llvm-project

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//===--- ParseAST.cpp - Provide the clang::ParseAST method ----------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the clang::ParseAST method.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/Parse/ParseAST.h"
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#include "clang/AST/ASTConsumer.h"
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#include "clang/AST/ASTContext.h"
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#include "clang/AST/ExternalASTSource.h"
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#include "clang/AST/Stmt.h"
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#include "clang/Parse/ParseDiagnostic.h"
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#include "clang/Parse/Parser.h"
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#include "clang/Sema/CodeCompleteConsumer.h"
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#include "clang/Sema/EnterExpressionEvaluationContext.h"
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#include "clang/Sema/Sema.h"
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#include "clang/Sema/SemaConsumer.h"
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#include "clang/Sema/TemplateInstCallback.h"
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#include "llvm/Support/CrashRecoveryContext.h"
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#include "llvm/Support/TimeProfiler.h"
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#include <cstdio>
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#include <memory>
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using namespace clang;
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namespace {
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/// Resets LLVM's pretty stack state so that stack traces are printed correctly
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/// when there are nested CrashRecoveryContexts and the inner one recovers from
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/// a crash.
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class ResetStackCleanup
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    : public llvm::CrashRecoveryContextCleanupBase<ResetStackCleanup,
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                                                   const void> {
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public:
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  ResetStackCleanup(llvm::CrashRecoveryContext *Context, const void *Top)
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      : llvm::CrashRecoveryContextCleanupBase<ResetStackCleanup, const void>(
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            Context, Top) {}
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  void recoverResources() override {
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    llvm::RestorePrettyStackState(resource);
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  }
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};
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/// If a crash happens while the parser is active, an entry is printed for it.
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class PrettyStackTraceParserEntry : public llvm::PrettyStackTraceEntry {
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  const Parser &P;
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public:
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  PrettyStackTraceParserEntry(const Parser &p) : P(p) {}
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  void print(raw_ostream &OS) const override;
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};
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/// If a crash happens while the parser is active, print out a line indicating
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/// what the current token is.
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void PrettyStackTraceParserEntry::print(raw_ostream &OS) const {
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  const Token &Tok = P.getCurToken();
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  if (Tok.is(tok::eof)) {
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    OS << "<eof> parser at end of file\n";
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    return;
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  }
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  if (Tok.getLocation().isInvalid()) {
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    OS << "<unknown> parser at unknown location\n";
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    return;
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  }
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  const Preprocessor &PP = P.getPreprocessor();
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  Tok.getLocation().print(OS, PP.getSourceManager());
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  if (Tok.isAnnotation()) {
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    OS << ": at annotation token\n";
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  } else {
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    // Do the equivalent of PP.getSpelling(Tok) except for the parts that would
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    // allocate memory.
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    bool Invalid = false;
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    const SourceManager &SM = P.getPreprocessor().getSourceManager();
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    unsigned Length = Tok.getLength();
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    const char *Spelling = SM.getCharacterData(Tok.getLocation(), &Invalid);
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    if (Invalid) {
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      OS << ": unknown current parser token\n";
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      return;
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    }
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    OS << ": current parser token '" << StringRef(Spelling, Length) << "'\n";
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  }
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}
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}  // namespace
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//===----------------------------------------------------------------------===//
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// Public interface to the file
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//===----------------------------------------------------------------------===//
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/// ParseAST - Parse the entire file specified, notifying the ASTConsumer as
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/// the file is parsed.  This inserts the parsed decls into the translation unit
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/// held by Ctx.
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///
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void clang::ParseAST(Preprocessor &PP, ASTConsumer *Consumer,
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                     ASTContext &Ctx, bool PrintStats,
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                     TranslationUnitKind TUKind,
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                     CodeCompleteConsumer *CompletionConsumer,
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                     bool SkipFunctionBodies) {
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  std::unique_ptr<Sema> S(
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      new Sema(PP, Ctx, *Consumer, TUKind, CompletionConsumer));
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  // Recover resources if we crash before exiting this method.
