Dolphin/Source/Core/VideoCommon/VertexLoaderARM64.cpp

// Copyright 2015 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#include "VideoCommon/VertexLoaderARM64.h"

#include <array>

#include "Common/CommonTypes.h"
#include "VideoCommon/CPMemory.h"
#include "VideoCommon/VertexLoaderManager.h"

using namespace Arm64Gen;

constexpr ARM64Reg src_reg = ARM64Reg::X0;
constexpr ARM64Reg dst_reg = ARM64Reg::X1;
constexpr ARM64Reg remaining_reg = ARM64Reg::W2;
constexpr ARM64Reg skipped_reg = ARM64Reg::W17;
constexpr ARM64Reg scratch1_reg = ARM64Reg::W16;
constexpr ARM64Reg scratch2_reg = ARM64Reg::W15;
constexpr ARM64Reg scratch3_reg = ARM64Reg::W14;
constexpr ARM64Reg saved_count = ARM64Reg::W12;

constexpr ARM64Reg stride_reg = ARM64Reg::X11;
constexpr ARM64Reg arraybase_reg = ARM64Reg::X10;
constexpr ARM64Reg scale_reg = ARM64Reg::X9;

static constexpr int GetLoadSize(int load_bytes)
{
  if (load_bytes == 1)
    return 1;
  else if (load_bytes <= 2)
    return 2;
  else if (load_bytes <= 4)
    return 4;
  else if (load_bytes <= 8)
    return 8;
  else
    return 16;
}

alignas(16) static const float scale_factors[] = {
    1.0 / (1ULL << 0),  1.0 / (1ULL << 1),  1.0 / (1ULL << 2),  1.0 / (1ULL << 3),
    1.0 / (1ULL << 4),  1.0 / (1ULL << 5),  1.0 / (1ULL << 6),  1.0 / (1ULL << 7),
    1.0 / (1ULL << 8),  1.0 / (1ULL << 9),  1.0 / (1ULL << 10), 1.0 / (1ULL << 11),
    1.0 / (1ULL << 12), 1.0 / (1ULL << 13), 1.0 / (1ULL << 14), 1.0 / (1ULL << 15),
    1.0 / (1ULL << 16), 1.0 / (1ULL << 17), 1.0 / (1ULL << 18), 1.0 / (1ULL << 19),
    1.0 / (1ULL << 20), 1.0 / (1ULL << 21), 1.0 / (1ULL << 22), 1.0 / (1ULL << 23),
    1.0 / (1ULL << 24), 1.0 / (1ULL << 25), 1.0 / (1ULL << 26), 1.0 / (1ULL << 27),
    1.0 / (1ULL << 28), 1.0 / (1ULL << 29), 1.0 / (1ULL << 30), 1.0 / (1ULL << 31),
};

VertexLoaderARM64::VertexLoaderARM64(const TVtxDesc& vtx_desc, const VAT& vtx_att)
    : VertexLoaderBase(vtx_desc, vtx_att), m_float_emit(this)
{
  AllocCodeSpace(4096);
  const Common::ScopedJITPageWriteAndNoExecute enable_jit_page_writes;
  ClearCodeSpace();
  GenerateVertexLoader();
  WriteProtect(true);
}

// Returns the register to use as the base and an offset from that register.
// For indexed attributes, the index is read into scratch1_reg, and then scratch1_reg with no offset
// is returned. For direct attributes, an offset from src_reg is returned.
std::pair<Arm64Gen::ARM64Reg, u32> VertexLoaderARM64::GetVertexAddr(CPArray array,
                                                                    VertexComponentFormat attribute)
{
  if (IsIndexed(attribute))
  {
    if (attribute == VertexComponentFormat::Index8)
    {
      LDURB(scratch1_reg, src_reg, m_src_ofs);
      m_src_ofs += 1;
    }
    else  // Index16
    {
      LDURH(scratch1_reg, src_reg, m_src_ofs);
      m_src_ofs += 2;
      REV16(scratch1_reg, scratch1_reg);
    }

    if (array == CPArray::Position)
    {
      EOR(scratch2_reg, scratch1_reg,
          attribute == VertexComponentFormat::Index8 ? LogicalImm(0xFF, GPRSize::B32) :
                                                       LogicalImm(0xFFFF, GPRSize::B32));
      m_skip_vertex = CBZ(scratch2_reg);
    }

