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Optimize op-assignment statement.

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This commit is contained in:
Stephen Chung
2020-05-25 20:14:31 +08:00
parent fca140ef55
commit 95e67c48bd
11 changed files with 341 additions and 234 deletions
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18
src/optimize.rs
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@@ -380,26 +380,26 @@ fn optimize_expr<'a>(expr: Expr, state: &mut State<'a>) -> Expr {
stmt => Expr::Stmt(Box::new((stmt, x.1))),
},
// id = expr
Expr::Assignment(x) => match x.1 {
//id = id2 = expr2
Expr::Assignment(x2) => match (x.0, x2.0) {
// var = var = expr2 -> var = expr2
Expr::Assignment(x) => match x.2 {
//id = id2 op= expr2
Expr::Assignment(x2) if x.1 == "=" => match (x.0, x2.0) {
// var = var op= expr2 -> var op= expr2
(Expr::Variable(a), Expr::Variable(b))
if a.1.is_none() && b.1.is_none() && a.0 == b.0 && a.3 == b.3 =>
{
// Assignment to the same variable - fold
state.set_dirty();
Expr::Assignment(Box::new((Expr::Variable(a), optimize_expr(x2.1, state), x.2)))
Expr::Assignment(Box::new((Expr::Variable(a), x2.1, optimize_expr(x2.2, state), x.3)))
}
// id1 = id2 = expr2
// id1 = id2 op= expr2
(id1, id2) => {
Expr::Assignment(Box::new((
id1, Expr::Assignment(Box::new((id2, optimize_expr(x2.1, state), x2.2))), x.2,
id1, x.1, Expr::Assignment(Box::new((id2, x2.1, optimize_expr(x2.2, state), x2.3))), x.3,
)))
}
},
// id = expr
expr => Expr::Assignment(Box::new((x.0, optimize_expr(expr, state), x.2))),
// id op= expr
expr => Expr::Assignment(Box::new((x.0, x.1, optimize_expr(expr, state), x.3))),
},
// lhs.rhs