/src/libwebp/src/dsp/cpu.c

Source
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING 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.
// -----------------------------------------------------------------------------
//
// CPU detection
//
// Author: Christian Duvivier (cduvivier@google.com)

#include "src/dsp/cpu.h"

#if defined(WEBP_HAVE_NEON_RTCD)
#include <stdio.h>
#include <string.h>
#endif

#if defined(WEBP_ANDROID_NEON)
#include <cpu-features.h>
#endif

#include <stddef.h>

#include "src/webp/types.h"

//------------------------------------------------------------------------------
// SSE2 detection.
//

// apple/darwin gcc-4.0.1 defines __PIC__, but not __pic__ with -fPIC.
#if (defined(__pic__) || defined(__PIC__)) && defined(__i386__)
static WEBP_INLINE void GetCPUInfo(int cpu_info[4], int info_type) {
  __asm__ volatile(
      "mov %%ebx, %%edi\n"
      "cpuid\n"
      "xchg %%edi, %%ebx\n"
      : "=a"(cpu_info[0]), "=D"(cpu_info[1]), "=c"(cpu_info[2]),
        "=d"(cpu_info[3])
      : "a"(info_type), "c"(0));
}
#elif defined(__i386__) || defined(__x86_64__)
static WEBP_INLINE void GetCPUInfo(int cpu_info[4], int info_type) {
  __asm__ volatile("cpuid\n"
                   : "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]),
                     "=d"(cpu_info[3])
                   : "a"(info_type), "c"(0));
}
#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_IX86))

#if defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 150030729  // >= VS2008 SP1
#include <intrin.h>
#define GetCPUInfo(info, type) __cpuidex(info, type, 0)  // set ecx=0
#define WEBP_HAVE_MSC_CPUID
#elif _MSC_VER > 1310
#include <intrin.h>
#define GetCPUInfo __cpuid
#define WEBP_HAVE_MSC_CPUID
#endif

#endif

// NaCl has no support for xgetbv or the raw opcode.
#if !defined(__native_client__) && (defined(__i386__) || defined(__x86_64__))
static WEBP_INLINE uint64_t xgetbv(void) {
  const uint32_t ecx = 0;
  uint32_t eax, edx;
  // Use the raw opcode for xgetbv for compatibility with older toolchains.
  __asm__ volatile(".byte 0x0f, 0x01, 0xd0\n"
                   : "=a"(eax), "=d"(edx)
                   : "c"(ecx));
  return ((uint64_t)edx << 32) | eax;
}
#elif (defined(_M_X64) || defined(_M_IX86)) && defined(_MSC_FULL_VER) && \
    _MSC_FULL_VER >= 160040219  // >= VS2010 SP1
#include <immintrin.h>
#define xgetbv() _xgetbv(0)
#elif defined(_MSC_VER) && defined(_M_IX86)
static WEBP_INLINE uint64_t xgetbv(void) {
  uint32_t eax_, edx_;
  __asm {
    xor ecx, ecx  // ecx = 0
    // Use the raw opcode for xgetbv for compatibility with older toolchains.
    __asm _emit 0x0f __asm _emit 0x01 __asm _emit 0xd0
    mov eax_, eax
    mov edx_, edx
  }
  return ((uint64_t)edx_ << 32) | eax_;
}
#else
#define xgetbv() 0U  // no AVX for older x64 or unrecognized toolchains.
#endif

#if defined(__i386__) || defined(__x86_64__) || defined(WEBP_HAVE_MSC_CPUID)

// helper function for run-time detection of slow SSSE3 platforms
static int CheckSlowModel(int info) {
  // Table listing display models with longer latencies for the bsr instruction
  // (ie 2 cycles vs 10/16 cycles) and some SSSE3 instructions like pshufb.
  // Refer to Intel 64 and IA-32 Architectures Optimization Reference Manual.
  static const uint8_t kSlowModels[] = {
      0x37, 0x4a, 0x4d,  // Silvermont Microarchitecture
      0x1c, 0x26, 0x27   // Atom Microarchitecture
  };
  const uint32_t model = ((info & 0xf0000) >> 12) | ((info >> 4) & 0xf);
  const uint32_t family = (info >> 8) & 0xf;
  if (family == 0x06) {
    size_t i;
    for (i = 0; i < sizeof(kSlowModels) / sizeof(kSlowModels[0]); ++i) {
      if (model == kSlowModels[i]) return 1;
    }
  }
  return 0;
}

static int x86CPUInfo(CPUFeature feature) {
  int max_cpuid_value;
  int cpu_info[4];
  int is_intel = 0;

