963 lines
34 KiB
Rust
963 lines
34 KiB
Rust
//! Module implementing the [`AST`] optimizer.
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use crate::ast::{Expr, ScriptFnDef, Stmt};
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use crate::builtin::get_builtin_binary_op_fn;
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use crate::dynamic::AccessMode;
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use crate::engine::{Imports, KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_PRINT, KEYWORD_TYPE_OF};
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use crate::parser::map_dynamic_to_expr;
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use crate::stdlib::{
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boxed::Box,
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hash::{Hash, Hasher},
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iter::empty,
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mem,
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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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use crate::token::is_valid_identifier;
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use crate::utils::get_hasher;
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use crate::{calc_native_fn_hash, Dynamic, Engine, Module, Position, Scope, StaticVec, AST};
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/// Level of optimization performed.
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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`][OptimizationLevel::None]?
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#[allow(dead_code)]
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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`][OptimizationLevel::Simple]?
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#[allow(dead_code)]
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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`][OptimizationLevel::Full]?
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#[allow(dead_code)]
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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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variables: Vec<(String, AccessMode, Expr)>,
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/// Activate constants propagation?
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propagate_constants: bool,
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/// An [`Engine`] instance for eager function evaluation.
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engine: &'a Engine,
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/// Collection of sub-modules.
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mods: Imports,
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/// [Module] containing 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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variables: vec![],
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propagate_constants: true,
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engine,
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mods: Default::default(),
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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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/// Prune the list of constants back to a specified size.
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#[inline(always)]
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pub fn restore_var(&mut self, len: usize) {
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self.variables.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_var(&mut self, name: &str, access: AccessMode, value: Expr) {
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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<&Expr> {
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if !self.propagate_constants {
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return None;
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}
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for (n, access, expr) in self.variables.iter().rev() {
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if n == name {
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return if access.is_read_only() {
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Some(expr)
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} else {
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None
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};
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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_native_fn_hash(empty(), fn_name, arg_values.iter().map(|a| a.type_id()));
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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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&mut Default::default(),
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state.lib,
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fn_name,
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hash_fn.unwrap(),
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arg_values.iter_mut().collect::<StaticVec<_>>().as_mut(),
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false,
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false,
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Position::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 block of [statements][Stmt].
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fn optimize_stmt_block(
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mut statements: Vec<Stmt>,
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pos: Position,
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state: &mut State,
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preserve_result: bool,
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count_promote_as_dirty: bool,
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) -> Stmt {
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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.variables.len(); // Original number of constants in the state, for restore later
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let orig_propagate_constants = state.propagate_constants;
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// Optimize each statement in the block
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statements.iter_mut().for_each(|stmt| {
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match stmt {
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// Add constant literals into the state
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Stmt::Const(var_def, Some(value_expr), _, _) => {
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optimize_expr(value_expr, state);
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if value_expr.is_constant() {
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state.push_var(&var_def.name, AccessMode::ReadOnly, value_expr.clone());
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}
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}
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Stmt::Const(var_def, None, _, _) => {
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state.push_var(&var_def.name, AccessMode::ReadOnly, Expr::Unit(var_def.pos));
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}
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// Add variables into the state
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Stmt::Let(var_def, expr, _, _) => {
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if let Some(value_expr) = expr {
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optimize_expr(value_expr, state);
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}
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state.push_var(
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&var_def.name,
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AccessMode::ReadWrite,
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Expr::Unit(var_def.pos),
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);
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}
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// Optimize the statement
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_ => optimize_stmt(stmt, state, preserve_result),
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}
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});
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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 {
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statements.pop()
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} else {
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None
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};
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statements.retain(|stmt| !stmt.is_pure());
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if let Some(stmt) = last_stmt {
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statements.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) = statements.pop() {
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match expr {
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Stmt::Let(_, expr, _, _) | Stmt::Const(_, 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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statements.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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statements.push(Stmt::Noop(pos))
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}
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// Optimize all the statements again
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let num_statements = statements.len();
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statements
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.iter_mut()
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.enumerate()
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.for_each(|(i, stmt)| optimize_stmt(stmt, state, i == num_statements));
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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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statements.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::Return(_, _, _) | 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 != statements.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_var(orig_constants_len);
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state.propagate_constants = orig_propagate_constants;
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match &statements[..] {
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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(statements, pos),
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// Only one const statement - leave it alone
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[x] if matches!(x, Stmt::Const(_, _, _, _)) => Stmt::Block(statements, 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(statements, pos),
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// Only one statement - promote
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[_] => {
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if count_promote_as_dirty {
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state.set_dirty();
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}
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statements.remove(0)
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}
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_ => Stmt::Block(statements, pos),
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}
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}
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/// Optimize a [statement][Stmt].
