1 //===- llvm/Support/Options.h - Debug options support -----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
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:
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);
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:
30 /// ScalarizeLoadStore =
31 /// M.getContext().getOption<bool,
33 /// &Scalarizer::ScalarizeLoadStore>();
35 //===----------------------------------------------------------------------===//
37 #include "llvm/ADT/DenseMap.h"
38 #include "llvm/Support/CommandLine.h"
44 // Options are keyed of the unique address of a static character synthesized
45 // based on template arguments.
46 template <typename ValT, typename Base, ValT(Base::*Mem)> class OptionKey {
51 template <typename ValT, typename Base, ValT(Base::*Mem)>
52 char OptionKey<ValT, Base, Mem>::ID = 0;
56 /// \brief Singleton class used to register debug options.
58 /// The OptionRegistry is responsible for managing lifetimes of the options and
59 /// provides interfaces for option registration and reading values from options.
60 /// This object is a singleton, only one instance should ever exist so that all
61 /// options are registered in teh same place.
62 class OptionRegistry {
64 DenseMap<void *, cl::Option *> Options;
66 /// \brief Adds a cl::Option to the registry.
68 /// \param Key unique key for option
69 /// \param O option to map to \p Key
71 /// Allocated cl::Options are owened by the OptionRegistry and are deallocated
72 /// on destruction or removal
73 void addOption(void *Key, cl::Option *O);
79 /// \brief Returns a reference to the singleton instance.
80 static OptionRegistry &instance();
82 /// \brief Registers an option with the OptionRegistry singleton.
84 /// \tparam ValT type of the option's data
85 /// \tparam Base class used to key the option
86 /// \tparam Mem member of \p Base used for keying the option
88 /// Options are keyed off the template parameters to generate unique static
89 /// characters. The template parameters are (1) the type of the data the
90 /// option stores (\p ValT), the class that will read the option (\p Base),
91 /// and the memeber that the class will store the data into (\p Mem).
92 template <typename ValT, typename Base, ValT(Base::*Mem)>
93 static void registerOption(const char *ArgStr, const char *Desc,
94 const ValT &InitValue) {
95 cl::opt<ValT> *Option = new cl::opt<ValT>(ArgStr, cl::desc(Desc),
96 cl::Hidden, cl::init(InitValue));
97 instance().addOption(&detail::OptionKey<ValT, Base, Mem>::ID, Option);
100 /// \brief Returns the value of the option.
102 /// \tparam ValT type of the option's data
103 /// \tparam Base class used to key the option
104 /// \tparam Mem member of \p Base used for keying the option
106 /// Reads option values based on the key generated by the template parameters.
107 /// Keying for get() is the same as keying for registerOption.
108 template <typename ValT, typename Base, ValT(Base::*Mem)> ValT get() const {
109 auto It = Options.find(&detail::OptionKey<ValT, Base, Mem>::ID);
110 assert(It != Options.end() && "Option not in OptionRegistry");
111 return *(cl::opt<ValT> *)It->second;