YJIT: code_gc(): Assert self is inline to avoid other_cb()

The derived `&mut` from `other_cb()` overlapped with the parameter
`ocb`.

Use `cfg!()` instead of `#[cfg...]` to avoid unused warnings.

Author: XrXr

yjit/src/asm/mod.rs

@@ -154,8 +154,9 @@ impl CodeBlock {
         }
 
         // Move the other CodeBlock to the same page if it's on the furthest page
-        #[cfg(not(test))]
-        self.other_cb().unwrap().set_page(next_page_idx.unwrap(), &jmp_ptr);
+        if cfg!(not(test)) {
+            self.other_cb().unwrap().set_page(next_page_idx.unwrap(), &jmp_ptr);
+        }
 
         return !self.dropped_bytes;
     }
@@ -584,6 +585,8 @@ impl CodeBlock {
 
     /// Code GC. Free code pages that are not on stack and reuse them.
     pub fn code_gc(&mut self, ocb: &mut OutlinedCb) {
+        assert!(self.inline(), "must use on inline code block");
+
         // The previous code GC failed to free any pages. Give up.
         if self.freed_pages.as_ref() == &Some(vec![]) {
             return;
@@ -641,7 +644,7 @@ impl CodeBlock {
         // Track which pages are free.
         let new_freed_pages = Rc::new(Some(freed_pages));
         let old_freed_pages = mem::replace(&mut self.freed_pages, Rc::clone(&new_freed_pages));
-        self.other_cb().unwrap().freed_pages = new_freed_pages;
+        ocb.unwrap().freed_pages = new_freed_pages;
         assert_eq!(1, Rc::strong_count(&old_freed_pages)); // will deallocate
 
         CodegenGlobals::incr_code_gc_count();