//===-- cpu_model.c - Support for __cpu_model builtin  ------------*- C -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file is based on LLVM's lib/Support/Host.cpp.
//  It implements the operating system Host concept and builtin
//  __cpu_model for the compiler_rt library, for x86 only.
//
//===----------------------------------------------------------------------===//

#if (defined(__i386__) || defined(_M_IX86) || defined(__x86_64__) ||           \
     defined(_M_X64)) &&                                                       \
    (defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER))

#include <assert.h>

#define bool int
#define true 1
#define false 0

#ifdef _MSC_VER
#include <intrin.h>
#endif

#ifndef __has_attribute
#define __has_attribute(attr) 0
#endif

enum VendorSignatures {
  SIG_INTEL = 0x756e6547, // Genu
  SIG_AMD = 0x68747541,   // Auth
};

enum ProcessorVendors {
  VENDOR_INTEL = 1,
  VENDOR_AMD,
  VENDOR_OTHER,
  VENDOR_MAX
};

enum ProcessorTypes {
  INTEL_BONNELL = 1,
  INTEL_CORE2,
  INTEL_COREI7,
  AMDFAM10H,
  AMDFAM15H,
  INTEL_SILVERMONT,
  INTEL_KNL,
  AMD_BTVER1,
  AMD_BTVER2,
  AMDFAM17H,
  INTEL_KNM,
  INTEL_GOLDMONT,
  INTEL_GOLDMONT_PLUS,
  INTEL_TREMONT,
  CPU_TYPE_MAX
};

enum ProcessorSubtypes {
  INTEL_COREI7_NEHALEM = 1,
  INTEL_COREI7_WESTMERE,
  INTEL_COREI7_SANDYBRIDGE,
  AMDFAM10H_BARCELONA,
  AMDFAM10H_SHANGHAI,
  AMDFAM10H_ISTANBUL,
  AMDFAM15H_BDVER1,
  AMDFAM15H_BDVER2,
  AMDFAM15H_BDVER3,
  AMDFAM15H_BDVER4,
  AMDFAM17H_ZNVER1,
  INTEL_COREI7_IVYBRIDGE,
  INTEL_COREI7_HASWELL,
  INTEL_COREI7_BROADWELL,
  INTEL_COREI7_SKYLAKE,
  INTEL_COREI7_SKYLAKE_AVX512,
  INTEL_COREI7_CANNONLAKE,
  INTEL_COREI7_ICELAKE_CLIENT,
  INTEL_COREI7_ICELAKE_SERVER,
  AMDFAM17H_ZNVER2,
  INTEL_COREI7_CASCADELAKE,
  CPU_SUBTYPE_MAX
};

enum ProcessorFeatures {
  FEATURE_CMOV = 0,
  FEATURE_MMX,
  FEATURE_POPCNT,
  FEATURE_SSE,
  FEATURE_SSE2,
  FEATURE_SSE3,
  FEATURE_SSSE3,
  FEATURE_SSE4_1,
  FEATURE_SSE4_2,
  FEATURE_AVX,
  FEATURE_AVX2,
  FEATURE_SSE4_A,
  FEATURE_FMA4,
  FEATURE_XOP,
  FEATURE_FMA,
  FEATURE_AVX512F,
  FEATURE_BMI,
  FEATURE_BMI2,
  FEATURE_AES,
  FEATURE_PCLMUL,
  FEATURE_AVX512VL,
  FEATURE_AVX512BW,
  FEATURE_AVX512DQ,
  FEATURE_AVX512CD,
  FEATURE_AVX512ER,
  FEATURE_AVX512PF,
  FEATURE_AVX512VBMI,
  FEATURE_AVX512IFMA,
  FEATURE_AVX5124VNNIW,
  FEATURE_AVX5124FMAPS,
  FEATURE_AVX512VPOPCNTDQ,
  FEATURE_AVX512VBMI2,
  FEATURE_GFNI,
  FEATURE_VPCLMULQDQ,
  FEATURE_AVX512VNNI,
  FEATURE_AVX512BITALG,
  FEATURE_AVX512BF16
};

