mirror of
https://github.com/dart-lang/sdk
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829ef92778
We originally sized the compressed heap at 2GB to avoid implementing alignment offsets. (When decompression is sign-extension + base, base should be the middle of a 4GB-aligned region.) After 8db0a975c1, the needed alignment offset is zero, and we no longer need to avoid the high bit being set.
TEST=ci
Change-Id: Ib6e6c40bcb9638e01867edd527b3acaaccec570b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/191321
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Liam Appelbe <liama@google.com>
71 lines
2.3 KiB
C++
71 lines
2.3 KiB
C++
// Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef RUNTIME_VM_VIRTUAL_MEMORY_COMPRESSED_H_
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#define RUNTIME_VM_VIRTUAL_MEMORY_COMPRESSED_H_
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#include "vm/globals.h"
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#include "vm/heap/pages.h"
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#include "vm/memory_region.h"
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namespace dart {
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#if defined(DART_COMPRESSED_POINTERS)
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static constexpr intptr_t kCompressedHeapSize = 4 * GB;
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static constexpr intptr_t kCompressedHeapAlignment = 4 * GB;
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static constexpr intptr_t kCompressedHeapPageSize = kOldPageSize;
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static constexpr intptr_t kCompressedHeapNumPages =
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kCompressedHeapSize / kOldPageSize;
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static constexpr intptr_t kCompressedHeapBitmapSize =
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kCompressedHeapNumPages / 8;
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#if !defined(HOST_OS_FUCHSIA)
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#define DART_COMPRESSED_HEAP
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#endif // !defined(HOST_OS_FUCHSIA)
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#endif // defined(DART_COMPRESSED_POINTERS)
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#if defined(DART_COMPRESSED_HEAP)
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// Utilities for allocating memory within a contiguous region of memory, for use
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// with compressed pointers.
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class VirtualMemoryCompressedHeap : public AllStatic {
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public:
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// Initializes the compressed heap. The callee must allocate a region of
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// kCompressedHeapSize bytes, aligned to kCompressedHeapSize.
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static void Init(void* compressed_heap_region);
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// Cleans up the compressed heap. The callee is responsible for freeing the
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// region's memory.
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static void Cleanup();
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// Allocates a segment of the compressed heap with the given size. Returns a
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// heap memory region if a large enough free segment can't be found.
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static MemoryRegion Allocate(intptr_t size, intptr_t alignment);
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// Frees a segment.
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static void Free(void* address, intptr_t size);
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// Returns whether the address is within the compressed heap.
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static bool Contains(void* address);
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// Returns a pointer to the compressed heap region.
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static void* GetRegion();
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private:
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static bool IsPageUsed(uword page_id);
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static void SetPageUsed(uword page_id);
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static void ClearPageUsed(uword page_id);
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static uword base_;
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static uint8_t* pages_;
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static uword minimum_free_page_id_;
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static Mutex* mutex_;
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};
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#endif // defined(DART_COMPRESSED_HEAP)
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} // namespace dart
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#endif // RUNTIME_VM_VIRTUAL_MEMORY_COMPRESSED_H_
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