1 files changed, 212 insertions, 0 deletions
diff --git a/media/highway/src/hwy/aligned_allocator.h b/media/highway/src/hwy/aligned_allocator.h
new file mode 100644
index 0000000000..f6bfca11ee
--- /dev/null
+++ b/media/highway/src/hwy/aligned_allocator.h
@@ -0,0 +1,212 @@
+// Copyright 2020 Google LLC
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef HIGHWAY_HWY_ALIGNED_ALLOCATOR_H_
+#define HIGHWAY_HWY_ALIGNED_ALLOCATOR_H_
+
+// Memory allocator with support for alignment and offsets.
+
+#include <stddef.h>
+
+#include <memory>
+
+#include "hwy/highway_export.h"
+
+namespace hwy {
+
+// Minimum alignment of allocated memory for use in HWY_ASSUME_ALIGNED, which
+// requires a literal. This matches typical L1 cache line sizes, which prevents
+// false sharing.
+#define HWY_ALIGNMENT 64
+
+// Pointers to functions equivalent to malloc/free with an opaque void* passed
+// to them.
+using AllocPtr = void* (*)(void* opaque, size_t bytes);
+using FreePtr = void (*)(void* opaque, void* memory);
+
+// Returns null or a pointer to at least `payload_size` (which can be zero)
+// bytes of newly allocated memory, aligned to the larger of HWY_ALIGNMENT and
+// the vector size. Calls `alloc` with the passed `opaque` pointer to obtain
+// memory or malloc() if it is null.
+HWY_DLLEXPORT void* AllocateAlignedBytes(size_t payload_size,
+                                         AllocPtr alloc_ptr, void* opaque_ptr);
+
+// Frees all memory. No effect if `aligned_pointer` == nullptr, otherwise it
+// must have been returned from a previous call to `AllocateAlignedBytes`.
+// Calls `free_ptr` with the passed `opaque_ptr` pointer to free the memory; if
+// `free_ptr` function is null, uses the default free().
+HWY_DLLEXPORT void FreeAlignedBytes(const void* aligned_pointer,
+                                    FreePtr free_ptr, void* opaque_ptr);
+
+// Class that deletes the aligned pointer passed to operator() calling the
+// destructor before freeing the pointer. This is equivalent to the
+// std::default_delete but for aligned objects. For a similar deleter equivalent
+// to free() for aligned memory see AlignedFreer().
+class AlignedDeleter {
+ public:
+  AlignedDeleter() : free_(nullptr), opaque_ptr_(nullptr) {}
+  AlignedDeleter(FreePtr free_ptr, void* opaque_ptr)
+      : free_(free_ptr), opaque_ptr_(opaque_ptr) {}
+
+  template <typename T>
+  void operator()(T* aligned_pointer) const {
+    return DeleteAlignedArray(aligned_pointer, free_, opaque_ptr_,
+                              TypedArrayDeleter<T>);
+  }
+
+ private:
+  template <typename T>
+  static void TypedArrayDeleter(void* ptr, size_t size_in_bytes) {
+    size_t elems = size_in_bytes / sizeof(T);
+    for (size_t i = 0; i < elems; i++) {
+      // Explicitly call the destructor on each element.
+      (static_cast<T*>(ptr) + i)->~T();
+    }
+  }
+
+  // Function prototype that calls the destructor for each element in a typed
+  // array. TypeArrayDeleter<T> would match this prototype.
+  using ArrayDeleter = void (*)(void* t_ptr, size_t t_size);
+
+  HWY_DLLEXPORT static void DeleteAlignedArray(void* aligned_pointer,
+                                               FreePtr free_ptr,
+                                               void* opaque_ptr,
+                                               ArrayDeleter deleter);
+
+  FreePtr free_;
+  void* opaque_ptr_;
+};
+
+// Unique pointer to T with custom aligned deleter. This can be a single
+// element U or an array of element if T is a U[]. The custom aligned deleter
+// will call the destructor on U or each element of a U[] in the array case.
+template <typename T>
+using AlignedUniquePtr = std::unique_ptr<T, AlignedDeleter>;
+
+// Aligned memory equivalent of make_unique<T> using the custom allocators
+// alloc/free with the passed `opaque` pointer. This function calls the
+// constructor with the passed Args... and calls the destructor of the object
+// when the AlignedUniquePtr is destroyed.
+template <typename T, typename... Args>
+AlignedUniquePtr<T> MakeUniqueAlignedWithAlloc(AllocPtr alloc, FreePtr free,
+                                               void* opaque, Args&&... args) {
+  T* ptr = static_cast<T*>(AllocateAlignedBytes(sizeof(T), alloc, opaque));
+  return AlignedUniquePtr<T>(new (ptr) T(std::forward<Args>(args)...),
+                             AlignedDeleter(free, opaque));
+}
+
+// Similar to MakeUniqueAlignedWithAlloc but using the default alloc/free
+// functions.
