kc3-lang/angle/src/compiler/preprocessor/MacroExpander.cpp

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• Author : Olli Etuaho
  Date : 2017-01-17 15:29:35
  Hash : 47c27e82
  Message : Manage preprocessor Macro objects with shared pointers This ensures that pointers to Macros that are removed from the macro set stay valid. Pointers to undef'd macros may need to be referred to if reenabling the macros has been deferred. BUG=chromium:681324 TEST=angle_unittests Change-Id: Ibbbabbcbd6b0a84254cda717ae63712e6d404ebd Reviewed-on: https://chromium-review.googlesource.com/427948 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>

• src/compiler/preprocessor/MacroExpander.cpp

• //
  // Copyright (c) 2011 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  #include "compiler/preprocessor/MacroExpander.h"
  
  #include <algorithm>
  
  #include "common/debug.h"
  #include "compiler/preprocessor/DiagnosticsBase.h"
  #include "compiler/preprocessor/Token.h"
  
  namespace pp
  {
  
  namespace
  {
  
  const size_t kMaxContextTokens = 10000;
  
  class TokenLexer : public Lexer
  {
    public:
      typedef std::vector<Token> TokenVector;
  
      TokenLexer(TokenVector *tokens)
      {
          tokens->swap(mTokens);
          mIter = mTokens.begin();
      }
  
      void lex(Token *token) override
      {
          if (mIter == mTokens.end())
          {
              token->reset();
              token->type = Token::LAST;
          }
          else
          {
              *token = *mIter++;
          }
      }
  
    private:
      TokenVector mTokens;
      TokenVector::const_iterator mIter;
  };
  
  }  // anonymous namespace
  
  class MacroExpander::ScopedMacroReenabler final : angle::NonCopyable
  {
    public:
      ScopedMacroReenabler(MacroExpander *expander);
      ~ScopedMacroReenabler();
  
    private:
      MacroExpander *mExpander;
  };
  
  MacroExpander::ScopedMacroReenabler::ScopedMacroReenabler(MacroExpander *expander)
      : mExpander(expander)
  {
      mExpander->mDeferReenablingMacros = true;
  }
  
  MacroExpander::ScopedMacroReenabler::~ScopedMacroReenabler()
  {
      mExpander->mDeferReenablingMacros = false;
      for (auto macro : mExpander->mMacrosToReenable)
      {
          // Copying the string here by using substr is a check for use-after-free. It detects
          // use-after-free more reliably than just toggling the disabled flag.
          ASSERT(macro->name.substr() != "");
          macro->disabled = false;
      }
      mExpander->mMacrosToReenable.clear();
  }
  
  MacroExpander::MacroExpander(Lexer *lexer,
                               MacroSet *macroSet,
                               Diagnostics *diagnostics,
                               int allowedMacroExpansionDepth)
      : mLexer(lexer),
        mMacroSet(macroSet),
        mDiagnostics(diagnostics),
        mTotalTokensInContexts(0),
        mAllowedMacroExpansionDepth(allowedMacroExpansionDepth),
        mDeferReenablingMacros(false)
  {
  }
  
  MacroExpander::~MacroExpander()
  {
      ASSERT(mMacrosToReenable.empty());
      for (MacroContext *context : mContextStack)
      {
          delete context;
      }
  }
  
  void MacroExpander::lex(Token *token)
  {
      while (true)
      {
          getToken(token);
  
          if (token->type != Token::IDENTIFIER)
              break;
  
          if (token->expansionDisabled())
              break;
  
          MacroSet::const_iterator iter = mMacroSet->find(token->text);
          if (iter == mMacroSet->end())
              break;
  
          std::shared_ptr<Macro> macro = iter->second;
          if (macro->disabled)
          {
              // If a particular token is not expanded, it is never expanded.
              token->setExpansionDisabled(true);
              break;
          }
  
          // Bump the expansion count before peeking if the next token is a '('
          // otherwise there could be a #undef of the macro before the next token.
          macro->expansionCount++;
          if ((macro->type == Macro::kTypeFunc) && !isNextTokenLeftParen())
          {
              // If the token immediately after the macro name is not a '(',
              // this macro should not be expanded.
              macro->expansionCount--;
              break;
          }
  
          pushMacro(macro, *token);
      }
  }
  
  void MacroExpander::getToken(Token *token)
  {
      if (mReserveToken.get())
      {
          *token = *mReserveToken;
          mReserveToken.reset();
          return;
      }
  