// The check below for i386 was copied from clang's cpuid.h (__get_cpuid_max).
// Check motivated by bug reports for OpenSSL crashing on CPUs without CPUID
// support. Consequently, for i386, the presence of CPUID is checked first
// via the corresponding eflags bit.
static bool isCpuIdSupported() {
#if defined(__GNUC__) || defined(__clang__)
#if defined(__i386__)
  int __cpuid_supported;
  __asm__("  pushfl\n"
          "  popl   %%eax\n"
          "  movl   %%eax,%%ecx\n"
          "  xorl   $0x00200000,%%eax\n"
          "  pushl  %%eax\n"
          "  popfl\n"
          "  pushfl\n"
          "  popl   %%eax\n"
          "  movl   $0,%0\n"
          "  cmpl   %%eax,%%ecx\n"
          "  je     1f\n"
          "  movl   $1,%0\n"
          "1:"
          : "=r"(__cpuid_supported)
          :
          : "eax", "ecx");
  if (!__cpuid_supported)
    return false;
#endif
  return true;
#endif
  return true;
}

// This code is copied from lib/Support/Host.cpp.
// Changes to either file should be mirrored in the other.

/// getX86CpuIDAndInfo - Execute the specified cpuid and return the 4 values in
/// the specified arguments.  If we can't run cpuid on the host, return true.
static bool getX86CpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
                               unsigned *rECX, unsigned *rEDX) {
#if defined(__GNUC__) || defined(__clang__)
#if defined(__x86_64__)
  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
  // FIXME: should we save this for Clang?
  __asm__("movq\t%%rbx, %%rsi\n\t"
          "cpuid\n\t"
          "xchgq\t%%rbx, %%rsi\n\t"
          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
          : "a"(value));
  return false;
#elif defined(__i386__)
  __asm__("movl\t%%ebx, %%esi\n\t"
          "cpuid\n\t"
          "xchgl\t%%ebx, %%esi\n\t"
          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
          : "a"(value));
  return false;
#else
  return true;
#endif
#elif defined(_MSC_VER)
  // The MSVC intrinsic is portable across x86 and x64.
  int registers[4];
  __cpuid(registers, value);
  *rEAX = registers[0];
  *rEBX = registers[1];
  *rECX = registers[2];
  *rEDX = registers[3];
  return false;
#else
  return true;
#endif
}

/// getX86CpuIDAndInfoEx - Execute the specified cpuid with subleaf and return
/// the 4 values in the specified arguments.  If we can't run cpuid on the host,
/// return true.
static bool getX86CpuIDAndInfoEx(unsigned value, unsigned subleaf,
                                 unsigned *rEAX, unsigned *rEBX, unsigned *rECX,
                                 unsigned *rEDX) {
#if defined(__GNUC__) || defined(__clang__)
#if defined(__x86_64__)
  // gcc doesn't know cpuid would clobber ebx/rbx. Preserve it manually.
  // FIXME: should we save this for Clang?
  __asm__("movq\t%%rbx, %%rsi\n\t"
          "cpuid\n\t"
          "xchgq\t%%rbx, %%rsi\n\t"
          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
          : "a"(value), "c"(subleaf));
  return false;
#elif defined(__i386__)
  __asm__("movl\t%%ebx, %%esi\n\t"
          "cpuid\n\t"
          "xchgl\t%%ebx, %%esi\n\t"
          : "=a"(*rEAX), "=S"(*rEBX), "=c"(*rECX), "=d"(*rEDX)
          : "a"(value), "c"(subleaf));
  return false;
#else
  return true;
#endif
#elif defined(_MSC_VER)
  int registers[4];
  __cpuidex(registers, value, subleaf);
  *rEAX = registers[0];
  *rEBX = registers[1];
  *rECX = registers[2];
  *rEDX = registers[3];
  return false;
#else
  return true;
#endif
}

// Read control register 0 (XCR0). Used to detect features such as AVX.
static bool getX86XCR0(unsigned *rEAX, unsigned *rEDX) {
#if defined(__GNUC__) || defined(__clang__)
  // Check xgetbv; this uses a .byte sequence instead of the instruction
  // directly because older assemblers do not include support for xgetbv and
  // there is no easy way to conditionally compile based on the assembler used.
  __asm__(".byte 0x0f, 0x01, 0xd0" : "=a"(*rEAX), "=d"(*rEDX) : "c"(0));
  return false;
#elif defined(_MSC_FULL_VER) && defined(_XCR_XFEATURE_ENABLED_MASK)
  unsigned long long Result = _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
  *rEAX = Result;
  *rEDX = Result >> 32;
  return false;
#else
  return true;
#endif
}

