1//===- llvm/IR/OptBisect.h - LLVM Bisect support ----------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file declares the interface for bisecting optimizations.
11///
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_IR_OPTBISECT_H
15#define LLVM_IR_OPTBISECT_H
16
17#include "llvm/ADT/StringRef.h"
18#include "llvm/Support/ManagedStatic.h"
19
20namespace llvm {
21
22class Pass;
23
24/// Extensions to this class implement mechanisms to disable passes and
25/// individual optimizations at compile time.
26class OptPassGate {
27public:
28 virtual ~OptPassGate() = default;
29
30 /// IRDescription is a textual description of the IR unit the pass is running
31 /// over.
32 virtual bool shouldRunPass(const Pass *P, StringRef IRDescription) {
33 return true;
34 }
35
36 /// isEnabled() should return true before calling shouldRunPass().
37 virtual bool isEnabled() const { return false; }
38};
39
40/// This class implements a mechanism to disable passes and individual
41/// optimizations at compile time based on a command line option
42/// (-opt-bisect-limit) in order to perform a bisecting search for
43/// optimization-related problems.
44class OptBisect : public OptPassGate {
45public:
46 /// Default constructor, initializes the OptBisect state based on the
47 /// -opt-bisect-limit command line argument.
48 ///
49 /// By default, bisection is disabled.
50 ///
51 /// Clients should not instantiate this class directly. All access should go
52 /// through LLVMContext.
53 OptBisect();
54
55 virtual ~OptBisect() = default;
56
57 /// Checks the bisect limit to determine if the specified pass should run.
58 ///
59 /// This forwards to checkPass().
60 bool shouldRunPass(const Pass *P, StringRef IRDescription) override;
61
62 /// isEnabled() should return true before calling shouldRunPass().
63 bool isEnabled() const override { return BisectEnabled; }
64
65 /// Checks the bisect limit to determine if the specified pass should run.
66 ///
67 /// If the bisect limit is set to -1, the function prints a message describing
68 /// the pass and the bisect number assigned to it and return true. Otherwise,
69 /// the function prints a message with the bisect number assigned to the
70 /// pass and indicating whether or not the pass will be run and return true if
71 /// the bisect limit has not yet been exceeded or false if it has.
72 ///
73 /// Most passes should not call this routine directly. Instead, they are
74 /// called through helper routines provided by the pass base classes. For
75 /// instance, function passes should call FunctionPass::skipFunction().
76 bool checkPass(const StringRef PassName, const StringRef TargetDesc);
77
78private:
79 bool BisectEnabled = false;
80 unsigned LastBisectNum = 0;
81};
82
83/// Singleton instance of the OptBisect class, so multiple pass managers don't
84/// need to coordinate their uses of OptBisect.
85extern ManagedStatic<OptBisect> OptBisector;
86} // end namespace llvm
87
88#endif // LLVM_IR_OPTBISECT_H
89