Add arm_cpu_features

Author: AntoinePrv

include/xsimd/config/xsimd_cpu_features_arm.hpp

@@ -0,0 +1,110 @@
+/***************************************************************************
+ * Copyright (c) Johan Mabille, Sylvain Corlay, Wolf Vollprecht and         *
+ * Martin Renou                                                             *
+ * Copyright (c) QuantStack                                                 *
+ * Copyright (c) Serge Guelton                                              *
+ *                                                                          *
+ * Distributed under the terms of the BSD 3-Clause License.                 *
+ *                                                                          *
+ * The full license is in the file LICENSE, distributed with this software. *
+ ***************************************************************************/
+
+#ifndef XSIMD_CPU_FEATURES_ARM_HPP
+#define XSIMD_CPU_FEATURES_ARM_HPP
+
+
+#include "./xsimd_config.hpp"
+
+#if XSIMD_WITH_LINUX_GETAUXVAL
+#include "./xsimd_getauxval.hpp"
+#endif
+
+namespace xsimd
+{
+    /**
+     * An opinionated CPU feature detection utility for ARM.
+     *
+     * Combines compile-time knowledge with runtime detection when available.
+     * On Linux, runtime detection uses getauxval to query the auxiliary vector.
+     * On other platforms, only compile-time information is used.
+     *
+     * This is well defined on all architectures. It will always return false on
+     * non-ARM architectures.
+     */
+    class arm_cpu_features
+    {
+    public:
+        arm_cpu_features() noexcept = default;
+
+        inline bool neon() const noexcept
+        {
+#if XSIMD_TARGET_ARM && !XSIMD_TARGET_ARM64 && XSIMD_WITH_LINUX_GETAUXVAL
+            return get_hwcap().all_bits_set<linux_hwcap_traits::aux::neon>();
+#else
+            return static_cast<bool>(XSIMD_WITH_NEON);
+#endif
+        }
+
+        constexpr bool neon64() const noexcept
+        {
+            return static_cast<bool>(XSIMD_WITH_NEON64);
+        }
+
+        inline bool sve() const noexcept
+        {
+#if XSIMD_TARGET_ARM64 && XSIMD_WITH_LINUX_GETAUXVAL
+            return get_hwcap().all_bits_set<linux_hwcap_traits::aux::sve>();
+#else
+            return false;
+#endif
+        }
+
+        inline bool i8mm() const noexcept
+        {
+#if XSIMD_TARGET_ARM64 && XSIMD_WITH_LINUX_GETAUXVAL
+            return get_hwcap2().all_bits_set<linux_hwcap2_traits::aux::i8mm>();
+#else
+            return false;
+#endif
+        }
+
+    private:
+#if XSIMD_TARGET_ARM && XSIMD_WITH_LINUX_GETAUXVAL
+        enum class status
+        {
+            hwcap_valid = 0,
+            hwcap2_valid = 1,
+        };
+
+        using status_bitset = utils::uint_bitset<status, std::uint32_t>;
+
+        mutable status_bitset m_status {};
+
+        mutable xsimd::linux_hwcap m_hwcap {};
+
+        inline xsimd::linux_hwcap const& get_hwcap() const noexcept
+        {
+            if (!m_status.bit_is_set<status::hwcap_valid>())
+            {
+                m_hwcap = xsimd::linux_hwcap::read();
+                m_status.set_bit<status::hwcap_valid>();
+            }
+            return m_hwcap;
+        }
+
+#if XSIMD_TARGET_ARM64
+        mutable xsimd::linux_hwcap2 m_hwcap2 {};
+        inline xsimd::linux_hwcap2 const& get_hwcap2() const noexcept
+        {
+            if (!m_status.bit_is_set<status::hwcap2_valid>())
+            {
+                m_hwcap2 = xsimd::linux_hwcap2::read();
+                m_status.set_bit<status::hwcap2_valid>();
+            }
+            return m_hwcap2;
+        }
+#endif
+#endif // XSIMD_TARGET_ARM && XSIMD_WITH_LINUX_GETAUXVAL
+    };
+}
+#endif