rhai/src/optimizer.rs

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//! Module implementing the [`AST`] optimizer.
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#![cfg(not(feature = "no_optimize"))]
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use crate::ast::{ASTFlags, Expr, OpAssignment, Stmt, StmtBlock, StmtBlockContainer, SwitchCases};
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use crate::engine::{KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF};
use crate::eval::{EvalState, GlobalRuntimeState};
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use crate::func::builtin::get_builtin_binary_op_fn;
use crate::func::hashing::get_hasher;
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use crate::tokenizer::{Span, Token};
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use crate::types::dynamic::AccessMode;
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use crate::{
calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, FnPtr, Position, Scope,
StaticVec, AST, INT,
};
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#[cfg(feature = "no_std")]
use std::prelude::v1::*;
use std::{
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any::TypeId,
convert::TryFrom,
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hash::{Hash, Hasher},
mem,
};
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/// Level of optimization performed.
#[derive(Debug, Eq, PartialEq, Hash, Clone, Copy)]
pub enum OptimizationLevel {
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/// No optimization performed.
None,
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/// Only perform simple optimizations without evaluating functions.
Simple,
/// Full optimizations performed, including evaluating functions.
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/// Take care that this may cause side effects as it essentially assumes that all functions are pure.
Full,
}
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impl Default for OptimizationLevel {
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#[inline(always)]
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fn default() -> Self {
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Self::Simple
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}
}
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/// Mutable state throughout an optimization pass.
#[derive(Debug, Clone)]
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struct OptimizerState<'a> {
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/// Has the [`AST`] been changed during this pass?
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changed: bool,
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/// Collection of constants to use for eager function evaluations.
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variables: StaticVec<(String, AccessMode, Option<Dynamic>)>,
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/// Activate constants propagation?
propagate_constants: bool,
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/// An [`Engine`] instance for eager function evaluation.
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engine: &'a Engine,
/// [Module][crate::Module] containing script-defined functions.
#[cfg(not(feature = "no_function"))]
lib: &'a [&'a crate::Module],
/// Optimization level.
optimization_level: OptimizationLevel,
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}
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impl<'a> OptimizerState<'a> {
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/// Create a new State.
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#[inline(always)]
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pub const fn new(
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engine: &'a Engine,
#[cfg(not(feature = "no_function"))] lib: &'a [&'a crate::Module],
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optimization_level: OptimizationLevel,
) -> Self {
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Self {
changed: false,
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variables: StaticVec::new_const(),
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propagate_constants: true,
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engine,
#[cfg(not(feature = "no_function"))]
lib,
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optimization_level,
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}
}
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/// Set the [`AST`] state to be dirty (i.e. changed).
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#[inline(always)]
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pub fn set_dirty(&mut self) {
self.changed = true;
}
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/// Set the [`AST`] state to be not dirty (i.e. unchanged).
#[inline(always)]
pub fn clear_dirty(&mut self) {
self.changed = false;
}
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/// Is the [`AST`] dirty (i.e. changed)?
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#[inline(always)]
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pub const fn is_dirty(&self) -> bool {
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self.changed
}
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/// Prune the list of constants back to a specified size.
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#[inline(always)]
pub fn restore_var(&mut self, len: usize) {
self.variables.truncate(len)
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}
/// Add a new variable to the list.
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#[inline(always)]
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pub fn push_var(
&mut self,
name: impl Into<String>,
access: AccessMode,
value: Option<Dynamic>,
) {
self.variables.push((name.into(), access, value))
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}
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/// Look up a constant from the list.
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#[inline]
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pub fn find_constant(&self, name: &str) -> Option<&Dynamic> {
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if !self.propagate_constants {
return None;
}
for (n, access, value) in self.variables.iter().rev() {
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if n == name {
return match access {
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AccessMode::ReadWrite => None,
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AccessMode::ReadOnly => value.as_ref(),
};
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}
}
None
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}
/// Call a registered function
#[inline]
pub fn call_fn_with_constant_arguments(
&self,
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fn_name: &str,
arg_values: &mut [Dynamic],
) -> Option<Dynamic> {
#[cfg(not(feature = "no_function"))]
let lib = self.lib;
#[cfg(feature = "no_function")]
let lib = &[];
self.engine
.call_native_fn(
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&mut GlobalRuntimeState::new(&self.engine),
&mut EvalState::new(),
lib,
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fn_name,
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calc_fn_hash(&fn_name, arg_values.len()),
&mut arg_values.iter_mut().collect::<StaticVec<_>>(),
false,
false,
Position::NONE,
0,
)
.ok()
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.map(|(v, ..)| v)
}
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}
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// Has a system function a Rust-native override?
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fn has_native_fn_override(
engine: &Engine,
hash_script: u64,
arg_types: impl AsRef<[TypeId]>,
) -> bool {
let hash_params = calc_fn_params_hash(arg_types.as_ref().iter().cloned());
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let hash = combine_hashes(hash_script, hash_params);
// First check the global namespace and packages, but skip modules that are standard because
// they should never conflict with system functions.
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let result = engine
.global_modules
.iter()
.filter(|m| !m.standard)
.any(|m| m.contains_fn(hash));
#[cfg(not(feature = "no_module"))]
// Then check sub-modules
let result = result
|| engine
.global_sub_modules
.values()
.any(|m| m.contains_qualified_fn(hash));
result
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}
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/// Optimize a block of [statements][Stmt].
