TailDuplication.h | Explore in Territory

//===- bolt/Passes/TailDuplication.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
//
//===----------------------------------------------------------------------===//
//
// This pass founds cases when BBs have layout:
// #BB0:
// <body>
// jmp #BB2
// ....
// #BB1
// <body>
// #BB2:
// <body>
//
// And duplicates #BB2 and puts it after #BB0:
// #BB0:
// <body>
// #BB2:
// <body>
// ....
// #BB1
// <body>
// #BB2:
// <body>
//
// The advantage is getting rid of an unconditional branch and hopefully to
// improve i-cache performance by reducing fragmentation The disadvantage is
// that if there is too much code duplication, we may end up evicting hot cache
// lines and causing the opposite effect, hurting i-cache performance This needs
// to be well balanced to achieve the optimal effect
//
//===----------------------------------------------------------------------===//

#ifndef BOLT_PASSES_TAILDUPLICATION_H
#define BOLT_PASSES_TAILDUPLICATION_H

#include "bolt/Passes/BinaryPasses.h"

namespace llvm {
namespace bolt {

/// Pass for duplicating blocks that would require a jump.
class TailDuplication : public BinaryFunctionPass { … };

} // namespace bolt
} // namespace llvm

#endif
llvm/bolt/include/bolt/Passes/TailDuplication.h
