917 lines
32 KiB
Rust
917 lines
32 KiB
Rust
//! Module implementing the AST optimizer.
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use crate::any::Dynamic;
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use crate::engine::{
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Engine, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_IS_DEF_FN, KEYWORD_IS_DEF_VAR, KEYWORD_PRINT,
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KEYWORD_TYPE_OF,
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};
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use crate::fn_call::run_builtin_binary_op;
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use crate::module::Module;
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use crate::parser::{map_dynamic_to_expr, BinaryExpr, Expr, ScriptFnDef, Stmt, AST};
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use crate::scope::{Entry as ScopeEntry, Scope};
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use crate::token::{is_valid_identifier, Position};
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use crate::{calc_fn_hash, StaticVec};
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#[cfg(not(feature = "no_function"))]
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use crate::parser::ReturnType;
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#[cfg(feature = "internals")]
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use crate::parser::CustomExpr;
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use crate::stdlib::{
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boxed::Box,
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iter::empty,
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string::{String, ToString},
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vec,
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vec::Vec,
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};
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/// Level of optimization performed.
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///
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/// Not available under the `no_optimize` feature.
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#[derive(Debug, Eq, PartialEq, Hash, Clone, Copy)]
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pub enum OptimizationLevel {
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/// No optimization performed.
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None,
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/// Only perform simple optimizations without evaluating functions.
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Simple,
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/// 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.
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Full,
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}
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impl OptimizationLevel {
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/// Is the `OptimizationLevel` None.
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#[inline(always)]
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pub fn is_none(self) -> bool {
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self == Self::None
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}
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/// Is the `OptimizationLevel` Simple.
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#[cfg(not(feature = "no_optimize"))]
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#[inline(always)]
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pub fn is_simple(self) -> bool {
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self == Self::Simple
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}
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/// Is the `OptimizationLevel` Full.
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#[cfg(not(feature = "no_optimize"))]
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#[inline(always)]
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pub fn is_full(self) -> bool {
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self == Self::Full
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}
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}
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/// Mutable state throughout an optimization pass.
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#[derive(Debug, Clone)]
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struct State<'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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constants: Vec<(String, Expr)>,
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/// An `Engine` instance for eager function evaluation.
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engine: &'a Engine,
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/// Library of script-defined functions.
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lib: &'a [&'a Module],
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/// Optimization level.
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optimization_level: OptimizationLevel,
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}
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impl<'a> State<'a> {
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/// Create a new State.
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#[inline(always)]
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pub fn new(engine: &'a Engine, lib: &'a [&'a Module], level: OptimizationLevel) -> Self {
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Self {
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changed: false,
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constants: vec![],
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engine,
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lib,
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optimization_level: level,
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}
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}
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/// Reset the state from dirty to clean.
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#[inline(always)]
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pub fn reset(&mut self) {
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self.changed = false;
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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) {
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self.changed = true;
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}
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/// Is the AST dirty (i.e. changed)?
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#[inline(always)]
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pub fn is_dirty(&self) -> bool {
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self.changed
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}
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/// Does a constant exist?
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#[inline(always)]
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pub fn contains_constant(&self, name: &str) -> bool {
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self.constants.iter().any(|(n, _)| n == name)
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}
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/// Prune the list of constants back to a specified size.
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#[inline(always)]
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pub fn restore_constants(&mut self, len: usize) {
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self.constants.truncate(len)
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}
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/// Add a new constant to the list.
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#[inline(always)]
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pub fn push_constant(&mut self, name: &str, value: Expr) {
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self.constants.push((name.into(), 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<&Expr> {
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for (n, expr) in self.constants.iter().rev() {
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if n == name {
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return Some(expr);
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}
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}
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None
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}
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}
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/// Call a registered function
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fn call_fn_with_constant_arguments(
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state: &State,
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fn_name: &str,
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arg_values: &mut [Dynamic],
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) -> Option<Dynamic> {
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// Search built-in's and external functions
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let hash_fn = calc_fn_hash(
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empty(),
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fn_name,
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arg_values.len(),
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arg_values.iter().map(|a| a.type_id()),
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);
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state
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.engine
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.call_native_fn(
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&mut Default::default(),
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state.lib,
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fn_name,
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hash_fn,
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arg_values.iter_mut().collect::<StaticVec<_>>().as_mut(),
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false,
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true,
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&None,
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)
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.ok()
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.map(|(v, _)| v)
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}
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/// Optimize a statement.
