Add HAVE_AES and HAVE_F16C

libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_AES.h

@@ -0,0 +1,19 @@
+// HAVE_AES
+
+#undef HAVE_AES
+
+/* GCC, Clang: -maes
+ *
+ * MSVC: No controlling compiler option nor indicating macro. The
+ *       documentation murkily says it's always enabled on Intel and only
+ *       Intel processors; see:
+ *       https://docs.microsoft.com/en-us/cpp/intrinsics/x86-intrinsics-list
+ *       https://docs.microsoft.com/en-us/cpp/intrinsics/x64-amd64-intrinsics-list)
+ *
+ * The AES-NI instructions which are widely supported in CPUs (since 2009 for
+ * Intel; also `latest` ARM and SPARC processors) and most modern compilers
+ * (according to Wikipedia). First added to GCC 4.4.7 (2012).
+ */
+#ifdef __AES__
+#  define HAVE_AES 1
+#endif

libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_F16C.h

@@ -0,0 +1,18 @@
+// HAVE_F16C
+
+#undef HAVE_F16C
+
+/* GCC, Clang: -mf16c
+ *
+ * MSVC: No controlling compiler option nor indicating macro. The
+ *       documentation murkily says it's always enabled on Intel and only
+ *       Intel processors; see:
+ *       https://docs.microsoft.com/en-us/cpp/intrinsics/x86-intrinsics-list
+ *       https://docs.microsoft.com/en-us/cpp/intrinsics/x64-amd64-intrinsics-list)
+ *
+ * Supported since Intel's Ivy Bridge (2012) and AMD's Bulldozer (2011). Added
+ * to GCC 4.6.4 (2013) at the latest.
+ */
+#ifdef __F16C__
+#  define HAVE_F16C 1
+#endif

libbuild2-autoconf/libbuild2/autoconf/checks/HAVE_SSE4_2.h

@@ -6,6 +6,9 @@
  *
  * MSVC: /arch:{AVX,AVX2,AVX512}
  *
+ * Supported since Intel's Nehalem (2008), AMD's Bulldozer (2011), and GCC 4.3
+ * (2008).
+ *
  * This code is based on
  * https://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/global/qsimd.h.
  */