Subzero. Native 64-bit int arithmetic on x86-64.

crosstest/mem_intrin.h

 /*
  * Simple sanity test of memcpy, memmove, and memset intrinsics.
  * (fixed length buffers, variable length buffers, etc.).
  * There is no include guard since this will be included multiple times,
  * under different namespaces.
  */
+#include "xdefs.h"
 
-int memcpy_test(uint8_t *buf, uint8_t *buf2, uint8_t init, size_t length);
-int memmove_test(uint8_t *buf, uint8_t *buf2, uint8_t init, size_t length);
-int memset_test(uint8_t *buf, uint8_t *buf2, uint8_t init, size_t length);
+int memcpy_test(uint8_t *buf, uint8_t *buf2, uint8_t init, SizeT length);
+int memmove_test(uint8_t *buf, uint8_t *buf2, uint8_t init, SizeT length);
+int memset_test(uint8_t *buf, uint8_t *buf2, uint8_t init, SizeT length);
 
 int memcpy_test_fixed_len(uint8_t init);
 int memmove_test_fixed_len(uint8_t init);
 int memset_test_fixed_len(uint8_t init);