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fn optimize_stmt(stmt: Stmt, state: &mut State, preserve_result: bool) -> Stmt {
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match stmt {
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// id op= expr
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Stmt::Assignment(x, pos) => Stmt::Assignment(
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Box::new((optimize_expr(x.0, state), x.1, optimize_expr(x.2, state))),
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pos,
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),
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// if false { if_block } -> Noop
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Stmt::IfThenElse(Expr::False(pos), x, _) if x.1.is_none() => {
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state.set_dirty();
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Stmt::Noop(pos)
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}
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// if true { if_block } -> if_block
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Stmt::IfThenElse(Expr::True(_), x, _) if x.1.is_none() => optimize_stmt(x.0, state, true),
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// if expr { Noop }
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Stmt::IfThenElse(condition, x, _) if x.1.is_none() && matches!(x.0, Stmt::Noop(_)) => {
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state.set_dirty();
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let pos = condition.position();
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let expr = optimize_expr(condition, state);
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if preserve_result {
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// -> { expr, Noop }
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let mut statements = Vec::new();
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statements.push(Stmt::Expr(expr));
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statements.push(x.0);
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Stmt::Block(statements, pos)
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} else {
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// -> expr
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Stmt::Expr(expr)
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}
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}
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// if expr { if_block }
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Stmt::IfThenElse(condition, x, pos) if x.1.is_none() => Stmt::IfThenElse(
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optimize_expr(condition, state),
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Box::new((optimize_stmt(x.0, state, true), None)),
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pos,
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),
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// if false { if_block } else { else_block } -> else_block
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Stmt::IfThenElse(Expr::False(_), x, _) if x.1.is_some() => {
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optimize_stmt(x.1.unwrap(), state, true)
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}
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// if true { if_block } else { else_block } -> if_block
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Stmt::IfThenElse(Expr::True(_), x, _) => optimize_stmt(x.0, state, true),
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// if expr { if_block } else { else_block }
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Stmt::IfThenElse(condition, x, pos) => Stmt::IfThenElse(
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optimize_expr(condition, state),
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Box::new((
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optimize_stmt(x.0, state, true),
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match optimize_stmt(x.1.unwrap(), state, true) {
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Stmt::Noop(_) => None, // Noop -> no else block
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stmt => Some(stmt),
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},
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)),
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pos,
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),
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// while false { block } -> Noop
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Stmt::While(Expr::False(pos), _, _) => {
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state.set_dirty();
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Stmt::Noop(pos)
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}
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// while true { block } -> loop { block }
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Stmt::While(Expr::True(_), block, pos) => {
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Stmt::Loop(Box::new(optimize_stmt(*block, state, false)), pos)
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}
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// while expr { block }
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Stmt::While(condition, block, pos) => {
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match optimize_stmt(*block, state, false) {
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// while expr { break; } -> { expr; }
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Stmt::Break(pos) => {
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// Only a single break statement - turn into running the guard expression once
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state.set_dirty();
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let mut statements = Vec::new();
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statements.push(Stmt::Expr(optimize_expr(condition, state)));
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if preserve_result {
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statements.push(Stmt::Noop(pos))
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}
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Stmt::Block(statements, pos)
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}
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// while expr { block }
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stmt => Stmt::While(optimize_expr(condition, state), Box::new(stmt), pos),
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}
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}
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// loop { block }
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Stmt::Loop(block, pos) => match optimize_stmt(*block, state, false) {
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// loop { break; } -> Noop
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Stmt::Break(pos) => {
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// Only a single break statement
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state.set_dirty();
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Stmt::Noop(pos)
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}
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// loop { block }
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stmt => Stmt::Loop(Box::new(stmt), pos),
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},
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// for id in expr { block }
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Stmt::For(iterable, x, pos) => {
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let (var_name, block) = *x;
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Stmt::For(
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optimize_expr(iterable, state),
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Box::new((var_name, optimize_stmt(block, state, false))),
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pos,
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)
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}
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// let id = expr;
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Stmt::Let(name, Some(expr), pos) => Stmt::Let(name, Some(optimize_expr(expr, state)), pos),
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// let id;
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stmt @ Stmt::Let(_, None, _) => stmt,
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// import expr as var;
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#[cfg(not(feature = "no_module"))]
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Stmt::Import(expr, alias, pos) => Stmt::Import(optimize_expr(expr, state), alias, pos),
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// { block }
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Stmt::Block(statements, pos) => {
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let orig_len = statements.len(); // Original number of statements in the block, for change detection
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let orig_constants_len = state.constants.len(); // Original number of constants in the state, for restore later
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// Optimize each statement in the block
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let mut result: Vec<_> = statements
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.into_iter()
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.map(|stmt| match stmt {
