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Fix optimizer constants propagation bug.

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This commit is contained in:
Stephen Chung
2023-04-24 12:17:23 +08:00
parent e28bdd5b17
commit 1a61ed167c
4 changed files with 68 additions and 59 deletions
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1
CHANGELOG.md
View File

@@ -13,6 +13,7 @@ Bug fixes
* Re-optimizing an AST via `optimize_ast` with constants now works correctly for closures. Previously the hidden `Share` nodes are not removed and causes variable-not-found errors during runtime if the constants are not available in the scope.
* Expressions such as `(v[0].func()).prop` now parse correctly.
* Shadowed variable exports are now handled correctly.
* Shadowed constant definitions are now optimized correctly when propagated (e.g. `const X = 1; const X = 1 + 1 + 1; X` now evaluates to 3 instead of 0).
New features
------------

99
src/optimizer.rs
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@@ -14,10 +14,12 @@ use crate::func::builtin::get_builtin_binary_op_fn;
use crate::func::hashing::get_hasher;
use crate::module::ModuleFlags;
use crate::tokenizer::Token;
use crate::types::scope::SCOPE_ENTRIES_INLINED;
use crate::{
calc_fn_hash, calc_fn_hash_full, Dynamic, Engine, FnPtr, ImmutableString, Position, Scope,
StaticVec, AST,
calc_fn_hash, calc_fn_hash_full, Dynamic, Engine, FnArgsVec, FnPtr, ImmutableString, Position,
Scope, AST,
};
use smallvec::SmallVec;
#[cfg(feature = "no_std")]
use std::prelude::v1::*;
use std::{
@@ -52,12 +54,12 @@ impl Default for OptimizationLevel {
#[derive(Debug, Clone)]
struct OptimizerState<'a> {
/// Has the [`AST`] been changed during this pass?
changed: bool,
/// Collection of variables/constants to use for eager function evaluations.
variables: StaticVec<(ImmutableString, Option<Dynamic>)>,
is_dirty: bool,
/// Stack of variables/constants for constants propagation.
variables: SmallVec<[(ImmutableString, Option<Dynamic>); SCOPE_ENTRIES_INLINED]>,
/// Activate constants propagation?
propagate_constants: bool,
/// An [`Engine`] instance for eager function evaluation.
/// [`Engine`] instance for eager function evaluation.
engine: &'a Engine,
/// The global runtime state.
global: GlobalRuntimeState,
@@ -84,8 +86,8 @@ impl<'a> OptimizerState<'a> {
}
Self {
changed: false,
variables: StaticVec::new_const(),
is_dirty: false,
variables: SmallVec::new_const(),
propagate_constants: true,
engine,
global: _global,
@@ -96,48 +98,42 @@ impl<'a> OptimizerState<'a> {
/// Set the [`AST`] state to be dirty (i.e. changed).
#[inline(always)]
pub fn set_dirty(&mut self) {
self.changed = true;
self.is_dirty = true;
}
/// Set the [`AST`] state to be not dirty (i.e. unchanged).
#[inline(always)]
pub fn clear_dirty(&mut self) {
self.changed = false;
self.is_dirty = false;
}
/// Is the [`AST`] dirty (i.e. changed)?
#[inline(always)]
pub const fn is_dirty(&self) -> bool {
self.changed
self.is_dirty
}
/// Prune the list of constants back to a specified size.
/// Rewind the variables stack back to a specified size.
#[inline(always)]
pub fn restore_var(&mut self, len: usize) {
pub fn rewind_var(&mut self, len: usize) {
self.variables.truncate(len);
}
/// Add a new variable to the list.
/// Add a new variable to the stack.
///
/// `Some(value)` if constant, `None` or otherwise.
/// `Some(value)` if literal constant (which can be used for constants propagation), `None` otherwise.
#[inline(always)]
pub fn push_var(&mut self, name: ImmutableString, value: Option<Dynamic>) {
self.variables.push((name, value));
}
/// Look up a constant from the list.
/// Look up a literal constant from the variables stack.
#[inline]
pub fn find_constant(&self, name: &str) -> Option<&Dynamic> {
if !self.propagate_constants {
return None;
}
for (n, value) in self.variables.iter().rev() {
if n.as_str() == name {
return value.as_ref();
}
}
None
pub fn find_literal_constant(&self, name: &str) -> Option<&Dynamic> {
self.variables
.iter()
.rev()
.find(|(n, _)| n.as_str() == name)
.and_then(|(_, value)| value.as_ref())
}
/// Call a registered function
#[inline]
pub fn call_fn_with_constant_arguments(
pub fn call_fn_with_const_args(
&mut self,
fn_name: &str,
op_token: Option<&Token>,
@@ -150,7 +146,7 @@ impl<'a> OptimizerState<'a> {
fn_name,
op_token,
calc_fn_hash(None, fn_name, arg_values.len()),
&mut arg_values.iter_mut().collect::<StaticVec<_>>(),
&mut arg_values.iter_mut().collect::<FnArgsVec<_>>(),
false,
Position::NONE,
)
@@ -225,19 +221,16 @@ fn optimize_stmt_block(
statements.iter_mut().for_each(|stmt| {
match stmt {
Stmt::Var(x, options, ..) => {
if options.contains(ASTFlags::CONSTANT) {
// Add constant literals into the state
optimize_expr(&mut x.1, state, false);
if x.1.is_constant() {
state
.push_var(x.0.name.clone(), Some(x.1.get_literal_value().unwrap()));
}
let value = if options.contains(ASTFlags::CONSTANT) && x.1.is_constant() {
// constant literal
Some(x.1.get_literal_value().unwrap())
} else {
// Add variables into the state
optimize_expr(&mut x.1, state, false);
state.push_var(x.0.name.clone(), None);
}
// variable
None
};
state.push_var(x.0.name.clone(), value);
}
// Optimize the statement
_ => optimize_stmt(stmt, state, preserve_result),
@@ -371,7 +364,7 @@ fn optimize_stmt_block(
}
// Pop the stack and remove all the local constants
state.restore_var(orig_constants_len);
state.rewind_var(orig_constants_len);
state.propagate_constants = orig_propagate_constants;
if !state.is_dirty() {
@@ -845,12 +838,16 @@ fn optimize_stmt(stmt: &mut Stmt, state: &mut OptimizerState, preserve_result: b
// Share constants
#[cfg(not(feature = "no_closure"))]
Stmt::Share(x) => {
let len = x.len();
x.retain(|(v, _)| !state.find_constant(v).is_some());
if x.len() != len {
let orig_len = x.len();
if state.propagate_constants {
x.retain(|(v, _)| state.find_literal_constant(v).is_none());
if x.len() != orig_len {
state.set_dirty();
}
}
}
// All other statements - skip
_ => (),
@@ -1141,8 +1138,8 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, _chaining: bool) {
&& state.optimization_level == OptimizationLevel::Simple // simple optimizations
&& x.constant_args() // all arguments are constants
=> {
let arg_values = &mut x.args.iter().map(|arg_expr| arg_expr.get_literal_value().unwrap()).collect::<StaticVec<_>>();
let arg_types: StaticVec<_> = arg_values.iter().map(Dynamic::type_id).collect();
let arg_values = &mut x.args.iter().map(|arg_expr| arg_expr.get_literal_value().unwrap()).collect::<FnArgsVec<_>>();
let arg_types = arg_values.iter().map(Dynamic::type_id).collect::<FnArgsVec<_>>();
match x.name.as_str() {
KEYWORD_TYPE_OF if arg_values.len() == 1 => {
@@ -1204,13 +1201,13 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, _chaining: bool) {
let has_script_fn = false;
if !has_script_fn {
let arg_values = &mut x.args.iter().map(Expr::get_literal_value).collect::<Option<StaticVec<_>>>().unwrap();
let arg_values = &mut x.args.iter().map(Expr::get_literal_value).collect::<Option<FnArgsVec<_>>>().unwrap();
let result = match x.name.as_str() {
KEYWORD_TYPE_OF if arg_values.len() == 1 => Some(state.engine.map_type_name(arg_values[0].type_name()).into()),
#[cfg(not(feature = "no_closure"))]
crate::engine::KEYWORD_IS_SHARED if arg_values.len() == 1 => Some(Dynamic::FALSE),
_ => state.call_fn_with_constant_arguments(&x.name, x.op_token.as_ref(), arg_values)
_ => state.call_fn_with_const_args(&x.name, x.op_token.as_ref(), arg_values)
};
if let Some(r) = result {
@@ -1246,9 +1243,9 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, _chaining: bool) {
// constant-name
#[cfg(not(feature = "no_module"))]
Expr::Variable(x, ..) if !x.1.is_empty() => (),
Expr::Variable(x, .., pos) if state.find_constant(&x.3).is_some() => {
Expr::Variable(x, .., pos) if state.propagate_constants && state.find_literal_constant(&x.3).is_some() => {
// Replace constant with value
*expr = Expr::from_dynamic(state.find_constant(&x.3).unwrap().clone(), *pos);
*expr = Expr::from_dynamic(state.find_literal_constant(&x.3).unwrap().clone(), *pos);
state.set_dirty();
}
@@ -1341,7 +1338,7 @@ impl Engine {
&self,
scope: Option<&Scope>,
statements: StmtBlockContainer,
#[cfg(not(feature = "no_function"))] functions: StaticVec<
#[cfg(not(feature = "no_function"))] functions: crate::StaticVec<
crate::Shared<crate::ast::ScriptFnDef>,
>,
optimization_level: OptimizationLevel,

