llvm/bolt/include/bolt/Passes/CMOVConversion.h

//===- bolt/Passes/CMOVConversion.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 finds the following patterns:
//         jcc
//        /   \
// (empty)    mov src, dst
//        \   /
//
// and replaces them with:
//
//   cmovcc src, dst
//
// The advantage of performing this conversion in BOLT (compared to compiler
// heuristic driven instruction selection) is that BOLT can use LBR
// misprediction information and only convert poorly predictable branches.
// Note that branch misprediction rate is different from branch bias.
// For well-predictable branches, it might be beneficial to leave jcc+mov as is
// from microarchitectural perspective to avoid unneeded dependencies (CMOV
// instruction has a dataflow dependence on flags and both operands).
//
//===----------------------------------------------------------------------===//

#ifndef BOLT_PASSES_CMOVCONVERSION_H
#define BOLT_PASSES_CMOVCONVERSION_H

#include "bolt/Passes/BinaryPasses.h"

namespace llvm {
namespace bolt {

/// Pass for folding eligible hammocks into CMOV's if profitable.
class CMOVConversion : public BinaryFunctionPass { … };

} // namespace bolt
} // namespace llvm

#endif