Rollup merge of #109234 - tmiasko:overflow-checks, r=cjgillot

Tweak implementation of overflow checking assertions

Extract and reuse logic controlling behaviour of overflow checking assertions instead of duplicating it three times.

r? `@cjgillot`

compiler/rustc_middle/src/mir/mod.rs

@@ -1268,6 +1268,13 @@ impl<'tcx> BasicBlockData<'tcx> {
 }
 
 impl<O> AssertKind<O> {
+    /// Returns true if this an overflow checking assertion controlled by -C overflow-checks.
+    pub fn is_optional_overflow_check(&self) -> bool {
+        use AssertKind::*;
+        use BinOp::*;
+        matches!(self, OverflowNeg(..) | Overflow(Add | Sub | Mul | Shl | Shr, ..))
+    }
+
     /// Getting a description does not require `O` to be printable, and does not
     /// require allocation.
     /// The caller is expected to handle `BoundsCheck` separately.
@@ -1992,16 +1999,6 @@ impl BorrowKind {
     }
 }
 
-impl BinOp {
-    /// The checkable operators are those whose overflow checking behavior is controlled by
-    /// -Coverflow-checks option. The remaining operators have either no overflow conditions (e.g.,
-    /// BitAnd, BitOr, BitXor) or are always checked for overflow (e.g., Div, Rem).
-    pub fn is_checkable(self) -> bool {
-        use self::BinOp::*;
-        matches!(self, Add | Sub | Mul | Shl | Shr)
-    }
-}
-
 impl<'tcx> Debug for Rvalue<'tcx> {
     fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result {
         use self::Rvalue::*;