Skip to content

miri: fix exact_div #69126

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Feb 14, 2020
Merged

miri: fix exact_div #69126

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 4 additions & 2 deletions src/librustc_mir/interpret/intrinsics.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -410,8 +410,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
) -> InterpResult<'tcx> {
// Performs an exact division, resulting in undefined behavior where
// `x % y != 0` or `y == 0` or `x == T::min_value() && y == -1`.
// First, check x % y != 0.
if self.binary_op(BinOp::Rem, a, b)?.to_bits()? != 0 {
// First, check x % y != 0 (or if that computation overflows).
let (res, overflow, _ty) = self.overflowing_binary_op(BinOp::Rem, a, b)?;
if overflow || res.to_bits(a.layout.size)? != 0 {
// Then, check if `b` is -1, which is the "min_value / -1" case.
let minus1 = Scalar::from_int(-1, dest.layout.size);
let b_scalar = b.to_scalar().unwrap();
Expand All @@ -421,6 +422,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
throw_ub_format!("exact_div: {} cannot be divided by {} without remainder", a, b,)
}
}
// `Rem` says this is all right, so we can let `Div` do its job.
self.binop_ignore_overflow(BinOp::Div, a, b, dest)
}
}