460f53bb86
Change log:c92ed25217..bcf2616e8eFull diff:c92ed25217..bcf2616e8eRoll chromium third_party 51c08cf9af..9d65a3cdda Change log:51c08cf9af..9d65a3cddaChanged dependencies: * src/base:a7a2409f9b..b802985ef4* src/build:03f39fd800..fc8308f6b6* src/buildtools:a9e946f166..94288c26d2* src/ios:e070a93062..289c450460* src/testing:f5b31b58c6..a5fce03148* src/third_party/catapult: https://chromium.googlesource.com/catapult.git/+log/d8600ccc2d..ce9b3742a1 * src/third_party/depot_tools:8de3800ce5..8fe4d8cbef* src/third_party/googletest/src:045e7f9ee4..08d5b1f33a* src/tools:e024720629..6e6e398687* src/tools/swarming_client:88229872dd..833f5ebf89DEPS diff:c92ed25217..bcf2616e8e/DEPS No update to Clang. TBR=buildbot@webrtc.org, BUG=None CQ_INCLUDE_TRYBOTS=master.internal.tryserver.corp.webrtc:linux_internal Change-Id: I22bf301fcec0103a1987a92f95ebf86e324dade7 Reviewed-on: https://webrtc-review.googlesource.com/77625 Reviewed-by: WebRTC Buildbot <buildbot@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23296}
54 lines
1.6 KiB
C++
54 lines
1.6 KiB
C++
// Copyright 2018 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ABSL_STRINGS_INTERNAL_BITS_H_
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#define ABSL_STRINGS_INTERNAL_BITS_H_
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#include <cstdint>
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#if defined(_MSC_VER) && defined(_M_X64)
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#include <intrin.h>
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#pragma intrinsic(_BitScanReverse64)
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#endif
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namespace absl {
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namespace strings_internal {
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// Returns the number of leading 0 bits in a 64-bit value.
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inline int CountLeadingZeros64(uint64_t n) {
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#if defined(__GNUC__)
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static_assert(sizeof(unsigned long long) == sizeof(n), // NOLINT(runtime/int)
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"__builtin_clzll does not take 64bit arg");
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return n == 0 ? 64 : __builtin_clzll(n);
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#elif defined(_MSC_VER) && defined(_M_X64)
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unsigned long result; // NOLINT(runtime/int)
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if (_BitScanReverse64(&result, n)) {
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return 63 - result;
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}
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return 64;
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#else
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int zeroes = 60;
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if (n >> 32) zeroes -= 32, n >>= 32;
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if (n >> 16) zeroes -= 16, n >>= 16;
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if (n >> 8) zeroes -= 8, n >>= 8;
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if (n >> 4) zeroes -= 4, n >>= 4;
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return "\4\3\2\2\1\1\1\1\0\0\0\0\0\0\0\0"[n] + zeroes;
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#endif
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}
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} // namespace strings_internal
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} // namespace absl
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#endif // ABSL_STRINGS_INTERNAL_BITS_H_
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