source/cpu_id.cc

/*
 *  Copyright 2011 The LibYuv Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS. All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "libyuv/cpu_id.h"

#ifdef _MSC_VER
#include <intrin.h>  // For __cpuidex()
#endif
#if !defined(__CLR_VER) && !defined(__native_client__) && defined(_M_X64) && \
    defined(_MSC_VER) && (_MSC_FULL_VER >= 160040219)
#include <immintrin.h>  // For _xgetbv()
#endif

#if !defined(__native_client__)
#include <stdlib.h>  // For getenv()
#endif

// For ArmCpuCaps() but unittested on all platforms
#include <stdio.h>
#include <string.h>

#include "libyuv/basic_types.h"  // For CPU_X86

#ifdef __cplusplus
namespace libyuv {
extern "C" {
#endif

// Low level cpuid for X86. Returns zeros on other CPUs.
#if !defined(__CLR_VER) && (defined(_M_IX86) || defined(_M_X64) || \
    defined(__i386__) || defined(__x86_64__))
LIBYUV_API
void CpuId(uint32 eax, uint32 ecx, uint32* cpu_info) {
#if defined(_MSC_VER)
  __cpuidex(reinterpret_cast<int*>(cpu_info), eax, ecx);
#else
  uint32 ebx, edx;
  asm volatile (  // NOLINT
#if defined( __i386__) && defined(__PIC__)
    // Preserve ebx for fpic 32 bit.
    "mov %%ebx, %%edi                          \n"
    "cpuid                                     \n"
    "xchg %%edi, %%ebx                         \n"
    : "=D" (ebx),
#else
    "cpuid                                     \n"
    : "+b" (ebx),
#endif  //  defined( __i386__) && defined(__PIC__)
      "+a" (eax), "+c" (ecx), "=d" (edx));
  cpu_info[0] = eax; cpu_info[1] = ebx; cpu_info[2] = ecx; cpu_info[3] = edx;
#endif  // defined(_MSC_VER)
}
#define HAS_XGETBV
// X86 CPUs have xgetbv to detect OS saves high parts of ymm registers.
int TestOsSaveYmm() {
  uint32 xcr0;
#if defined(_MSC_VER)
  xcr0 = (uint32)_xgetbv(0);  /* min VS2010 SP1 compiler is required */
#else
  asm volatile ("xgetbv" : "=a" (xcr0) : "c" (0) : "%edx" );  // NOLINT
#endif  // defined(_MSC_VER)
  return((xcr0 & 6) == 6);  // Is ymm saved?
}
#else
LIBYUV_API
void CpuId(uint32 eax, uint32 ecx, uint32* cpu_info) {
  cpu_info[0] = cpu_info[1] = cpu_info[2] = cpu_info[3] = 0;
}
#endif

// based on libvpx arm_cpudetect.c
// For Arm, but public to allow testing on any CPU
LIBYUV_API
int ArmCpuCaps(const char* cpuinfo_name) {
  FILE* f = fopen(cpuinfo_name, "r");
  if (f) {
    char buf[512];
    while (fgets(buf, 511, f)) {
      if (memcmp(buf, "Features", 8) == 0) {
        char* p = strstr(buf, " neon");
        if (p && (p[5] == ' ' || p[5] == '\n')) {
          fclose(f);
          return kCpuHasNEON;
        }
      }
    }
    fclose(f);
  }
  return 0;
}

#if defined(__mips__) && defined(__linux__)
static int MipsCpuCaps(const char* search_string) {
  const char* file_name = "/proc/cpuinfo";
  char cpuinfo_line[256];
  FILE* f = NULL;
  if ((f = fopen(file_name, "r")) != NULL) {
    while (fgets(cpuinfo_line, sizeof(cpuinfo_line), f) != NULL) {
      if (strstr(cpuinfo_line, search_string) != NULL) {
        fclose(f);
        return kCpuHasMIPS_DSP;
      }
    }
    fclose(f);
  }
  /* Did not find string in the proc file, or not Linux ELF. */
  return 0;
}
#endif

// CPU detect function for SIMD instruction sets.
LIBYUV_API
int cpu_info_ = kCpuInit;  // cpu_info is not initialized yet.

