Add FileCheck to cycle.rs

Author: Shunpoco

tests/mir-opt/copy-prop/cycle.rs

@@ -1,4 +1,3 @@
-// skip-filecheck
 // EMIT_MIR_FOR_EACH_PANIC_STRATEGY
 //! Tests that cyclic assignments don't hang CopyProp, and result in reasonable code.
 //@ test-mir-pass: CopyProp
@@ -8,6 +7,18 @@ fn val() -> i32 {
 
 // EMIT_MIR cycle.main.CopyProp.diff
 fn main() {
+    // CHECK-LABEL: fn main(
+    // CHECK: debug x => [[x:_.*]];
+    // CHECK: debug y => [[y:_.*]];
+    // CHECK: debug z => [[y]];
+    // CHECK-NOT: StorageLive([[y]]);
+    // CHECK: [[y]] = copy [[x]];
+    // CHECK-NOT: StorageLive(_3);
+    // CHECK-NOT: _3 = copy [[y]];
+    // CHECK-NOT: StorageLive(_4);
+    // CHECK-NOT: _4 = copy _3;
+    // CHECK-NOT: _1 = move _4;
+    // CHECK: [[x]] = copy [[y]];
     let mut x = val();
     let y = x;
     let z = y;