    LDR(IndexType::Unsigned, scratch2_reg, stride_reg, static_cast<u8>(array) * 4);
    MUL(scratch1_reg, scratch1_reg, scratch2_reg);

    LDR(IndexType::Unsigned, EncodeRegTo64(scratch2_reg), arraybase_reg,
        static_cast<u8>(array) * 8);
    ADD(EncodeRegTo64(scratch1_reg), EncodeRegTo64(scratch1_reg), EncodeRegTo64(scratch2_reg));
    return {EncodeRegTo64(scratch1_reg), 0};
  }
  else
  {
    return {src_reg, m_src_ofs};
  }
}

void VertexLoaderARM64::ReadVertex(VertexComponentFormat attribute, ComponentFormat format,
                                   int count_in, int count_out, bool dequantize,
                                   u8 scaling_exponent, AttributeFormat* native_format,
                                   ARM64Reg reg, u32 offset)
{
  ARM64Reg coords = count_in == 3 ? ARM64Reg::Q31 : ARM64Reg::D31;
  ARM64Reg scale = count_in == 3 ? ARM64Reg::Q30 : ARM64Reg::D30;

  int elem_size = GetElementSize(format);
  int load_bytes = elem_size * count_in;
  int load_size = GetLoadSize(load_bytes);
  load_size <<= 3;

  m_float_emit.LDUR(load_size, coords, reg, offset);

  if (format < ComponentFormat::Float)
  {
    // Extend and convert to float
    switch (format)
    {
    case ComponentFormat::UByte:
      m_float_emit.UXTL(8, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      m_float_emit.UXTL(16, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      break;
    case ComponentFormat::Byte:
      m_float_emit.SXTL(8, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      m_float_emit.SXTL(16, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      break;
    case ComponentFormat::UShort:
      m_float_emit.REV16(8, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      m_float_emit.UXTL(16, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      break;
    case ComponentFormat::Short:
      m_float_emit.REV16(8, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      m_float_emit.SXTL(16, EncodeRegToDouble(coords), EncodeRegToDouble(coords));
      break;
    }

    m_float_emit.SCVTF(32, coords, coords);

    if (dequantize && scaling_exponent)
    {
      m_float_emit.LDR(32, IndexType::Unsigned, scale, scale_reg, scaling_exponent * 4);
      m_float_emit.FMUL(32, coords, coords, scale, 0);
    }
  }
  else
  {
    m_float_emit.REV32(8, coords, coords);
  }

  const u32 write_size = count_out == 3 ? 128 : count_out * 32;
  m_float_emit.STUR(write_size, coords, dst_reg, m_dst_ofs);

  // Z-Freeze
  if (native_format == &m_native_vtx_decl.position)
  {
    CMP(remaining_reg, 3);
    FixupBranch dont_store = B(CC_GE);
    MOVP2R(EncodeRegTo64(scratch2_reg), VertexLoaderManager::position_cache.data());
    m_float_emit.STR(128, coords, EncodeRegTo64(scratch2_reg), ArithOption(remaining_reg, true));
    SetJumpTarget(dont_store);
  }
  else if (native_format == &m_native_vtx_decl.normals[0])
  {
    FixupBranch dont_store = CBNZ(remaining_reg);
    MOVP2R(EncodeRegTo64(scratch2_reg), VertexLoaderManager::normal_cache.data());
    m_float_emit.STR(128, IndexType::Unsigned, coords, EncodeRegTo64(scratch2_reg), 0);
    SetJumpTarget(dont_store);
  }
  else if (native_format == &m_native_vtx_decl.normals[1])
  {
    FixupBranch dont_store = CBNZ(remaining_reg);
    MOVP2R(EncodeRegTo64(scratch2_reg), VertexLoaderManager::tangent_cache.data());
    m_float_emit.STR(128, IndexType::Unsigned, coords, EncodeRegTo64(scratch2_reg), 0);
    SetJumpTarget(dont_store);
  }
  else if (native_format == &m_native_vtx_decl.normals[2])
  {
    FixupBranch dont_store = CBNZ(remaining_reg);
    MOVP2R(EncodeRegTo64(scratch2_reg), VertexLoaderManager::binormal_cache.data());
    m_float_emit.STR(128, IndexType::Unsigned, coords, EncodeRegTo64(scratch2_reg), 0);
    SetJumpTarget(dont_store);
  }

