erik.corry@gmail.com | c3b670f | 2011-10-05 21:44:48 +0000 | [diff] [blame] | 1 | // Copyright 2006-2008 the V8 project authors. All rights reserved. |
| 2 | // Redistribution and use in source and binary forms, with or without |
| 3 | // modification, are permitted provided that the following conditions are |
| 4 | // met: |
| 5 | // |
| 6 | // * Redistributions of source code must retain the above copyright |
| 7 | // notice, this list of conditions and the following disclaimer. |
| 8 | // * Redistributions in binary form must reproduce the above |
| 9 | // copyright notice, this list of conditions and the following |
| 10 | // disclaimer in the documentation and/or other materials provided |
| 11 | // with the distribution. |
| 12 | // * Neither the name of Google Inc. nor the names of its |
| 13 | // contributors may be used to endorse or promote products derived |
| 14 | // from this software without specific prior written permission. |
| 15 | // |
| 16 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 17 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 18 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 19 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 20 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 21 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 22 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 23 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 24 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 25 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 26 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 27 | |
| 28 | #ifndef V8_COMPILER_INTRINSICS_H_ |
| 29 | #define V8_COMPILER_INTRINSICS_H_ |
| 30 | |
| 31 | namespace v8 { |
| 32 | namespace internal { |
| 33 | |
| 34 | class CompilerIntrinsics { |
| 35 | public: |
| 36 | // Returns number of zero bits preceding least significant 1 bit. |
| 37 | // Undefined for zero value. |
| 38 | INLINE(static int CountTrailingZeros(uint32_t value)); |
| 39 | |
| 40 | // Returns number of zero bits following most significant 1 bit. |
| 41 | // Undefined for zero value. |
| 42 | INLINE(static int CountLeadingZeros(uint32_t value)); |
yangguo@chromium.org | efdb9d7 | 2012-04-26 08:21:05 +0000 | [diff] [blame] | 43 | |
| 44 | // Returns the number of bits set. |
| 45 | INLINE(static int CountSetBits(uint32_t value)); |
erik.corry@gmail.com | c3b670f | 2011-10-05 21:44:48 +0000 | [diff] [blame] | 46 | }; |
| 47 | |
| 48 | #ifdef __GNUC__ |
| 49 | int CompilerIntrinsics::CountTrailingZeros(uint32_t value) { |
| 50 | return __builtin_ctz(value); |
| 51 | } |
| 52 | |
| 53 | int CompilerIntrinsics::CountLeadingZeros(uint32_t value) { |
| 54 | return __builtin_clz(value); |
| 55 | } |
| 56 | |
yangguo@chromium.org | efdb9d7 | 2012-04-26 08:21:05 +0000 | [diff] [blame] | 57 | int CompilerIntrinsics::CountSetBits(uint32_t value) { |
| 58 | return __builtin_popcount(value); |
| 59 | } |
| 60 | |
erik.corry@gmail.com | c3b670f | 2011-10-05 21:44:48 +0000 | [diff] [blame] | 61 | #elif defined(_MSC_VER) |
| 62 | |
| 63 | #pragma intrinsic(_BitScanForward) |
| 64 | #pragma intrinsic(_BitScanReverse) |
| 65 | |
| 66 | int CompilerIntrinsics::CountTrailingZeros(uint32_t value) { |
| 67 | unsigned long result; //NOLINT |
| 68 | _BitScanForward(&result, static_cast<long>(value)); //NOLINT |
| 69 | return static_cast<int>(result); |
| 70 | } |
| 71 | |
| 72 | int CompilerIntrinsics::CountLeadingZeros(uint32_t value) { |
| 73 | unsigned long result; //NOLINT |
| 74 | _BitScanReverse(&result, static_cast<long>(value)); //NOLINT |
| 75 | return 31 - static_cast<int>(result); |
| 76 | } |
| 77 | |
yangguo@chromium.org | efdb9d7 | 2012-04-26 08:21:05 +0000 | [diff] [blame] | 78 | int CompilerIntrinsics::CountSetBits(uint32_t value) { |
| 79 | // Manually count set bits. |
| 80 | value = ((value >> 1) & 0x55555555) + (value & 0x55555555); |
| 81 | value = ((value >> 2) & 0x33333333) + (value & 0x33333333); |
| 82 | value = ((value >> 4) & 0x0f0f0f0f) + (value & 0x0f0f0f0f); |
| 83 | value = ((value >> 8) & 0x00ff00ff) + (value & 0x00ff00ff); |
| 84 | value = ((value >> 16) & 0x0000ffff) + (value & 0x0000ffff); |
| 85 | return value; |
| 86 | } |
| 87 | |
erik.corry@gmail.com | c3b670f | 2011-10-05 21:44:48 +0000 | [diff] [blame] | 88 | #else |
| 89 | #error Unsupported compiler |
| 90 | #endif |
| 91 | |
| 92 | } } // namespace v8::internal |
| 93 | |
| 94 | #endif // V8_COMPILER_INTRINSICS_H_ |