      // First pop all empty macro contexts.
      while (!mContextStack.empty() && mContextStack.back()->empty())
      {
          popMacro();
      }
  
      if (!mContextStack.empty())
      {
          *token = mContextStack.back()->get();
      }
      else
      {
          ASSERT(mTotalTokensInContexts == 0);
          mLexer->lex(token);
      }
  }
  
  void MacroExpander::ungetToken(const Token &token)
  {
      if (!mContextStack.empty())
      {
          MacroContext *context = mContextStack.back();
          context->unget();
          ASSERT(context->replacements[context->index] == token);
      }
      else
      {
          ASSERT(!mReserveToken.get());
          mReserveToken.reset(new Token(token));
      }
  }
  
  bool MacroExpander::isNextTokenLeftParen()
  {
      Token token;
      getToken(&token);
  
      bool lparen = token.type == '(';
      ungetToken(token);
  
      return lparen;
  }
  
  bool MacroExpander::pushMacro(std::shared_ptr<Macro> macro, const Token &identifier)
  {
      ASSERT(!macro->disabled);
      ASSERT(!identifier.expansionDisabled());
      ASSERT(identifier.type == Token::IDENTIFIER);
      ASSERT(identifier.text == macro->name);
  
      std::vector<Token> replacements;
      if (!expandMacro(*macro, identifier, &replacements))
          return false;
  
      // Macro is disabled for expansion until it is popped off the stack.
      macro->disabled = true;
  
      MacroContext *context = new MacroContext;
      context->macro        = macro;
      context->replacements.swap(replacements);
      mContextStack.push_back(context);
      mTotalTokensInContexts += context->replacements.size();
      return true;
  }
  
  void MacroExpander::popMacro()
  {
      ASSERT(!mContextStack.empty());
  
      MacroContext *context = mContextStack.back();
      mContextStack.pop_back();
  
      ASSERT(context->empty());
      ASSERT(context->macro->disabled);
      ASSERT(context->macro->expansionCount > 0);
      if (mDeferReenablingMacros)
      {
          mMacrosToReenable.push_back(context->macro);
      }
      else
      {
          context->macro->disabled = false;
      }
      context->macro->expansionCount--;
      mTotalTokensInContexts -= context->replacements.size();
      delete context;
  }
  
  bool MacroExpander::expandMacro(const Macro &macro,
                                  const Token &identifier,
                                  std::vector<Token> *replacements)
  {
      replacements->clear();
  
      // In the case of an object-like macro, the replacement list gets its location
      // from the identifier, but in the case of a function-like macro, the replacement
      // list gets its location from the closing parenthesis of the macro invocation.
      // This is tested by dEQP-GLES3.functional.shaders.preprocessor.predefined_macros.*
      SourceLocation replacementLocation = identifier.location;
      if (macro.type == Macro::kTypeObj)
      {
          replacements->assign(macro.replacements.begin(), macro.replacements.end());
  
          if (macro.predefined)
          {
              const char kLine[] = "__LINE__";
              const char kFile[] = "__FILE__";
  
              ASSERT(replacements->size() == 1);
              Token &repl = replacements->front();
              if (macro.name == kLine)
              {
                  repl.text = ToString(identifier.location.line);
              }
              else if (macro.name == kFile)
              {
                  repl.text = ToString(identifier.location.file);
              }
          }
      }
      else
      {
          ASSERT(macro.type == Macro::kTypeFunc);
          std::vector<MacroArg> args;
          args.reserve(macro.parameters.size());
          if (!collectMacroArgs(macro, identifier, &args, &replacementLocation))
              return false;
  
          replaceMacroParams(macro, args, replacements);
      }
  
      for (std::size_t i = 0; i < replacements->size(); ++i)
      {
          Token &repl = replacements->at(i);
          if (i == 0)
          {
              // The first token in the replacement list inherits the padding
              // properties of the identifier token.
              repl.setAtStartOfLine(identifier.atStartOfLine());
              repl.setHasLeadingSpace(identifier.hasLeadingSpace());
          }
          repl.location = replacementLocation;
      }
      return true;
  }
  
  bool MacroExpander::collectMacroArgs(const Macro &macro,
                                       const Token &identifier,
                                       std::vector<MacroArg> *args,
                                       SourceLocation *closingParenthesisLocation)
  {
      Token token;
      getToken(&token);
      ASSERT(token.type == '(');
  
      args->push_back(MacroArg());
  
