//===- llvm/IR/OptBisect.h - LLVM Bisect support ----------------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file declares the interface for bisecting optimizations.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_OPTBISECT_H
#define LLVM_IR_OPTBISECT_H
#include "llvm/ADT/StringRef.h"
#include <limits>
namespace llvm {
class Pass;
/// Extensions to this class implement mechanisms to disable passes and
/// individual optimizations at compile time.
class OptPassGate {
public:
virtual ~OptPassGate() = default;
/// IRDescription is a textual description of the IR unit the pass is running
/// over.
virtual bool shouldRunPass(const StringRef PassName,
StringRef IRDescription) {
return true;
}
/// isEnabled() should return true before calling shouldRunPass().
virtual bool isEnabled() const { return false; }
};
/// This class implements a mechanism to disable passes and individual
/// optimizations at compile time based on a command line option
/// (-opt-bisect-limit) in order to perform a bisecting search for
/// optimization-related problems.
class OptBisect : public OptPassGate {
public:
/// Default constructor. Initializes the state to "disabled". The bisection
/// will be enabled by the cl::opt call-back when the command line option
/// is processed.
/// Clients should not instantiate this class directly. All access should go
/// through LLVMContext.
OptBisect() = default;
virtual ~OptBisect() = default;
/// Checks the bisect limit to determine if the specified pass should run.
///
/// This forwards to checkPass().
bool shouldRunPass(const StringRef PassName,
StringRef IRDescription) override;
/// isEnabled() should return true before calling shouldRunPass().
bool isEnabled() const override { return BisectLimit != Disabled; }
/// Set the new optimization limit and reset the counter. Passing
/// OptBisect::Disabled disables the limiting.
void setLimit(int Limit) {
BisectLimit = Limit;
LastBisectNum = 0;
}
/// Checks the bisect limit to determine if the specified pass should run.
///
/// If the bisect limit is set to -1, the function prints a message describing
/// the pass and the bisect number assigned to it and return true. Otherwise,
/// the function prints a message with the bisect number assigned to the
/// pass and indicating whether or not the pass will be run and return true if
/// the bisect limit has not yet been exceeded or false if it has.
///
/// Most passes should not call this routine directly. Instead, they are
/// called through helper routines provided by the pass base classes. For
/// instance, function passes should call FunctionPass::skipFunction().
bool checkPass(const StringRef PassName, const StringRef TargetDesc);
static const int Disabled = std::numeric_limits<int>::max();
private:
int BisectLimit = Disabled;
int LastBisectNum = 0;
};
/// Singleton instance of the OptBisect class, so multiple pass managers don't
/// need to coordinate their uses of OptBisect.
OptPassGate &getGlobalPassGate();
} // end namespace llvm
#endif // LLVM_IR_OPTBISECT_H