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fn optimize_stmt(stmt: &mut Stmt, state: &mut State, preserve_result: bool) {
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match stmt {
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// expr op= expr
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Stmt::Assignment(x, _) => match x.0 {
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Expr::Variable(_) => optimize_expr(&mut x.2, state),
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_ => {
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optimize_expr(&mut x.0, state);
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optimize_expr(&mut x.2, state);
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}
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},
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// if false { if_block } -> Noop
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Stmt::If(Expr::BoolConstant(false, pos), x, _) if x.1.is_none() => {
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state.set_dirty();
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*stmt = Stmt::Noop(*pos);
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}
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// if true { if_block } -> if_block
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Stmt::If(Expr::BoolConstant(true, _), x, _) if x.1.is_none() => {
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*stmt = mem::take(&mut x.0);
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optimize_stmt(stmt, state, true);
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}
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// if expr { Noop }
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Stmt::If(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 mut expr = mem::take(condition);
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optimize_expr(&mut expr, state);
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*stmt = if preserve_result {
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// -> { expr, Noop }
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Stmt::Block(vec![Stmt::Expr(expr), mem::take(&mut x.0)], 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::If(condition, x, _) if x.1.is_none() => {
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optimize_expr(condition, state);
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optimize_stmt(&mut x.0, state, true);
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}
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// if false { if_block } else { else_block } -> else_block
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Stmt::If(Expr::BoolConstant(false, _), x, _) if x.1.is_some() => {
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*stmt = mem::take(x.1.as_mut().unwrap());
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optimize_stmt(stmt, state, true);
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}
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// if true { if_block } else { else_block } -> if_block
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Stmt::If(Expr::BoolConstant(true, _), x, _) => {
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*stmt = mem::take(&mut x.0);
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optimize_stmt(stmt, state, true);
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}
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// if expr { if_block } else { else_block }
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Stmt::If(condition, x, _) => {
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optimize_expr(condition, state);
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optimize_stmt(&mut x.0, state, true);
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if let Some(else_block) = x.1.as_mut() {
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optimize_stmt(else_block, state, true);
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match else_block {
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Stmt::Noop(_) => x.1 = None, // Noop -> no else block
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_ => (),
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}
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}
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}
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// switch const { ... }
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Stmt::Switch(expr, x, pos) if expr.is_constant() => {
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let value = expr.get_constant_value().unwrap();
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let hasher = &mut get_hasher();
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value.hash(hasher);
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let hash = hasher.finish();
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state.set_dirty();
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let table = &mut x.0;
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if let Some(stmt) = table.get_mut(&hash) {
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optimize_stmt(stmt, state, true);
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*expr = Expr::Stmt(Box::new(vec![mem::take(stmt)].into()), *pos);
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} else if let Some(def_stmt) = x.1.as_mut() {
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optimize_stmt(def_stmt, state, true);
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*expr = Expr::Stmt(Box::new(vec![mem::take(def_stmt)].into()), *pos);
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} else {
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*expr = Expr::Unit(*pos);
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}
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}
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// switch
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Stmt::Switch(expr, x, _) => {
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optimize_expr(expr, state);
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x.0.values_mut()
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.for_each(|stmt| optimize_stmt(stmt, state, true));
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if let Some(def_stmt) = x.1.as_mut() {
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optimize_stmt(def_stmt, state, true);
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match def_stmt {
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Stmt::Noop(_) | Stmt::Expr(Expr::Unit(_)) => x.1 = None,
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_ => (),
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}
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}
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}
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// while false { block } -> Noop
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Stmt::While(Expr::BoolConstant(false, pos), _, _) => {
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state.set_dirty();
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*stmt = Stmt::Noop(*pos)
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}