  native_format->components = count_out;
  native_format->enable = true;
  native_format->offset = m_dst_ofs;
  native_format->type = ComponentFormat::Float;
  native_format->integer = false;
  m_dst_ofs += sizeof(float) * count_out;

  if (attribute == VertexComponentFormat::Direct)
    m_src_ofs += load_bytes;
}

void VertexLoaderARM64::ReadColor(VertexComponentFormat attribute, ColorFormat format, ARM64Reg reg,
                                  u32 offset)
{
  int load_bytes = 0;
  switch (format)
  {
  case ColorFormat::RGB888:
  case ColorFormat::RGB888x:
  case ColorFormat::RGBA8888:
    LDUR(scratch2_reg, reg, offset);

    if (format != ColorFormat::RGBA8888)
      ORR(scratch2_reg, scratch2_reg, LogicalImm(0xFF000000, GPRSize::B32));
    STR(IndexType::Unsigned, scratch2_reg, dst_reg, m_dst_ofs);
    load_bytes = format == ColorFormat::RGB888 ? 3 : 4;
    break;

  case ColorFormat::RGB565:
    //                   RRRRRGGG GGGBBBBB
    // AAAAAAAA BBBBBBBB GGGGGGGG RRRRRRRR
    LDURH(scratch3_reg, reg, offset);

    REV16(scratch3_reg, scratch3_reg);

    // B
    AND(scratch2_reg, scratch3_reg, LogicalImm(0x1F, GPRSize::B32));
    ORR(scratch2_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 3));
    ORR(scratch2_reg, scratch2_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 5));
    ORR(scratch1_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 16));

    // G
    UBFM(scratch2_reg, scratch3_reg, 5, 10);
    ORR(scratch2_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 2));
    ORR(scratch2_reg, scratch2_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 6));
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 8));

    // R
    UBFM(scratch2_reg, scratch3_reg, 11, 15);
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 3));
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 2));

    // A
    ORR(scratch1_reg, scratch1_reg, LogicalImm(0xFF000000, GPRSize::B32));

    STR(IndexType::Unsigned, scratch1_reg, dst_reg, m_dst_ofs);
    load_bytes = 2;
    break;

  case ColorFormat::RGBA4444:
    //                   BBBBAAAA RRRRGGGG
    //           REV16 - RRRRGGGG BBBBAAAA
    // AAAAAAAA BBBBBBBB GGGGGGGG RRRRRRRR
    LDURH(scratch3_reg, reg, offset);

    // R
    UBFM(scratch1_reg, scratch3_reg, 4, 7);

    // G
    AND(scratch2_reg, scratch3_reg, LogicalImm(0xF, GPRSize::B32));
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 8));

    // B
    UBFM(scratch2_reg, scratch3_reg, 12, 15);
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 16));

    // A
    UBFM(scratch2_reg, scratch3_reg, 8, 11);
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 24));

    // Final duplication
    ORR(scratch1_reg, scratch1_reg, scratch1_reg, ArithOption(scratch1_reg, ShiftType::LSL, 4));

    STR(IndexType::Unsigned, scratch1_reg, dst_reg, m_dst_ofs);
    load_bytes = 2;
    break;

  case ColorFormat::RGBA6666:
    //          RRRRRRGG GGGGBBBB BBAAAAAA
    // AAAAAAAA BBBBBBBB GGGGGGGG RRRRRRRR
    LDUR(scratch3_reg, reg, offset - 1);

    REV32(scratch3_reg, scratch3_reg);