      // Defer reenabling macros until args collection is finished to avoid the possibility of
      // infinite recursion. Otherwise infinite recursion might happen when expanding the args after
      // macros have been popped from the context stack when parsing the args.
      ScopedMacroReenabler deferReenablingMacros(this);
  
      int openParens = 1;
      while (openParens != 0)
      {
          getToken(&token);
  
          if (token.type == Token::LAST)
          {
              mDiagnostics->report(Diagnostics::PP_MACRO_UNTERMINATED_INVOCATION, identifier.location,
                                   identifier.text);
              // Do not lose EOF token.
              ungetToken(token);
              return false;
          }
  
          bool isArg = false;  // True if token is part of the current argument.
          switch (token.type)
          {
              case '(':
                  ++openParens;
                  isArg = true;
                  break;
              case ')':
                  --openParens;
                  isArg                       = openParens != 0;
                  *closingParenthesisLocation = token.location;
                  break;
              case ',':
                  // The individual arguments are separated by comma tokens, but
                  // the comma tokens between matching inner parentheses do not
                  // seperate arguments.
                  if (openParens == 1)
                      args->push_back(MacroArg());
                  isArg = openParens != 1;
                  break;
              default:
                  isArg = true;
                  break;
          }
          if (isArg)
          {
              MacroArg &arg = args->back();
              // Initial whitespace is not part of the argument.
              if (arg.empty())
                  token.setHasLeadingSpace(false);
              arg.push_back(token);
          }
      }
  
      const Macro::Parameters &params = macro.parameters;
      // If there is only one empty argument, it is equivalent to no argument.
      if (params.empty() && (args->size() == 1) && args->front().empty())
      {
          args->clear();
      }
      // Validate the number of arguments.
      if (args->size() != params.size())
      {
          Diagnostics::ID id = args->size() < macro.parameters.size()
                                   ? Diagnostics::PP_MACRO_TOO_FEW_ARGS
                                   : Diagnostics::PP_MACRO_TOO_MANY_ARGS;
          mDiagnostics->report(id, identifier.location, identifier.text);
          return false;
      }
  
      // Pre-expand each argument before substitution.
      // This step expands each argument individually before they are
      // inserted into the macro body.
      size_t numTokens = 0;
      for (auto &arg : *args)
      {
          TokenLexer lexer(&arg);
          if (mAllowedMacroExpansionDepth < 1)
          {
              mDiagnostics->report(Diagnostics::PP_MACRO_INVOCATION_CHAIN_TOO_DEEP, token.location,
                                   token.text);
              return false;
          }
          MacroExpander expander(&lexer, mMacroSet, mDiagnostics, mAllowedMacroExpansionDepth - 1);
  
          arg.clear();
          expander.lex(&token);
          while (token.type != Token::LAST)
          {
              arg.push_back(token);
              expander.lex(&token);
              numTokens++;
              if (numTokens + mTotalTokensInContexts > kMaxContextTokens)
              {
                  mDiagnostics->report(Diagnostics::PP_OUT_OF_MEMORY, token.location, token.text);
                  return false;
              }
          }
      }
      return true;
  }
  
  void MacroExpander::replaceMacroParams(const Macro &macro,
                                         const std::vector<MacroArg> &args,
                                         std::vector<Token> *replacements)
  {
      for (std::size_t i = 0; i < macro.replacements.size(); ++i)
      {
          if (!replacements->empty() &&
              replacements->size() + mTotalTokensInContexts > kMaxContextTokens)
          {
              const Token &token = replacements->back();
              mDiagnostics->report(Diagnostics::PP_OUT_OF_MEMORY, token.location, token.text);
              return;
          }
  
          const Token &repl = macro.replacements[i];
          if (repl.type != Token::IDENTIFIER)
          {
              replacements->push_back(repl);
              continue;
          }
  
          // TODO(alokp): Optimize this.
          // There is no need to search for macro params every time.
          // The param index can be cached with the replacement token.
          Macro::Parameters::const_iterator iter =
              std::find(macro.parameters.begin(), macro.parameters.end(), repl.text);
          if (iter == macro.parameters.end())
          {
              replacements->push_back(repl);
              continue;
          }
  
          std::size_t iArg    = std::distance(macro.parameters.begin(), iter);
          const MacroArg &arg = args[iArg];
          if (arg.empty())
          {
              continue;
          }
          std::size_t iRepl = replacements->size();
          replacements->insert(replacements->end(), arg.begin(), arg.end());
          // The replacement token inherits padding properties from
          // macro replacement token.
          replacements->at(iRepl).setHasLeadingSpace(repl.hasLeadingSpace());
      }
  }
  
  MacroExpander::MacroContext::MacroContext() : macro(0), index(0)
  {
  }
  
  bool MacroExpander::MacroContext::empty() const
  {
      return index == replacements.size();
  }
  
  const Token &MacroExpander::MacroContext::get()
  {
      return replacements[index++];
  }
  
  void MacroExpander::MacroContext::unget()
  {
      ASSERT(index > 0);
      --index;
  }
  
  }  // namespace pp