kc3-lang/angle/src/libANGLE/renderer/vulkan/AllocatorHelperPool.h

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• Hash : 93b659f9
  Author :
  Date : 2025-07-04T12:35:29
  

  Remove PoolAllocator push/pop feature
  
  PoolAllocator would manage a stack of memory pools upon client
  calling push() and pop(). This made the code unnecessarily complicated.
  The feature was only used with nesting of one, to mark the memory
  unused after a shader compile.
  
  Fix by removing the push/pop feature. Instantiate PoolAllocator in
  places the previous push() was and uninstantiating instead of previous
  pop().
  
  This removes the feature where the PoolAllocator would hold on to
  the allocated memory in order to reuse it. This is seen as a
  progression: the allocator is held by the compiler, the compiler is
  held by the shader and each shader typically see only one compile.
  Thus the free pages were just leaking unused until the shader was
  destroyed. Instead, destructing the PoolAllocator instead of pop()
  will donate the memory back to platform/OS, where it is likely
  more useful.
  
  To preserve existing Vulkan behavior, add PoolAllocator::reset()
  which would mark the memory unused but leave them reserved for the
  PoolAllocator.
  
  Removes UB where PageHeader::nextPage would be accessed after
  ~PageHeader.
  
  Bug: angleproject:429513168
  Change-Id: I21e58b46e0887380db3a2cab5ce22f0042cfae9e
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6701153
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Auto-Submit: Kimmo Kinnunen <kkinnunen@apple.com>
  Commit-Queue: Kimmo Kinnunen <kkinnunen@apple.com>
  Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
  

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• src/libANGLE/renderer/vulkan/AllocatorHelperPool.h

• //
  // Copyright 2022 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.
  //
  // AllocatorHelperPool:
  //    Manages the pool allocators used in the command buffers.
  //
  
  #ifndef LIBANGLE_RENDERER_VULKAN_ALLOCATORHELPERPOOL_H_
  #define LIBANGLE_RENDERER_VULKAN_ALLOCATORHELPERPOOL_H_
  
  #include "common/PoolAlloc.h"
  #include "common/vulkan/vk_headers.h"
  #include "libANGLE/renderer/vulkan/vk_command_buffer_utils.h"
  #include "libANGLE/renderer/vulkan/vk_wrapper.h"
  
  namespace rx
  {
  namespace vk
  {
  namespace priv
  {
  class SecondaryCommandBuffer;
  }  // namespace priv
  
  using DedicatedCommandMemoryAllocator = angle::PoolAllocator;
  
  // Used in CommandBufferHelperCommon
  class DedicatedCommandBlockAllocator
  {
    public:
      DedicatedCommandBlockAllocator() = default;
      void resetAllocator();
  
      DedicatedCommandMemoryAllocator *getAllocator() { return &mAllocator; }
  
    private:
      static constexpr size_t kDefaultPoolAllocatorPageSize = 16 * 1024;
      // Using a pool allocator per CBH to avoid threading issues that occur w/ shared allocator
      // between multiple CBHs.
      DedicatedCommandMemoryAllocator mAllocator{kDefaultPoolAllocatorPageSize, 1};
  };
  
  // Used in SecondaryCommandBuffer
  class DedicatedCommandBlockPool final
  {
    public:
      DedicatedCommandBlockPool()
          : mAllocator(nullptr),
            mCurrentWritePointer(nullptr),
            mCurrentBytesRemaining(0),
            mCommandBuffer(nullptr)
      {}
  
      static constexpr size_t kCommandHeaderSize = 4;
      using CommandHeaderIDType                  = uint16_t;
      // Make sure the size of command header ID type is less than total command header size.
      static_assert(sizeof(CommandHeaderIDType) < kCommandHeaderSize, "Check size of CommandHeader");
      // Pool Alloc uses 16kB pages w/ 16byte header = 16368bytes. To minimize waste
      //  using a 16368/12 = 1364. Also better perf than 1024 due to fewer block allocations
      static constexpr size_t kBlockSize = 1360;
      // Make sure block size is 8-byte aligned to avoid ASAN errors.
      static_assert((kBlockSize % 8) == 0, "Check kBlockSize alignment");
  
      void setCommandBuffer(priv::SecondaryCommandBuffer *commandBuffer)
      {
          mCommandBuffer = commandBuffer;
      }
      void resetCommandBuffer() { mCommandBuffer = nullptr; }
  
      void reset(CommandBufferCommandTracker *commandBufferTracker);
  
      // Initialize the SecondaryCommandBuffer by setting the allocator it will use
      angle::Result initialize(DedicatedCommandMemoryAllocator *allocator);
  
      bool valid() const { return mAllocator != nullptr; }
      bool empty() const;
  
      void getMemoryUsageStats(size_t *usedMemoryOut, size_t *allocatedMemoryOut) const;
  
      void onNewVariableSizedCommand(const size_t requiredSize,
                                     const size_t allocationSize,
                                     uint8_t **headerOut)
      {
          if (mCurrentBytesRemaining < requiredSize)
          {
              // variable size command can potentially exceed default cmd allocation blockSize
              if (requiredSize <= kBlockSize)
              {
                  allocateNewBlock();
              }
              else
              {
                  // Make sure allocation is 4-byte aligned
                  const size_t alignedSize = roundUpPow2<size_t>(requiredSize, 4);
                  ASSERT((alignedSize % 4) == 0);
                  allocateNewBlock(alignedSize);
              }
          }
  
          *headerOut = updateHeaderAndAllocatorParams(allocationSize);
      }
  
      void onNewCommand(const size_t requiredSize, const size_t allocationSize, uint8_t **headerOut)
      {
          if (mCurrentBytesRemaining < requiredSize)
          {
              ASSERT(requiredSize <= kBlockSize);
              allocateNewBlock();
          }
  
          *headerOut = updateHeaderAndAllocatorParams(allocationSize);
      }
  
    private:
      void allocateNewBlock(size_t blockSize = kBlockSize);
  
      uint8_t *updateHeaderAndAllocatorParams(size_t allocationSize)
      {
          mCurrentBytesRemaining -= allocationSize;
          uint8_t *headerPointer = mCurrentWritePointer;
          mCurrentWritePointer += allocationSize;
          // Set next cmd header to Invalid (0) so cmd sequence will be terminated
          reinterpret_cast<CommandHeaderIDType &>(*mCurrentWritePointer) = 0;
  
          return headerPointer;
      }
  
      // Using a pool allocator per CBH to avoid threading issues that occur w/ shared allocator
      // between multiple CBHs.
      DedicatedCommandMemoryAllocator *mAllocator;
      uint8_t *mCurrentWritePointer;
      size_t mCurrentBytesRemaining;
  
      // Points to the parent command buffer.
      priv::SecondaryCommandBuffer *mCommandBuffer;
  };
  
  }  // namespace vk
  }  // namespace rx
  
  #endif  // LIBANGLE_RENDERER_VULKAN_ALLOCATORHELPERPOOL_H_
  

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