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Fix bug in optimizer.

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This commit is contained in:
Stephen Chung 2021-01-12 23:52:50 +08:00
parent 8c47d61456
commit fe65bf6137
5 changed files with 64 additions and 21 deletions
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1
RELEASES.md
View File

@ -8,6 +8,7 @@ Bug fixes
---------
* Bug in `FileModuleResolver::clear_cache_for_path` path mapping fixed.
* Some optimizer fringe cases is fixed - related to constants propagation when the evil `eval` is present.
Breaking changes
----------------

2
src/ast.rs
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@ -1070,6 +1070,8 @@ pub struct CustomExpr {
pub keywords: StaticVec<Expr>,
/// List of tokens actually parsed.
pub tokens: Vec<ImmutableString>,
/// Delta number of variables in the scope.
pub scope_delta: isize,
}
impl fmt::Debug for CustomExpr {

71
src/optimize.rs
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@ -58,6 +58,8 @@ struct State<'a> {
changed: bool,
/// Collection of constants to use for eager function evaluations.
variables: Vec<(String, AccessMode, Expr)>,
/// Activate constants propagation?
propagate_constants: bool,
/// An [`Engine`] instance for eager function evaluation.
engine: &'a Engine,
/// Collection of sub-modules.
@ -75,6 +77,7 @@ impl<'a> State<'a> {
Self {
changed: false,
variables: vec![],
propagate_constants: true,
engine,
mods: (&engine.global_sub_modules).into(),
lib,
@ -109,6 +112,10 @@ impl<'a> State<'a> {
/// Look up a constant from the list.
#[inline]
pub fn find_constant(&self, name: &str) -> Option<&Expr> {
if !self.propagate_constants {
return None;
}
for (n, access, expr) in self.variables.iter().rev() {
if n == name {
return if access.is_read_only() {
@ -160,26 +167,37 @@ fn optimize_stmt_block(
) -> Stmt {
let orig_len = statements.len(); // Original number of statements in the block, for change detection
let orig_constants_len = state.variables.len(); // Original number of constants in the state, for restore later
let orig_propagate_constants = state.propagate_constants;
// Optimize each statement in the block
statements.iter_mut().for_each(|stmt| match stmt {
// Add constant literals into the state
Stmt::Const(var_def, Some(expr), _, _) if expr.is_constant() => {
state.push_var(&var_def.name, AccessMode::ReadOnly, mem::take(expr));
statements.iter_mut().for_each(|stmt| {
match stmt {
// Add constant literals into the state
Stmt::Const(var_def, Some(value_expr), _, _) => {
optimize_expr(value_expr, state);
if value_expr.is_constant() {
state.push_var(&var_def.name, AccessMode::ReadOnly, value_expr.clone());
}
}
Stmt::Const(var_def, None, _, _) => {
state.push_var(&var_def.name, AccessMode::ReadOnly, Expr::Unit(var_def.pos));
}
// Add variables into the state
Stmt::Let(var_def, expr, _, _) => {
if let Some(value_expr) = expr {
optimize_expr(value_expr, state);
}
state.push_var(
&var_def.name,
AccessMode::ReadWrite,
Expr::Unit(var_def.pos),
);
}
// Optimize the statement
_ => optimize_stmt(stmt, state, preserve_result),
}
Stmt::Const(var_def, None, _, _) => {
state.push_var(&var_def.name, AccessMode::ReadOnly, Expr::Unit(var_def.pos));
}
// Add variables into the state
Stmt::Let(var_def, _, _, _) => {
state.push_var(
&var_def.name,
AccessMode::ReadWrite,
Expr::Unit(var_def.pos),
);
}
// Optimize the statement
_ => optimize_stmt(stmt, state, preserve_result),
});
// Remove all raw expression statements that are pure except for the very last statement
@ -251,6 +269,8 @@ fn optimize_stmt_block(
// Pop the stack and remove all the local constants
state.restore_var(orig_constants_len);
state.propagate_constants = orig_propagate_constants;
match &statements[..] {
// No statements in block - change to No-op
[] => {
@ -637,6 +657,10 @@ fn optimize_expr(expr: &mut Expr, state: &mut State) {
(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));
@ -726,7 +750,12 @@ fn optimize_expr(expr: &mut Expr, state: &mut State) {
}
// Custom syntax
Expr::Custom(x, _) => x.keywords.iter_mut().for_each(|expr| optimize_expr(expr, state)),
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
_ => (),
@ -790,7 +819,11 @@ fn optimize_top_level(
Stmt::Const(var_def, None, _, _) => {
state.push_var(&var_def.name, AccessMode::ReadOnly, Expr::Unit(var_def.pos));
}
Stmt::Let(var_def, _, _, _) => {
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,

9
src/parser.rs
View File

@ -1995,7 +1995,14 @@ fn parse_custom_syntax(
}
}
Ok(Expr::Custom(Box::new(CustomExpr { keywords, tokens }), pos))
Ok(Expr::Custom(
Box::new(CustomExpr {
keywords,
tokens,
scope_delta: syntax.scope_delta,
}),
pos,
))
}
/// Parse an expression.

2
tests/optimizer.rs
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@ -55,7 +55,7 @@ fn test_optimizer_parse() -> Result<(), Box<EvalAltResult>> {
let ast = engine.compile("{ const DECISION = false; if DECISION { 42 } else { 123 } }")?;
assert!(format!("{:?}", ast).starts_with(r#"AST { source: None, statements: [Block([Const(Ident("DECISION" @ 1:9), Some(Unit(0:0)), false, 1:3), Expr(IntegerConstant(123, 1:53))], 1:1)]"#));
assert!(format!("{:?}", ast).starts_with(r#"AST { source: None, statements: [Block([Const(Ident("DECISION" @ 1:9), Some(BoolConstant(false, 1:20)), false, 1:3), Expr(IntegerConstant(123, 1:53))], 1:1)]"#));
let ast = engine.compile("if 1 == 2 { 42 }")?;