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// Add constant literals into the state
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Stmt::Const(name, Some(expr), pos) if expr.is_literal() => {
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state.set_dirty();
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state.push_constant(&name.0, expr);
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Stmt::Noop(pos) // No need to keep constants
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}
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Stmt::Const(name, Some(expr), pos) if expr.is_literal() => {
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let expr = optimize_expr(expr, state);
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Stmt::Const(name, Some(expr), pos)
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}
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Stmt::Const(name, None, pos) => {
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state.set_dirty();
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state.push_constant(&name.0, Expr::Unit(name.1));
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Stmt::Noop(pos) // No need to keep constants
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}
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// Optimize the statement
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stmt => optimize_stmt(stmt, state, preserve_result),
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})
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.collect();
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// Remove all raw expression statements that are pure except for the very last statement
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let last_stmt = if preserve_result { result.pop() } else { None };
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result.retain(|stmt| !stmt.is_pure());
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if let Some(stmt) = last_stmt {
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result.push(stmt);
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}
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// Remove all let/import statements at the end of a block - the new variables will go away anyway.
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// But be careful only remove ones that have no initial values or have values that are pure expressions,
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// otherwise there may be side effects.
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let mut removed = false;
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while let Some(expr) = result.pop() {
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match expr {
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Stmt::Let(_, expr, _) => {
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removed = expr.as_ref().map(Expr::is_pure).unwrap_or(true)
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}
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#[cfg(not(feature = "no_module"))]
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Stmt::Import(expr, _, _) => removed = expr.is_pure(),
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_ => {
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result.push(expr);
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break;
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}
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}
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}
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if preserve_result {
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if removed {
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result.push(Stmt::Noop(pos))
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}
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// Optimize all the statements again
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result = result
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.into_iter()
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.rev()
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.enumerate()
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.map(|(i, stmt)| optimize_stmt(stmt, state, i == 0))
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.rev()
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.collect();
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}
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// Remove everything following the the first return/throw
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let mut dead_code = false;
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result.retain(|stmt| {
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if dead_code {
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return false;
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}
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match stmt {
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Stmt::ReturnWithVal(_, _, _) | Stmt::Break(_) => dead_code = true,
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_ => (),
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}
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true
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});
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// Change detection
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if orig_len != result.len() {
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state.set_dirty();
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}
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// Pop the stack and remove all the local constants
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state.restore_constants(orig_constants_len);
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match &result[..] {
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// No statements in block - change to No-op
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[] => {
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state.set_dirty();
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Stmt::Noop(pos)
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}
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// Only one let statement - leave it alone
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[x] if matches!(x, Stmt::Let(_, _, _)) => Stmt::Block(result, pos),
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// Only one import statement - leave it alone
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#[cfg(not(feature = "no_module"))]
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[x] if matches!(x, Stmt::Import(_, _, _)) => Stmt::Block(result, pos),
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// Only one statement - promote
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[_] => {
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state.set_dirty();
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result.remove(0)
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}
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_ => Stmt::Block(result, pos),
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}
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}
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// try { block } catch ( var ) { block }
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Stmt::TryCatch(x) if (x.0).0.is_pure() => {
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// If try block is pure, there will never be any exceptions
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state.set_dirty();
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let pos = (x.0).0.position();
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let mut statements: Vec<_> = Default::default();
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statements.push(optimize_stmt((x.0).0, state, preserve_result));
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statements.push(Stmt::Noop(pos));
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Stmt::Block(statements, pos)
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}
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// try { block } catch ( var ) { block }
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Stmt::TryCatch(x) => {
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let ((try_block, try_pos), var_name, (catch_block, catch_pos)) = *x;
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Stmt::TryCatch(Box::new((
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(optimize_stmt(try_block, state, false), try_pos),
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var_name,
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(optimize_stmt(catch_block, state, false), catch_pos),
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)))
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}
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// expr;
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Stmt::Expr(expr) => Stmt::Expr(optimize_expr(expr, state)),
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// return expr;
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Stmt::ReturnWithVal(ret, Some(expr), pos) => {
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Stmt::ReturnWithVal(ret, Some(optimize_expr(expr, state)), pos)
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}
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// All other statements - skip
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stmt => stmt,
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}
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}
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/// Optimize an expression.
