+check_c_source_runs("
+ #ifdef _MSC_VER
+ # include <intrin.h>
+ #else
+ # include <x86intrin.h>
+ #endif
+ int main(void) {
+ unsigned long long x = -1, y = 1, r;
+ unsigned char cf;
+ cf = _addcarry_u64(1, x, y, &r);
+ return !(cf == 1 && r == 1);
+ }
+ " ADDCARRY_U64)
+if (ADDCARRY_U64)
+ add_definitions(-DHAVE_ADDCARRY_U64)
+endif()
+
+check_c_source_runs("
+ int main(void) {
+ char buf[16] = { 0, 1, 2 };
+ int *p = (int *)(buf + 1);
+ int *q = (int *)(buf + 2);
+ return (*p == *q);
+ }
+ " RELAXED_ALIGNMENT)
+if (NOT RELAXED_ALIGNMENT)
+ add_definitions(-DSTRICT_ALIGNMENT)
+endif()
+