Re-enable the early otherwise branch optimization

Author: dianqk

compiler/rustc_mir_transform/src/early_otherwise_branch.rs

@@ -96,8 +96,7 @@ pub struct EarlyOtherwiseBranch;
 
 impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
-        // unsound: https://github.com/rust-lang/rust/issues/95162
-        sess.mir_opt_level() >= 3 && sess.opts.unstable_opts.unsound_mir_opts
+        sess.mir_opt_level() >= 2
     }
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {

tests/codegen/enum/enum-early-otherwise-branch.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: -O -Zmir-opt-level=3 -Zunsound-mir-opts
+//@ compile-flags: -O
 
 #![crate_type = "lib"]