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fn optimize_stmt_block(
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mut statements: StmtBlockContainer,
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state: &mut OptimizerState,
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preserve_result: bool,
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is_internal: bool,
reduce_return: bool,
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) -> StmtBlockContainer {
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if statements.is_empty() {
return statements;
}
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let mut is_dirty = state.is_dirty();
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let is_pure = if is_internal {
Stmt::is_internally_pure
} else {
Stmt::is_pure
};
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// Flatten blocks
loop {
if let Some(n) = statements.iter().enumerate().find_map(|(i, s)| match s {
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Stmt::Block(block, ..) if !block.iter().any(Stmt::is_block_dependent) => Some(i),
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_ => None,
}) {
let (first, second) = statements.split_at_mut(n);
let stmt = mem::take(&mut second[0]);
let mut stmts = match stmt {
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Stmt::Block(block, ..) => block,
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stmt => unreachable!("Stmt::Block expected but gets {:?}", stmt),
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};
statements = first
.iter_mut()
.map(mem::take)
.chain(stmts.iter_mut().map(mem::take))
.chain(second.iter_mut().skip(1).map(mem::take))
.collect();
} else {
break;
}
is_dirty = true;
}
// Optimize
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loop {
state.clear_dirty();
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let orig_constants_len = state.variables.len(); // Original number of constants in the state, for restore later
let orig_propagate_constants = state.propagate_constants;
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// Remove everything following control flow breaking statements
let mut dead_code = false;
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statements.retain(|stmt| {
if dead_code {
state.set_dirty();
false
} else if stmt.is_control_flow_break() {
dead_code = true;
true
} else {
true
}
});
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// Optimize each statement in the block
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for stmt in statements.iter_mut() {
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match stmt {
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Stmt::Var(x, options, ..) => {
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if options.contains(ASTFlags::CONSTANT) {
// Add constant literals into the state
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optimize_expr(&mut x.1, state, false);
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if x.1.is_constant() {
state.push_var(
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x.0.name.as_str(),
AccessMode::ReadOnly,
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x.1.get_literal_value(),
);
}
} else {
// Add variables into the state
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optimize_expr(&mut x.1, state, false);
state.push_var(x.0.name.as_str(), AccessMode::ReadWrite, None);
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}
}
// Optimize the statement
_ => optimize_stmt(stmt, state, preserve_result),
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}
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}
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// Remove all pure statements except the last one
let mut index = 0;
let mut first_non_constant = statements
.iter()
.rev()
.enumerate()
.find_map(|(i, stmt)| match stmt {
stmt if !is_pure(stmt) => Some(i),
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Stmt::Var(x, ..) if x.1.is_constant() => Some(i),
Stmt::Expr(e) if !e.is_constant() => Some(i),
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#[cfg(not(feature = "no_module"))]
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Stmt::Import(x, ..) if !x.0.is_constant() => Some(i),
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_ => None,
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})
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.map_or(0, |n| statements.len() - n - 1);
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while index < statements.len() {
if preserve_result && index >= statements.len() - 1 {
break;
} else {
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match statements[index] {
ref stmt if is_pure(stmt) && index >= first_non_constant => {
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state.set_dirty();
statements.remove(index);
}
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ref stmt if stmt.is_pure() => {
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state.set_dirty();
if index < first_non_constant {
first_non_constant -= 1;
}
statements.remove(index);
}
_ => index += 1,
}
}
}
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// Remove all pure statements that do not return values at the end of a block.
// We cannot remove anything for non-pure statements due to potential side-effects.
if preserve_result {
loop {
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match statements[..] {
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// { return; } -> {}
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[Stmt::Return(None, options, ..)]
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if reduce_return && !options.contains(ASTFlags::BREAK) =>
{
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state.set_dirty();
statements.clear();
}
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[ref stmt] if !stmt.returns_value() && is_pure(stmt) => {
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state.set_dirty();
statements.clear();
}
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// { ...; return; } -> { ... }
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[.., ref last_stmt, Stmt::Return(None, options, ..)]
if reduce_return
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&& !options.contains(ASTFlags::BREAK)
&& !last_stmt.returns_value() =>
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{
state.set_dirty();
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statements.pop().unwrap();
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}
// { ...; return val; } -> { ...; val }
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[.., Stmt::Return(ref mut expr, options, pos)]
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if reduce_return && !options.contains(ASTFlags::BREAK) =>
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{
state.set_dirty();
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*statements.last_mut().unwrap() = expr
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.as_mut()
.map_or_else(|| Stmt::Noop(pos), |e| Stmt::Expr(mem::take(e)));
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}
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// { ...; stmt; noop } -> done
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[.., ref second_last_stmt, Stmt::Noop(..)]
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if second_last_stmt.returns_value() =>
{
break
}
// { ...; stmt_that_returns; pure_non_value_stmt } -> { ...; stmt_that_returns; noop }
// { ...; stmt; pure_non_value_stmt } -> { ...; stmt }
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[.., ref second_last_stmt, ref last_stmt]
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if !last_stmt.returns_value() && is_pure(last_stmt) =>
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{
state.set_dirty();
if second_last_stmt.returns_value() {
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*statements.last_mut().unwrap() = Stmt::Noop(last_stmt.position());
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} else {
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statements.pop().unwrap();
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}
}
_ => break,
}
}
} else {
loop {
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match statements[..] {
[ref stmt] if is_pure(stmt) => {
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state.set_dirty();
statements.clear();
}
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// { ...; return; } -> { ... }
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[.., Stmt::Return(None, options, ..)]
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if reduce_return && !options.contains(ASTFlags::BREAK) =>
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{
state.set_dirty();
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statements.pop().unwrap();
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}
// { ...; return pure_val; } -> { ... }
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[.., Stmt::Return(Some(ref expr), options, ..)]
if reduce_return
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&& !options.contains(ASTFlags::BREAK)
&& expr.is_pure() =>
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{
state.set_dirty();
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statements.pop().unwrap();
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}
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[.., ref last_stmt] if is_pure(last_stmt) => {
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state.set_dirty();
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statements.pop().unwrap();
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}
_ => break,
}
}
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}
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// Pop the stack and remove all the local constants
state.restore_var(orig_constants_len);
state.propagate_constants = orig_propagate_constants;
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if !state.is_dirty() {
break;
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}
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is_dirty = true;
}
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if is_dirty {
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state.set_dirty();
}
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statements.shrink_to_fit();
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statements
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}
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/// Optimize a [statement][Stmt].
