Merge pull request #21475 from charris/backport-21467

MAINT: Mark `npy_memchr` with `no_sanitize("alignment")` on clang

numpy/core/src/multiarray/common.h

@@ -248,6 +248,15 @@ npy_uint_alignment(int itemsize)
  * compared to memchr it returns one stride past end instead of NULL if needle
  * is not found.
  */
+#ifdef __clang__
+    /*
+     * The code below currently makes use of !NPY_ALIGNMENT_REQUIRED, which
+     * should be OK but causes the clang sanitizer to warn.  It may make
+     * sense to modify the code to avoid this "unaligned" access but
+     * it would be good to carefully check the performance changes.
+     */
+    __attribute__((no_sanitize("alignment")))
+#endif
 static NPY_INLINE char *
 npy_memchr(char * haystack, char needle,
            npy_intp stride, npy_intp size, npy_intp * psubloopsize, int invert)