================ @@ -0,0 +1,323 @@ +//===- llvm/ADT/PagedVector.h - 'Lazyly allocated' vectors --------*- C++ +//-*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file defines the PagedVector class. +// +//===----------------------------------------------------------------------===// +#ifndef LLVM_ADT_PAGEDVECTOR_H +#define LLVM_ADT_PAGEDVECTOR_H + +#include "llvm/ADT/PointerIntPair.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/iterator_range.h" +#include "llvm/Support/Allocator.h" +#include <cassert> +#include <vector> + +namespace llvm { +/// A vector that allocates memory in pages. +/// +/// Order is kept, but memory is allocated only when one element of the page is +/// accessed. This introduces a level of indirection, but it is useful when you +/// have a sparsely initialised vector where the full size is allocated upfront. +/// +/// As a side effect the elements are initialised later than in a normal vector. +/// On the first access to one of the elements of a given page all, the elements +/// of the page are initialised. This also means that the elements of the page +/// are initialised beyond the size of the vector. +/// +/// Similarly on destruction the elements are destroyed only when the page is +/// not needed anymore, delaying invoking the destructor of the elements. +/// +/// Notice that this does not have iterators, because if you have iterators it +/// probably means you are going to touch all the memory in any case, so better +/// use a std::vector in the first place. +template <typename T, size_t PageSize = 1024 / sizeof(T)> class PagedVector { + static_assert(PageSize > 1, "PageSize must be greater than 0. Most likely " + "you want it to be greater than 16."); + /// The actual number of element in the vector which can be accessed. + size_t Size = 0; + + /// The position of the initial element of the page in the Data vector. + /// Pages are allocated contiguously in the Data vector. + mutable SmallVector<T *, 0> PageToDataPtrs; ---------------- vgvassilev wrote:
Looks like there was a comment here: https://github.com/llvm/llvm-project/pull/66430#discussion_r1330540304 I guess the idea was to be able to merge the `InvalidPage` into this. https://github.com/llvm/llvm-project/pull/66430 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
