xxhsum with auto-dispatch displays the locally detected vector extension

using command -V
ex: compiled as 64-bit x86 autoVec (AVX2 detected) little endian with GCC 13.3.0

Makefile

@@ -81,6 +81,7 @@ LIBXXH = libxxhash.$(SHARED_EXT_VER)
 XXHSUM_SRC_DIR = cli
 XXHSUM_SPLIT_SRCS = $(XXHSUM_SRC_DIR)/xxhsum.c \
                     $(XXHSUM_SRC_DIR)/xsum_os_specific.c \
+                    $(XXHSUM_SRC_DIR)/xsum_arch.c \
                     $(XXHSUM_SRC_DIR)/xsum_output.c \
                     $(XXHSUM_SRC_DIR)/xsum_sanity_check.c \
                     $(XXHSUM_SRC_DIR)/xsum_bench.c

cli/xsum_arch.c

@@ -0,0 +1,51 @@
+/*
+ * xxhsum - Command line interface for xxhash algorithms
+ * Copyright (C) 2013-2021 Yann Collet
+ *
+ * GPL v2 License
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * You can contact the author at:
+ *   - xxHash homepage: https://www.xxhash.com
+ *   - xxHash source repository: https://github.com/Cyan4973/xxHash
+ */
+
+#if ((defined(__x86_64__) || defined(_M_AMD64) || defined(_M_X64)) && !defined(_M_ARM64EC)) || defined(__i386__) || defined(_M_IX86) || defined(_M_IX86_FP)
+#if defined(XXHSUM_DISPATCH)
+
+#include "../xxh_x86dispatch.h"
+#define XXH_INLINE_ALL /* XXH_* vector types */
+#include "../xxhash.h"
+
+const char* XSUM_autox86(void)
+{
+    int vecVersion = XXH_featureTest();
+    switch(vecVersion) {
+        case XXH_SCALAR:
+            return "x86 autoVec (scalar: no vector extension detected)";
+        case XXH_SSE2:
+            return "x86 autoVec (SSE2 detected)";
+        case XXH_AVX2:
+            return "x86 autoVec (AVX2 detected)";
+        case XXH_AVX512:
+            return "x86 autoVec (AVX512 detected)";
+        default:;
+    }
+    return " autoVec (error detecting vector extension)";
+}
+
+#endif /* XXHSUM_DISPATCH */
+#endif /* x86 */

cli/xsum_arch.h

@@ -89,7 +89,8 @@
 /* Try to detect the architecture. */
 #if defined(XSUM_ARCH_X86)
 #  if defined(XXHSUM_DISPATCH)
-#    define XSUM_ARCH XSUM_ARCH_X86 " autoVec"
+     const char* XSUM_autox86(void);
+#    define XSUM_ARCH XSUM_autox86()
 #  elif defined(__AVX512F__)
 #    define XSUM_ARCH XSUM_ARCH_X86 " + AVX512"
 #  elif defined(__AVX2__)

xxh_x86dispatch.c

@@ -368,7 +368,7 @@ static xxh_u64 XXH_xgetbv(void)
  * @return The best @ref XXH_VECTOR implementation.
  * @see XXH_VECTOR_TYPES
  */
-static int XXH_featureTest(void)
+int XXH_featureTest(void)
 {
     xxh_u32 abcd[4];
     xxh_u32 max_leaves;

xxh_x86dispatch.h

@@ -41,6 +41,14 @@
 extern "C" {
 #endif
 
+/*!
+ * @brief Returns the best XXH3 implementation for x86
+ *
+ * @return The best @ref XXH_VECTOR implementation.
+ * @see XXH_VECTOR_TYPES
+ */
+XXH_PUBLIC_API int XXH_featureTest(void);
+
 XXH_PUBLIC_API XXH64_hash_t  XXH3_64bits_dispatch(XXH_NOESCAPE const void* input, size_t len);
 XXH_PUBLIC_API XXH64_hash_t  XXH3_64bits_withSeed_dispatch(XXH_NOESCAPE const void* input, size_t len, XXH64_hash_t seed);
 XXH_PUBLIC_API XXH64_hash_t  XXH3_64bits_withSecret_dispatch(XXH_NOESCAPE const void* input, size_t len, XXH_NOESCAPE const void* secret, size_t secretLen);