Disable non-required MIR opts with optimize(none)

Author: clubby789

compiler/rustc_attr/src/builtin.rs

@@ -63,6 +63,12 @@ pub enum OptimizeAttr {
     Size,
 }
 
+impl OptimizeAttr {
+    pub fn do_not_optimize(&self) -> bool {
+        matches!(self, Self::None)
+    }
+}
+
 /// Represents the following attributes:
 ///
 /// - `#[stable]`

compiler/rustc_mir_transform/src/abort_unwinding_calls.rs

@@ -116,4 +116,8 @@ impl<'tcx> crate::MirPass<'tcx> for AbortUnwindingCalls {
         // We may have invalidated some `cleanup` blocks so clean those up now.
         super::simplify::remove_dead_blocks(body);
     }
+
+    fn is_required(&self) -> bool {
+        true
+    }
 }