2
src/types/scope.rs
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@@ -12,7 +12,7 @@ use std::{
};
/// Keep a number of entries inline (since [`Dynamic`] is usually small enough).
const SCOPE_ENTRIES_INLINED: usize = 8;
pub const SCOPE_ENTRIES_INLINED: usize = 8;
/// Type containing information about the current scope. Useful for keeping state between
/// [`Engine`][crate::Engine] evaluation runs.

21
tests/optimizer.rs
View File

@@ -5,15 +5,14 @@ use rhai::{Engine, EvalAltResult, Module, OptimizationLevel, Scope, INT};
#[test]
fn test_optimizer() -> Result<(), Box<EvalAltResult>> {
let mut engine = Engine::new();
engine.set_optimization_level(OptimizationLevel::Full);
engine.set_optimization_level(OptimizationLevel::Simple);
#[cfg(not(feature = "no_function"))]
assert_eq!(
engine.eval::<INT>(
"
fn foo(x) { print(x); return; }
fn foo2(x) { if x > 0 {} return; }
42
const X = 0;
const X = 40 + 2 - 1 + 1;
X
"
)?,
42
@@ -202,6 +201,18 @@ fn test_optimizer_full() -> Result<(), Box<EvalAltResult>> {
engine.set_optimization_level(OptimizationLevel::Full);
#[cfg(not(feature = "no_function"))]
assert_eq!(
engine.eval::<INT>(
"
fn foo(x) { print(x); return; }
fn foo2(x) { if x > 0 {} return; }
42
"
)?,
42
);
engine
.register_type_with_name::<TestStruct>("TestStruct")
.register_fn("ts", |n: INT| TestStruct(n))