Index: lib/sanitizer_common/sanitizer_platform_limits_posix.h
===================================================================
--- lib/sanitizer_common/sanitizer_platform_limits_posix.h
+++ lib/sanitizer_common/sanitizer_platform_limits_posix.h
@@ -635,9 +635,12 @@
 #ifndef __mips__
 #if defined(__sparc__)
 #if __GLIBC_PREREQ (2, 20)
-    // On sparc glibc 2.19 and earlier sa_flags was unsigned long, and
-    // __glibc_reserved0 didn't exist.
+    // On sparc glibc 2.19 and earlier sa_flags was unsigned long.
+#if defined(__arch64__)
+    // To maintain ABI compatibility on sparc64 when switching to an int,
+    // __glibc_reserved0 was added.
     int __glibc_reserved0;
+#endif
     int sa_flags;
 #else
     unsigned long sa_flags;