+ * Inline functions or macros to extract possibly-unaligned big-endian
+ * integral values.
+ */
+#include "funcattrs.h"
+
+/*
+ * If we have versions of GCC or Clang that support an __attribute__
+ * to say "if we're building with unsigned behavior sanitization,
+ * don't complain about undefined behavior in this function", we
+ * label these functions with that attribute - we *know* it's undefined
+ * in the C standard, but we *also* know it does what we want with
+ * the ISA we're targeting and the compiler we're using.
+ *
+ * For GCC 4.9.0 and later, we use __attribute__((no_sanitize_undefined));
+ * pre-5.0 GCC doesn't have __has_attribute, and I'm not sure whether
+ * GCC or Clang first had __attribute__((no_sanitize(XXX)).
+ *
+ * For Clang, we check for __attribute__((no_sanitize(XXX)) with
+ * __has_attribute, as there are versions of Clang that support
+ * __attribute__((no_sanitize("undefined")) but don't support
+ * __attribute__((no_sanitize_undefined)).
+ *
+ * We define this here, rather than in funcattrs.h, because we
+ * only want it used here, we don't want it to be broadly used.
+ * (Any printer will get this defined, but this should at least
+ * make it harder for people to find.)
+ */
+#if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 409)
+#define UNALIGNED_OK __attribute__((no_sanitize_undefined))
+#elif __has_attribute(no_sanitize)
+#define UNALIGNED_OK __attribute__((no_sanitize("undefined")))
+#else
+#define UNALIGNED_OK
+#endif
+
+#if (defined(__i386__) || defined(_M_IX86) || defined(__X86__) || defined(__x86_64__) || defined(_M_X64)) || \
+ (defined(__arm__) || defined(_M_ARM) || defined(__aarch64__)) || \
+ (defined(__m68k__) && (!defined(__mc68000__) && !defined(__mc68010__))) || \
+ (defined(__ppc__) || defined(__ppc64__) || defined(_M_PPC) || defined(_ARCH_PPC) || defined(_ARCH_PPC64)) || \
+ (defined(__s390__) || defined(__s390x__) || defined(__zarch__))
+/*
+ * The processor natively handles unaligned loads, so we can just
+ * cast the pointer and fetch through it.
+ *
+ * XXX - are those all the x86 tests we need?
+ * XXX - do we need to worry about ARMv1 through ARMv5, which didn't
+ * support unaligned loads, and, if so, do we need to worry about all
+ * of them, or just some of them, e.g. ARMv5?
+ * XXX - are those the only 68k tests we need not to generated
+ * unaligned accesses if the target is the 68000 or 68010?
+ * XXX - are there any tests we don't need, because some definitions are for
+ * compilers that also predefine the GCC symbols?
+ * XXX - do we need to test for both 32-bit and 64-bit versions of those
+ * architectures in all cases?