kc3-lang/angle/src/common/hash_utils.h

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• Hash : 35fd3063
  Author :
  Date : 2018-11-20T10:02:48
  

  Use xxHash for faster hash map lookups.
  
  This most strongly affects the Vulkan back-end which uses a hash map
  to cache VkPipelines. It also should speed up some parts of the D3D11
  back-end.
  
  Bug: angleproject:2522
  Change-Id: I10801654f043abce17339c30d7bf62bc8644e49c
  Reviewed-on: https://chromium-review.googlesource.com/c/1316889
  Commit-Queue: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  

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• src/common/hash_utils.h

• //
  // Copyright 2018 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // hash_utils.h: Hashing based helper functions.
  
  #ifndef COMMON_HASHUTILS_H_
  #define COMMON_HASHUTILS_H_
  
  #include "common/debug.h"
  #include "common/third_party/xxhash/xxhash.h"
  
  namespace angle
  {
  // Computes a hash of "key". Any data passed to this function must be multiples of
  // 4 bytes, since the PMurHash32 method can only operate increments of 4-byte words.
  inline std::size_t ComputeGenericHash(const void *key, size_t keySize)
  {
      static constexpr unsigned int kSeed = 0xABCDEF98;
  
      // We can't support "odd" alignments.  ComputeGenericHash requires aligned types
      ASSERT(keySize % 4 == 0);
  #if defined(ANGLE_IS_64_BIT_CPU)
      return XXH64(key, keySize, kSeed);
  #else
      return XXH32(key, keySize, kSeed);
  #endif  // defined(ANGLE_IS_64_BIT_CPU)
  }
  
  template <typename T>
  std::size_t ComputeGenericHash(const T &key)
  {
      static_assert(sizeof(key) % 4 == 0, "ComputeGenericHash requires aligned types");
      return ComputeGenericHash(&key, sizeof(key));
  }
  }  // namespace angle
  
  #endif  // COMMON_HASHUTILS_H_
  

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