Add absl::HwasanTagPointer() to allow users to change HWASAN tags

It's NOOP without HWASAN.

PiperOrigin-RevId: 543045322
Change-Id: Ibb5f28d316bfc5e8aa51861fd55e50ecb517a9a3

absl/base/dynamic_annotations.h

diff --git a/absl/base/dynamic_annotations.h b/absl/base/dynamic_annotations.h
index 3ea7c15..7ba8912 100644
--- a/absl/base/dynamic_annotations.h
+++ b/absl/base/dynamic_annotations.h
@@ -46,6 +46,7 @@
 #define ABSL_BASE_DYNAMIC_ANNOTATIONS_H_
 
 #include <stddef.h>
+#include <stdint.h>
 
 #include "absl/base/attributes.h"
 #include "absl/base/config.h"
@@ -53,6 +54,10 @@
 #include "absl/base/macros.h"
 #endif
 
+#ifdef ABSL_HAVE_HWADDRESS_SANITIZER
+#include <sanitizer/hwasan_interface.h>
+#endif
+
 // TODO(rogeeff): Remove after the backward compatibility period.
 #include "absl/base/internal/dynamic_annotations.h"  // IWYU pragma: export
 
@@ -111,7 +116,7 @@
 
 #if ABSL_INTERNAL_RACE_ANNOTATIONS_ENABLED == 1
 // Some of the symbols used in this section (e.g. AnnotateBenignRaceSized) are
-// defined by the compiler-based santizer implementation, not by the Abseil
+// defined by the compiler-based sanitizer implementation, not by the Abseil
 // library. Therefore they do not use ABSL_INTERNAL_C_SYMBOL.
 
 // -------------------------------------------------------------
@@ -457,6 +462,26 @@
 #endif  // ABSL_HAVE_ADDRESS_SANITIZER
 
 // -------------------------------------------------------------------------
+// HWAddress sanitizer annotations
+
+#ifdef __cplusplus
+namespace absl {
+#ifdef ABSL_HAVE_HWADDRESS_SANITIZER
+// Under HWASAN changes the tag of the pointer.
+template <typename T>
+T* HwasanTagPointer(T* ptr, uintptr_t tag) {
+  return reinterpret_cast<T*>(__hwasan_tag_pointer(ptr, tag));
+}
+#else
+template <typename T>
+T* HwasanTagPointer(T* ptr, uintptr_t) {
+  return ptr;
+}
+#endif
+}  // namespace absl
+#endif
+
+// -------------------------------------------------------------------------
 // Undefine the macros intended only for this file.
 
 #undef ABSL_INTERNAL_RACE_ANNOTATIONS_ENABLED