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fn optimize_expr(expr: Expr, state: &mut State) -> Expr {
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// These keywords are handled specially
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const DONT_EVAL_KEYWORDS: &[&str] = &[
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KEYWORD_PRINT, // side effects
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KEYWORD_DEBUG, // side effects
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KEYWORD_EVAL, // arbitrary scripts
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KEYWORD_IS_DEF_FN, // functions collection is volatile
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KEYWORD_IS_DEF_VAR, // variables scope is volatile
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];
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match expr {
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// expr - do not promote because there is a reason it is wrapped in an `Expr::Expr`
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Expr::Expr(x) => Expr::Expr(Box::new(optimize_expr(*x, state))),
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// ( stmt )
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Expr::Stmt(x) => match optimize_stmt(x.0, state, true) {
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// ( Noop ) -> ()
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Stmt::Noop(_) => {
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state.set_dirty();
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Expr::Unit(x.1)
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}
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// ( expr ) -> expr
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Stmt::Expr(expr) => {
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state.set_dirty();
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expr
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}
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// ( stmt )
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stmt => Expr::Stmt(Box::new((stmt, x.1))),
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},
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|
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// lhs.rhs
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#[cfg(not(feature = "no_object"))]
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Expr::Dot(x) => match (x.lhs, x.rhs) {
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// map.string
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(Expr::Map(m), Expr::Property(p)) if m.0.iter().all(|(_, x)| x.is_pure()) => {
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let ((prop, _, _), _) = p.as_ref();
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// Map 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 pos = m.1;
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m.0.into_iter().find(|((name, _), _)| name == prop)
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.map(|(_, mut expr)| { expr.set_position(pos); expr })
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.unwrap_or_else(|| Expr::Unit(pos))
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}
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// lhs.rhs
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(lhs, rhs) => Expr::Dot(Box::new(BinaryExpr {
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lhs: optimize_expr(lhs, state),
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rhs: optimize_expr(rhs, state),
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pos: x.pos
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}))
