Acknowledge comments

tests/mir-opt/dest-prop/copy_propagation_arg.rs

@@ -30,7 +30,7 @@ fn bar(mut x: u8) {
 fn baz(mut x: i32) -> i32 {
     // CHECK-LABEL: fn baz(
     // CHECK: debug x => [[x:_.*]];
-    // CHECK-NOT: [[x]] = {{_.*}}
+    // CHECK-NOT: [[x]] =
     // self-assignment to a function argument should be eliminated
     x = x;
     x

tests/mir-opt/dest-prop/simple.rs

@@ -5,8 +5,11 @@
 fn nrvo(init: fn(&mut [u8; 1024])) -> [u8; 1024] {
     // CHECK-LABEL: fn nrvo(
     // CHECK: debug init => [[init:_.*]];
+    // CHECK: debug buf => [[buf:_.*]];
+    // CHECK: [[buf]] = [const 0_u8; 1024];
     // CHECK-NOT: {{_.*}} = [[init]];
     // CHECK: move [[init]](move {{_.*}})
+    // CHECK: {{_.*}} = [[buf]]
     let mut buf = [0; 1024];
     init(&mut buf);
     buf

tests/mir-opt/dest-prop/union.rs

@@ -8,6 +8,8 @@ fn val() -> u32 {
 
 // EMIT_MIR union.main.DestinationPropagation.diff
 fn main() {
+    // CHECK-LABEL: fn args(
+    // CHECK: {{_.*}} = Un { us: const 1_u32 };
     union Un {
         us: u32,
     }