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// while expr { block }
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Stmt::While(condition, block, _) => {
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optimize_stmt(block, state, false);
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optimize_expr(condition, state);
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match **block {
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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![Stmt::Expr(mem::take(condition))];
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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 = Stmt::Block(statements, pos);
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}
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_ => (),
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}
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}
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// do { block } while false | do { block } until true -> { block }
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Stmt::Do(block, Expr::BoolConstant(true, _), false, _)
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| Stmt::Do(block, Expr::BoolConstant(false, _), true, _) => {
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state.set_dirty();
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optimize_stmt(block.as_mut(), state, false);
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*stmt = mem::take(block.as_mut());
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}
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// do { block } while|until expr
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Stmt::Do(block, condition, _, _) => {
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optimize_stmt(block.as_mut(), state, false);
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optimize_expr(condition, state);
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}
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// for id in expr { block }
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Stmt::For(iterable, x, _) => {
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optimize_expr(iterable, state);
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optimize_stmt(&mut x.1, state, false);
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}
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// let id = expr;
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Stmt::Let(_, Some(expr), _, _) => optimize_expr(expr, state),
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// let id;
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Stmt::Let(_, None, _, _) => (),
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// import expr as var;
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#[cfg(not(feature = "no_module"))]
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Stmt::Import(expr, _, _) => optimize_expr(expr, state),
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// { block }
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Stmt::Block(statements, pos) => {
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*stmt = optimize_stmt_block(mem::take(statements), *pos, state, preserve_result, true);
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}
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// try { block } catch ( var ) { block }
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Stmt::TryCatch(x, _, _) if x.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.position();
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optimize_stmt(&mut x.0, state, preserve_result);
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let mut statements = match mem::take(&mut x.0) {
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Stmt::Block(statements, _) => statements,
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stmt => vec![stmt],
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};
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statements.push(Stmt::Noop(pos));
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*stmt = 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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optimize_stmt(&mut x.0, state, false);
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optimize_stmt(&mut x.2, state, false);
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}
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// {}
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Stmt::Expr(Expr::Stmt(x, pos)) if x.is_empty() => {
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state.set_dirty();
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*stmt = Stmt::Noop(*pos);
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}
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// {...};
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Stmt::Expr(Expr::Stmt(x, pos)) => {
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state.set_dirty();
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*stmt = Stmt::Block(mem::take(x).into_vec(), *pos);
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}
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// expr;
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Stmt::Expr(expr) => optimize_expr(expr, state),
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// return expr;
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Stmt::Return(_, Some(ref mut expr), _) => optimize_expr(expr, state),
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// All other statements - skip
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_ => (),
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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 State) {
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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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];
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match expr {
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// {}
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Expr::Stmt(x, pos) if x.is_empty() => { state.set_dirty(); *expr = Expr::Unit(*pos) }
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// { stmt; ... } - do not count promotion as dirty because it gets turned back into an array
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Expr::Stmt(x, pos) => match optimize_stmt_block(mem::take(x).into_vec(), *pos, state, true, false) {
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// {}
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Stmt::Noop(_) => { state.set_dirty(); *expr = Expr::Unit(*pos); }
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// { stmt, .. }
|
|
Stmt::Block(statements, _) => *x = Box::new(statements.into()),
|
|
// { expr }
|
|
Stmt::Expr(inner) => { state.set_dirty(); *expr = inner; }
|
|
// { stmt }
|
|
stmt => x.push(stmt),
|
|
}
|
|
|
|
// lhs.rhs
|
|
#[cfg(not(feature = "no_object"))]
|
|
Expr::Dot(x, _) => match (&mut x.lhs, &mut x.rhs) {
|
|
// map.string
|
|
(Expr::Map(m, pos), Expr::Property(p)) if m.iter().all(|(_, x)| x.is_pure()) => {
|
|
let prop = &p.2.name;
|
|
// Map literal where everything is pure - promote the indexed item.