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}
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|
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// lhs[rhs]
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#[cfg(not(feature = "no_index"))]
|
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Expr::Index(x) => match (x.lhs, x.rhs) {
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// array[int]
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(Expr::Array(mut a), Expr::IntegerConstant(i))
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if i.0 >= 0 && (i.0 as usize) < a.0.len() && a.0.iter().all(Expr::is_pure) =>
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{
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// 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 expr = a.0.remove(i.0 as usize);
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expr.set_position(a.1);
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expr
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}
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// map[string]
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(Expr::Map(m), Expr::StringConstant(s)) if m.0.iter().all(|(_, x)| x.is_pure()) => {
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// Map 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 pos = m.1;
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m.0.into_iter().find(|((name, _), _)| *name == s.0)
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.map(|(_, mut expr)| { expr.set_position(pos); expr })
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.unwrap_or_else(|| Expr::Unit(pos))
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}
|
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// string[int]
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(Expr::StringConstant(s), Expr::IntegerConstant(i)) if i.0 >= 0 && (i.0 as usize) < s.0.chars().count() => {
|
|
// String literal indexing - get the character
|
|
state.set_dirty();
|
|
Expr::CharConstant(Box::new((s.0.chars().nth(i.0 as usize).unwrap(), s.1)))
|
|
}
|
|
// lhs[rhs]
|
|
(lhs, rhs) => Expr::Index(Box::new(BinaryExpr {
|
|
lhs: optimize_expr(lhs, state),
|
|
rhs: optimize_expr(rhs, state),
|
|
pos: x.pos
|
|
})),
|
|
},
|
|
// [ items .. ]
|
|
#[cfg(not(feature = "no_index"))]
|
|
Expr::Array(a) => Expr::Array(Box::new((a.0
|
|
.into_iter().map(|expr| optimize_expr(expr, state))
|
|
.collect(), a.1))),
|
|
// [ items .. ]
|
|
#[cfg(not(feature = "no_object"))]
|
|
Expr::Map(m) => Expr::Map(Box::new((m.0
|
|
.into_iter().map(|((key, pos), expr)| ((key, pos), optimize_expr(expr, state)))
|
|
.collect(), m.1))),
|
|
// lhs in rhs
|
|
Expr::In(x) => match (x.lhs, x.rhs) {
|
|
// "xxx" in "xxxxx"
|
|
(Expr::StringConstant(a), Expr::StringConstant(b)) => {
|
|
state.set_dirty();
|
|
if b.0.contains(a.0.as_str()) { Expr::True(a.1) } else { Expr::False(a.1) }
|
|
}
|
|
// 'x' in "xxxxx"
|
|
(Expr::CharConstant(a), Expr::StringConstant(b)) => {
|
|
state.set_dirty();
|
|
if b.0.contains(a.0) { Expr::True(a.1) } else { Expr::False(a.1) }
|
|
}
|
|
// "xxx" in #{...}
|
|
(Expr::StringConstant(a), Expr::Map(b)) => {
|
|
state.set_dirty();
|
|
if b.0.iter().find(|((name, _), _)| *name == a.0).is_some() {
|
|
Expr::True(a.1)
|
|
} else {
|
|
Expr::False(a.1)
|
|
}
|
|
}
|
|
// 'x' in #{...}
|
|
(Expr::CharConstant(a), Expr::Map(b)) => {
|
|
state.set_dirty();
|
|
let ch = a.0.to_string();
|
|
|
|
if b.0.iter().find(|((name, _), _)| name == &ch).is_some() {
|
|
Expr::True(a.1)
|
|
} else {
|
|
Expr::False(a.1)
|
|
}
|
|
}
|
|
// lhs in rhs
|
|
(lhs, rhs) => Expr::In(Box::new(BinaryExpr {
|
|
lhs: optimize_expr(lhs, state),
|
|
