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llvm-mirror/include/llvm/Support/Options.h
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

120 lines
4.5 KiB
C++

//===- llvm/Support/Options.h - Debug options support -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This file declares helper objects for defining debug options that can be
/// configured via the command line. The new API currently builds on the cl::opt
/// API, but does not require the use of static globals.
///
/// With this API options are registered during initialization. For passes, this
/// happens during pass initialization. Passes with options will call a static
/// registerOptions method during initialization that registers options with the
/// OptionRegistry. An example implementation of registerOptions is:
///
/// static void registerOptions() {
/// OptionRegistry::registerOption<bool, Scalarizer,
/// &Scalarizer::ScalarizeLoadStore>(
/// "scalarize-load-store",
/// "Allow the scalarizer pass to scalarize loads and store", false);
/// }
///
/// When reading data for options the interface is via the LLVMContext. Option
/// data for passes should be read from the context during doInitialization. An
/// example of reading the above option would be:
///
/// ScalarizeLoadStore =
/// M.getContext().getOption<bool,
/// Scalarizer,
/// &Scalarizer::ScalarizeLoadStore>();
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_OPTIONS_H
#define LLVM_SUPPORT_OPTIONS_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/CommandLine.h"
namespace llvm {
namespace detail {
// Options are keyed of the unique address of a static character synthesized
// based on template arguments.
template <typename ValT, typename Base, ValT(Base::*Mem)> class OptionKey {
public:
static char ID;
};
template <typename ValT, typename Base, ValT(Base::*Mem)>
char OptionKey<ValT, Base, Mem>::ID = 0;
} // namespace detail
/// Singleton class used to register debug options.
///
/// The OptionRegistry is responsible for managing lifetimes of the options and
/// provides interfaces for option registration and reading values from options.
/// This object is a singleton, only one instance should ever exist so that all
/// options are registered in the same place.
class OptionRegistry {
private:
DenseMap<void *, cl::Option *> Options;
/// Adds a cl::Option to the registry.
///
/// \param Key unique key for option
/// \param O option to map to \p Key
///
/// Allocated cl::Options are owned by the OptionRegistry and are deallocated
/// on destruction or removal
void addOption(void *Key, cl::Option *O);
public:
~OptionRegistry();
OptionRegistry() {}
/// Returns a reference to the singleton instance.
static OptionRegistry &instance();
/// Registers an option with the OptionRegistry singleton.
///
/// \tparam ValT type of the option's data
/// \tparam Base class used to key the option
/// \tparam Mem member of \p Base used for keying the option
///
/// Options are keyed off the template parameters to generate unique static
/// characters. The template parameters are (1) the type of the data the
/// option stores (\p ValT), the class that will read the option (\p Base),
/// and the member that the class will store the data into (\p Mem).
template <typename ValT, typename Base, ValT(Base::*Mem)>
static void registerOption(StringRef ArgStr, StringRef Desc,
const ValT &InitValue) {
cl::opt<ValT> *Option = new cl::opt<ValT>(ArgStr, cl::desc(Desc),
cl::Hidden, cl::init(InitValue));
instance().addOption(&detail::OptionKey<ValT, Base, Mem>::ID, Option);
}
/// Returns the value of the option.
///
/// \tparam ValT type of the option's data
/// \tparam Base class used to key the option
/// \tparam Mem member of \p Base used for keying the option
///
/// Reads option values based on the key generated by the template parameters.
/// Keying for get() is the same as keying for registerOption.
template <typename ValT, typename Base, ValT(Base::*Mem)> ValT get() const {
auto It = Options.find(&detail::OptionKey<ValT, Base, Mem>::ID);
assert(It != Options.end() && "Option not in OptionRegistry");
return *(cl::opt<ValT> *)It->second;
}
};
} // namespace llvm
#endif