include/llvm/IR/OptBisect.h

   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