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fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: bool) {
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match stmt {
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// var = var op expr => var op= expr
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Stmt::Assignment(x, ..)
if x.0.is_none()
&& x.1.lhs.is_variable_access(true)
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&& matches!(&x.1.rhs, Expr::FnCall(x2, ..)
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if Token::lookup_from_syntax(&x2.name).map(|t| t.has_op_assignment()).unwrap_or(false)
&& x2.args.len() == 2
&& x2.args[0].get_variable_name(true) == x.1.lhs.get_variable_name(true)
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) =>
{
match x.1.rhs {
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Expr::FnCall(ref mut x2, ..) => {
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state.set_dirty();
x.0 = Some(OpAssignment::new_from_base(&x2.name));
let value = mem::take(&mut x2.args[1]);
if let Expr::Stack(slot, pos) = value {
x.1.rhs =
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Expr::from_dynamic(mem::take(x2.constants.get_mut(slot).unwrap()), pos);
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} else {
x.1.rhs = value;
}
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}
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ref expr => unreachable!("Expr::FnCall expected but gets {:?}", expr),
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}
}
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// expr op= expr
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Stmt::Assignment(x, ..) => {
if !x.1.lhs.is_variable_access(false) {
optimize_expr(&mut x.1.lhs, state, false);
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}
optimize_expr(&mut x.1.rhs, state, false);
}
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// if expr {}
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Stmt::If(x, ..) if x.1.is_empty() && x.2.is_empty() => {
let condition = &mut x.0;
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state.set_dirty();
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let pos = condition.start_position();
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let mut expr = mem::take(condition);
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optimize_expr(&mut expr, state, false);
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*stmt = if preserve_result {
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// -> { expr, Noop }
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(
[Stmt::Expr(expr.into()), Stmt::Noop(pos)],
pos,
Position::NONE,
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)
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.into()
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} else {
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// -> expr
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Stmt::Expr(expr.into())
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};
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}
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// if false { if_block } -> Noop
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Stmt::If(x, ..) if matches!(x.0, Expr::BoolConstant(false, ..)) && x.2.is_empty() => {
if let Expr::BoolConstant(false, pos) = x.0 {
state.set_dirty();
*stmt = Stmt::Noop(pos);
} else {
unreachable!("`Expr::BoolConstant`");
}
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}
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// if false { if_block } else { else_block } -> else_block
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Stmt::If(x, ..) if matches!(x.0, Expr::BoolConstant(false, ..)) => {
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state.set_dirty();
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*stmt =
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match optimize_stmt_block(mem::take(&mut *x.2), state, preserve_result, true, false)
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{
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statements if statements.is_empty() => Stmt::Noop(x.2.position()),
statements => (statements, x.2.span()).into(),
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}
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}
// if true { if_block } else { else_block } -> if_block
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Stmt::If(x, ..) if matches!(x.0, Expr::BoolConstant(true, ..)) => {
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state.set_dirty();
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*stmt =
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match optimize_stmt_block(mem::take(&mut *x.1), state, preserve_result, true, false)
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{
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statements if statements.is_empty() => Stmt::Noop(x.1.position()),
statements => (statements, x.1.span()).into(),
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}
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}
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// if expr { if_block } else { else_block }
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Stmt::If(x, ..) => {
let (condition, body, other) = x.as_mut();
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optimize_expr(condition, state, false);
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**body =
optimize_stmt_block(mem::take(&mut **body), state, preserve_result, true, false);
**other =
optimize_stmt_block(mem::take(&mut **other), state, preserve_result, true, false);
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}
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// switch const { ... }
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Stmt::Switch(x, pos) if x.0.is_constant() => {
let (
match_expr,
SwitchCases {
cases,
ranges,
def_case,
},
) = x.as_mut();
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let value = match_expr.get_literal_value().unwrap();
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let hasher = &mut get_hasher();
value.hash(hasher);
let hash = hasher.finish();
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// First check hashes
if let Some(block) = cases.get_mut(&hash) {
if let Some(mut condition) = mem::take(&mut block.condition) {
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// switch const { case if condition => stmt, _ => def } => if condition { stmt } else { def }
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optimize_expr(&mut condition, state, false);
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let def_stmt =
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optimize_stmt_block(mem::take(def_case), state, true, true, false);
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*stmt = Stmt::If(
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(
condition,
mem::take(&mut block.statements),
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StmtBlock::new_with_span(
def_stmt,
def_case.span_or_else(*pos, Position::NONE),
),
)
.into(),
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match_expr.start_position(),
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);
} else {
// Promote the matched case
let statements = optimize_stmt_block(
mem::take(&mut block.statements),
state,
true,
true,
false,
);
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*stmt = (statements, block.statements.span()).into();
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}
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state.set_dirty();
return;
}
// Then check ranges
if value.is::<INT>() && !ranges.is_empty() {
let value = value.as_int().expect("`INT`");
// Only one range or all ranges without conditions
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if ranges.len() == 1 || ranges.iter().all(|(.., c)| !c.has_condition()) {
for (.., block) in
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ranges
.iter_mut()