rhs: optimize_expr(rhs, state),
|
|
pos: x.pos
|
|
})),
|
|
},
|
|
// lhs && rhs
|
|
Expr::And(x) => match (x.lhs, x.rhs) {
|
|
// true && rhs -> rhs
|
|
(Expr::True(_), rhs) => {
|
|
state.set_dirty();
|
|
rhs
|
|
}
|
|
// false && rhs -> false
|
|
(Expr::False(pos), _) => {
|
|
state.set_dirty();
|
|
Expr::False(pos)
|
|
}
|
|
// lhs && true -> lhs
|
|
(lhs, Expr::True(_)) => {
|
|
state.set_dirty();
|
|
optimize_expr(lhs, state)
|
|
}
|
|
// lhs && rhs
|
|
(lhs, rhs) => Expr::And(Box::new(BinaryExpr {
|
|
lhs: optimize_expr(lhs, state),
|
|
rhs: optimize_expr(rhs, state),
|
|
pos: x.pos
|
|
})),
|
|
},
|
|
// lhs || rhs
|
|
Expr::Or(x) => match (x.lhs, x.rhs) {
|
|
// false || rhs -> rhs
|
|
(Expr::False(_), rhs) => {
|
|
state.set_dirty();
|
|
rhs
|
|
}
|
|
// true || rhs -> true
|
|
(Expr::True(pos), _) => {
|
|
state.set_dirty();
|
|
Expr::True(pos)
|
|
}
|
|
// lhs || false
|
|
(lhs, Expr::False(_)) => {
|
|
state.set_dirty();
|
|
optimize_expr(lhs, state)
|
|
}
|
|
// lhs || rhs
|
|
(lhs, rhs) => Expr::Or(Box::new(BinaryExpr {
|
|
lhs: optimize_expr(lhs, state),
|
|
rhs: optimize_expr(rhs, state),
|
|
pos: x.pos
|
|
})),
|
|
},
|
|
|
|
// Do not call some special keywords
|
|
Expr::FnCall(mut x) if DONT_EVAL_KEYWORDS.contains(&(x.0).0.as_ref()) => {
|
|
x.3 = x.3.into_iter().map(|a| optimize_expr(a, state)).collect();
|
|
Expr::FnCall(x)
|
|
}
|
|
|
|
// Call built-in operators
|
|
Expr::FnCall(mut x)
|
|
if x.1.is_none() // Non-qualified
|
|
&& state.optimization_level == OptimizationLevel::Simple // simple optimizations
|
|
&& x.3.len() == 2 // binary call
|
|
&& x.3.iter().all(Expr::is_constant) // all arguments are constants
|
|
&& !is_valid_identifier((x.0).0.chars()) // cannot be scripted
|
|
=> {
|
|
let ((name, _, _, pos), _, _, args, _) = x.as_mut();
|
|
|
|
let arg_values: StaticVec<_> = args.iter().map(|e| e.get_constant_value().unwrap()).collect();
|
|
let arg_types: StaticVec<_> = arg_values.iter().map(Dynamic::type_id).collect();
|
|
|
|
// Search for overloaded operators (can override built-in).
|
|
if !state.engine.has_override_by_name_and_arguments(state.lib, name, arg_types.as_ref(), false) {
|
|
if let Some(expr) = run_builtin_binary_op(name, &arg_values[0], &arg_values[1])
|
|
.ok().flatten()
|
|
.and_then(|result| map_dynamic_to_expr(result, *pos))
|
|
{
|
|
state.set_dirty();
|
|
return expr;
|
|
}
|
|
}
|
|
|
|
x.3 = x.3.into_iter().map(|a| optimize_expr(a, state)).collect();
|
|
Expr::FnCall(x)
|
|
}
|
|
|
|
// Eagerly call functions
|
|
Expr::FnCall(mut x)
|
|
if x.1.is_none() // Non-qualified
|
|
&& state.optimization_level == OptimizationLevel::Full // full optimizations
|
|
&& x.3.iter().all(Expr::is_constant) // all arguments are constants
|
|
=> {
|
|
let ((name, _, _, pos), _, _, args, def_value) = x.as_mut();
|
|
|
|
// First search for script-defined functions (can override built-in)
|
|
#[cfg(not(feature = "no_function"))]
|
|
let has_script_fn = state.lib.iter().any(|&m| m.get_script_fn(name, args.len(), false).is_some());
|
|
#[cfg(feature = "no_function")]
|
|
let has_script_fn = false;
|
|
|
|
if !has_script_fn {
|
|
let mut arg_values: StaticVec<_> = args.iter().map(|e| e.get_constant_value().unwrap()).collect();
|
|
|
|
// Save the typename of the first argument if it is `type_of()`
|
|
// This is to avoid `call_args` being passed into the closure
|
|
let arg_for_type_of = if name == KEYWORD_TYPE_OF && arg_values.len() == 1 {
|
|
state.engine.map_type_name(arg_values[0].type_name())
|
|
} else {
|
|
""
|
|
};
|
|
|
|
if let Some(expr) = call_fn_with_constant_arguments(&state, name, arg_values.as_mut())
|
|
.or_else(|| {
|
|
if !arg_for_type_of.is_empty() {
|
|
// Handle `type_of()`
|
|
Some(arg_for_type_of.to_string().into())
|
|