|
|
// All other items can be thrown away.
|
|
state.set_dirty();
|
|
*expr = mem::take(m).into_iter().find(|(x, _)| &x.name == prop)
|
|
.map(|(_, mut expr)| { expr.set_position(*pos); expr })
|
|
.unwrap_or_else(|| Expr::Unit(*pos));
|
|
}
|
|
// var.rhs
|
|
(Expr::Variable(_), rhs) => optimize_expr(rhs, state),
|
|
// lhs.rhs
|
|
(lhs, rhs) => { optimize_expr(lhs, state); optimize_expr(rhs, state); }
|
|
}
|
|
|
|
// lhs[rhs]
|
|
#[cfg(not(feature = "no_index"))]
|
|
Expr::Index(x, _) => match (&mut x.lhs, &mut x.rhs) {
|
|
// array[int]
|
|
(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.
|
|
// All other items can be thrown away.
|
|
state.set_dirty();
|
|
let mut result = a.remove(*i as usize);
|
|
result.set_position(*pos);
|
|
*expr = result;
|
|
}
|
|
// map[string]
|
|
(Expr::Map(m, pos), Expr::StringConstant(s, _)) if m.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();
|
|
*expr = mem::take(m).into_iter().find(|(x, _)| x.name == *s)
|
|
.map(|(_, mut expr)| { expr.set_position(*pos); expr })
|
|
.unwrap_or_else(|| Expr::Unit(*pos));
|
|
}
|
|
// string[int]
|
|
(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();
|
|
*expr = Expr::CharConstant(s.chars().nth(*i as usize).unwrap(), *pos);
|
|
}
|
|
// var[rhs]
|
|
(Expr::Variable(_), rhs) => optimize_expr(rhs, state),
|
|
// lhs[rhs]
|
|
(lhs, rhs) => { optimize_expr(lhs, state); optimize_expr(rhs, state); }
|
|
},
|
|
// [ constant .. ]
|
|
#[cfg(not(feature = "no_index"))]
|
|
Expr::Array(_, _) if expr.is_constant() => {
|
|
state.set_dirty();
|
|
*expr = Expr::DynamicConstant(Box::new(expr.get_constant_value().unwrap()), expr.position());
|
|
}
|
|
// [ items .. ]
|
|
#[cfg(not(feature = "no_index"))]
|
|
Expr::Array(x, _) => x.iter_mut().for_each(|expr| optimize_expr(expr, state)),
|
|
// #{ key:constant, .. }
|
|
#[cfg(not(feature = "no_object"))]
|
|
Expr::Map(_, _) if expr.is_constant() => {
|
|
state.set_dirty();
|
|
*expr = Expr::DynamicConstant(Box::new(expr.get_constant_value().unwrap()), expr.position());
|
|
}
|
|
// #{ key:value, .. }
|
|
#[cfg(not(feature = "no_object"))]
|
|
Expr::Map(x, _) => x.iter_mut().for_each(|(_, expr)| optimize_expr(expr, state)),
|
|
// lhs in rhs
|
|
Expr::In(x, _) => match (&mut x.lhs, &mut x.rhs) {
|
|
// "xxx" in "xxxxx"
|
|
(Expr::StringConstant(a, pos), Expr::StringConstant(b, _)) => {
|
|
state.set_dirty();
|
|
*expr = Expr::BoolConstant( b.contains(a.as_str()), *pos);
|
|
}
|
|
// 'x' in "xxxxx"
|
|
(Expr::CharConstant(a, pos), Expr::StringConstant(b, _)) => {
|
|
