utils/TableGen/ClangASTNodesEmitter.cpp

//=== ClangASTNodesEmitter.cpp - Generate Clang AST node tables -*- 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
//
//===----------------------------------------------------------------------===//
//
// These tablegen backends emit Clang AST node tables
//
//===----------------------------------------------------------------------===//

#include "ClangASTEmitters.h"
#include "TableGenBackends.h"

#include "llvm/TableGen/Error.h"
#include "llvm/TableGen/Record.h"
#include "llvm/TableGen/TableGenBackend.h"
#include <cctype>
#include <map>
#include <set>
#include <string>
using namespace llvm;

/// ClangASTNodesEmitter - The top-level class emits .inc files containing
///  declarations of Clang statements.
///
namespace {
class ClangASTNodesEmitter {
  // A map from a node to each of its derived nodes.
  typedef std::multimap<Record*, Record*> ChildMap;
  typedef ChildMap::const_iterator ChildIterator;

  RecordKeeper &Records;
  Record *Root = nullptr;
  const std::string &NodeClassName;
  const std::string &BaseSuffix;
  std::string MacroHierarchyName;
  ChildMap Tree;

  // Create a macro-ized version of a name
  static std::string macroName(std::string S) {
    for (unsigned i = 0; i < S.size(); ++i)
      S[i] = std::toupper(S[i]);

    return S;
  }

  const std::string &macroHierarchyName() {
    assert(Root && "root node not yet derived!");
    if (MacroHierarchyName.empty())
      MacroHierarchyName = macroName(Root->getName());
    return MacroHierarchyName;
  }

  // Return the name to be printed in the base field. Normally this is
  // the record's name plus the base suffix, but if it is the root node and
  // the suffix is non-empty, it's just the suffix.
  std::string baseName(Record &R) {
    if (&R == Root && !BaseSuffix.empty())
      return BaseSuffix;

    return R.getName().str() + BaseSuffix;
  }

  void deriveChildTree();

  std::pair<Record *, Record *> EmitNode(raw_ostream& OS, Record *Base);
public:
  explicit ClangASTNodesEmitter(RecordKeeper &R, const std::string &N,
                                const std::string &S)
    : Records(R), NodeClassName(N), BaseSuffix(S) {}

  // run - Output the .inc file contents
  void run(raw_ostream &OS);
};
} // end anonymous namespace

//===----------------------------------------------------------------------===//
// Statement Node Tables (.inc file) generation.
//===----------------------------------------------------------------------===//

// Returns the first and last non-abstract subrecords
// Called recursively to ensure that nodes remain contiguous
std::pair<Record *, Record *> ClangASTNodesEmitter::EmitNode(raw_ostream &OS,
                                                             Record *Base) {
  std::string BaseName = macroName(Base->getName());

  ChildIterator i = Tree.lower_bound(Base), e = Tree.upper_bound(Base);

  Record *First = nullptr, *Last = nullptr;
  if (!Base->getValueAsBit(AbstractFieldName))
    First = Last = Base;

  for (; i != e; ++i) {
    Record *R = i->second;
    bool Abstract = R->getValueAsBit(AbstractFieldName);
    std::string NodeName = macroName(R->getName());

    OS << "#ifndef " << NodeName << "\n";
    OS << "#  define " << NodeName << "(Type, Base) "
        << BaseName << "(Type, Base)\n";
    OS << "#endif\n";

    if (Abstract)
      OS << "ABSTRACT_" << macroHierarchyName() << "(" << NodeName << "("
          << R->getName() << ", " << baseName(*Base) << "))\n";
    else
      OS << NodeName << "(" << R->getName() << ", "
          << baseName(*Base) << ")\n";

    if (Tree.find(R) != Tree.end()) {
      const std::pair<Record *, Record *> &Result
        = EmitNode(OS, R);
      if (!First && Result.first)
        First = Result.first;
      if (Result.second)
        Last = Result.second;
    } else {
      if (!Abstract) {
        Last = R;

        if (!First)
          First = R;
      }
    }

    OS << "#undef " << NodeName << "\n\n";
  }

  if (First) {
    assert (Last && "Got a first node but not a last node for a range!");
    if (Base == Root)
      OS << "LAST_" << macroHierarchyName() << "_RANGE(";
    else
      OS << macroHierarchyName() << "_RANGE(";
    OS << Base->getName() << ", " << First->getName() << ", "
       << Last->getName() << ")\n\n";
  }

  return std::make_pair(First, Last);
}

void ClangASTNodesEmitter::deriveChildTree() {
  assert(Root == nullptr && "already computed tree");