static void detectX86FamilyModel(unsigned EAX, unsigned *Family,
                                 unsigned *Model) {
  *Family = (EAX >> 8) & 0xf; // Bits 8 - 11
  *Model = (EAX >> 4) & 0xf;  // Bits 4 - 7
  if (*Family == 6 || *Family == 0xf) {
    if (*Family == 0xf)
      // Examine extended family ID if family ID is F.
      *Family += (EAX >> 20) & 0xff; // Bits 20 - 27
    // Examine extended model ID if family ID is 6 or F.
    *Model += ((EAX >> 16) & 0xf) << 4; // Bits 16 - 19
  }
}

static void getIntelProcessorTypeAndSubtype(unsigned Family, unsigned Model,
                                            unsigned Brand_id,
                                            unsigned Features,
                                            unsigned Features2, unsigned *Type,
                                            unsigned *Subtype) {
  if (Brand_id != 0)
    return;
  switch (Family) {
  case 6:
    switch (Model) {
    case 0x0f: // Intel Core 2 Duo processor, Intel Core 2 Duo mobile
               // processor, Intel Core 2 Quad processor, Intel Core 2 Quad
               // mobile processor, Intel Core 2 Extreme processor, Intel
               // Pentium Dual-Core processor, Intel Xeon processor, model
               // 0Fh. All processors are manufactured using the 65 nm process.
    case 0x16: // Intel Celeron processor model 16h. All processors are
               // manufactured using the 65 nm process
    case 0x17: // Intel Core 2 Extreme processor, Intel Xeon processor, model
               // 17h. All processors are manufactured using the 45 nm process.
               //
               // 45nm: Penryn , Wolfdale, Yorkfield (XE)
    case 0x1d: // Intel Xeon processor MP. All processors are manufactured using
               // the 45 nm process.
      *Type = INTEL_CORE2; // "penryn"
      break;
    case 0x1a: // Intel Core i7 processor and Intel Xeon processor. All
               // processors are manufactured using the 45 nm process.
    case 0x1e: // Intel(R) Core(TM) i7 CPU         870  @ 2.93GHz.
               // As found in a Summer 2010 model iMac.
    case 0x1f:
    case 0x2e:              // Nehalem EX
      *Type = INTEL_COREI7; // "nehalem"
      *Subtype = INTEL_COREI7_NEHALEM;
      break;
    case 0x25: // Intel Core i7, laptop version.
    case 0x2c: // Intel Core i7 processor and Intel Xeon processor. All
               // processors are manufactured using the 32 nm process.
    case 0x2f: // Westmere EX
      *Type = INTEL_COREI7; // "westmere"
      *Subtype = INTEL_COREI7_WESTMERE;
      break;
    case 0x2a: // Intel Core i7 processor. All processors are manufactured
               // using the 32 nm process.
    case 0x2d:
      *Type = INTEL_COREI7; //"sandybridge"
      *Subtype = INTEL_COREI7_SANDYBRIDGE;
      break;
    case 0x3a:
    case 0x3e:              // Ivy Bridge EP
      *Type = INTEL_COREI7; // "ivybridge"
      *Subtype = INTEL_COREI7_IVYBRIDGE;
      break;

    // Haswell:
    case 0x3c:
    case 0x3f:
    case 0x45:
    case 0x46:
      *Type = INTEL_COREI7; // "haswell"
      *Subtype = INTEL_COREI7_HASWELL;
      break;

    // Broadwell:
    case 0x3d:
    case 0x47:
    case 0x4f:
    case 0x56:
      *Type = INTEL_COREI7; // "broadwell"
      *Subtype = INTEL_COREI7_BROADWELL;
      break;

    // Skylake:
    case 0x4e:              // Skylake mobile
    case 0x5e:              // Skylake desktop
    case 0x8e:              // Kaby Lake mobile
    case 0x9e:              // Kaby Lake desktop
      *Type = INTEL_COREI7; // "skylake"
      *Subtype = INTEL_COREI7_SKYLAKE;
      break;

    // Skylake Xeon:
    case 0x55:
      *Type = INTEL_COREI7;
      if (Features2 & (1 << (FEATURE_AVX512VNNI - 32)))
        *Subtype = INTEL_COREI7_CASCADELAKE; // "cascadelake"
      else
        *Subtype = INTEL_COREI7_SKYLAKE_AVX512; // "skylake-avx512"
      break;

