Duckstation/src/common/intrin.h

// SPDX-FileCopyrightText: 2019-2023 Connor McLaughlin <stenzek@gmail.com>
// SPDX-License-Identifier: (GPL-3.0 OR CC-BY-NC-ND-4.0)

// Includes appropriate intrinsic header based on platform.

#pragma once

#include "types.h"

#include <type_traits>

#if defined(CPU_ARCH_X86) || defined(CPU_ARCH_X64)
#define CPU_ARCH_SSE 1
#include <emmintrin.h>
#elif defined(CPU_ARCH_ARM64)
#define CPU_ARCH_NEON 1
#if defined(_MSC_VER) && !defined(__clang__)
#include <arm64_neon.h>
#else
#include <arm_neon.h>
#endif
#endif

#ifdef __APPLE__
#include <stdlib.h> // alloca
#else
#include <malloc.h> // alloca
#endif

template<typename T>
static inline void MemsetPtrs(T* ptr, T value, u32 count)
{
  static_assert(std::is_pointer_v<T>, "T is pointer type");
  static_assert(sizeof(T) == sizeof(void*), "T isn't a fat pointer");
  T* dest = ptr;

#if defined(CPU_ARCH_SSE) || defined(CPU_ARCH_NEON)
  static constexpr u32 PTRS_PER_VECTOR = (16 / sizeof(T));
  const u32 aligned_count = count / PTRS_PER_VECTOR;
  const u32 remaining_count = count % PTRS_PER_VECTOR;

#if defined(CPU_ARCH_SSE)
  const __m128i svalue = _mm_set1_epi64x(reinterpret_cast<intptr_t>(value));
#elif defined(CPU_ARCH_NEON)
  const uint64x2_t svalue = vdupq_n_u64(reinterpret_cast<uintptr_t>(value));
#endif

  // Clang gets way too eager and tries to unroll these, emitting thousands of instructions.
#ifdef __clang__
#pragma clang loop unroll(disable)
#endif
  for (u32 i = 0; i < aligned_count; i++)
  {
#if defined(CPU_ARCH_SSE)
    _mm_store_si128(reinterpret_cast<__m128i*>(dest), svalue);
#elif defined(CPU_ARCH_NEON)
    vst1q_u64(reinterpret_cast<u64*>(dest), svalue);
#endif
    dest += PTRS_PER_VECTOR;
  }
#else
  const u32 remaining_count = count;
#endif

  for (u32 i = 0; i < remaining_count; i++)
    *(dest++) = value;
}