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

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• Author : Stuart Morgan
  Date : 2019-08-14 12:25:12
  Hash : 9d737966
  Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

• src/compiler/preprocessor/MacroExpander.cpp

• //
  // Copyright 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 <GLSLANG/ShaderLang.h>
  #include <algorithm>
  
  #include "common/debug.h"
  #include "compiler/preprocessor/DiagnosticsBase.h"
  #include "compiler/preprocessor/Token.h"
  
  namespace angle
  {
  
  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 (const std::shared_ptr<Macro> &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,
                               const PreprocessorSettings &settings,
                               bool parseDefined)
      : mLexer(lexer),
        mMacroSet(macroSet),
        mDiagnostics(diagnostics),
        mParseDefined(parseDefined),
        mTotalTokensInContexts(0),
        mSettings(settings),
        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;
  
          // Defined operator is parsed here since it may be generated by macro expansion.
          // Defined operator produced by macro expansion has undefined behavior according to C++
          // spec, which the GLSL spec references (see C++14 draft spec section 16.1.4), but this
          // behavior is needed for passing dEQP tests, which enforce stricter compatibility between
          // implementations.
          if (mParseDefined && token->text == kDefined)
          {
              // Defined inside a macro is forbidden in WebGL.
              if (!mContextStack.empty() && sh::IsWebGLBasedSpec(mSettings.shaderSpec))
                  break;
  
              bool paren = false;
              getToken(token);
              if (token->type == '(')
              {
                  paren = true;
                  getToken(token);
              }
              if (token->type != Token::IDENTIFIER)
              {
                  mDiagnostics->report(Diagnostics::PP_UNEXPECTED_TOKEN, token->location,
                                       token->text);
                  break;
              }
              auto iter              = mMacroSet->find(token->text);
              std::string expression = iter != mMacroSet->end() ? "1" : "0";
  
              if (paren)
              {
                  getToken(token);
                  if (token->type != ')')
                  {
                      mDiagnostics->report(Diagnostics::PP_UNEXPECTED_TOKEN, token->location,
                                           token->text);
                      break;
                  }
              }
  
              // We have a valid defined operator.
              // Convert the current token into a CONST_INT token.
              token->type = Token::CONST_INT;
              token->text = expression;
              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 (mSettings.maxMacroExpansionDepth < 1)
          {
              mDiagnostics->report(Diagnostics::PP_MACRO_INVOCATION_CHAIN_TOO_DEEP, token.location,
                                   token.text);
              return false;
          }
          PreprocessorSettings nestedSettings(mSettings.shaderSpec);
          nestedSettings.maxMacroExpansionDepth = mSettings.maxMacroExpansionDepth - 1;
          MacroExpander expander(&lexer, mMacroSet, mDiagnostics, nestedSettings, mParseDefined);
  
          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) {}
  
  MacroExpander::MacroContext::~MacroContext() {}
  
  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
  
  }  // namespace angle