    // Cannonlake:
    case 0x66:
      *Type = INTEL_COREI7;
      *Subtype = INTEL_COREI7_CANNONLAKE; // "cannonlake"
      break;

    // Icelake:
    case 0x7d:
    case 0x7e:
      *Type = INTEL_COREI7;
      *Subtype = INTEL_COREI7_ICELAKE_CLIENT; // "icelake-client"
      break;

    // Icelake Xeon:
    case 0x6a:
    case 0x6c:
      *Type = INTEL_COREI7;
      *Subtype = INTEL_COREI7_ICELAKE_SERVER; // "icelake-server"
      break;

    case 0x1c: // Most 45 nm Intel Atom processors
    case 0x26: // 45 nm Atom Lincroft
    case 0x27: // 32 nm Atom Medfield
    case 0x35: // 32 nm Atom Midview
    case 0x36: // 32 nm Atom Midview
      *Type = INTEL_BONNELL;
      break; // "bonnell"

    // Atom Silvermont codes from the Intel software optimization guide.
    case 0x37:
    case 0x4a:
    case 0x4d:
    case 0x5a:
    case 0x5d:
    case 0x4c: // really airmont
      *Type = INTEL_SILVERMONT;
      break; // "silvermont"
    // Goldmont:
    case 0x5c: // Apollo Lake
    case 0x5f: // Denverton
      *Type = INTEL_GOLDMONT;
      break; // "goldmont"
    case 0x7a:
      *Type = INTEL_GOLDMONT_PLUS;
      break;
    case 0x86:
      *Type = INTEL_TREMONT;
      break;

    case 0x57:
      *Type = INTEL_KNL; // knl
      break;

    case 0x85:
      *Type = INTEL_KNM; // knm
      break;

    default: // Unknown family 6 CPU.
      break;
    }
    break;
  default:
    break; // Unknown.
  }
}

static void getAMDProcessorTypeAndSubtype(unsigned Family, unsigned Model,
                                          unsigned Features, unsigned Features2,
                                          unsigned *Type, unsigned *Subtype) {
  // FIXME: this poorly matches the generated SubtargetFeatureKV table.  There
  // appears to be no way to generate the wide variety of AMD-specific targets
  // from the information returned from CPUID.
  switch (Family) {
  case 16:
    *Type = AMDFAM10H; // "amdfam10"
    switch (Model) {
    case 2:
      *Subtype = AMDFAM10H_BARCELONA;
      break;
    case 4:
      *Subtype = AMDFAM10H_SHANGHAI;
      break;
    case 8:
      *Subtype = AMDFAM10H_ISTANBUL;
      break;
    }
    break;
  case 20:
    *Type = AMD_BTVER1;
    break; // "btver1";
  case 21:
    *Type = AMDFAM15H;
    if (Model >= 0x60 && Model <= 0x7f) {
      *Subtype = AMDFAM15H_BDVER4;
      break; // "bdver4"; 60h-7Fh: Excavator
    }
    if (Model >= 0x30 && Model <= 0x3f) {
      *Subtype = AMDFAM15H_BDVER3;
      break; // "bdver3"; 30h-3Fh: Steamroller
    }
    if ((Model >= 0x10 && Model <= 0x1f) || Model == 0x02) {
      *Subtype = AMDFAM15H_BDVER2;
      break; // "bdver2"; 02h, 10h-1Fh: Piledriver
    }
    if (Model <= 0x0f) {
      *Subtype = AMDFAM15H_BDVER1;
      break; // "bdver1"; 00h-0Fh: Bulldozer
    }
    break;
  case 22:
    *Type = AMD_BTVER2;
    break; // "btver2"
  case 23:
    *Type = AMDFAM17H;
    if (Model >= 0x30 && Model <= 0x3f) {
      *Subtype = AMDFAM17H_ZNVER2;
      break; // "znver2"; 30h-3fh: Zen2
    }
    if (Model <= 0x0f) {
      *Subtype = AMDFAM17H_ZNVER1;
      break; // "znver1"; 00h-0Fh: Zen1
    }
    break;
  default:
    break; // "generic"
  }
}

static void getAvailableFeatures(unsigned ECX, unsigned EDX, unsigned MaxLeaf,
                                 unsigned *FeaturesOut,
                                 unsigned *Features2Out) {
  unsigned Features = 0;
  unsigned Features2 = 0;
  unsigned EAX, EBX;