  // get the highest feature value cpuid supports
  GetCPUInfo(cpu_info, 0);
  max_cpuid_value = cpu_info[0];
  if (max_cpuid_value < 1) {
    return 0;
  } else {
    const int VENDOR_ID_INTEL_EBX = 0x756e6547;  // uneG
    const int VENDOR_ID_INTEL_EDX = 0x49656e69;  // Ieni
    const int VENDOR_ID_INTEL_ECX = 0x6c65746e;  // letn
    is_intel = (cpu_info[1] == VENDOR_ID_INTEL_EBX &&
                cpu_info[2] == VENDOR_ID_INTEL_ECX &&
                cpu_info[3] == VENDOR_ID_INTEL_EDX);  // genuine Intel?
  }

  GetCPUInfo(cpu_info, 1);
  if (feature == kSSE2) {
    return !!(cpu_info[3] & (1 << 26));
  }
  if (feature == kSSE3) {
    return !!(cpu_info[2] & (1 << 0));
  }
  if (feature == kSlowSSSE3) {
    if (is_intel && (cpu_info[2] & (1 << 9))) {  // SSSE3?
      return CheckSlowModel(cpu_info[0]);
    }
    return 0;
  }

  if (feature == kSSE4_1) {
    return !!(cpu_info[2] & (1 << 19));
  }
  if (feature == kAVX) {
    // bits 27 (OSXSAVE) & 28 (256-bit AVX)
    if ((cpu_info[2] & 0x18000000) == 0x18000000) {
      // XMM state and YMM state enabled by the OS.
      return (xgetbv() & 0x6) == 0x6;
    }
  }
  if (feature == kAVX2) {
    if (x86CPUInfo(kAVX) && max_cpuid_value >= 7) {
      GetCPUInfo(cpu_info, 7);
      return !!(cpu_info[1] & (1 << 5));
    }
  }
  return 0;
}
WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
VP8CPUInfo VP8GetCPUInfo = x86CPUInfo;
#elif defined(WEBP_ANDROID_NEON)  // NB: needs to be before generic NEON test.
static int AndroidCPUInfo(CPUFeature feature) {
  const AndroidCpuFamily cpu_family = android_getCpuFamily();
  const uint64_t cpu_features = android_getCpuFeatures();
  if (feature == kNEON) {
    return cpu_family == ANDROID_CPU_FAMILY_ARM &&
           (cpu_features & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
  }
  return 0;
}
WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
VP8CPUInfo VP8GetCPUInfo = AndroidCPUInfo;
#elif defined(EMSCRIPTEN)         // also needs to be before generic NEON test
// Use compile flags as an indicator of SIMD support instead of a runtime check.
static int wasmCPUInfo(CPUFeature feature) {
  switch (feature) {
#ifdef WEBP_HAVE_SSE2
    case kSSE2:
      return 1;
#endif
#ifdef WEBP_HAVE_SSE41
    case kSSE3:
    case kSlowSSSE3:
    case kSSE4_1:
      return 1;
#endif
#ifdef WEBP_HAVE_NEON
    case kNEON:
      return 1;
#endif
    default:
      break;
  }
  return 0;
}
WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
VP8CPUInfo VP8GetCPUInfo = wasmCPUInfo;
#elif defined(WEBP_HAVE_NEON)
// In most cases this function doesn't check for NEON support (it's assumed by
// the configuration), but enables turning off NEON at runtime, for testing
// purposes, by setting VP8GetCPUInfo = NULL.
static int armCPUInfo(CPUFeature feature) {
  if (feature != kNEON) return 0;
#if defined(__linux__) && defined(WEBP_HAVE_NEON_RTCD)
  {
    int has_neon = 0;
    char line[200];
    FILE* const cpuinfo = fopen("/proc/cpuinfo", "r");
    if (cpuinfo == NULL) return 0;
    while (fgets(line, sizeof(line), cpuinfo)) {
      if (!strncmp(line, "Features", 8)) {
        if (strstr(line, " neon ") != NULL) {
          has_neon = 1;
          break;
        }
      }
    }
    fclose(cpuinfo);
    return has_neon;
  }
#else
  return 1;
#endif
}
WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
VP8CPUInfo VP8GetCPUInfo = armCPUInfo;
#elif defined(WEBP_USE_MIPS32) || defined(WEBP_USE_MIPS_DSP_R2) || \
    defined(WEBP_USE_MSA)
static int mipsCPUInfo(CPUFeature feature) {
  if ((feature == kMIPS32) || (feature == kMIPSdspR2) || (feature == kMSA)) {
    return 1;
  } else {
    return 0;
  }
}
WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
VP8CPUInfo VP8GetCPUInfo = mipsCPUInfo;
#else
WEBP_EXTERN VP8CPUInfo VP8GetCPUInfo;
VP8CPUInfo VP8GetCPUInfo = NULL;
#endif

Coverage Report

Created: 2025-11-16 06:26