    // A
    UBFM(scratch2_reg, scratch3_reg, 0, 5);
    ORR(scratch2_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 2));
    ORR(scratch2_reg, scratch2_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 6));
    ORR(scratch1_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 24));

    // B
    UBFM(scratch2_reg, scratch3_reg, 6, 11);
    ORR(scratch2_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 2));
    ORR(scratch2_reg, scratch2_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 6));
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 16));

    // G
    UBFM(scratch2_reg, scratch3_reg, 12, 17);
    ORR(scratch2_reg, ARM64Reg::WSP, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 2));
    ORR(scratch2_reg, scratch2_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 6));
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 8));

    // R
    UBFM(scratch2_reg, scratch3_reg, 18, 23);
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSL, 2));
    ORR(scratch1_reg, scratch1_reg, scratch2_reg, ArithOption(scratch2_reg, ShiftType::LSR, 4));

    STR(IndexType::Unsigned, scratch1_reg, dst_reg, m_dst_ofs);

    load_bytes = 3;
    break;
  }
  if (attribute == VertexComponentFormat::Direct)
    m_src_ofs += load_bytes;
}

void VertexLoaderARM64::GenerateVertexLoader()
{
  // The largest input vertex (with the position matrix index and all texture matrix indices
  // enabled, and all components set as direct) is 129 bytes (corresponding to a 156-byte
  // output). This is small enough that we can always use the unscaled load/store instructions
  // (which allow an offset from -256 to +255).
  ASSERT(m_vertex_size <= 255);

  // R0 - Source pointer
  // R1 - Destination pointer
  // R2 - Count
  // R30 - LR
  //
  // R0 return how many
  //
  // Registers we don't have to worry about saving
  // R9-R17 are caller saved temporaries
  // R18 is a temporary or platform specific register(iOS)
  //
  // VFP registers
  // We can touch all except v8-v15
  // If we need to use those, we need to retain the lower 64bits(!) of the register

  bool has_tc = false;
  bool has_tc_scale = false;
  for (size_t i = 0; i < m_VtxDesc.high.TexCoord.Size(); i++)
  {
    has_tc |= m_VtxDesc.high.TexCoord[i] != VertexComponentFormat::NotPresent;
    has_tc_scale |= (m_VtxAttr.GetTexFrac(i) != 0);
  }

  bool need_scale = (m_VtxAttr.g0.ByteDequant && m_VtxAttr.g0.PosFrac) ||
                    (has_tc && has_tc_scale) ||
                    (m_VtxDesc.low.Normal != VertexComponentFormat::NotPresent);

  AlignCode16();
  if (IsIndexed(m_VtxDesc.low.Position))
    MOV(skipped_reg, ARM64Reg::WZR);
  ADD(saved_count, remaining_reg, 1);

  MOVP2R(stride_reg, g_main_cp_state.array_strides.data());
  MOVP2R(arraybase_reg, VertexLoaderManager::cached_arraybases.data());

  if (need_scale)
    MOVP2R(scale_reg, scale_factors);

  const u8* loop_start = GetCodePtr();

  if (m_VtxDesc.low.PosMatIdx)
  {
    LDRB(IndexType::Unsigned, scratch1_reg, src_reg, m_src_ofs);
    AND(scratch1_reg, scratch1_reg, LogicalImm(0x3F, GPRSize::B32));
    STR(IndexType::Unsigned, scratch1_reg, dst_reg, m_dst_ofs);

    // Z-Freeze
    CMP(remaining_reg, 3);
    FixupBranch dont_store = B(CC_GE);
    MOVP2R(EncodeRegTo64(scratch2_reg), VertexLoaderManager::position_matrix_index_cache.data());
    STR(scratch1_reg, EncodeRegTo64(scratch2_reg), ArithOption(remaining_reg, true));
    SetJumpTarget(dont_store);

    m_native_vtx_decl.posmtx.components = 4;
    m_native_vtx_decl.posmtx.enable = true;
    m_native_vtx_decl.posmtx.offset = m_dst_ofs;
    m_native_vtx_decl.posmtx.type = ComponentFormat::UByte;
    m_native_vtx_decl.posmtx.integer = true;
    m_src_ofs += sizeof(u8);
    m_dst_ofs += sizeof(u32);
  }

  std::array<u32, 8> texmatidx_ofs;
  for (size_t i = 0; i < m_VtxDesc.low.TexMatIdx.Size(); i++)
  {
    if (m_VtxDesc.low.TexMatIdx[i])
      texmatidx_ofs[i] = m_src_ofs++;
  }

