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protect agains division by zero in constant folding

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This commit is contained in:
Dennis Ranke
2021-10-24 22:56:10 +02:00
parent d4a5d62255
commit b8b0a21ef9
1 changed files with 19 additions and 4 deletions
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23
src/constfold.rs
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@@ -39,7 +39,10 @@ fn fold_expr(expr: &mut ast::Expression) {
use ast::BinOp::*;
match expr.expr {
ast::Expr::BinOp {
ref mut left, op, ref mut right, ..
ref mut left,
op,
ref mut right,
..
} => {
fold_expr(left);
fold_expr(right);
@@ -50,8 +53,20 @@ fn fold_expr(expr: &mut ast::Expression) {
Add => left.wrapping_add(right),
Sub => left.wrapping_sub(right),
Mul => left.wrapping_mul(right),
Div => left / right, // TODO: protect agains division by zero
Rem => left % right, // TODO: check correct behavior with negative operands
Div => {
if let Some(result) = left.checked_div(right) {
result
} else {
return;
}
}
Rem => {
if let Some(result) = left.checked_rem(right) {
result
} else {
return;
}
}
And => left & right,
Or => left | right,
Xor => left ^ right,
@@ -64,7 +79,7 @@ fn fold_expr(expr: &mut ast::Expression) {
};
expr.expr = ast::Expr::I32Const(result);
}
_ => ()
_ => (),
}
}
ast::Expr::I32Const(_) | ast::Expr::Variable { .. } => (),