add support for speculative loads

crates/cpu/tests/rename_execute_retire.rs

@@ -788,8 +788,7 @@ impl<'a, C: PhantomConstCpuConfig> MockNextPcState<'a, C> {
             return ty.new_sim(zeroed(MOpInstance[MOp]));
         }
         let peek_size = self.random_state.random_u64(u32::from_le_bytes(*b"pdoi")) as usize
-            % (16 * ty.capacity());
-        let peek_size = peek_size.min(ty.capacity());
+            % (ty.capacity() + 1);
         ty.from_iter_sim(
             zeroed(MOpInstance[MOp]),
             self.fetch_queue.iter().take(peek_size),