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  llvm::CrashRecoveryContextCleanupRegistrar<Sema> CleanupSema(S.get());
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  ParseAST(*S.get(), PrintStats, SkipFunctionBodies);
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}
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void clang::ParseAST(Sema &S, bool PrintStats, bool SkipFunctionBodies) {
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  // Collect global stats on Decls/Stmts (until we have a module streamer).
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  if (PrintStats) {
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    Decl::EnableStatistics();
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    Stmt::EnableStatistics();
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  }
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  // Also turn on collection of stats inside of the Sema object.
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  bool OldCollectStats = PrintStats;
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  std::swap(OldCollectStats, S.CollectStats);
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  // Initialize the template instantiation observer chain.
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  // FIXME: See note on "finalize" below.
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  initialize(S.TemplateInstCallbacks, S);
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  ASTConsumer *Consumer = &S.getASTConsumer();
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  std::unique_ptr<Parser> ParseOP(
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      new Parser(S.getPreprocessor(), S, SkipFunctionBodies));
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  Parser &P = *ParseOP.get();
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  llvm::CrashRecoveryContextCleanupRegistrar<const void, ResetStackCleanup>
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      CleanupPrettyStack(llvm::SavePrettyStackState());
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  PrettyStackTraceParserEntry CrashInfo(P);
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  // Recover resources if we crash before exiting this method.
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  llvm::CrashRecoveryContextCleanupRegistrar<Parser>
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    CleanupParser(ParseOP.get());
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  S.getPreprocessor().EnterMainSourceFile();
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  ExternalASTSource *External = S.getASTContext().getExternalSource();
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  if (External)
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    External->StartTranslationUnit(Consumer);
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  // If a PCH through header is specified that does not have an include in
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  // the source, or a PCH is being created with #pragma hdrstop with nothing
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  // after the pragma, there won't be any tokens or a Lexer.
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  bool HaveLexer = S.getPreprocessor().getCurrentLexer();
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  if (HaveLexer) {
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    llvm::TimeTraceScope TimeScope("Frontend");
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    P.Initialize();
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    Parser::DeclGroupPtrTy ADecl;
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    Sema::ModuleImportState ImportState;
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    EnterExpressionEvaluationContext PotentiallyEvaluated(
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        S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
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    for (bool AtEOF = P.ParseFirstTopLevelDecl(ADecl, ImportState); !AtEOF;
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         AtEOF = P.ParseTopLevelDecl(ADecl, ImportState)) {
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      // If we got a null return and something *was* parsed, ignore it.  This
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      // is due to a top-level semicolon, an action override, or a parse error
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      // skipping something.
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      if (ADecl && !Consumer->HandleTopLevelDecl(ADecl.get()))
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        return;
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    }
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  }
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  // Process any TopLevelDecls generated by #pragma weak.
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  for (Decl *D : S.WeakTopLevelDecls())
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    Consumer->HandleTopLevelDecl(DeclGroupRef(D));
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  Consumer->HandleTranslationUnit(S.getASTContext());
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  // Finalize the template instantiation observer chain.
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  // FIXME: This (and init.) should be done in the Sema class, but because
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  // Sema does not have a reliable "Finalize" function (it has a
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  // destructor, but it is not guaranteed to be called ("-disable-free")).
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  // So, do the initialization above and do the finalization here:
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  finalize(S.TemplateInstCallbacks, S);
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  std::swap(OldCollectStats, S.CollectStats);
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  if (PrintStats) {
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    llvm::errs() << "\nSTATISTICS:\n";
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    if (HaveLexer) P.getActions().PrintStats();
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    S.getASTContext().PrintStats();
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    Decl::PrintStats();
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    Stmt::PrintStats();
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    Consumer->PrintStats();
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  }
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}
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