#define setFeature(F)                                                          \
  do {                                                                         \
    if (F < 32)                                                                \
      Features |= 1U << (F & 0x1f);                                            \
    else if (F < 64)                                                           \
      Features2 |= 1U << ((F - 32) & 0x1f);                                    \
  } while (0)

  if ((EDX >> 15) & 1)
    setFeature(FEATURE_CMOV);
  if ((EDX >> 23) & 1)
    setFeature(FEATURE_MMX);
  if ((EDX >> 25) & 1)
    setFeature(FEATURE_SSE);
  if ((EDX >> 26) & 1)
    setFeature(FEATURE_SSE2);

  if ((ECX >> 0) & 1)
    setFeature(FEATURE_SSE3);
  if ((ECX >> 1) & 1)
    setFeature(FEATURE_PCLMUL);
  if ((ECX >> 9) & 1)
    setFeature(FEATURE_SSSE3);
  if ((ECX >> 12) & 1)
    setFeature(FEATURE_FMA);
  if ((ECX >> 19) & 1)
    setFeature(FEATURE_SSE4_1);
  if ((ECX >> 20) & 1)
    setFeature(FEATURE_SSE4_2);
  if ((ECX >> 23) & 1)
    setFeature(FEATURE_POPCNT);
  if ((ECX >> 25) & 1)
    setFeature(FEATURE_AES);

  // If CPUID indicates support for XSAVE, XRESTORE and AVX, and XGETBV
  // indicates that the AVX registers will be saved and restored on context
  // switch, then we have full AVX support.
  const unsigned AVXBits = (1 << 27) | (1 << 28);
  bool HasAVX = ((ECX & AVXBits) == AVXBits) && !getX86XCR0(&EAX, &EDX) &&
                ((EAX & 0x6) == 0x6);
  bool HasAVX512Save = HasAVX && ((EAX & 0xe0) == 0xe0);

  if (HasAVX)
    setFeature(FEATURE_AVX);

  bool HasLeaf7 =
      MaxLeaf >= 0x7 && !getX86CpuIDAndInfoEx(0x7, 0x0, &EAX, &EBX, &ECX, &EDX);

  if (HasLeaf7 && ((EBX >> 3) & 1))
    setFeature(FEATURE_BMI);
  if (HasLeaf7 && ((EBX >> 5) & 1) && HasAVX)
    setFeature(FEATURE_AVX2);
  if (HasLeaf7 && ((EBX >> 8) & 1))
    setFeature(FEATURE_BMI2);
  if (HasLeaf7 && ((EBX >> 16) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512F);
  if (HasLeaf7 && ((EBX >> 17) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512DQ);
  if (HasLeaf7 && ((EBX >> 21) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512IFMA);
  if (HasLeaf7 && ((EBX >> 26) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512PF);
  if (HasLeaf7 && ((EBX >> 27) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512ER);
  if (HasLeaf7 && ((EBX >> 28) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512CD);
  if (HasLeaf7 && ((EBX >> 30) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512BW);
  if (HasLeaf7 && ((EBX >> 31) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512VL);

  if (HasLeaf7 && ((ECX >> 1) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512VBMI);
  if (HasLeaf7 && ((ECX >> 6) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512VBMI2);
  if (HasLeaf7 && ((ECX >> 8) & 1))
    setFeature(FEATURE_GFNI);
  if (HasLeaf7 && ((ECX >> 10) & 1) && HasAVX)
    setFeature(FEATURE_VPCLMULQDQ);
  if (HasLeaf7 && ((ECX >> 11) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512VNNI);
  if (HasLeaf7 && ((ECX >> 12) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512BITALG);
  if (HasLeaf7 && ((ECX >> 14) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512VPOPCNTDQ);

  if (HasLeaf7 && ((EDX >> 2) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX5124VNNIW);
  if (HasLeaf7 && ((EDX >> 3) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX5124FMAPS);

  bool HasLeaf7Subleaf1 =
      MaxLeaf >= 0x7 && !getX86CpuIDAndInfoEx(0x7, 0x1, &EAX, &EBX, &ECX, &EDX);
  if (HasLeaf7Subleaf1 && ((EAX >> 5) & 1) && HasAVX512Save)
    setFeature(FEATURE_AVX512BF16);