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.filter(|&&mut (start, end, inclusive, ..)| {
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(!inclusive && (start..end).contains(&value))
|| (inclusive && (start..=end).contains(&value))
})
{
if let Some(mut condition) = mem::take(&mut block.condition) {
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// switch const { range if condition => stmt, _ => def } => if condition { stmt } else { def }
optimize_expr(&mut condition, state, false);
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let def_stmt =
optimize_stmt_block(mem::take(def_case), state, true, true, false);
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*stmt = Stmt::If(
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(
condition,
mem::take(&mut block.statements),
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StmtBlock::new_with_span(
def_stmt,
def_case.span_or_else(*pos, Position::NONE),
),
)
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.into(),
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match_expr.start_position(),
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);
} else {
// Promote the matched case
let statements = mem::take(&mut *block.statements);
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let statements =
optimize_stmt_block(statements, state, true, true, false);
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*stmt = (statements, block.statements.span()).into();
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}
state.set_dirty();
return;
}
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} else {
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// Multiple ranges - clear the table and just keep the right ranges
if !cases.is_empty() {
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state.set_dirty();
cases.clear();
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}
let old_ranges_len = ranges.len();
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ranges.retain(|&mut (start, end, inclusive, ..)| {
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(!inclusive && (start..end).contains(&value))
|| (inclusive && (start..=end).contains(&value))
});
if ranges.len() != old_ranges_len {
state.set_dirty();
}
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for (.., block) in ranges.iter_mut() {
let statements = mem::take(&mut *block.statements);
*block.statements =
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optimize_stmt_block(statements, state, preserve_result, true, false);
if let Some(mut condition) = mem::take(&mut block.condition) {
optimize_expr(&mut condition, state, false);
match condition {
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Expr::Unit(..) | Expr::BoolConstant(true, ..) => state.set_dirty(),
_ => block.condition = Some(condition),
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}
}
}
return;
}
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}
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// Promote the default case
state.set_dirty();
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let def_stmt = optimize_stmt_block(mem::take(def_case), state, true, true, false);
*stmt = (def_stmt, def_case.span_or_else(*pos, Position::NONE)).into();
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}
// switch
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Stmt::Switch(x, ..) => {
let (
match_expr,
SwitchCases {
cases,
ranges,
def_case,
..
},
) = x.as_mut();
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optimize_expr(match_expr, state, false);
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// Optimize cases
for block in cases.values_mut() {
let statements = mem::take(&mut *block.statements);
*block.statements =
optimize_stmt_block(statements, state, preserve_result, true, false);
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if let Some(mut condition) = mem::take(&mut block.condition) {
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optimize_expr(&mut condition, state, false);
match condition {
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Expr::Unit(..) | Expr::BoolConstant(true, ..) => state.set_dirty(),
_ => block.condition = Some(condition),
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}
}
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}
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// Remove false cases
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cases.retain(|_, block| match block.condition {
Some(Expr::BoolConstant(false, ..)) => {
state.set_dirty();
false
}
_ => true,
});
// Optimize ranges
for (.., block) in ranges.iter_mut() {
let statements = mem::take(&mut *block.statements);
*block.statements =
optimize_stmt_block(statements, state, preserve_result, true, false);
if let Some(mut condition) = mem::take(&mut block.condition) {
optimize_expr(&mut condition, state, false);
match condition {
Expr::Unit(..) | Expr::BoolConstant(true, ..) => state.set_dirty(),
_ => block.condition = Some(condition),
}
}
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}
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// Remove false ranges
ranges.retain(|(.., block)| match block.condition {
Some(Expr::BoolConstant(false, ..)) => {
state.set_dirty();
false
}
_ => true,
});
let def_block = mem::take(&mut ***def_case);
***def_case = optimize_stmt_block(def_block, state, preserve_result, true, false);
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}
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// while false { block } -> Noop
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Stmt::While(x, ..) if matches!(x.0, Expr::BoolConstant(false, ..)) => match x.0 {
Expr::BoolConstant(false, pos) => {
state.set_dirty();
*stmt = Stmt::Noop(pos)
}
_ => unreachable!("`Expr::BoolConstant"),
},
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// while expr { block }
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Stmt::While(x, ..) => {
let (condition, body) = x.as_mut();
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optimize_expr(condition, state, false);
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if let Expr::BoolConstant(true, pos) = condition {
*condition = Expr::Unit(*pos);
}
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**body = optimize_stmt_block(mem::take(&mut **body), state, false, true, false);
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2021-03-13 16:43:05 +01:00
if body.len() == 1 {
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match body[0] {
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// while expr { break; } -> { expr; }
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Stmt::BreakLoop(options, pos) if options.contains(ASTFlags::BREAK) => {
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// Only a single break statement - turn into running the guard expression once
state.set_dirty();
if !condition.is_unit() {
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let mut statements = vec![Stmt::Expr(mem::take(condition).into())];
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if preserve_result {
statements.push(Stmt::Noop(pos))
}
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*stmt = (statements, Span::new(pos, Position::NONE)).into();
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} else {
*stmt = Stmt::Noop(pos);
};
}
_ => (),
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}
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}
}
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// do { block } until true -> { block }
Stmt::Do(x, options, ..)
if matches!(x.0, Expr::BoolConstant(true, ..))
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&& options.contains(ASTFlags::NEGATED) =>
{
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state.set_dirty();
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*stmt = (
optimize_stmt_block(mem::take(&mut *x.1), state, false, true, false),
x.1.span(),
)
.into();
}
// do { block } while false -> { block }
Stmt::Do(x, options, ..)
if matches!(x.0, Expr::BoolConstant(false, ..))
