operation,
})),
));
continue 'functions;
}
} else if matches!(
operation,
ScoreboardOperation::Times | ScoreboardOperation::Divide
) {
let original_fraction = match operation {
ScoreboardOperation::Times => Fraction::from(*value),
ScoreboardOperation::Divide => Fraction::from(*value).inverse(),
_ => unreachable!(),
};
let mut subsequent_nodes = commands
.optimizer
.iter_at(&node_id)
.map(|(_, other_node)| {
if let Node::BinaryOperation(BinaryOperation {
id: new_target,
lhs: ScoreboardValue::Scoreboard(also_new_target),
rhs: ScoreboardValue::Static(new_value),
operation,
}) = other_node
{
if new_target == also_new_target
&& new_target == target
&& matches!(
operation,
ScoreboardOperation::Times | ScoreboardOperation::Divide
)
{
return Some(match operation {
ScoreboardOperation::Times => Fraction::from(*new_value),
ScoreboardOperation::Divide => {
Fraction::from(*new_value).inverse()
}
_ => unreachable!(),
});
}
}
None
})
.take_while(Option::is_some)
.map(Option::unwrap)
.peekable();
if subsequent_nodes.peek().is_some() {
let (optimized_value, len) = optimize_multiplicative(
std::iter::once(original_fraction).chain(subsequent_nodes),
);
let (new_operation, new_value) = match optimized_value {
Fraction {
numerator,
denominator: 1,
} => (ScoreboardOperation::Times, numerator),
Fraction {
numerator: 1,
denominator,
} => (ScoreboardOperation::Divide, denominator),
_ => break,
};
for i in 0..((len - 1) as usize) {
commands.commands.push(OptimizeCommand::new(
(node_id.0, node_id.1 + i),
OptimizeCommandKind::Delete,
));
}
commands.commands.push(OptimizeCommand::new(
node_id,
OptimizeCommandKind::Replace(Node::BinaryOperation(BinaryOperation {
id: *target,
lhs: ScoreboardValue::Scoreboard(*lhs_id),
rhs: ScoreboardValue::Static(new_value),
operation: new_operation,
})),
));
continue 'functions;
}
}
}
}
}
}
#[derive(Debug)]
struct Fraction {
numerator: i32,
denominator: i32,
}
impl Fraction {
const ONE: Fraction = Fraction {
numerator: 1,
denominator: 1,
};
fn simplify(&mut self) {
let mut a = self.numerator;
let mut b = self.denominator;
while b != 0 {
let temp = b;
b = a % b;
a = temp;
}
self.numerator /= a;
self.denominator /= a;
}
fn inverse(self) -> Fraction {
Fraction {
numerator: self.denominator,
denominator: self.numerator,
}
}
}
impl From<i32> for Fraction {
fn from(val: i32) -> Self {
Fraction {
numerator: val,
denominator: 1,
}
}
}
impl Mul for Fraction {
type Output = Self;
fn mul(self, rhs: Self) -> Self::Output {
let mut result = Fraction {
numerator: ScoreboardOperation::Times.evaluate(self.numerator, rhs.numerator),
denominator: ScoreboardOperation::Times.evaluate(self.denominator, rhs.denominator),
};
result.simplify();
result
}
}
fn optimize_additive(operations: impl Iterator<Item = i32>) -> (i32, u32) {
operations.fold((0, 0), |(acc, len), x| {
(ScoreboardOperation::Plus.evaluate(acc, x), len + 1)
})
}
fn optimize_multiplicative(operations: impl Iterator<Item = Fraction>) -> (Fraction, u32) {
operations.fold((Fraction::ONE, 0), |(acc, len), x| (acc * x, len + 1))
}