commit aad15c0e5b202d8223d075540ab157c5eece39c3
author Evan Brown <ezb@google.com> Wed Jul 02 09:39:21 2025 -0700
committer Copybara-Service <copybara-worker@google.com> Wed Jul 02 09:40:09 2025 -0700
tree 99a428ddcc8b016065099110e5911fadbc7bae5f
parent ddbb5170bb81762bca5493b1dda9160d76b5887b

Assume that control bytes don't alias CommonFields.

PiperOrigin-RevId: 778538667
Change-Id: Ibcd7433923f88726cc83afd9bf09604bf3979eeb

absl/container/internal/raw_hash_set.h

diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 5f5a1d9..3e764a5 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -964,7 +964,14 @@
 
   ctrl_t* control() const {
     ABSL_SWISSTABLE_ASSERT(capacity() > 0);
-    ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(heap_or_soo_.control().get());
+    // Assume that the control bytes don't alias `this`.
+    ctrl_t* ctrl = heap_or_soo_.control().get();
+    [[maybe_unused]] size_t num_control_bytes = NumControlBytes(capacity());
+    ABSL_ASSUME(reinterpret_cast<uintptr_t>(ctrl + num_control_bytes) <=
+                    reinterpret_cast<uintptr_t>(this) ||
+                reinterpret_cast<uintptr_t>(this + 1) <=
+                    reinterpret_cast<uintptr_t>(ctrl));
+    ABSL_SWISSTABLE_IGNORE_UNINITIALIZED_RETURN(ctrl);
   }
 
   void set_control(ctrl_t* c) { heap_or_soo_.control().set(c); }