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&& !options.contains(ASTFlags::NEGATED) =>
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{
state.set_dirty();
*stmt = (
optimize_stmt_block(mem::take(&mut *x.1), state, false, true, false),
x.1.span(),
)
.into();
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}
// do { block } while|until expr
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Stmt::Do(x, ..) => {
optimize_expr(&mut x.0, state, false);
*x.1 = optimize_stmt_block(mem::take(&mut *x.1), state, false, true, false);
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}
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// for id in expr { block }
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Stmt::For(x, ..) => {
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optimize_expr(&mut x.2, state, false);
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*x.3 = optimize_stmt_block(mem::take(&mut *x.3), state, false, true, false);
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}
2020-03-18 03:36:50 +01:00
// let id = expr;
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Stmt::Var(x, options, ..) if !options.contains(ASTFlags::CONSTANT) => {
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optimize_expr(&mut x.1, state, false)
}
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// import expr as var;
2020-07-26 09:53:22 +02:00
#[cfg(not(feature = "no_module"))]
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Stmt::Import(x, ..) => optimize_expr(&mut x.0, state, false),
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// { block }
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Stmt::Block(block) => {
let span = block.span();
let statements = block.take_statements().into_vec().into();
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let mut block = optimize_stmt_block(statements, state, preserve_result, true, false);
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match block.as_mut_slice() {
[] => {
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state.set_dirty();
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*stmt = Stmt::Noop(span.start());
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}
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// Only one statement which is not block-dependent - promote
[s] if !s.is_block_dependent() => {
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state.set_dirty();
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*stmt = mem::take(s);
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}
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_ => *stmt = (block, span).into(),
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}
2020-03-09 14:57:07 +01:00
}
2021-03-13 16:43:05 +01:00
// try { pure try_block } catch ( var ) { catch_block } -> try_block
2022-02-08 02:02:15 +01:00
Stmt::TryCatch(x, ..) if x.try_block.iter().all(Stmt::is_pure) => {
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// If try block is pure, there will never be any exceptions
state.set_dirty();
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*stmt = (
optimize_stmt_block(mem::take(&mut *x.try_block), state, false, true, false),
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x.try_block.span(),
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)
.into();
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}
2021-03-13 16:43:05 +01:00
// try { try_block } catch ( var ) { catch_block }
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Stmt::TryCatch(x, ..) => {
*x.try_block =
optimize_stmt_block(mem::take(&mut *x.try_block), state, false, true, false);
*x.catch_block =
optimize_stmt_block(mem::take(&mut *x.catch_block), state, false, true, false);
2020-10-27 11:18:19 +01:00
}
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Stmt::Expr(expr) => {
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optimize_expr(expr, state, false);
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match expr.as_mut() {
// func(...)
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Expr::FnCall(x, pos) => {
state.set_dirty();
*stmt = Stmt::FnCall(mem::take(x), *pos);
}
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// {...};
Expr::Stmt(x) => {
if x.is_empty() {
state.set_dirty();
*stmt = Stmt::Noop(x.position());
} else {
state.set_dirty();
*stmt = mem::take(&mut **x).into();
}
}
// expr;
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_ => (),
}
}
2022-02-16 10:51:14 +01:00
2020-03-18 03:36:50 +01:00
// return expr;
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Stmt::Return(Some(ref mut expr), ..) => optimize_expr(expr, state, false),
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2020-03-18 03:36:50 +01:00
// All other statements - skip
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_ => (),
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}
}
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/// Optimize an [expression][Expr].
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fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, chaining: bool) {
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// These keywords are handled specially
const DONT_EVAL_KEYWORDS: &[&str] = &[
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KEYWORD_PRINT, // side effects
KEYWORD_DEBUG, // side effects
KEYWORD_EVAL, // arbitrary scripts
];
2020-03-17 03:27:43 +01:00
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let _chaining = chaining;
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match expr {
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// {}
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Expr::Stmt(x) if x.is_empty() => { state.set_dirty(); *expr = Expr::Unit(x.position()) }
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// { stmt; ... } - do not count promotion as dirty because it gets turned back into an array
Expr::Stmt(x) => {
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***x = optimize_stmt_block(mem::take(&mut **x), state, true, true, false);
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// { Stmt(Expr) } - promote
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match x.as_mut().as_mut() {
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[ Stmt::Expr(e) ] => { state.set_dirty(); *expr = mem::take(e); }
_ => ()
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}
}
2020-03-18 03:36:50 +01:00
// lhs.rhs
#[cfg(not(feature = "no_object"))]
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Expr::Dot(x,_, ..) if !_chaining => match (&mut x.lhs, &mut x.rhs) {
// map.string
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(Expr::Map(m, pos), Expr::Property(p, ..)) if m.0.iter().all(|(.., x)| x.is_pure()) => {
let prop = p.2.as_str();
// Map literal where everything is pure - promote the indexed item.
// All other items can be thrown away.
state.set_dirty();
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*expr = mem::take(&mut m.0).into_iter().find(|(x, ..)| x.name == prop)
.map(|(.., mut expr)| { expr.set_position(*pos); expr })
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.unwrap_or_else(|| Expr::Unit(*pos));
}
2020-11-03 06:08:19 +01:00
// var.rhs
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(Expr::Variable(..), rhs) => optimize_expr(rhs, state, true),
// lhs.rhs
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(lhs, rhs) => { optimize_expr(lhs, state, false); optimize_expr(rhs, state, true); }
}
2021-06-02 08:29:18 +02:00
// ....lhs.rhs
#[cfg(not(feature = "no_object"))]
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Expr::Dot(x,_, ..) => { optimize_expr(&mut x.lhs, state, false); optimize_expr(&mut x.rhs, state, _chaining); }
2020-03-11 04:03:18 +01:00
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// lhs[rhs]
#[cfg(not(feature = "no_index"))]
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Expr::Index(x, ..) if !_chaining => match (&mut x.lhs, &mut x.rhs) {
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// array[int]
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(Expr::Array(a, pos), Expr::IntegerConstant(i, ..)) if *i >= 0 && (*i as usize) < a.len() && a.iter().all(Expr::is_pure) => {
// Array literal where everything is pure - promote the indexed item.
