clang/Frontend/LayoutOverrideSource.h

0001 //===--- LayoutOverrideSource.h --Override Record Layouts -------*- C++ -*-===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef LLVM_CLANG_FRONTEND_LAYOUTOVERRIDESOURCE_H
0010 #define LLVM_CLANG_FRONTEND_LAYOUTOVERRIDESOURCE_H
0011
0012 #include "clang/AST/ExternalASTSource.h"
0013 #include "clang/Basic/LLVM.h"
0014 #include "llvm/ADT/StringMap.h"
0015 #include "llvm/ADT/StringRef.h"
0016
0017 namespace clang {
0018   /// An external AST source that overrides the layout of
0019   /// a specified set of record types.
0020   ///
0021   /// This class is used only for testing the ability of external AST sources
0022   /// to override the layout of record types. Its input is the output format
0023   /// of the command-line argument -fdump-record-layouts.
0024   class LayoutOverrideSource : public ExternalASTSource {
0025     /// The layout of a given record.
0026     struct Layout {
0027       /// The size of the record.
0028       uint64_t Size;
0029
0030       /// The alignment of the record.
0031       uint64_t Align;
0032
0033       /// The offsets of non-virtual base classes in the record.
0034       SmallVector<CharUnits, 8> BaseOffsets;
0035
0036       /// The offsets of virtual base classes in the record.
0037       SmallVector<CharUnits, 8> VBaseOffsets;
0038
0039       /// The offsets of the fields, in source order.
0040       SmallVector<uint64_t, 8> FieldOffsets;
0041     };
0042
0043     /// The set of layouts that will be overridden.
0044     llvm::StringMap<Layout> Layouts;
0045
0046   public:
0047     /// Create a new AST source that overrides the layout of some
0048     /// set of record types.
0049     ///
0050     /// The file is the result of passing -fdump-record-layouts to a file.
0051     explicit LayoutOverrideSource(StringRef Filename);
0052
0053     /// If this particular record type has an overridden layout,
0054     /// return that layout.
0055     bool
0056     layoutRecordType(const RecordDecl *Record,
0057        uint64_t &Size, uint64_t &Alignment,
0058        llvm::DenseMap<const FieldDecl *, uint64_t> &FieldOffsets,
0059        llvm::DenseMap<const CXXRecordDecl *, CharUnits> &BaseOffsets,
0060        llvm::DenseMap<const CXXRecordDecl *,
0061                       CharUnits> &VirtualBaseOffsets) override;
0062
0063     /// Dump the overridden layouts.
0064     void dump();
0065   };
0066 }
0067
0068 #endif