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 31namespace v8 { 32namespace internal { 33 34class 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)); 43}; 44 45#ifdef __GNUC__ 46int CompilerIntrinsics::CountTrailingZeros(uint32_t value) { 47 return __builtin_ctz(value); 48} 49 50int CompilerIntrinsics::CountLeadingZeros(uint32_t value) { 51 return __builtin_clz(value); 52} 53 54#elif defined(_MSC_VER) 55 56#pragma intrinsic(_BitScanForward) 57#pragma intrinsic(_BitScanReverse) 58 59int CompilerIntrinsics::CountTrailingZeros(uint32_t value) { 60 unsigned long result; //NOLINT 61 _BitScanForward(&result, static_cast<long>(value)); //NOLINT 62 return static_cast<int>(result); 63} 64 65int CompilerIntrinsics::CountLeadingZeros(uint32_t value) { 66 unsigned long result; //NOLINT 67 _BitScanReverse(&result, static_cast<long>(value)); //NOLINT 68 return 31 - static_cast<int>(result); 69} 70 71#else 72#error Unsupported compiler 73#endif 74 75} } // namespace v8::internal 76 77#endif // V8_COMPILER_INTRINSICS_H_ 78