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| 14 | pmbaty | 1 | //===- llvm/IR/OptBisect.h - LLVM Bisect support ----------------*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | /// |
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| 9 | /// \file |
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| 10 | /// This file declares the interface for bisecting optimizations. |
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| 11 | /// |
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| 12 | //===----------------------------------------------------------------------===// |
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| 13 | |||
| 14 | #ifndef LLVM_IR_OPTBISECT_H |
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| 15 | #define LLVM_IR_OPTBISECT_H |
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| 16 | |||
| 17 | #include "llvm/ADT/StringRef.h" |
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| 18 | #include <limits> |
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| 19 | |||
| 20 | namespace llvm { |
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| 21 | |||
| 22 | class Pass; |
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| 23 | |||
| 24 | /// Extensions to this class implement mechanisms to disable passes and |
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| 25 | /// individual optimizations at compile time. |
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| 26 | class OptPassGate { |
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| 27 | public: |
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| 28 | virtual ~OptPassGate() = default; |
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| 29 | |||
| 30 | /// IRDescription is a textual description of the IR unit the pass is running |
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| 31 | /// over. |
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| 32 | virtual bool shouldRunPass(const StringRef PassName, |
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| 33 | StringRef IRDescription) { |
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| 34 | return true; |
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| 35 | } |
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| 36 | |||
| 37 | /// isEnabled() should return true before calling shouldRunPass(). |
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| 38 | virtual bool isEnabled() const { return false; } |
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| 39 | }; |
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| 40 | |||
| 41 | /// This class implements a mechanism to disable passes and individual |
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| 42 | /// optimizations at compile time based on a command line option |
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| 43 | /// (-opt-bisect-limit) in order to perform a bisecting search for |
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| 44 | /// optimization-related problems. |
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| 45 | class OptBisect : public OptPassGate { |
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| 46 | public: |
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| 47 | /// Default constructor. Initializes the state to "disabled". The bisection |
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| 48 | /// will be enabled by the cl::opt call-back when the command line option |
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| 49 | /// is processed. |
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| 50 | /// Clients should not instantiate this class directly. All access should go |
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| 51 | /// through LLVMContext. |
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| 52 | OptBisect() = default; |
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| 53 | |||
| 54 | virtual ~OptBisect() = default; |
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| 55 | |||
| 56 | /// Checks the bisect limit to determine if the specified pass should run. |
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| 57 | /// |
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| 58 | /// This forwards to checkPass(). |
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| 59 | bool shouldRunPass(const StringRef PassName, |
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| 60 | StringRef IRDescription) override; |
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| 61 | |||
| 62 | /// isEnabled() should return true before calling shouldRunPass(). |
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| 63 | bool isEnabled() const override { return BisectLimit != Disabled; } |
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| 64 | |||
| 65 | /// Set the new optimization limit and reset the counter. Passing |
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| 66 | /// OptBisect::Disabled disables the limiting. |
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| 67 | void setLimit(int Limit) { |
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| 68 | BisectLimit = Limit; |
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| 69 | LastBisectNum = 0; |
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| 70 | } |
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| 71 | |||
| 72 | /// Checks the bisect limit to determine if the specified pass should run. |
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| 73 | /// |
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| 74 | /// If the bisect limit is set to -1, the function prints a message describing |
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| 75 | /// the pass and the bisect number assigned to it and return true. Otherwise, |
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| 76 | /// the function prints a message with the bisect number assigned to the |
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| 77 | /// pass and indicating whether or not the pass will be run and return true if |
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| 78 | /// the bisect limit has not yet been exceeded or false if it has. |
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| 79 | /// |
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| 80 | /// Most passes should not call this routine directly. Instead, they are |
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| 81 | /// called through helper routines provided by the pass base classes. For |
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| 82 | /// instance, function passes should call FunctionPass::skipFunction(). |
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| 83 | bool checkPass(const StringRef PassName, const StringRef TargetDesc); |
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| 84 | |||
| 85 | static const int Disabled = std::numeric_limits<int>::max(); |
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| 86 | |||
| 87 | private: |
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| 88 | int BisectLimit = Disabled; |
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| 89 | int LastBisectNum = 0; |
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| 90 | }; |
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| 91 | |||
| 92 | /// Singleton instance of the OptBisect class, so multiple pass managers don't |
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| 93 | /// need to coordinate their uses of OptBisect. |
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| 94 | OptPassGate &getGlobalPassGate(); |
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| 95 | |||
| 96 | } // end namespace llvm |
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| 97 | |||
| 98 | #endif // LLVM_IR_OPTBISECT_H |