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78 lines
2.8 KiB
78 lines
2.8 KiB
13 years ago
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// Copyright 2006-2008 the V8 project authors. All rights reserved.
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14 years ago
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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13 years ago
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#ifndef V8_COMPILER_INTRINSICS_H_
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#define V8_COMPILER_INTRINSICS_H_
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namespace v8 {
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namespace internal {
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class CompilerIntrinsics {
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public:
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// Returns number of zero bits preceding least significant 1 bit.
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// Undefined for zero value.
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INLINE(static int CountTrailingZeros(uint32_t value));
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// Returns number of zero bits following most significant 1 bit.
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// Undefined for zero value.
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INLINE(static int CountLeadingZeros(uint32_t value));
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};
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#ifdef __GNUC__
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int CompilerIntrinsics::CountTrailingZeros(uint32_t value) {
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return __builtin_ctz(value);
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}
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int CompilerIntrinsics::CountLeadingZeros(uint32_t value) {
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return __builtin_clz(value);
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}
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#elif defined(_MSC_VER)
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#pragma intrinsic(_BitScanForward)
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#pragma intrinsic(_BitScanReverse)
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int CompilerIntrinsics::CountTrailingZeros(uint32_t value) {
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unsigned long result; //NOLINT
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_BitScanForward(&result, static_cast<long>(value)); //NOLINT
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return static_cast<int>(result);
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}
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int CompilerIntrinsics::CountLeadingZeros(uint32_t value) {
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unsigned long result; //NOLINT
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_BitScanReverse(&result, static_cast<long>(value)); //NOLINT
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return 31 - static_cast<int>(result);
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}
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#else
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#error Unsupported compiler
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#endif
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} } // namespace v8::internal
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#endif // V8_COMPILER_INTRINSICS_H_
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