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// All other items can be thrown away.
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state.set_dirty();
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let mut result = mem::take(&mut a[*i as usize]);
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result.set_position(*pos);
*expr = result;
}
// array[-int]
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(Expr::Array(a, pos), Expr::IntegerConstant(i, ..)) if *i < 0 && i.checked_abs().map(|n| n as usize <= a.len()).unwrap_or(false) && a.iter().all(Expr::is_pure) => {
// Array literal where everything is pure - promote the indexed item.
// All other items can be thrown away.
state.set_dirty();
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let index = a.len() - i.abs() as usize;
let mut result = mem::take(&mut a[index]);
result.set_position(*pos);
*expr = result;
}
// map[string]
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(Expr::Map(m, pos), Expr::StringConstant(s, ..)) if m.0.iter().all(|(.., x)| x.is_pure()) => {
// Map literal where everything is pure - promote the indexed item.
// All other items can be thrown away.
state.set_dirty();
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*expr = mem::take(&mut m.0).into_iter().find(|(x, ..)| x.name.as_str() == s.as_str())
.map(|(.., mut expr)| { expr.set_position(*pos); expr })
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.unwrap_or_else(|| Expr::Unit(*pos));
}
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// int[int]
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(Expr::IntegerConstant(n, pos), Expr::IntegerConstant(i, ..)) if *i >= 0 && (*i as usize) < (std::mem::size_of_val(n) * 8) => {
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// Bit-field literal indexing - get the bit
state.set_dirty();
*expr = Expr::BoolConstant((*n & (1 << (*i as usize))) != 0, *pos);
}
// int[-int]
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(Expr::IntegerConstant(n, pos), Expr::IntegerConstant(i, ..)) if *i < 0 && i.checked_abs().map(|i| i as usize <= (std::mem::size_of_val(n) * 8)).unwrap_or(false) => {
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// Bit-field literal indexing - get the bit
state.set_dirty();
*expr = Expr::BoolConstant((*n & (1 << (std::mem::size_of_val(n) * 8 - i.abs() as usize))) != 0, *pos);
}
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// string[int]
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(Expr::StringConstant(s, pos), Expr::IntegerConstant(i, ..)) if *i >= 0 && (*i as usize) < s.chars().count() => {
// String literal indexing - get the character
state.set_dirty();
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*expr = Expr::CharConstant(s.chars().nth(*i as usize).unwrap(), *pos);
}
// string[-int]
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(Expr::StringConstant(s, pos), Expr::IntegerConstant(i, ..)) if *i < 0 && i.checked_abs().map(|n| n as usize <= s.chars().count()).unwrap_or(false) => {
// String literal indexing - get the character
state.set_dirty();
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*expr = Expr::CharConstant(s.chars().rev().nth(i.abs() as usize - 1).unwrap(), *pos);
}
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// var[rhs]
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(Expr::Variable(..), rhs) => optimize_expr(rhs, state, true),
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// lhs[rhs]
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(lhs, rhs) => { optimize_expr(lhs, state, false); optimize_expr(rhs, state, true); }
},
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// ...[lhs][rhs]
#[cfg(not(feature = "no_index"))]
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Expr::Index(x, ..) => { optimize_expr(&mut x.lhs, state, false); optimize_expr(&mut x.rhs, state, _chaining); }
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// ``
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Expr::InterpolatedString(x, pos) if x.is_empty() => {
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state.set_dirty();
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*expr = Expr::StringConstant(state.engine.const_empty_string(), *pos);
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}
// `...`
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Expr::InterpolatedString(x, ..) if x.len() == 1 && matches!(x[0], Expr::StringConstant(..)) => {
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state.set_dirty();
*expr = mem::take(&mut x[0]);
}
// `... ${ ... } ...`
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Expr::InterpolatedString(x, ..) => {
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x.iter_mut().for_each(|expr| optimize_expr(expr, state, false));
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let mut n = 0;
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// Merge consecutive strings
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while n < x.len() - 1 {
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match (mem::take(&mut x[n]), mem::take(&mut x[n+1])) {
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(Expr::StringConstant(mut s1, pos), Expr::StringConstant(s2, ..)) => { s1 += s2; x[n] = Expr::StringConstant(s1, pos); x.remove(n+1); state.set_dirty(); }
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(expr1, Expr::Unit(..)) => { x[n] = expr1; x.remove(n+1); state.set_dirty(); }
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(Expr::Unit(..), expr2) => { x[n+1] = expr2; x.remove(n); state.set_dirty(); }
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(expr1, Expr::StringConstant(s, ..)) if s.is_empty() => { x[n] = expr1; x.remove(n+1); state.set_dirty(); }
(Expr::StringConstant(s, ..), expr2) if s.is_empty()=> { x[n+1] = expr2; x.remove(n); state.set_dirty(); }
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(expr1, expr2) => { x[n] = expr1; x[n+1] = expr2; n += 1; }
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}
}
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x.shrink_to_fit();
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}
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// [ constant .. ]
#[cfg(not(feature = "no_index"))]
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Expr::Array(..) if expr.is_constant() => {
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state.set_dirty();
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*expr = Expr::DynamicConstant(expr.get_literal_value().unwrap().into(), expr.position());
