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      1 //===--- ParseAST.cpp - Provide the clang::ParseAST method ----------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the clang::ParseAST method.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/Parse/ParseAST.h"
     15 #include "clang/AST/ASTConsumer.h"
     16 #include "clang/AST/ASTContext.h"
     17 #include "clang/AST/ExternalASTSource.h"
     18 #include "clang/AST/Stmt.h"
     19 #include "clang/Parse/ParseDiagnostic.h"
     20 #include "clang/Parse/Parser.h"
     21 #include "clang/Sema/CodeCompleteConsumer.h"
     22 #include "clang/Sema/Sema.h"
     23 #include "clang/Sema/SemaConsumer.h"
     24 #include "llvm/Support/CrashRecoveryContext.h"
     25 #include <cstdio>
     26 #include <memory>
     27 
     28 using namespace clang;
     29 
     30 namespace {
     31 
     32 /// Resets LLVM's pretty stack state so that stack traces are printed correctly
     33 /// when there are nested CrashRecoveryContexts and the inner one recovers from
     34 /// a crash.
     35 class ResetStackCleanup
     36     : public llvm::CrashRecoveryContextCleanupBase<ResetStackCleanup,
     37                                                    const void> {
     38 public:
     39   ResetStackCleanup(llvm::CrashRecoveryContext *Context, const void *Top)
     40       : llvm::CrashRecoveryContextCleanupBase<ResetStackCleanup, const void>(
     41             Context, Top) {}
     42   void recoverResources() override {
     43     llvm::RestorePrettyStackState(resource);
     44   }
     45 };
     46 
     47 /// If a crash happens while the parser is active, an entry is printed for it.
     48 class PrettyStackTraceParserEntry : public llvm::PrettyStackTraceEntry {
     49   const Parser &P;
     50 public:
     51   PrettyStackTraceParserEntry(const Parser &p) : P(p) {}
     52   void print(raw_ostream &OS) const override;
     53 };
     54 
     55 /// If a crash happens while the parser is active, print out a line indicating
     56 /// what the current token is.
     57 void PrettyStackTraceParserEntry::print(raw_ostream &OS) const {
     58   const Token &Tok = P.getCurToken();
     59   if (Tok.is(tok::eof)) {
     60     OS << "<eof> parser at end of file\n";
     61     return;
     62   }
     63 
     64   if (Tok.getLocation().isInvalid()) {
     65     OS << "<unknown> parser at unknown location\n";
     66     return;
     67   }
     68 
     69   const Preprocessor &PP = P.getPreprocessor();
     70   Tok.getLocation().print(OS, PP.getSourceManager());
     71   if (Tok.isAnnotation()) {
     72     OS << ": at annotation token\n";
     73   } else {
     74     // Do the equivalent of PP.getSpelling(Tok) except for the parts that would
     75     // allocate memory.
     76     bool Invalid = false;
     77     const SourceManager &SM = P.getPreprocessor().getSourceManager();
     78     unsigned Length = Tok.getLength();
     79     const char *Spelling = SM.getCharacterData(Tok.getLocation(), &Invalid);
     80     if (Invalid) {
     81       OS << ": unknown current parser token\n";
     82       return;
     83     }
     84     OS << ": current parser token '" << StringRef(Spelling, Length) << "'\n";
     85   }
     86 }
     87 
     88 }  // namespace
     89 
     90 //===----------------------------------------------------------------------===//
     91 // Public interface to the file
     92 //===----------------------------------------------------------------------===//
     93 
     94 /// ParseAST - Parse the entire file specified, notifying the ASTConsumer as
     95 /// the file is parsed.  This inserts the parsed decls into the translation unit
     96 /// held by Ctx.
     97 ///
     98 void clang::ParseAST(Preprocessor &PP, ASTConsumer *Consumer,
     99                      ASTContext &Ctx, bool PrintStats,
    100                      TranslationUnitKind TUKind,
    101                      CodeCompleteConsumer *CompletionConsumer,
    102                      bool SkipFunctionBodies) {
    103 
    104   std::unique_ptr<Sema> S(
    105       new Sema(PP, Ctx, *Consumer, TUKind, CompletionConsumer));
    106 
    107   // Recover resources if we crash before exiting this method.
    108   llvm::CrashRecoveryContextCleanupRegistrar<Sema> CleanupSema(S.get());
    109 
    110   ParseAST(*S.get(), PrintStats, SkipFunctionBodies);
    111 }
    112 
    113 void clang::ParseAST(Sema &S, bool PrintStats, bool SkipFunctionBodies) {
    114   // Collect global stats on Decls/Stmts (until we have a module streamer).
    115   if (PrintStats) {
    116     Decl::EnableStatistics();
    117     Stmt::EnableStatistics();
    118   }
    119 
    120   // Also turn on collection of stats inside of the Sema object.
    121   bool OldCollectStats = PrintStats;
    122   std::swap(OldCollectStats, S.CollectStats);
    123 
    124   ASTConsumer *Consumer = &S.getASTConsumer();
    125 
    126   std::unique_ptr<Parser> ParseOP(
    127       new Parser(S.getPreprocessor(), S, SkipFunctionBodies));
    128   Parser &P = *ParseOP.get();
    129 
    130   llvm::CrashRecoveryContextCleanupRegistrar<const void, ResetStackCleanup>
    131       CleanupPrettyStack(llvm::SavePrettyStackState());
    132   PrettyStackTraceParserEntry CrashInfo(P);
    133 
    134   // Recover resources if we crash before exiting this method.
    135   llvm::CrashRecoveryContextCleanupRegistrar<Parser>
    136     CleanupParser(ParseOP.get());
    137 
    138   S.getPreprocessor().EnterMainSourceFile();
    139   P.Initialize();
    140 
    141   // C11 6.9p1 says translation units must have at least one top-level
    142   // declaration. C++ doesn't have this restriction. We also don't want to
    143   // complain if we have a precompiled header, although technically if the PCH
    144   // is empty we should still emit the (pedantic) diagnostic.
    145   Parser::DeclGroupPtrTy ADecl;
    146   ExternalASTSource *External = S.getASTContext().getExternalSource();
    147   if (External)
    148     External->StartTranslationUnit(Consumer);
    149 
    150   if (P.ParseTopLevelDecl(ADecl)) {
    151     if (!External && !S.getLangOpts().CPlusPlus)
    152       P.Diag(diag::ext_empty_translation_unit);
    153   } else {
    154     do {
    155       // If we got a null return and something *was* parsed, ignore it.  This
    156       // is due to a top-level semicolon, an action override, or a parse error
    157       // skipping something.
    158       if (ADecl && !Consumer->HandleTopLevelDecl(ADecl.get()))
    159         return;
    160     } while (!P.ParseTopLevelDecl(ADecl));
    161   }
    162 
    163   // Process any TopLevelDecls generated by #pragma weak.
    164   for (Decl *D : S.WeakTopLevelDecls())
    165     Consumer->HandleTopLevelDecl(DeclGroupRef(D));
    166 
    167   Consumer->HandleTranslationUnit(S.getASTContext());
    168 
    169   std::swap(OldCollectStats, S.CollectStats);
    170   if (PrintStats) {
    171     llvm::errs() << "\nSTATISTICS:\n";
    172     P.getActions().PrintStats();
    173     S.getASTContext().PrintStats();
    174     Decl::PrintStats();
    175     Stmt::PrintStats();
    176     Consumer->PrintStats();
    177   }
    178 }
    179