} else {
|
|
// Otherwise use the default value, if any
|
|
def_value.map(|v| v.into())
|
|
}
|
|
})
|
|
.and_then(|result| map_dynamic_to_expr(result, *pos))
|
|
{
|
|
state.set_dirty();
|
|
return expr;
|
|
}
|
|
}
|
|
|
|
x.3 = x.3.into_iter().map(|a| optimize_expr(a, state)).collect();
|
|
Expr::FnCall(x)
|
|
}
|
|
|
|
// id(args ..) -> optimize function call arguments
|
|
Expr::FnCall(mut x) => {
|
|
x.3 = x.3.into_iter().map(|a| optimize_expr(a, state)).collect();
|
|
Expr::FnCall(x)
|
|
}
|
|
|
|
// constant-name
|
|
Expr::Variable(x) if x.1.is_none() && state.contains_constant(&(x.0).0) => {
|
|
let (name, pos) = x.0;
|
|
state.set_dirty();
|
|
|
|
// Replace constant with value
|
|
let mut expr = state.find_constant(&name).unwrap().clone();
|
|
expr.set_position(pos);
|
|
expr
|
|
}
|
|
|
|
// Custom syntax
|
|
#[cfg(feature = "internals")]
|
|
Expr::Custom(x) => Expr::Custom(Box::new((
|
|
CustomExpr(
|
|
(x.0).0.into_iter().map(|expr| optimize_expr(expr, state)).collect(),
|
|
(x.0).1),
|
|
x.1
|
|
))),
|
|
|
|
// All other expressions - skip
|
|
expr => expr,
|
|
}
|
|
}
|
|
|
|
fn optimize(
|
|
statements: Vec<Stmt>,
|
|
engine: &Engine,
|
|
scope: &Scope,
|
|
lib: &[&Module],
|
|
level: OptimizationLevel,
|
|
) -> Vec<Stmt> {
|
|
// If optimization level is None then skip optimizing
|
|
if level == OptimizationLevel::None {
|
|
return statements;
|
|
}
|
|
|
|
// Set up the state
|
|
let mut state = State::new(engine, lib, level);
|
|
|
|
// Add constants from the scope into the state
|
|
scope
|
|
.to_iter()
|
|
// Get all the constants that can be made into a constant literal.
|
|
.filter(|ScopeEntry { typ, .. }| typ.is_constant())
|
|
.for_each(
|
|
|ScopeEntry {
|
|
name, expr, value, ..
|
|
}| {
|
|
if let Some(val) = expr
|
|
.as_ref()
|
|
.map(|expr| expr.as_ref().clone())
|
|
.or_else(|| map_dynamic_to_expr(value.clone(), Position::none()))
|
|
{
|
|
state.push_constant(name.as_ref(), val);
|
|
}
|
|
},
|
|
);
|
|
|
|
let orig_constants_len = state.constants.len();
|
|
|
|
let mut result = statements;
|
|
|
|
// Optimization loop
|
|
loop {
|
|
state.reset();
|
|
state.restore_constants(orig_constants_len);
|
|
|
|
let num_statements = result.len();
|
|
|
|
result = result
|
|
.into_iter()
|
|
.enumerate()
|
|
.map(|(i, stmt)| {
|
|
match stmt {
|
|
Stmt::Const(var_def, Some(expr), pos) => {
|
|
// Load constants
|
|
let expr = optimize_expr(expr, &mut state);
|
|
|
|
if expr.is_literal() {
|
|
state.push_constant(&var_def.0, expr.clone());
|
|
}
|
|
|
|
// Keep it in the global scope
|
|
if expr.is_unit() {
|
|
state.set_dirty();
|
|
Stmt::Const(var_def, None, pos)
|
|
} else {
|
|
Stmt::Const(var_def, Some(expr), pos)
|
|
}
|
|
}
|
|
Stmt::Const(ref var_def, None, _) => {
|
|
state.push_constant(&var_def.0, Expr::Unit(var_def.1));
|
|
|
|
// Keep it in the global scope
|
|
stmt
|
|
}
|
|
_ => {
|
|
// Keep all variable declarations at this level
|
|
// and always keep the last return value
|
|
let keep = match stmt {
|
|
Stmt::Let(_, _, _) => true,
|
|
#[cfg(not(feature = "no_module"))]
|
|
Stmt::Import(_, _, _) => true,
|
|
_ => i == num_statements - 1,
|
|
};
|
|
optimize_stmt(stmt, &mut state, keep)
|
|
}
|
|
}
|
|
})
|
|
.collect();
|
|
|
|
if !state.is_dirty() {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Eliminate code that is pure but always keep the last statement
|
|
let last_stmt = result.pop();
|
|
|
|
// Remove all pure statements at global level
|
|
result.retain(|stmt| !stmt.is_pure());
|
|
|
|
// Add back the last statement unless it is a lone No-op
|
|
if let Some(stmt) = last_stmt {
|
|
if !result.is_empty() || !stmt.is_noop() {
|
|
result.push(stmt);
|
|
}
|
|
}
|
|
|
|
result
|
|
}
|
|
|
|
/// Optimize an AST.
