fixup! clearer reasoning

Author: tesuji

compiler/rustc_mir_transform/src/gvn.rs

@@ -1410,10 +1410,10 @@ impl<'tcx> MutVisitor<'tcx> for VnState<'_, 'tcx> {
                 return;
             }
 
-            let value = match lhs.as_local() {
-                Some(local) => self.locals[local],
-                None => self.simplify_rvalue(rvalue, location),
-            };
+            let value = lhs
+                .as_local()
+                .and_then(|local| self.locals[local])
+                .or_else(|| self.simplify_rvalue(rvalue, location));
             debug!(?value);
             let Some(value) = value else { return };