state.set_dirty();
|
|
*expr = Expr::BoolConstant(b.contains(*a), *pos);
|
|
}
|
|
// "xxx" in #{...}
|
|
(Expr::StringConstant(a, pos), Expr::Map(b, _)) => {
|
|
state.set_dirty();
|
|
*expr = Expr::BoolConstant(b.iter().find(|(x, _)| x.name == *a).is_some(), *pos);
|
|
}
|
|
// 'x' in #{...}
|
|
(Expr::CharConstant(a, pos), Expr::Map(b, _)) => {
|
|
state.set_dirty();
|
|
let ch = a.to_string();
|
|
*expr = Expr::BoolConstant(b.iter().find(|(x, _)| x.name == &ch).is_some(), *pos);
|
|
}
|
|
// lhs in rhs
|
|
(lhs, rhs) => { optimize_expr(lhs, state); optimize_expr(rhs, state); }
|
|
},
|
|
// lhs && rhs
|
|
Expr::And(x, _) => match (&mut x.lhs, &mut x.rhs) {
|
|
// true && rhs -> rhs
|
|
(Expr::BoolConstant(true, _), rhs) => {
|
|
state.set_dirty();
|
|
optimize_expr(rhs, state);
|
|
*expr = mem::take(rhs);
|
|
}
|
|
// false && rhs -> false
|
|
(Expr::BoolConstant(false, pos), _) => {
|
|
state.set_dirty();
|
|
*expr = Expr::BoolConstant(false, *pos);
|
|
}
|
|
// lhs && true -> lhs
|
|
(lhs, Expr::BoolConstant(true, _)) => {
|
|
state.set_dirty();
|
|
optimize_expr(lhs, state);
|
|
*expr = mem::take(lhs);
|
|
}
|
|
// lhs && rhs
|
|
(lhs, rhs) => { optimize_expr(lhs, state); optimize_expr(rhs, state); }
|
|
},
|
|
// lhs || rhs
|
|
Expr::Or(ref mut x, _) => match (&mut x.lhs, &mut x.rhs) {
|
|
// false || rhs -> rhs
|
|
(Expr::BoolConstant(false, _), rhs) => {
|
|
state.set_dirty();
|
|
optimize_expr(rhs, state);
|
|
*expr = mem::take(rhs);
|
|
}
|
|
// true || rhs -> true
|
|
(Expr::BoolConstant(true, pos), _) => {
|
|
state.set_dirty();
|
|
*expr = Expr::BoolConstant(true, *pos);
|
|
}
|
|
// lhs || false
|
|
(lhs, Expr::BoolConstant(false, _)) => {
|
|
state.set_dirty();
|
|
optimize_expr(lhs, state);
|
|
*expr = mem::take(lhs);
|
|
}
|
|
// lhs || rhs
|
|
(lhs, rhs) => { optimize_expr(lhs, state); optimize_expr(rhs, state); }
|
|
},
|
|
|
|
// eval!
|
|
Expr::FnCall(x, _) if x.name == KEYWORD_EVAL => {
|
|
state.propagate_constants = false;
|
|
}
|
|
// Do not call some special keywords
|
|
Expr::FnCall(x, _) if DONT_EVAL_KEYWORDS.contains(&x.name.as_ref()) => {
|
|
x.args.iter_mut().for_each(|a| optimize_expr(a, state));
|
|
}
|
|
|
|
// Call built-in operators
|
|
Expr::FnCall(x, pos)
|
|
if x.namespace.is_none() // Non-qualified
|
|
&& state.optimization_level == OptimizationLevel::Simple // simple optimizations
|
|
&& x.args.len() == 2 // binary call
|
|
&& x.args.iter().all(Expr::is_constant) // all arguments are constants
|
|
&& !is_valid_identifier(x.name.chars()) // cannot be scripted
|
|
=> {
|
|
let mut arg_values: StaticVec<_> = x.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(Some(&state.mods), state.lib, x.name.as_ref(), arg_types.as_ref()) {
|
|
if let Some(result) = get_builtin_binary_op_fn(x.name.as_ref(), &arg_values[0], &arg_values[1])
|
|
.and_then(|f| {
|
|
let ctx = (state.engine, x.name.as_ref(), state.lib).into();
|
|
let (first, second) = arg_values.split_first_mut().unwrap();
|
|
(f)(ctx, &mut [ first, &mut second[0] ]).ok()
|
|
})
|
|
.and_then(|result| map_dynamic_to_expr(result, *pos))
|
|
{
|
|
state.set_dirty();
|
|
*expr = result;
|
|
return;
|
|
}
|
|
}
|
|
|
|
x.args.iter_mut().for_each(|a| optimize_expr(a, state));
|
|
}
|
|
|
|
// Eagerly call functions
|
|
Expr::FnCall(x, pos)
|
|
if x.namespace.is_none() // Non-qualified
|
|
&& state.optimization_level == OptimizationLevel::Full // full optimizations
|
|
&& x.args.iter().all(Expr::is_constant) // all arguments are constants
|
|
=> {
|
|
// 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(x.name.as_ref(), x.args.len(), false).is_some());
|
|
#[cfg(feature = "no_function")]
|
|
let has_script_fn = false;
|
|
|
|
if !has_script_fn {
|
|
let mut arg_values: StaticVec<_> = x.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 x.name == KEYWORD_TYPE_OF && arg_values.len() == 1 {
|
|
state.engine.map_type_name(arg_values[0].type_name())
|
|
} else {
|
|
""
|
|
};
|
|
|
|
if let Some(result) = call_fn_with_constant_arguments(&state, x.name.as_ref(), 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 {
|
|
None
|
|
}
|
|
})
|
|
.and_then(|result| map_dynamic_to_expr(result, *pos))
|
|
{
|
|
state.set_dirty();
|
|
*expr = result;
|
|
return;
|
|
}
|
|
}
|
|
|
|
x.args.iter_mut().for_each(|a| optimize_expr(a, state));
|
|
}
|
|
|
|
// id(args ..) -> optimize function call arguments
|
|
Expr::FnCall(x, _) => x.args.iter_mut().for_each(|a| optimize_expr(a, state)),
|
|
|
|
// constant-name
|
|
Expr::Variable(x) if x.1.is_none() && state.find_constant(&x.2.name).is_some() => {
|
|
state.set_dirty();
|
|
|
|
// Replace constant with value
|
|
let mut result = state.find_constant(&x.2.name).unwrap().clone();
|
|
result.set_position(x.2.pos);
|
|
*expr = result;
|
|
}
|
|
|
|
// Custom syntax
|
|
Expr::Custom(x, _) => {
|
|
if x.scope_delta != 0 {
|
|
state.propagate_constants = false;
|
|
}
|
|
x.keywords.iter_mut().for_each(|expr| optimize_expr(expr, state));
|
|
}
|
|
|
|
// All other expressions - skip
|
|
_ => (),
|
|
}
|
|
}
|
|
|
|
/// Optimize a block of [statements][Stmt] at top level.
