kc3-lang/angle/src/libANGLE/renderer/metal/mtl_library_cache.h

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• Hash : 9b00af52
  Author :
  Date : 2023-02-01T11:10:32
  

  Metal: Add an in-memory MTLLibrary cache.
  
  Add a small cache for (msl + compile parameters) -> MTLLibrary at the
  egl::Display level. In regular executions of Chrome, the same shaders
  (particularly vertex) are compiled multiple times in different programs.
  
  Tested for a regular Chrome startup + open wikipedia + motionmark 1.2:
  112/282 (40%) cache hits.
  
  Several different caching methods were profiled (LinkProgram perf test)
   - struct key with std::map                             : 303309
   - struct key with std::unordered_map                   : 308090
   - binary blob key with std::map                        : 263595
   - binary blob key with std::unordered_map              : 286051
   - struct key + is_transparent with std::unordered_map  : 304877
   - struct key + is_transparent with absl::flat_hash_map : 335686
  
  Using is_transparent allows us to search the hash map without
  copying the shader source string to construct the key structure.
  
  Bug: chromium:1385510
  Change-Id: Ieec4ba526fe286276a4af7114d89cde32a8f9e1d
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4214012
  Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
  Commit-Queue: Geoff Lang <geofflang@chromium.org>
  Reviewed-by: Kenneth Russell <kbr@chromium.org>
  

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• src/libANGLE/renderer/metal/mtl_library_cache.h

• //
  // Copyright 2023 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.
  //
  // mtl_library_cache.h:
  //    Defines classes for caching of mtl libraries
  //
  
  #ifndef LIBANGLE_RENDERER_METAL_MTL_LIBRARY_CACHE_H_
  #define LIBANGLE_RENDERER_METAL_MTL_LIBRARY_CACHE_H_
  
  #include "libANGLE/renderer/metal/mtl_utils.h"
  
  #include <type_traits>
  
  namespace rx
  {
  namespace mtl
  {
  
  class LibraryCache
  {
    public:
      LibraryCache()  = default;
      ~LibraryCache() = default;
  
      AutoObjCPtr<id<MTLLibrary>> getOrCompileShaderLibrary(
          ContextMtl *context,
          const std::string &source,
          const std::map<std::string, std::string> &macros,
          bool enableFastMath,
          AutoObjCPtr<NSError *> *errorOut);
  
    private:
      struct LibraryKey
      {
          std::string source;
          std::map<std::string, std::string> macros;
          bool enableFastMath;
  
          using LValueTuple = decltype(std::tie(std::as_const(source),
                                                std::as_const(macros),
                                                std::as_const(enableFastMath)));
  
          LibraryKey() = default;
          explicit LibraryKey(const LValueTuple &fromTuple);
  
          LValueTuple tie() const;
      };
  
      struct LibraryKeyCompare
      {
          // Mark this comparator as transparent. This allows types that are not LibraryKey to be used
          // as a key for unordered_map::find. We can avoid the construction of a LibraryKey (which
          // copies std::strings) when searching the cache.
          using is_transparent = void;
  
          // Hash functions for keys and lvalue tuples of keys
          size_t operator()(const LibraryKey::LValueTuple &k) const;
          size_t operator()(const LibraryKey &k) const;
  
          // Comparison operators for all key/lvalue combinations need by a map
          bool operator()(const LibraryKey &a, const LibraryKey &b) const;
          bool operator()(const LibraryKey &a, const LibraryKey::LValueTuple &b) const;
          bool operator()(const LibraryKey::LValueTuple &a, const LibraryKey &b) const;
      };
  
      angle::HashMap<LibraryKey, AutoObjCPtr<id<MTLLibrary>>, LibraryKeyCompare, LibraryKeyCompare>
          mCache;
  };
  
  }  // namespace mtl
  }  // namespace rx
  
  #endif  // LIBANGLE_RENDERER_METAL_MTL_LIBRARY_CACHE_H_
  

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