// Test environment variable for disabling CPU features. Any non-zero value
// to disable. Zero ignored to make it easy to set the variable on/off.
#if !defined(__native_client__)
static bool TestEnv(const char* name) {
  const char* var = getenv(name);
  if (var) {
    if (var[0] != '0') {
      return true;
    }
  }
  return false;
}
#else  // nacl does not support getenv().
static bool TestEnv(const char*) {
  return false;
}
#endif

LIBYUV_API
int InitCpuFlags(void) {
#if !defined(__CLR_VER) && defined(CPU_X86)
  uint32 cpu_info1[4] = { 0, 0, 0, 0 };
  uint32 cpu_info7[4] = { 0, 0, 0, 0 };
  CpuId(1, 0, cpu_info1);
  CpuId(7, 0, cpu_info7);
  cpu_info_ = ((cpu_info1[3] & 0x04000000) ? kCpuHasSSE2 : 0) |
              ((cpu_info1[2] & 0x00000200) ? kCpuHasSSSE3 : 0) |
              ((cpu_info1[2] & 0x00080000) ? kCpuHasSSE41 : 0) |
              ((cpu_info1[2] & 0x00100000) ? kCpuHasSSE42 : 0) |
              ((cpu_info7[1] & 0x00000200) ? kCpuHasERMS : 0) |
              ((cpu_info1[2] & 0x00001000) ? kCpuHasFMA3 : 0) |
              kCpuHasX86;
#ifdef HAS_XGETBV
  if ((cpu_info1[2] & 0x18000000) == 0x18000000 &&  // AVX and OSSave
      TestOsSaveYmm()) {  // Saves YMM.
    cpu_info_ |= ((cpu_info7[1] & 0x00000020) ? kCpuHasAVX2 : 0) |
                 kCpuHasAVX;
  }
#endif
  // Environment variable overrides for testing.
  if (TestEnv("LIBYUV_DISABLE_X86")) {
    cpu_info_ &= ~kCpuHasX86;
  }
  if (TestEnv("LIBYUV_DISABLE_SSE2")) {
    cpu_info_ &= ~kCpuHasSSE2;
  }
  if (TestEnv("LIBYUV_DISABLE_SSSE3")) {
    cpu_info_ &= ~kCpuHasSSSE3;
  }
  if (TestEnv("LIBYUV_DISABLE_SSE41")) {
    cpu_info_ &= ~kCpuHasSSE41;
  }
  if (TestEnv("LIBYUV_DISABLE_SSE42")) {
    cpu_info_ &= ~kCpuHasSSE42;
  }
  if (TestEnv("LIBYUV_DISABLE_AVX")) {
    cpu_info_ &= ~kCpuHasAVX;
  }
  if (TestEnv("LIBYUV_DISABLE_AVX2")) {
    cpu_info_ &= ~kCpuHasAVX2;
  }
  if (TestEnv("LIBYUV_DISABLE_ERMS")) {
    cpu_info_ &= ~kCpuHasERMS;
  }
  if (TestEnv("LIBYUV_DISABLE_FMA3")) {
    cpu_info_ &= ~kCpuHasFMA3;
  }
#elif defined(__mips__) && defined(__linux__)
  // Linux mips parse text file for dsp detect.
  cpu_info_ = MipsCpuCaps("dsp");  // set kCpuHasMIPS_DSP.
#if defined(__mips_dspr2)
  cpu_info_ |= kCpuHasMIPS_DSPR2;
#endif
  cpu_info_ |= kCpuHasMIPS;

  if (getenv("LIBYUV_DISABLE_MIPS")) {
    cpu_info_ &= ~kCpuHasMIPS;
  }
  if (getenv("LIBYUV_DISABLE_MIPS_DSP")) {
    cpu_info_ &= ~kCpuHasMIPS_DSP;
  }
  if (getenv("LIBYUV_DISABLE_MIPS_DSPR2")) {
    cpu_info_ &= ~kCpuHasMIPS_DSPR2;
  }
#elif defined(__arm__)
#if defined(__linux__) && (defined(__ARM_NEON__) || defined(LIBYUV_NEON)) && \
    !defined(__native_client__)
  // Linux arm parse text file for neon detect.
  cpu_info_ = ArmCpuCaps("/proc/cpuinfo");
#elif defined(__ARM_NEON__) || defined(__native_client__)
  // gcc -mfpu=neon defines __ARM_NEON__
  // Enable Neon if you want support for Neon and Arm, and use MaskCpuFlags
  // to disable Neon on devices that do not have it.
  cpu_info_ = kCpuHasNEON;
#endif
  cpu_info_ |= kCpuHasARM;
  if (TestEnv("LIBYUV_DISABLE_NEON")) {
    cpu_info_ &= ~kCpuHasNEON;
  }
#endif  // __arm__
  if (TestEnv("LIBYUV_DISABLE_ASM")) {
    cpu_info_ = 0;
  }
  return cpu_info_;
}

LIBYUV_API
void MaskCpuFlags(int enable_flags) {
  cpu_info_ = InitCpuFlags() & enable_flags;
}

#ifdef __cplusplus
}  // extern "C"
}  // namespace libyuv
#endif