  unsigned MaxExtLevel;
  getX86CpuIDAndInfo(0x80000000, &MaxExtLevel, &EBX, &ECX, &EDX);

  bool HasExtLeaf1 = MaxExtLevel >= 0x80000001 &&
                     !getX86CpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
  if (HasExtLeaf1 && ((ECX >> 6) & 1))
    setFeature(FEATURE_SSE4_A);
  if (HasExtLeaf1 && ((ECX >> 11) & 1))
    setFeature(FEATURE_XOP);
  if (HasExtLeaf1 && ((ECX >> 16) & 1))
    setFeature(FEATURE_FMA4);

  *FeaturesOut = Features;
  *Features2Out = Features2;
#undef setFeature
}

#if defined(HAVE_INIT_PRIORITY)
#define CONSTRUCTOR_ATTRIBUTE __attribute__((__constructor__ 101))
#elif __has_attribute(__constructor__)
#define CONSTRUCTOR_ATTRIBUTE __attribute__((__constructor__))
#else
// FIXME: For MSVC, we should make a function pointer global in .CRT$X?? so that
// this runs during initialization.
#define CONSTRUCTOR_ATTRIBUTE
#endif

#ifndef _WIN32
__attribute__((visibility("hidden")))
#endif
int __cpu_indicator_init(void) CONSTRUCTOR_ATTRIBUTE;

#ifndef _WIN32
__attribute__((visibility("hidden")))
#endif
struct __processor_model {
  unsigned int __cpu_vendor;
  unsigned int __cpu_type;
  unsigned int __cpu_subtype;
  unsigned int __cpu_features[1];
} __cpu_model = {0, 0, 0, {0}};

#ifndef _WIN32
__attribute__((visibility("hidden")))
#endif
unsigned int __cpu_features2;

// A constructor function that is sets __cpu_model and __cpu_features2 with
// the right values.  This needs to run only once.  This constructor is
// given the highest priority and it should run before constructors without
// the priority set.  However, it still runs after ifunc initializers and
// needs to be called explicitly there.

int CONSTRUCTOR_ATTRIBUTE __cpu_indicator_init(void) {
  unsigned EAX, EBX, ECX, EDX;
  unsigned MaxLeaf = 5;
  unsigned Vendor;
  unsigned Model, Family, Brand_id;
  unsigned Features = 0;
  unsigned Features2 = 0;

  // This function needs to run just once.
  if (__cpu_model.__cpu_vendor)
    return 0;

  if (!isCpuIdSupported())
    return -1;

  // Assume cpuid insn present. Run in level 0 to get vendor id.
  if (getX86CpuIDAndInfo(0, &MaxLeaf, &Vendor, &ECX, &EDX) || MaxLeaf < 1) {
    __cpu_model.__cpu_vendor = VENDOR_OTHER;
    return -1;
  }
  getX86CpuIDAndInfo(1, &EAX, &EBX, &ECX, &EDX);
  detectX86FamilyModel(EAX, &Family, &Model);
  Brand_id = EBX & 0xff;

  // Find available features.
  getAvailableFeatures(ECX, EDX, MaxLeaf, &Features, &Features2);
  __cpu_model.__cpu_features[0] = Features;
  __cpu_features2 = Features2;

  if (Vendor == SIG_INTEL) {
    // Get CPU type.
    getIntelProcessorTypeAndSubtype(Family, Model, Brand_id, Features,
                                    Features2, &(__cpu_model.__cpu_type),
                                    &(__cpu_model.__cpu_subtype));
    __cpu_model.__cpu_vendor = VENDOR_INTEL;
  } else if (Vendor == SIG_AMD) {
    // Get CPU type.
    getAMDProcessorTypeAndSubtype(Family, Model, Features, Features2,
                                  &(__cpu_model.__cpu_type),
                                  &(__cpu_model.__cpu_subtype));
    __cpu_model.__cpu_vendor = VENDOR_AMD;
  } else
    __cpu_model.__cpu_vendor = VENDOR_OTHER;

  assert(__cpu_model.__cpu_vendor < VENDOR_MAX);
  assert(__cpu_model.__cpu_type < CPU_TYPE_MAX);
  assert(__cpu_model.__cpu_subtype < CPU_SUBTYPE_MAX);

  return 0;
}

#endif