  // Position
  {
    const int pos_elements = m_VtxAttr.g0.PosElements == CoordComponentCount::XY ? 2 : 3;

    const auto [reg, offset] = GetVertexAddr(CPArray::Position, m_VtxDesc.low.Position);
    ReadVertex(m_VtxDesc.low.Position, m_VtxAttr.g0.PosFormat, pos_elements, pos_elements,
               m_VtxAttr.g0.ByteDequant, m_VtxAttr.g0.PosFrac, &m_native_vtx_decl.position, reg,
               offset);
  }

  if (m_VtxDesc.low.Normal != VertexComponentFormat::NotPresent)
  {
    static constexpr Common::EnumMap<u8, ComponentFormat::InvalidFloat7> SCALE_MAP = {7, 6, 15, 14,
                                                                                      0, 0, 0,  0};
    const u8 scaling_exponent = SCALE_MAP[m_VtxAttr.g0.NormalFormat];

    // Normal
    auto [reg, offset] = GetVertexAddr(CPArray::Normal, m_VtxDesc.low.Normal);
    ReadVertex(m_VtxDesc.low.Normal, m_VtxAttr.g0.NormalFormat, 3, 3, true, scaling_exponent,
               &m_native_vtx_decl.normals[0], reg, offset);

    if (m_VtxAttr.g0.NormalElements == NormalComponentCount::NTB)
    {
      const bool index3 = IsIndexed(m_VtxDesc.low.Normal) && m_VtxAttr.g0.NormalIndex3;
      const int elem_size = GetElementSize(m_VtxAttr.g0.NormalFormat);
      const int load_bytes = elem_size * 3;

      // Tangent
      // If in Index3 mode, and indexed components are used, replace the index with a new index.
      if (index3)
        std::tie(reg, offset) = GetVertexAddr(CPArray::Normal, m_VtxDesc.low.Normal);
      // The tangent comes after the normal; even in index3 mode, an extra offset of load_bytes is
      // applied. Note that this is different from adding 1 to the index, as the stride for indices
      // may be different from the size of the tangent itself.
      ReadVertex(m_VtxDesc.low.Normal, m_VtxAttr.g0.NormalFormat, 3, 3, true, scaling_exponent,
                 &m_native_vtx_decl.normals[1], reg, offset + load_bytes);
      // Binormal
      if (index3)
        std::tie(reg, offset) = GetVertexAddr(CPArray::Normal, m_VtxDesc.low.Normal);
      ReadVertex(m_VtxDesc.low.Normal, m_VtxAttr.g0.NormalFormat, 3, 3, true, scaling_exponent,
                 &m_native_vtx_decl.normals[2], reg, offset + load_bytes * 2);
    }
  }

  for (u8 i = 0; i < m_VtxDesc.low.Color.Size(); i++)
  {
    m_native_vtx_decl.colors[i].components = 4;
    m_native_vtx_decl.colors[i].type = ComponentFormat::UByte;
    m_native_vtx_decl.colors[i].integer = false;

    if (m_VtxDesc.low.Color[i] != VertexComponentFormat::NotPresent)
    {
      const auto [reg, offset] = GetVertexAddr(CPArray::Color0 + i, m_VtxDesc.low.Color[i]);
      ReadColor(m_VtxDesc.low.Color[i], m_VtxAttr.GetColorFormat(i), reg, offset);
      m_native_vtx_decl.colors[i].components = 4;
      m_native_vtx_decl.colors[i].enable = true;
      m_native_vtx_decl.colors[i].offset = m_dst_ofs;
      m_native_vtx_decl.colors[i].type = ComponentFormat::UByte;
      m_native_vtx_decl.colors[i].integer = false;
      m_dst_ofs += 4;
    }
  }

