Add regression test for #130769

Author: jieyouxu

tests/ui/mir/early-otherwise-branch-ice.rs

@@ -0,0 +1,18 @@
+// Changes in https://github.com/rust-lang/rust/pull/129047 lead to several mir-opt ICE regressions,
+// this test is added to make sure this does not regress.
+
+//@ compile-flags: -C opt-level=3
+//@ check-pass
+
+#![crate_type = "lib"]
+
+use std::task::Poll;
+
+pub fn poll(val: Poll<Result<Option<Vec<u8>>, u8>>) {
+    match val {
+        Poll::Ready(Ok(Some(_trailers))) => {}
+        Poll::Ready(Err(_err)) => {}
+        Poll::Ready(Ok(None)) => {}
+        Poll::Pending => {}
+    }
+}