|
|
fn optimize_top_level(
|
|
mut 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 {
|
|
statements.shrink_to_fit();
|
|
return statements;
|
|
}
|
|
|
|
// Set up the state
|
|
let mut state = State::new(engine, lib, level);
|
|
|
|
// Add constants and variables from the scope
|
|
scope.iter().for_each(|(name, constant, value)| {
|
|
if !constant {
|
|
state.push_var(name, AccessMode::ReadWrite, Expr::Unit(Position::NONE));
|
|
} else if let Some(val) = map_dynamic_to_expr(value, Position::NONE) {
|
|
state.push_var(name, AccessMode::ReadOnly, val);
|
|
} else {
|
|
state.push_var(name, AccessMode::ReadOnly, Expr::Unit(Position::NONE));
|
|
}
|
|
});
|
|
|
|
let orig_constants_len = state.variables.len();
|
|
|
|
// Optimization loop
|
|
loop {
|
|
state.reset();
|
|
state.restore_var(orig_constants_len);
|
|
|
|
let num_statements = statements.len();
|
|
|
|
statements.iter_mut().enumerate().for_each(|(i, stmt)| {
|
|
match stmt {
|
|
Stmt::Const(var_def, expr, _, _) if expr.is_some() => {
|
|
// Load constants
|
|
let value_expr = expr.as_mut().unwrap();
|
|
optimize_expr(value_expr, &mut state);
|
|
|
|
if value_expr.is_constant() {
|
|
state.push_var(&var_def.name, AccessMode::ReadOnly, value_expr.clone());
|
|
}
|
|
|
|
// Keep it in the global scope
|
|
if value_expr.is_unit() {
|
|
state.set_dirty();
|
|
*expr = None;
|
|
}
|
|
}
|
|
Stmt::Const(var_def, None, _, _) => {
|
|
state.push_var(&var_def.name, AccessMode::ReadOnly, Expr::Unit(var_def.pos));
|
|
}
|
|
Stmt::Let(var_def, expr, _, _) => {
|
|
if let Some(value_expr) = expr {
|
|
optimize_expr(value_expr, &mut state);
|
|
}
|
|
|
|
state.push_var(
|
|
&var_def.name,
|
|
AccessMode::ReadWrite,
|
|
Expr::Unit(var_def.pos),
|
|
);
|
|
}
|
|
_ => {
|
|
// Keep all variable declarations at this level
|
|
// and always keep the last return value
|
|
let keep = match stmt {
|
|
Stmt::Let(_, _, _, _) | Stmt::Const(_, _, _, _) => true,
|
|
#[cfg(not(feature = "no_module"))]
|
|
Stmt::Import(_, _, _) => true,
|
|
_ => i == num_statements - 1,
|
|
};
|
|
optimize_stmt(stmt, &mut state, keep);
|
|
}
|
|
}
|
|
});
|
|
|
|
if !state.is_dirty() {
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Eliminate code that is pure but always keep the last statement
|
|
let last_stmt = statements.pop();
|
|
|
|
// Remove all pure statements at global level
|
|
statements.retain(|stmt| !stmt.is_pure());
|
|
|
|
// Add back the last statement unless it is a lone No-op
|
|
if let Some(stmt) = last_stmt {
|
|
if !statements.is_empty() || !stmt.is_noop() {
|
|
statements.push(stmt);
|
|
}
|
|
}
|
|
|
|
statements.shrink_to_fit();
|
|
statements
|
|
}
|
|
|
|
/// Optimize an [`AST`].
|
|
pub fn optimize_into_ast(
|
|
engine: &Engine,
|
|
scope: &Scope,
|
|
mut 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(),
|
|
lib: None,
|
|
#[cfg(not(feature = "no_module"))]
|
|
mods: Default::default(),
|
|
comments: Default::default(),
|
|
})
|
|
.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_top_level(
|
|
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::Return((crate::ast::ReturnType::Return, _), Some(expr), _) => {
|
|
Stmt::Expr(expr)
|
|
}
|
|
// { return; } -> ()
|
|
Stmt::Return((crate::ast::ReturnType::Return, pos), None, _) => {
|
|
Stmt::Expr(Expr::Unit(pos))
|
|
}
|
|
// All others
|
|
stmt => stmt,
|
|
};
|
|
fn_def
|
|
})
|
|
.for_each(|fn_def| {
|
|
module.set_script_fn(fn_def);
|
|
});
|
|
} else {
|
|
_functions.into_iter().for_each(|fn_def| {
|
|
module.set_script_fn(fn_def);
|
|
});
|
|
}
|
|
|
|
module
|
|
};
|
|
|
|
#[cfg(feature = "no_function")]
|
|
let lib = Default::default();
|
|
|
|
statements.shrink_to_fit();
|
|
|
|
AST::new(
|
|
match level {
|
|
OptimizationLevel::None => statements,
|
|
OptimizationLevel::Simple | OptimizationLevel::Full => {
|
|
optimize_top_level(statements, engine, &scope, &[&lib], level)
|
|
}
|
|
},
|
|
lib,
|
|
)
|
|
}
|