LLVM  9.0.0svn
OptBisect.h
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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 
19 namespace llvm {
20 
21 class Pass;
22 
23 /// Extensions to this class implement mechanisms to disable passes and
24 /// individual optimizations at compile time.
25 class OptPassGate {
26 public:
27  virtual ~OptPassGate() = default;
28 
29  /// IRDescription is a textual description of the IR unit the pass is running
30  /// over.
31  virtual bool shouldRunPass(const Pass *P, StringRef IRDescription) {
32  return true;
33  }
34 
35  /// isEnabled should return true before calling shouldRunPass
36  virtual bool isEnabled() const { return false; }
37 };
38 
39 /// This class implements a mechanism to disable passes and individual
40 /// optimizations at compile time based on a command line option
41 /// (-opt-bisect-limit) in order to perform a bisecting search for
42 /// optimization-related problems.
43 class OptBisect : public OptPassGate {
44 public:
45  /// Default constructor, initializes the OptBisect state based on the
46  /// -opt-bisect-limit command line argument.
47  ///
48  /// By default, bisection is disabled.
49  ///
50  /// Clients should not instantiate this class directly. All access should go
51  /// through LLVMContext.
52  OptBisect();
53 
54  virtual ~OptBisect() = default;
55 
56  /// Checks the bisect limit to determine if the specified pass should run.
57  ///
58  /// If the bisect limit is set to -1, the function prints a message describing
59  /// the pass and the bisect number assigned to it and return true. Otherwise,
60  /// the function prints a message with the bisect number assigned to the
61  /// pass and indicating whether or not the pass will be run and return true if
62  /// the bisect limit has not yet been exceeded or false if it has.
63  ///
64  /// Most passes should not call this routine directly. Instead, they are
65  /// called through helper routines provided by the pass base classes. For
66  /// instance, function passes should call FunctionPass::skipFunction().
67  bool shouldRunPass(const Pass *P, StringRef IRDescription) override;
68 
69  /// isEnabled should return true before calling shouldRunPass
70  bool isEnabled() const override { return BisectEnabled; }
71 private:
72  bool checkPass(const StringRef PassName, const StringRef TargetDesc);
73 
74  bool BisectEnabled = false;
75  unsigned LastBisectNum = 0;
76 };
77 
78 } // end namespace llvm
79 
80 #endif // LLVM_IR_OPTBISECT_H
Pass interface - Implemented by all 'passes'.
Definition: Pass.h:80
virtual ~OptPassGate()=default
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Extensions to this class implement mechanisms to disable passes and individual optimizations at compi...
Definition: OptBisect.h:25
virtual bool shouldRunPass(const Pass *P, StringRef IRDescription)
IRDescription is a textual description of the IR unit the pass is running over.
Definition: OptBisect.h:31
bool isEnabled() const override
isEnabled should return true before calling shouldRunPass
Definition: OptBisect.h:70
virtual bool isEnabled() const
isEnabled should return true before calling shouldRunPass
Definition: OptBisect.h:36
This class implements a mechanism to disable passes and individual optimizations at compile time base...
Definition: OptBisect.h:43
#define P(N)
print lazy value Lazy Value Info Printer Pass
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48