+template <typename T, typename... Args>
+AlignedUniquePtr<T> MakeUniqueAligned(Args&&... args) {
+  T* ptr = static_cast<T*>(AllocateAlignedBytes(
+      sizeof(T), /*alloc_ptr=*/nullptr, /*opaque_ptr=*/nullptr));
+  return AlignedUniquePtr<T>(new (ptr) T(std::forward<Args>(args)...),
+                             AlignedDeleter());
+}
+
+// Helpers for array allocators (avoids overflow)
+namespace detail {
+
+// Returns x such that 1u << x == n (if n is a power of two).
+static inline constexpr size_t ShiftCount(size_t n) {
+  return (n <= 1) ? 0 : 1 + ShiftCount(n / 2);
+}
+
+template <typename T>
+T* AllocateAlignedItems(size_t items, AllocPtr alloc_ptr, void* opaque_ptr) {
+  constexpr size_t size = sizeof(T);
+
+  constexpr bool is_pow2 = (size & (size - 1)) == 0;
+  constexpr size_t bits = ShiftCount(size);
+  static_assert(!is_pow2 || (1ull << bits) == size, "ShiftCount is incorrect");
+
+  const size_t bytes = is_pow2 ? items << bits : items * size;
+  const size_t check = is_pow2 ? bytes >> bits : bytes / size;
+  if (check != items) {
+    return nullptr;  // overflowed
+  }
+  return static_cast<T*>(AllocateAlignedBytes(bytes, alloc_ptr, opaque_ptr));
+}
+
+}  // namespace detail
+
+// Aligned memory equivalent of make_unique<T[]> for array types using the
+// custom allocators alloc/free. This function calls the constructor with the
+// passed Args... on every created item. The destructor of each element will be
+// called when the AlignedUniquePtr is destroyed.
+template <typename T, typename... Args>
+AlignedUniquePtr<T[]> MakeUniqueAlignedArrayWithAlloc(
+    size_t items, AllocPtr alloc, FreePtr free, void* opaque, Args&&... args) {
+  T* ptr = detail::AllocateAlignedItems<T>(items, alloc, opaque);
+  if (ptr != nullptr) {
+    for (size_t i = 0; i < items; i++) {
+      new (ptr + i) T(std::forward<Args>(args)...);
+    }
+  }
+  return AlignedUniquePtr<T[]>(ptr, AlignedDeleter(free, opaque));
+}
+
+template <typename T, typename... Args>
+AlignedUniquePtr<T[]> MakeUniqueAlignedArray(size_t items, Args&&... args) {
+  return MakeUniqueAlignedArrayWithAlloc<T, Args...>(
+      items, nullptr, nullptr, nullptr, std::forward<Args>(args)...);
+}
+
+// Custom deleter for std::unique_ptr equivalent to using free() as a deleter
+// but for aligned memory.
+class AlignedFreer {
+ public:
+  // Pass address of this to ctor to skip deleting externally-owned memory.
+  static void DoNothing(void* /*opaque*/, void* /*aligned_pointer*/) {}
+
+  AlignedFreer() : free_(nullptr), opaque_ptr_(nullptr) {}
+  AlignedFreer(FreePtr free_ptr, void* opaque_ptr)
+      : free_(free_ptr), opaque_ptr_(opaque_ptr) {}
+
+  template <typename T>
+  void operator()(T* aligned_pointer) const {
+    // TODO(deymo): assert that we are using a POD type T.
+    FreeAlignedBytes(aligned_pointer, free_, opaque_ptr_);
+  }
+
+ private:
+  FreePtr free_;
+  void* opaque_ptr_;
+};
+
+// Unique pointer to single POD, or (if T is U[]) an array of POD. For non POD
+// data use AlignedUniquePtr.
+template <typename T>
+using AlignedFreeUniquePtr = std::unique_ptr<T, AlignedFreer>;
+
+// Allocate an aligned and uninitialized array of POD values as a unique_ptr.
+// Upon destruction of the unique_ptr the aligned array will be freed.
+template <typename T>
+AlignedFreeUniquePtr<T[]> AllocateAligned(const size_t items, AllocPtr alloc,
+                                          FreePtr free, void* opaque) {
+  return AlignedFreeUniquePtr<T[]>(
+      detail::AllocateAlignedItems<T>(items, alloc, opaque),
+      AlignedFreer(free, opaque));
+}
+
+// Same as previous AllocateAligned(), using default allocate/free functions.
+template <typename T>
+AlignedFreeUniquePtr<T[]> AllocateAligned(const size_t items) {
+  return AllocateAligned<T>(items, nullptr, nullptr, nullptr);
+}
+
+}  // namespace hwy
+#endif  // HIGHWAY_HWY_ALIGNED_ALLOCATOR_H_