llvm/clang/include/clang/CodeGen/ConstantInitBuilder.h

//===- ConstantInitBuilder.h - Builder for LLVM IR constants ----*- 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
//
//===----------------------------------------------------------------------===//
//
// This class provides a convenient interface for building complex
// global initializers of the sort that are frequently required for
// language ABIs.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_CODEGEN_CONSTANTINITBUILDER_H
#define LLVM_CLANG_CODEGEN_CONSTANTINITBUILDER_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/GlobalValue.h"
#include "clang/AST/CharUnits.h"
#include "clang/CodeGen/ConstantInitFuture.h"

#include <vector>

namespace clang {
class GlobalDecl;
class PointerAuthSchema;
class QualType;

namespace CodeGen {
class CodeGenModule;

/// A convenience builder class for complex constant initializers,
/// especially for anonymous global structures used by various language
/// runtimes.
///
/// The basic usage pattern is expected to be something like:
///    ConstantInitBuilder builder(CGM);
///    auto toplevel = builder.beginStruct();
///    toplevel.addInt(CGM.SizeTy, widgets.size());
///    auto widgetArray = builder.beginArray();
///    for (auto &widget : widgets) {
///      auto widgetDesc = widgetArray.beginStruct();
///      widgetDesc.addInt(CGM.SizeTy, widget.getPower());
///      widgetDesc.add(CGM.GetAddrOfConstantStringFromLiteral(widget.getName()));
///      widgetDesc.add(CGM.GetAddrOfGlobal(widget.getInitializerDecl()));
///      widgetDesc.finishAndAddTo(widgetArray);
///    }
///    widgetArray.finishAndAddTo(toplevel);
///    auto global = toplevel.finishAndCreateGlobal("WIDGET_LIST", Align,
///                                                 /*constant*/ true);
class ConstantInitBuilderBase { … };

/// A concrete base class for struct and array aggregate
/// initializer builders.
class ConstantAggregateBuilderBase { … };

template <class Impl, class Traits>
class ConstantAggregateBuilderTemplateBase
    : public Traits::AggregateBuilderBase { … };

template <class Traits>
class ConstantArrayBuilderTemplateBase
  : public ConstantAggregateBuilderTemplateBase<typename Traits::ArrayBuilder,
                                                Traits> { … };

/// A template class designed to allow other frontends to
/// easily customize the builder classes used by ConstantInitBuilder,
/// and thus to extend the API to work with the abstractions they
/// prefer.  This would probably not be necessary if C++ just
/// supported extension methods.
template <class Traits>
class ConstantStructBuilderTemplateBase
  : public ConstantAggregateBuilderTemplateBase<typename Traits::StructBuilder,
                                                Traits> { … };

/// A template class designed to allow other frontends to
/// easily customize the builder classes used by ConstantInitBuilder,
/// and thus to extend the API to work with the abstractions they
/// prefer.  This would probably not be necessary if C++ just
/// supported extension methods.
template <class Traits>
class ConstantInitBuilderTemplateBase : public ConstantInitBuilderBase { … };

class ConstantInitBuilder;
class ConstantStructBuilder;
class ConstantArrayBuilder;

struct ConstantInitBuilderTraits { … };

/// The standard implementation of ConstantInitBuilder used in Clang.
class ConstantInitBuilder
    : public ConstantInitBuilderTemplateBase<ConstantInitBuilderTraits> { … };

/// A helper class of ConstantInitBuilder, used for building constant
/// array initializers.
class ConstantArrayBuilder
    : public ConstantArrayBuilderTemplateBase<ConstantInitBuilderTraits> { … };

/// A helper class of ConstantInitBuilder, used for building constant
/// struct initializers.
class ConstantStructBuilder
    : public ConstantStructBuilderTemplateBase<ConstantInitBuilderTraits> { … };

}  // end namespace CodeGen
}  // end namespace clang

#endif