|
|
pub fn optimize_into_ast(
|
|
engine: &Engine,
|
|
scope: &Scope,
|
|
statements: Vec<Stmt>,
|
|
_functions: Vec<ScriptFnDef>,
|
|
level: OptimizationLevel,
|
|
) -> AST {
|
|
let level = if cfg!(feature = "no_optimize") {
|
|
OptimizationLevel::None
|
|
} else {
|
|
level
|
|
};
|
|
|
|
#[cfg(not(feature = "no_function"))]
|
|
let lib = {
|
|
let mut module = Module::new();
|
|
|
|
if !level.is_none() {
|
|
// We only need the script library's signatures for optimization purposes
|
|
let mut lib2 = Module::new();
|
|
|
|
_functions
|
|
.iter()
|
|
.map(|fn_def| {
|
|
ScriptFnDef {
|
|
name: fn_def.name.clone(),
|
|
access: fn_def.access,
|
|
body: Default::default(),
|
|
params: fn_def.params.clone(),
|
|
#[cfg(not(feature = "no_closure"))]
|
|
externals: fn_def.externals.clone(),
|
|
pos: fn_def.pos,
|
|
lib: None,
|
|
}
|
|
.into()
|
|
})
|
|
.for_each(|fn_def| {
|
|
lib2.set_script_fn(fn_def);
|
|
});
|
|
|
|
_functions
|
|
.into_iter()
|
|
.map(|mut fn_def| {
|
|
let pos = fn_def.body.position();
|
|
|
|
// Optimize the function body
|
|
let mut body =
|
|
optimize(vec![fn_def.body], engine, &Scope::new(), &[&lib2], level);
|
|
|
|
// {} -> Noop
|
|
fn_def.body = match body.pop().unwrap_or_else(|| Stmt::Noop(pos)) {
|
|
// { return val; } -> val
|
|
Stmt::ReturnWithVal((ReturnType::Return, _), Some(expr), _) => {
|
|
Stmt::Expr(expr)
|
|
}
|
|
// { return; } -> ()
|
|
Stmt::ReturnWithVal((ReturnType::Return, pos), None, _) => {
|
|
Stmt::Expr(Expr::Unit(pos))
|
|
}
|
|
// All others
|
|
stmt => stmt,
|
|
};
|
|
fn_def.into()
|
|
})
|
|
.for_each(|fn_def| {
|
|
module.set_script_fn(fn_def);
|
|
});
|
|
} else {
|
|
_functions.into_iter().for_each(|fn_def| {
|
|
module.set_script_fn(fn_def.into());
|
|
});
|
|
}
|
|
|
|
module
|
|
};
|
|
|
|
#[cfg(feature = "no_function")]
|
|
let lib = Default::default();
|
|
|
|
AST::new(
|
|
match level {
|
|
OptimizationLevel::None => statements,
|
|
OptimizationLevel::Simple | OptimizationLevel::Full => {
|
|
optimize(statements, engine, &scope, &[&lib], level)
|
|
}
|
|
},
|
|
lib,
|
|
)
|
|
}
|