llvm/compiler-rt/lib/sanitizer_common/sanitizer_allocator_primary32.h

//===-- sanitizer_allocator_primary32.h -------------------------*- 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
//
//===----------------------------------------------------------------------===//
//
// Part of the Sanitizer Allocator.
//
//===----------------------------------------------------------------------===//
#ifndef SANITIZER_ALLOCATOR_H
#error This file must be included inside sanitizer_allocator.h
#endif

template<class SizeClassAllocator> struct SizeClassAllocator32LocalCache;

// SizeClassAllocator32 -- allocator for 32-bit address space.
// This allocator can theoretically be used on 64-bit arch, but there it is less
// efficient than SizeClassAllocator64.
//
// [kSpaceBeg, kSpaceBeg + kSpaceSize) is the range of addresses which can
// be returned by MmapOrDie().
//
// Region:
//   a result of a single call to MmapAlignedOrDieOnFatalError(kRegionSize,
//                                                             kRegionSize).
// Since the regions are aligned by kRegionSize, there are exactly
// kNumPossibleRegions possible regions in the address space and so we keep
// a ByteMap possible_regions to store the size classes of each Region.
// 0 size class means the region is not used by the allocator.
//
// One Region is used to allocate chunks of a single size class.
// A Region looks like this:
// UserChunk1 .. UserChunkN <gap> MetaChunkN .. MetaChunk1
//
// In order to avoid false sharing the objects of this class should be
// chache-line aligned.

struct SizeClassAllocator32FlagMasks { … };

template <class Params>
class SizeClassAllocator32 { … };