  // Emit statements
  const std::vector<Record*> Stmts
    = Records.getAllDerivedDefinitions(NodeClassName);

  for (unsigned i = 0, e = Stmts.size(); i != e; ++i) {
    Record *R = Stmts[i];

    if (auto B = R->getValueAsOptionalDef(BaseFieldName))
      Tree.insert(std::make_pair(B, R));
    else if (Root)
      PrintFatalError(R->getLoc(),
                      Twine("multiple root nodes in \"") + NodeClassName
                        + "\" hierarchy");
    else
      Root = R;
  }

  if (!Root)
    PrintFatalError(Twine("didn't find root node in \"") + NodeClassName
                      + "\" hierarchy");
}

void ClangASTNodesEmitter::run(raw_ostream &OS) {
  deriveChildTree();

  emitSourceFileHeader("List of AST nodes of a particular kind", OS);

  // Write the preamble
  OS << "#ifndef ABSTRACT_" << macroHierarchyName() << "\n";
  OS << "#  define ABSTRACT_" << macroHierarchyName() << "(Type) Type\n";
  OS << "#endif\n";

  OS << "#ifndef " << macroHierarchyName() << "_RANGE\n";
  OS << "#  define "
     << macroHierarchyName() << "_RANGE(Base, First, Last)\n";
  OS << "#endif\n\n";

  OS << "#ifndef LAST_" << macroHierarchyName() << "_RANGE\n";
  OS << "#  define LAST_"
     << macroHierarchyName() << "_RANGE(Base, First, Last) "
     << macroHierarchyName() << "_RANGE(Base, First, Last)\n";
  OS << "#endif\n\n";

  EmitNode(OS, Root);

  OS << "#undef " << macroHierarchyName() << "\n";
  OS << "#undef " << macroHierarchyName() << "_RANGE\n";
  OS << "#undef LAST_" << macroHierarchyName() << "_RANGE\n";
  OS << "#undef ABSTRACT_" << macroHierarchyName() << "\n";
}

void clang::EmitClangASTNodes(RecordKeeper &RK, raw_ostream &OS,
                              const std::string &N, const std::string &S) {
  ClangASTNodesEmitter(RK, N, S).run(OS);
}

// Emits and addendum to a .inc file to enumerate the clang declaration
// contexts.
void clang::EmitClangDeclContext(RecordKeeper &Records, raw_ostream &OS) {
  // FIXME: Find a .td file format to allow for this to be represented better.

  emitSourceFileHeader("List of AST Decl nodes", OS);

  OS << "#ifndef DECL_CONTEXT\n";
  OS << "#  define DECL_CONTEXT(DECL)\n";
  OS << "#endif\n";

  OS << "#ifndef DECL_CONTEXT_BASE\n";
  OS << "#  define DECL_CONTEXT_BASE(DECL) DECL_CONTEXT(DECL)\n";
  OS << "#endif\n";

  typedef std::set<Record*> RecordSet;
  typedef std::vector<Record*> RecordVector;

  RecordVector DeclContextsVector
    = Records.getAllDerivedDefinitions(DeclContextNodeClassName);
  RecordVector Decls = Records.getAllDerivedDefinitions(DeclNodeClassName);
  RecordSet DeclContexts (DeclContextsVector.begin(), DeclContextsVector.end());

  for (RecordVector::iterator i = Decls.begin(), e = Decls.end(); i != e; ++i) {
    Record *R = *i;

    if (Record *B = R->getValueAsOptionalDef(BaseFieldName)) {
      if (DeclContexts.find(B) != DeclContexts.end()) {
        OS << "DECL_CONTEXT_BASE(" << B->getName() << ")\n";
        DeclContexts.erase(B);
      }
    }
  }

  // To keep identical order, RecordVector may be used
  // instead of RecordSet.
  for (RecordVector::iterator
         i = DeclContextsVector.begin(), e = DeclContextsVector.end();
       i != e; ++i)
    if (DeclContexts.find(*i) != DeclContexts.end())
      OS << "DECL_CONTEXT(" << (*i)->getName() << ")\n";

  OS << "#undef DECL_CONTEXT\n";
  OS << "#undef DECL_CONTEXT_BASE\n";
}