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}
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// [ items .. ]
#[cfg(not(feature = "no_index"))]
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Expr::Array(x, ..) => x.iter_mut().for_each(|expr| optimize_expr(expr, state, false)),
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// #{ key:constant, .. }
#[cfg(not(feature = "no_object"))]
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Expr::Map(..) if expr.is_constant() => {
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state.set_dirty();
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*expr = Expr::DynamicConstant(expr.get_literal_value().unwrap().into(), expr.position());
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}
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// #{ key:value, .. }
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#[cfg(not(feature = "no_object"))]
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Expr::Map(x, ..) => x.0.iter_mut().for_each(|(.., expr)| optimize_expr(expr, state, false)),
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// lhs && rhs
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Expr::And(x, ..) => match (&mut x.lhs, &mut x.rhs) {
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// true && rhs -> rhs
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(Expr::BoolConstant(true, ..), rhs) => { state.set_dirty(); optimize_expr(rhs, state, false); *expr = mem::take(rhs); }
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// false && rhs -> false
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(Expr::BoolConstant(false, pos), ..) => { state.set_dirty(); *expr = Expr::BoolConstant(false, *pos); }
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// lhs && true -> lhs
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(lhs, Expr::BoolConstant(true, ..)) => { state.set_dirty(); optimize_expr(lhs, state, false); *expr = mem::take(lhs); }
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// lhs && rhs
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(lhs, rhs) => { optimize_expr(lhs, state, false); optimize_expr(rhs, state, false); }
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},
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// lhs || rhs
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Expr::Or(ref mut x, ..) => match (&mut x.lhs, &mut x.rhs) {
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// false || rhs -> rhs
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(Expr::BoolConstant(false, ..), rhs) => { state.set_dirty(); optimize_expr(rhs, state, false); *expr = mem::take(rhs); }
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// true || rhs -> true
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(Expr::BoolConstant(true, pos), ..) => { state.set_dirty(); *expr = Expr::BoolConstant(true, *pos); }
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// lhs || false
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(lhs, Expr::BoolConstant(false, ..)) => { state.set_dirty(); optimize_expr(lhs, state, false); *expr = mem::take(lhs); }
2020-03-18 03:36:50 +01:00
// lhs || rhs
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(lhs, rhs) => { optimize_expr(lhs, state, false); optimize_expr(rhs, state, false); }
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},
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// eval!
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Expr::FnCall(x, ..) if x.name == KEYWORD_EVAL => {
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state.propagate_constants = false;
}
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// Fn
Expr::FnCall(x, pos)
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if !x.is_qualified() // Non-qualified
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&& state.optimization_level == OptimizationLevel::Simple // simple optimizations
&& x.args.len() == 1
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&& x.name == KEYWORD_FN_PTR
&& x.args[0].is_constant()
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=> {
let fn_name = match x.args[0] {
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Expr::Stack(slot, ..) => x.constants[slot].clone(),
Expr::StringConstant(ref s, ..) => s.clone().into(),
_ => Dynamic::UNIT
};
if let Ok(fn_ptr) = fn_name.into_immutable_string().map_err(|err| err.into()).and_then(FnPtr::try_from) {
state.set_dirty();
*expr = Expr::DynamicConstant(Box::new(fn_ptr.into()), *pos);
} else {
optimize_expr(&mut x.args[0], state, false);
}
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}
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// Do not call some special keywords
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Expr::FnCall(x, ..) if DONT_EVAL_KEYWORDS.contains(&x.name.as_ref()) => {
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x.args.iter_mut().for_each(|a| optimize_expr(a, state, false));
}
2020-03-19 12:53:42 +01:00
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// Call built-in operators
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Expr::FnCall(x, pos)
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if !x.is_qualified() // Non-qualified
&& state.optimization_level == OptimizationLevel::Simple // simple optimizations
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&& x.args.iter().all(Expr::is_constant) // all arguments are constants
//&& !is_valid_identifier(x.name.chars()) // cannot be scripted
=> {
let arg_values = &mut x.args.iter().map(|e| match e {
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Expr::Stack(slot, ..) => x.constants[*slot].clone(),
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_ => e.get_literal_value().unwrap()
}).collect::<StaticVec<_>>();
let arg_types: StaticVec<_> = arg_values.iter().map(Dynamic::type_id).collect();
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match x.name.as_str() {
KEYWORD_TYPE_OF if arg_values.len() == 1 => {
state.set_dirty();
*expr = Expr::from_dynamic(state.engine.map_type_name(arg_values[0].type_name()).into(), *pos);
return;
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}
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#[cfg(not(feature = "no_closure"))]
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crate::engine::KEYWORD_IS_SHARED if arg_values.len() == 1 => {
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state.set_dirty();
*expr = Expr::from_dynamic(Dynamic::FALSE, *pos);
return;
}
// Overloaded operators can override built-in.
