Add a test for simple matches

src/test/mir-opt/simple-match.rs

@@ -0,0 +1,39 @@
+// Test that we don't generate unnecessarily large MIR for very simple matches
+
+fn match_bool(x: bool) -> usize {
+    match x {
+        true => 10,
+        _ => 20,
+    }
+}
+
+fn main() {}
+
+
+// END RUST SOURCE
+// START rustc.match_bool.mir_map.0.mir
+// bb0: {
+//     FakeRead(ForMatchedPlace, _1);
+//     switchInt(_1) -> [false: bb3, otherwise: bb2];
+// }
+// bb1 (cleanup): {
+//     resume;
+// }
+// bb2: {
+//     falseEdges -> [real: bb4, imaginary: bb3];
+// }
+// bb3: {
+//     _0 = const 20usize;
+//     goto -> bb5;
+// }
+// bb4: {
+//     _0 = const 10usize;
+//     goto -> bb5;
+// }
+// bb5: {
+//     goto -> bb6;
+// }
+// bb6: {
+//     return;
+// }
+// END rustc.match_bool.mir_map.0.mir