Unnamed repository; edit this file 'description' to name the repository.
Catch overflow in shift binop evaluation
| -rw-r--r-- | crates/hir-ty/src/consteval/tests.rs | 6 | ||||
| -rw-r--r-- | crates/hir-ty/src/mir/eval.rs | 41 |
2 files changed, 27 insertions, 20 deletions
diff --git a/crates/hir-ty/src/consteval/tests.rs b/crates/hir-ty/src/consteval/tests.rs index b700864f7d..5a850f6d57 100644 --- a/crates/hir-ty/src/consteval/tests.rs +++ b/crates/hir-ty/src/consteval/tests.rs @@ -97,8 +97,10 @@ fn bit_op() { check_number(r#"const GOAL: u8 = !0 & !(!0 >> 1)"#, 128); check_number(r#"const GOAL: i8 = !0 & !(!0 >> 1)"#, 0); check_number(r#"const GOAL: i8 = 1 << 7"#, (1i8 << 7) as i128); - // FIXME: report panic here - check_number(r#"const GOAL: i8 = 1 << 8"#, 0); + check_number(r#"const GOAL: i8 = -1 << 2"#, (-1i8 << 2) as i128); + check_fail(r#"const GOAL: i8 = 1 << 8"#, |e| { + e == ConstEvalError::MirEvalError(MirEvalError::Panic("Overflow in Shl".to_string())) + }); } #[test] diff --git a/crates/hir-ty/src/mir/eval.rs b/crates/hir-ty/src/mir/eval.rs index 9811cd9192..7ff68774bc 100644 --- a/crates/hir-ty/src/mir/eval.rs +++ b/crates/hir-ty/src/mir/eval.rs @@ -860,6 +860,16 @@ impl Evaluator<'_> { let is_signed = matches!(ty.as_builtin(), Some(BuiltinType::Int(_))); let l128 = i128::from_le_bytes(pad16(lc, is_signed)); let r128 = i128::from_le_bytes(pad16(rc, is_signed)); + let check_overflow = |r: i128| { + // FIXME: this is not very correct, and only catches the basic cases. + let r = r.to_le_bytes(); + for &k in &r[lc.len()..] { + if k != 0 && (k != 255 || !is_signed) { + return Err(MirEvalError::Panic(format!("Overflow in {op:?}"))); + } + } + Ok(Owned(r[0..lc.len()].into())) + }; match op { BinOp::Ge | BinOp::Gt | BinOp::Le | BinOp::Lt | BinOp::Eq | BinOp::Ne => { let r = op.run_compare(l128, r128) as u8; @@ -888,28 +898,23 @@ impl Evaluator<'_> { BinOp::BitXor => l128 ^ r128, _ => unreachable!(), }; - let r = r.to_le_bytes(); - for &k in &r[lc.len()..] { - if k != 0 && (k != 255 || !is_signed) { - return Err(MirEvalError::Panic(format!("Overflow in {op:?}"))); - } - } - Owned(r[0..lc.len()].into()) + check_overflow(r)? } BinOp::Shl | BinOp::Shr => { - let shift_amount = if r128 < 0 { - return Err(MirEvalError::Panic(format!("Overflow in {op:?}"))); - } else if r128 > 128 { + let r = 'b: { + if let Ok(shift_amount) = u32::try_from(r128) { + let r = match op { + BinOp::Shl => l128.checked_shl(shift_amount), + BinOp::Shr => l128.checked_shr(shift_amount), + _ => unreachable!(), + }; + if let Some(r) = r { + break 'b r; + } + }; return Err(MirEvalError::Panic(format!("Overflow in {op:?}"))); - } else { - r128 as u8 - }; - let r = match op { - BinOp::Shl => l128 << shift_amount, - BinOp::Shr => l128 >> shift_amount, - _ => unreachable!(), }; - Owned(r.to_le_bytes()[0..lc.len()].into()) + check_overflow(r)? } BinOp::Offset => not_supported!("offset binop"), } |