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_ if x.args.len() == 2 && !has_native_fn_override(state.engine, x.hashes.native, arg_types.as_ref()) => {
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if let Some(result) = get_builtin_binary_op_fn(x.name.as_ref(), &arg_values[0], &arg_values[1])
.and_then(|f| {
#[cfg(not(feature = "no_function"))]
let lib = state.lib;
#[cfg(feature = "no_function")]
let lib = &[];
let context = (state.engine, x.name.as_str(), lib).into();
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let (first, second) = arg_values.split_first_mut().unwrap();
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(f)(context, &mut [ first, &mut second[0] ]).ok()
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}) {
state.set_dirty();
*expr = Expr::from_dynamic(result, *pos);
return;
}
}
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_ => ()
}
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x.args.iter_mut().for_each(|a| optimize_expr(a, state, false));
// Move constant arguments
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let constants = &mut x.constants;
x.args.iter_mut().for_each(|arg| {
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if let Some(value) = arg.get_literal_value() {
state.set_dirty();
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constants.push(value);
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*arg = Expr::Stack(constants.len()-1, arg.start_position());
}
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});
}
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// Eagerly call functions
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Expr::FnCall(x, pos)
if !x.is_qualified() // non-qualified
&& state.optimization_level == OptimizationLevel::Full // full optimizations
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&& x.args.iter().all(Expr::is_constant) // all arguments are constants
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=> {
// First search for script-defined functions (can override built-in)
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#[cfg(not(feature = "no_function"))]
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let has_script_fn = state.lib.iter().any(|&m| m.get_script_fn(&x.name, x.args.len()).is_some());
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#[cfg(feature = "no_function")]
let has_script_fn = false;
if !has_script_fn {
let arg_values = &mut x.args.iter().map(|e| match e {
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Expr::Stack(slot, ..) => x.constants[*slot].clone(),
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_ => e.get_literal_value().unwrap()
}).collect::<StaticVec<_>>();
let result = match x.name.as_str() {
KEYWORD_TYPE_OF if arg_values.len() == 1 => Some(state.engine.map_type_name(arg_values[0].type_name()).into()),
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#[cfg(not(feature = "no_closure"))]
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crate::engine::KEYWORD_IS_SHARED if arg_values.len() == 1 => Some(Dynamic::FALSE),
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_ => state.call_fn_with_constant_arguments(&x.name, arg_values)
};
if let Some(result) = result {
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state.set_dirty();
*expr = Expr::from_dynamic(result, *pos);
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return;
}
}
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x.args.iter_mut().for_each(|a| optimize_expr(a, state, false));
}
2020-03-19 12:53:42 +01:00
// id(args ..) or xxx.id(args ..) -> optimize function call arguments
Expr::FnCall(x, ..) | Expr::MethodCall(x, ..) => for arg in x.args.iter_mut() {
optimize_expr(arg, state, false);
// Move constant arguments
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if let Some(value) = arg.get_literal_value() {
state.set_dirty();
x.constants.push(value);
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*arg = Expr::Stack(x.constants.len()-1, arg.start_position());
}
},
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2020-03-18 03:36:50 +01:00
// constant-name
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#[cfg(not(feature = "no_module"))]
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Expr::Variable(.., x) if x.1.is_some() => (),
Expr::Variable(.., pos, x) if state.find_constant(&x.2).is_some() => {
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// Replace constant with value
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*expr = Expr::from_dynamic(state.find_constant(&x.2).unwrap().clone(), *pos);
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state.set_dirty();
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}
2020-03-19 12:53:42 +01:00
2020-07-09 13:54:28 +02:00
// Custom syntax
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Expr::Custom(x, ..) => {
if x.scope_may_be_changed {
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state.propagate_constants = false;
}
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x.inputs.iter_mut().for_each(|expr| optimize_expr(expr, state, false));
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}
2020-07-09 13:54:28 +02:00
2020-03-18 03:36:50 +01:00
// All other expressions - skip
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_ => (),
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}
}
2020-12-26 16:21:16 +01:00
/// Optimize a block of [statements][Stmt] at top level.
///
/// Constants and variables from the scope are added.
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fn optimize_top_level(
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statements: StmtBlockContainer,
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engine: &Engine,
scope: &Scope,
#[cfg(not(feature = "no_function"))] lib: &[&crate::Module],
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optimization_level: OptimizationLevel,
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) -> StmtBlockContainer {
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let mut statements = statements;
// If optimization level is None then skip optimizing
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if optimization_level == OptimizationLevel::None {
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statements.shrink_to_fit();
return statements;
}
// Set up the state
let mut state = OptimizerState::new(
engine,
#[cfg(not(feature = "no_function"))]
lib,
optimization_level,
);
// Add constants and variables from the scope
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for (name, constant, value) in scope.iter() {
if !constant {
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state.push_var(name, AccessMode::ReadWrite, None);
} else {
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state.push_var(name, AccessMode::ReadOnly, Some(value));
}
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}
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optimize_stmt_block(statements, &mut state, true, false, true)
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}
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/// Optimize an [`AST`].
2020-03-18 11:41:18 +01:00
pub fn optimize_into_ast(
engine: &Engine,
scope: &Scope,
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statements: StmtBlockContainer,
#[cfg(not(feature = "no_function"))] functions: StaticVec<
crate::Shared<crate::ast::ScriptFnDef>,
>,
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optimization_level: OptimizationLevel,
) -> AST {
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let mut statements = statements;
2020-09-24 17:32:54 +02:00
#[cfg(not(feature = "no_function"))]
let lib = {
let mut module = crate::Module::new();
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if optimization_level != OptimizationLevel::None {
// We only need the script library's signatures for optimization purposes
let mut lib2 = crate::Module::new();
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for fn_def in &functions {
lib2.set_script_fn(crate::ast::ScriptFnDef {
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name: fn_def.name.clone(),
access: fn_def.access,
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body: crate::ast::StmtBlock::NONE,
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params: fn_def.params.clone(),
#[cfg(not(feature = "no_module"))]
environ: None,
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#[cfg(not(feature = "no_function"))]
#[cfg(feature = "metadata")]
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comments: None,
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});
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}
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let lib2 = &[&lib2];
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for fn_def in functions {
let mut fn_def = crate::func::native::shared_take_or_clone(fn_def);
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// Optimize the function body
let body = mem::take(&mut *fn_def.body);
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*fn_def.body = optimize_top_level(body, engine, scope, lib2, optimization_level);
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module.set_script_fn(fn_def);
}
} else {
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for fn_def in functions {
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module.set_script_fn(fn_def);
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}
}
module
};
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statements.shrink_to_fit();
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AST::new(
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match optimization_level {
OptimizationLevel::None => statements,
OptimizationLevel::Simple | OptimizationLevel::Full => optimize_top_level(
statements,
engine,
&scope,
#[cfg(not(feature = "no_function"))]
&[&lib],
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optimization_level,
),
},
#[cfg(not(feature = "no_function"))]
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lib,
)
}