  for (u8 i = 0; i < m_VtxDesc.high.TexCoord.Size(); i++)
  {
    m_native_vtx_decl.texcoords[i].offset = m_dst_ofs;
    m_native_vtx_decl.texcoords[i].type = ComponentFormat::Float;
    m_native_vtx_decl.texcoords[i].integer = false;

    const int elements = m_VtxAttr.GetTexElements(i) == TexComponentCount::S ? 1 : 2;
    if (m_VtxDesc.high.TexCoord[i] != VertexComponentFormat::NotPresent)
    {
      const auto [reg, offset] = GetVertexAddr(CPArray::TexCoord0 + i, m_VtxDesc.high.TexCoord[i]);
      u8 scaling_exponent = m_VtxAttr.GetTexFrac(i);
      ReadVertex(m_VtxDesc.high.TexCoord[i], m_VtxAttr.GetTexFormat(i), elements,
                 m_VtxDesc.low.TexMatIdx[i] ? 2 : elements, m_VtxAttr.g0.ByteDequant,
                 scaling_exponent, &m_native_vtx_decl.texcoords[i], reg, offset);
    }
    if (m_VtxDesc.low.TexMatIdx[i])
    {
      m_native_vtx_decl.texcoords[i].components = 3;
      m_native_vtx_decl.texcoords[i].enable = true;
      m_native_vtx_decl.texcoords[i].type = ComponentFormat::Float;
      m_native_vtx_decl.texcoords[i].integer = false;

      LDRB(IndexType::Unsigned, scratch2_reg, src_reg, texmatidx_ofs[i]);
      m_float_emit.UCVTF(ARM64Reg::S31, scratch2_reg);

      if (m_VtxDesc.high.TexCoord[i] != VertexComponentFormat::NotPresent)
      {
        m_float_emit.STR(32, IndexType::Unsigned, ARM64Reg::D31, dst_reg, m_dst_ofs);
        m_dst_ofs += sizeof(float);
      }
      else
      {
        m_native_vtx_decl.texcoords[i].offset = m_dst_ofs;

        STUR(ARM64Reg::SP, dst_reg, m_dst_ofs);
        m_float_emit.STR(32, IndexType::Unsigned, ARM64Reg::D31, dst_reg, m_dst_ofs + 8);

        m_dst_ofs += sizeof(float) * 3;
      }
    }
  }

  // Prepare for the next vertex.
  ADD(dst_reg, dst_reg, m_dst_ofs);
  const u8* cont = GetCodePtr();
  ADD(src_reg, src_reg, m_src_ofs);

  SUBS(remaining_reg, remaining_reg, 1);
  B(CCFlags::CC_GE, loop_start);

  if (IsIndexed(m_VtxDesc.low.Position))
  {
    SUB(ARM64Reg::W0, saved_count, skipped_reg);
    RET(ARM64Reg::X30);

    SetJumpTarget(m_skip_vertex);
    ADD(skipped_reg, skipped_reg, 1);
    B(cont);
  }
  else
  {
    MOV(ARM64Reg::W0, saved_count);
    RET(ARM64Reg::X30);
  }

  FlushIcache();

  ASSERT_MSG(VIDEO, m_vertex_size == m_src_ofs,
             "Vertex size from vertex loader ({}) does not match expected vertex size ({})!\nVtx "
             "desc: {:08x} {:08x}\nVtx attr: {:08x} {:08x} {:08x}",
             m_src_ofs, m_vertex_size, m_VtxDesc.low.Hex, m_VtxDesc.high.Hex, m_VtxAttr.g0.Hex,
             m_VtxAttr.g1.Hex, m_VtxAttr.g2.Hex);
  m_native_vtx_decl.stride = m_dst_ofs;
}

int VertexLoaderARM64::RunVertices(const u8* src, u8* dst, int count)
{
  m_numLoadedVertices += count;
  return ((int (*)(const u8* src, u8* dst, int count))region)(src, dst, count - 1);
}