1 //===- llvm/Support/Options.h - Debug options support -----------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 /// \file 10 /// This file declares helper objects for defining debug options that can be 11 /// configured via the command line. The new API currently builds on the cl::opt 12 /// API, but does not require the use of static globals. 13 /// 14 /// With this API options are registered during initialization. For passes, this 15 /// happens during pass initialization. Passes with options will call a static 16 /// registerOptions method during initialization that registers options with the 17 /// OptionRegistry. An example implementation of registerOptions is: 18 /// 19 /// static void registerOptions() { 20 /// OptionRegistry::registerOption<bool, Scalarizer, 21 /// &Scalarizer::ScalarizeLoadStore>( 22 /// "scalarize-load-store", 23 /// "Allow the scalarizer pass to scalarize loads and store", false); 24 /// } 25 /// 26 /// When reading data for options the interface is via the LLVMContext. Option 27 /// data for passes should be read from the context during doInitialization. An 28 /// example of reading the above option would be: 29 /// 30 /// ScalarizeLoadStore = 31 /// M.getContext().getOption<bool, 32 /// Scalarizer, 33 /// &Scalarizer::ScalarizeLoadStore>(); 34 /// 35 //===----------------------------------------------------------------------===// 36 37 #ifndef LLVM_SUPPORT_OPTIONS_H 38 #define LLVM_SUPPORT_OPTIONS_H 39 40 #include "llvm/ADT/DenseMap.h" 41 #include "llvm/Support/CommandLine.h" 42 43 namespace llvm { 44 45 namespace detail { 46 47 // Options are keyed of the unique address of a static character synthesized 48 // based on template arguments. 49 template <typename ValT, typename Base, ValT(Base::*Mem)> class OptionKey { 50 public: 51 static char ID; 52 }; 53 54 template <typename ValT, typename Base, ValT(Base::*Mem)> 55 char OptionKey<ValT, Base, Mem>::ID = 0; 56 57 } // namespace detail 58 59 /// \brief Singleton class used to register debug options. 60 /// 61 /// The OptionRegistry is responsible for managing lifetimes of the options and 62 /// provides interfaces for option registration and reading values from options. 63 /// This object is a singleton, only one instance should ever exist so that all 64 /// options are registered in the same place. 65 class OptionRegistry { 66 private: 67 DenseMap<void *, cl::Option *> Options; 68 69 /// \brief Adds a cl::Option to the registry. 70 /// 71 /// \param Key unique key for option 72 /// \param O option to map to \p Key 73 /// 74 /// Allocated cl::Options are owned by the OptionRegistry and are deallocated 75 /// on destruction or removal 76 void addOption(void *Key, cl::Option *O); 77 78 public: 79 ~OptionRegistry(); 80 OptionRegistry() {} 81 82 /// \brief Returns a reference to the singleton instance. 83 static OptionRegistry &instance(); 84 85 /// \brief Registers an option with the OptionRegistry singleton. 86 /// 87 /// \tparam ValT type of the option's data 88 /// \tparam Base class used to key the option 89 /// \tparam Mem member of \p Base used for keying the option 90 /// 91 /// Options are keyed off the template parameters to generate unique static 92 /// characters. The template parameters are (1) the type of the data the 93 /// option stores (\p ValT), the class that will read the option (\p Base), 94 /// and the member that the class will store the data into (\p Mem). 95 template <typename ValT, typename Base, ValT(Base::*Mem)> 96 static void registerOption(StringRef ArgStr, StringRef Desc, 97 const ValT &InitValue) { 98 cl::opt<ValT> *Option = new cl::opt<ValT>(ArgStr, cl::desc(Desc), 99 cl::Hidden, cl::init(InitValue)); 100 instance().addOption(&detail::OptionKey<ValT, Base, Mem>::ID, Option); 101 } 102 103 /// \brief Returns the value of the option. 104 /// 105 /// \tparam ValT type of the option's data 106 /// \tparam Base class used to key the option 107 /// \tparam Mem member of \p Base used for keying the option 108 /// 109 /// Reads option values based on the key generated by the template parameters. 110 /// Keying for get() is the same as keying for registerOption. 111 template <typename ValT, typename Base, ValT(Base::*Mem)> ValT get() const { 112 auto It = Options.find(&detail::OptionKey<ValT, Base, Mem>::ID); 113 assert(It != Options.end() && "Option not in OptionRegistry"); 114 return *(cl::opt<ValT> *)It->second; 115 } 116 }; 117 118 } // namespace llvm 119 120 #endif 121
