disas/libvixl/vixl/compiler-intrinsics.h

   1 // Copyright 2015, ARM Limited
   2 // All rights reserved.
   3 //
   4 // Redistribution and use in source and binary forms, with or without
   5 // modification, are permitted provided that the following conditions are met:
   6 //
   7 //   * Redistributions of source code must retain the above copyright notice,
   8 //     this list of conditions and the following disclaimer.
   9 //   * Redistributions in binary form must reproduce the above copyright notice,
  10 //     this list of conditions and the following disclaimer in the documentation
  11 //     and/or other materials provided with the distribution.
  12 //   * Neither the name of ARM Limited nor the names of its contributors may be
  13 //     used to endorse or promote products derived from this software without
  14 //     specific prior written permission.
  15 //
  16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
  17 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  18 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  19 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  20 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  22 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  23 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  24 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  25 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26
  27
  28 #ifndef VIXL_COMPILER_INTRINSICS_H
  29 #define VIXL_COMPILER_INTRINSICS_H
  30
  31 #include "globals.h"
  32
  33 namespace vixl {
  34
  35 // Helper to check whether the version of GCC used is greater than the specified
  36 // requirement.
  37 #define MAJOR 1000000
  38 #define MINOR 1000
  39 #if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
  40 #define GCC_VERSION_OR_NEWER(major, minor, patchlevel)                         \
  41     ((__GNUC__ * MAJOR + __GNUC_MINOR__ * MINOR + __GNUC_PATCHLEVEL__) >=      \
  42      ((major) * MAJOR + (minor) * MINOR + (patchlevel)))
  43 #elif defined(__GNUC__) && defined(__GNUC_MINOR__)
  44 #define GCC_VERSION_OR_NEWER(major, minor, patchlevel)                         \
  45     ((__GNUC__ * MAJOR + __GNUC_MINOR__ * MINOR) >=                            \
  46      ((major) * MAJOR + (minor) * MINOR + (patchlevel)))
  47 #else
  48 #define GCC_VERSION_OR_NEWER(major, minor, patchlevel) 0
  49 #endif
  50
  51
  52 #if defined(__clang__) && !defined(VIXL_NO_COMPILER_BUILTINS)
  53
  54 #define COMPILER_HAS_BUILTIN_CLRSB    (__has_builtin(__builtin_clrsb))
  55 #define COMPILER_HAS_BUILTIN_CLZ      (__has_builtin(__builtin_clz))
  56 #define COMPILER_HAS_BUILTIN_CTZ      (__has_builtin(__builtin_ctz))
  57 #define COMPILER_HAS_BUILTIN_FFS      (__has_builtin(__builtin_ffs))
  58 #define COMPILER_HAS_BUILTIN_POPCOUNT (__has_builtin(__builtin_popcount))
  59
  60 #elif defined(__GNUC__) && !defined(VIXL_NO_COMPILER_BUILTINS)
  61 // The documentation for these builtins is available at:
  62 // https://gcc.gnu.org/onlinedocs/gcc-$MAJOR.$MINOR.$PATCHLEVEL/gcc//Other-Builtins.html
  63
  64 # define COMPILER_HAS_BUILTIN_CLRSB    (GCC_VERSION_OR_NEWER(4, 7, 0))
  65 # define COMPILER_HAS_BUILTIN_CLZ      (GCC_VERSION_OR_NEWER(3, 4, 0))
  66 # define COMPILER_HAS_BUILTIN_CTZ      (GCC_VERSION_OR_NEWER(3, 4, 0))
  67 # define COMPILER_HAS_BUILTIN_FFS      (GCC_VERSION_OR_NEWER(3, 4, 0))
  68 # define COMPILER_HAS_BUILTIN_POPCOUNT (GCC_VERSION_OR_NEWER(3, 4, 0))
  69
  70 #else
  71 // One can define VIXL_NO_COMPILER_BUILTINS to force using the manually
  72 // implemented C++ methods.
  73
  74 #define COMPILER_HAS_BUILTIN_BSWAP    false
  75 #define COMPILER_HAS_BUILTIN_CLRSB    false
  76 #define COMPILER_HAS_BUILTIN_CLZ      false
  77 #define COMPILER_HAS_BUILTIN_CTZ      false
  78 #define COMPILER_HAS_BUILTIN_FFS      false
  79 #define COMPILER_HAS_BUILTIN_POPCOUNT false
  80
  81 #endif
  82
  83
  84 template<typename V>
  85 inline bool IsPowerOf2(V value) {
  86   return (value != 0) && ((value & (value - 1)) == 0);
  87 }
  88
  89
  90 // Declaration of fallback functions.
  91 int CountLeadingSignBitsFallBack(int64_t value, int width);
  92 int CountLeadingZerosFallBack(uint64_t value, int width);
  93 int CountSetBitsFallBack(uint64_t value, int width);
  94 int CountTrailingZerosFallBack(uint64_t value, int width);
  95
  96
  97 // Implementation of intrinsics functions.
  98 // TODO: The implementations could be improved for sizes different from 32bit
  99 // and 64bit: we could mask the values and call the appropriate builtin.
 100
 101 template<typename V>
 102 inline int CountLeadingSignBits(V value, int width = (sizeof(V) * 8)) {
 103 #if COMPILER_HAS_BUILTIN_CLRSB
 104   if (width == 32) {
 105     return __builtin_clrsb(value);
 106   } else if (width == 64) {
 107     return __builtin_clrsbll(value);
 108   }
 109 #endif
 110   return CountLeadingSignBitsFallBack(value, width);
 111 }
 112
 113
 114 template<typename V>
 115 inline int CountLeadingZeros(V value, int width = (sizeof(V) * 8)) {
 116 #if COMPILER_HAS_BUILTIN_CLZ
 117   if (width == 32) {
 118     return (value == 0) ? 32 : __builtin_clz(static_cast<unsigned>(value));
 119   } else if (width == 64) {
 120     return (value == 0) ? 64 : __builtin_clzll(value);
 121   }
 122 #endif
 123   return CountLeadingZerosFallBack(value, width);
 124 }
 125
 126
 127 template<typename V>
 128 inline int CountSetBits(V value, int width = (sizeof(V) * 8)) {
 129 #if COMPILER_HAS_BUILTIN_POPCOUNT
 130   if (width == 32) {
 131     return __builtin_popcount(static_cast<unsigned>(value));
 132   } else if (width == 64) {
 133     return __builtin_popcountll(value);
 134   }
 135 #endif
 136   return CountSetBitsFallBack(value, width);
 137 }
 138
 139
 140 template<typename V>
 141 inline int CountTrailingZeros(V value, int width = (sizeof(V) * 8)) {
 142 #if COMPILER_HAS_BUILTIN_CTZ
 143   if (width == 32) {
 144     return (value == 0) ? 32 : __builtin_ctz(static_cast<unsigned>(value));
 145   } else if (width == 64) {
 146     return (value == 0) ? 64 : __builtin_ctzll(value);
 147   }
 148 #endif
 149   return CountTrailingZerosFallBack(value, width);
 150 }
 151
 152 }  // namespace vixl
 153
 154 #endif  // VIXL_COMPILER_INTRINSICS_H
 155