Revert "Auto merge of #115105 - cjgillot:dest-prop-default, r=oli-obk"

This reverts commit cfb730450f, reversing
changes made to 91c0823ee6.

compiler/rustc_mir_transform/src/dest_prop.rs

@@ -160,7 +160,7 @@ impl<'tcx> MirPass<'tcx> for DestinationPropagation {
         //  2. Despite being an overall perf improvement, this still causes a 30% regression in
         //     keccak. We can temporarily fix this by bounding function size, but in the long term
         //     we should fix this by being smarter about invalidating analysis results.
-        sess.mir_opt_level() >= 2
+        sess.mir_opt_level() >= 3
     }
 
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {