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aarch32_cpudetect.c (2578B)

      1 /*
      2 * Copyright (c) 2023, Alliance for Open Media. All rights reserved.
      3 *
      4 * This source code is subject to the terms of the BSD 2 Clause License and
      5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
      6 * was not distributed with this source code in the LICENSE file, you can
      7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
      8 * Media Patent License 1.0 was not distributed with this source code in the
      9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
     10 */
     11 // Feature detection code for Armv7-A / AArch32.
     12 
     13 #include "arm_cpudetect.h"
     14 
     15 #if !CONFIG_RUNTIME_CPU_DETECT
     16 
     17 static int arm_get_cpu_caps(void) {
     18  // This function should actually be a no-op. There is no way to adjust any of
     19  // these because the RTCD tables do not exist: the functions are called
     20  // statically.
     21  int flags = 0;
     22 #if HAVE_NEON
     23  flags |= HAS_NEON;
     24 #endif  // HAVE_NEON
     25  return flags;
     26 }
     27 
     28 #elif defined(_MSC_VER)  // end !CONFIG_RUNTIME_CPU_DETECT
     29 
     30 static int arm_get_cpu_caps(void) {
     31  int flags = 0;
     32 #if HAVE_NEON
     33  // MSVC has no inline __asm support for Arm, but it does let you __emit
     34  // instructions via their assembled hex code.
     35  // All of these instructions should be essentially nops.
     36  __try {
     37    // VORR q0,q0,q0
     38    __emit(0xF2200150);
     39    flags |= HAS_NEON;
     40  } __except (GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION) {
     41    // Ignore exception.
     42  }
     43 #endif  // HAVE_NEON
     44  return flags;
     45 }
     46 
     47 #elif defined(AOM_USE_ANDROID_CPU_FEATURES)
     48 
     49 static int arm_get_cpu_caps(void) {
     50  int flags = 0;
     51 #if HAVE_NEON
     52  uint64_t features = android_getCpuFeatures();
     53  if (features & ANDROID_CPU_ARM_FEATURE_NEON) flags |= HAS_NEON;
     54 #endif  // HAVE_NEON
     55  return flags;
     56 }
     57 
     58 #elif defined(__linux__)  // end defined(AOM_USE_ANDROID_CPU_FEATURES)
     59 
     60 #include <sys/auxv.h>
     61 
     62 // Define hwcap values ourselves: building with an old auxv header where these
     63 // hwcap values are not defined should not prevent features from being enabled.
     64 #define AOM_AARCH32_HWCAP_NEON (1 << 12)
     65 
     66 static int arm_get_cpu_caps(void) {
     67  int flags = 0;
     68  unsigned long hwcap = getauxval(AT_HWCAP);
     69 #if HAVE_NEON
     70  if (hwcap & AOM_AARCH32_HWCAP_NEON) flags |= HAS_NEON;
     71 #endif  // HAVE_NEON
     72  return flags;
     73 }
     74 #else   // end __linux__
     75 #error \
     76    "Runtime CPU detection selected, but no CPU detection method " \
     77 "available for your platform. Rerun cmake with -DCONFIG_RUNTIME_CPU_DETECT=0."
     78 #endif
     79 
     80 int aom_arm_cpu_caps(void) {
     81  int flags = 0;
     82  if (arm_cpu_env_flags(&flags)) {
     83    return flags;
     84  }
     85  return arm_get_cpu_caps() & arm_cpu_env_mask();
     86 }