llvm/bolt/include/bolt/Core/FunctionLayout.h

//===- bolt/Core/FunctionLayout.h - Fragmented Function Layout --*- 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 contains the declaration of the FunctionLayout class. The layout of
// a function is the order of basic blocks, in which we will arrange them in the
// new binary. Normally, when not optimizing for code layout, the blocks of a
// function are contiguous. However, we can split the layout into multiple
// fragments. The blocks within a fragment are contiguous, but the fragments
// itself are disjoint. Fragments could be used to enhance code layout, e.g. to
// separate the blocks into hot and cold sections.
//
//===----------------------------------------------------------------------===//

#ifndef BOLT_CORE_FUNCTION_LAYOUT_H
#define BOLT_CORE_FUNCTION_LAYOUT_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/iterator.h"
#include "llvm/ADT/iterator_range.h"
#include <iterator>

namespace llvm {
namespace bolt {

class BinaryFunction;
class BinaryBasicBlock;
class FunctionLayout;

class FragmentNum { … };

/// A freestanding subset of contiguous blocks of a function.
class FunctionFragment { … };

/// The function layout represents the fragments we split a function into and
/// the order of basic blocks within each fragment.
///
/// Internally, the function layout stores blocks across fragments contiguously.
/// This is necessary to retain compatibility with existing code and tests that
/// iterate  over all blocks of the layout and depend on that order. When
/// writing new code, avoid iterating using FunctionLayout::blocks() by
/// iterating either over fragments or over BinaryFunction::begin()..end().
class FunctionLayout { … };

} // namespace bolt
} // namespace llvm

#endif