| //===--- CacheTokens.cpp - Caching of lexer tokens for PTH support --------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This provides a possible implementation of PTH support for Clang that is |
| // based on caching lexed tokens and identifiers. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Basic/Diagnostic.h" |
| #include "clang/Basic/FileManager.h" |
| #include "clang/Basic/FileSystemStatCache.h" |
| #include "clang/Basic/IdentifierTable.h" |
| #include "clang/Basic/SourceManager.h" |
| #include "clang/Frontend/Utils.h" |
| #include "clang/Lex/Lexer.h" |
| #include "clang/Lex/PTHManager.h" |
| #include "clang/Lex/Preprocessor.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/Support/EndianStream.h" |
| #include "llvm/Support/FileSystem.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include "llvm/Support/OnDiskHashTable.h" |
| #include "llvm/Support/Path.h" |
| |
| // FIXME: put this somewhere else? |
| #ifndef S_ISDIR |
| #define S_ISDIR(x) (((x)&_S_IFDIR)!=0) |
| #endif |
| |
| using namespace clang; |
| |
| //===----------------------------------------------------------------------===// |
| // PTH-specific stuff. |
| //===----------------------------------------------------------------------===// |
| |
| typedef uint32_t Offset; |
| |
| namespace { |
| class PTHEntry { |
| Offset TokenData, PPCondData; |
| |
| public: |
| PTHEntry() {} |
| |
| PTHEntry(Offset td, Offset ppcd) |
| : TokenData(td), PPCondData(ppcd) {} |
| |
| Offset getTokenOffset() const { return TokenData; } |
| Offset getPPCondTableOffset() const { return PPCondData; } |
| }; |
| |
| |
| class PTHEntryKeyVariant { |
| union { |
| const FileEntry *FE; |
| // FIXME: Use "StringRef Path;" when MSVC 2013 is dropped. |
| const char *PathPtr; |
| }; |
| size_t PathSize; |
| enum { IsFE = 0x1, IsDE = 0x2, IsNoExist = 0x0 } Kind; |
| FileData *Data; |
| |
| public: |
| PTHEntryKeyVariant(const FileEntry *fe) : FE(fe), Kind(IsFE), Data(nullptr) {} |
| |
| PTHEntryKeyVariant(FileData *Data, StringRef Path) |
| : PathPtr(Path.data()), PathSize(Path.size()), Kind(IsDE), |
| Data(new FileData(*Data)) {} |
| |
| explicit PTHEntryKeyVariant(StringRef Path) |
| : PathPtr(Path.data()), PathSize(Path.size()), Kind(IsNoExist), |
| Data(nullptr) {} |
| |
| bool isFile() const { return Kind == IsFE; } |
| |
| StringRef getString() const { |
| return Kind == IsFE ? FE->getName() : StringRef(PathPtr, PathSize); |
| } |
| |
| unsigned getKind() const { return (unsigned) Kind; } |
| |
| void EmitData(raw_ostream& Out) { |
| using namespace llvm::support; |
| endian::Writer<little> LE(Out); |
| switch (Kind) { |
| case IsFE: { |
| // Emit stat information. |
| llvm::sys::fs::UniqueID UID = FE->getUniqueID(); |
| LE.write<uint64_t>(UID.getFile()); |
| LE.write<uint64_t>(UID.getDevice()); |
| LE.write<uint64_t>(FE->getModificationTime()); |
| LE.write<uint64_t>(FE->getSize()); |
| } break; |
| case IsDE: |
| // Emit stat information. |
| LE.write<uint64_t>(Data->UniqueID.getFile()); |
| LE.write<uint64_t>(Data->UniqueID.getDevice()); |
| LE.write<uint64_t>(Data->ModTime); |
| LE.write<uint64_t>(Data->Size); |
| delete Data; |
| break; |
| default: |
| break; |
| } |
| } |
| |
| unsigned getRepresentationLength() const { |
| return Kind == IsNoExist ? 0 : 4 * 8; |
| } |
| }; |
| |
| class FileEntryPTHEntryInfo { |
| public: |
| typedef PTHEntryKeyVariant key_type; |
| typedef key_type key_type_ref; |
| |
| typedef PTHEntry data_type; |
| typedef const PTHEntry& data_type_ref; |
| |
| typedef unsigned hash_value_type; |
| typedef unsigned offset_type; |
| |
| static hash_value_type ComputeHash(PTHEntryKeyVariant V) { |
| return llvm::HashString(V.getString()); |
| } |
| |
| static std::pair<unsigned,unsigned> |
| EmitKeyDataLength(raw_ostream& Out, PTHEntryKeyVariant V, |
| const PTHEntry& E) { |
| using namespace llvm::support; |
| endian::Writer<little> LE(Out); |
| |
| unsigned n = V.getString().size() + 1 + 1; |
| LE.write<uint16_t>(n); |
| |
| unsigned m = V.getRepresentationLength() + (V.isFile() ? 4 + 4 : 0); |
| LE.write<uint8_t>(m); |
| |
| return std::make_pair(n, m); |
| } |
| |
| static void EmitKey(raw_ostream& Out, PTHEntryKeyVariant V, unsigned n){ |
| using namespace llvm::support; |
| // Emit the entry kind. |
| endian::Writer<little>(Out).write<uint8_t>((unsigned)V.getKind()); |
| // Emit the string. |
| Out.write(V.getString().data(), n - 1); |
| } |
| |
| static void EmitData(raw_ostream& Out, PTHEntryKeyVariant V, |
| const PTHEntry& E, unsigned) { |
| using namespace llvm::support; |
| endian::Writer<little> LE(Out); |
| |
| // For file entries emit the offsets into the PTH file for token data |
| // and the preprocessor blocks table. |
| if (V.isFile()) { |
| LE.write<uint32_t>(E.getTokenOffset()); |
| LE.write<uint32_t>(E.getPPCondTableOffset()); |
| } |
| |
| // Emit any other data associated with the key (i.e., stat information). |
| V.EmitData(Out); |
| } |
| }; |
| |
| class OffsetOpt { |
| bool valid; |
| Offset off; |
| public: |
| OffsetOpt() : valid(false) {} |
| bool hasOffset() const { return valid; } |
| Offset getOffset() const { assert(valid); return off; } |
| void setOffset(Offset o) { off = o; valid = true; } |
| }; |
| } // end anonymous namespace |
| |
| typedef llvm::OnDiskChainedHashTableGenerator<FileEntryPTHEntryInfo> PTHMap; |
| |
| namespace { |
| class PTHWriter { |
| typedef llvm::DenseMap<const IdentifierInfo*,uint32_t> IDMap; |
| typedef llvm::StringMap<OffsetOpt, llvm::BumpPtrAllocator> CachedStrsTy; |
| |
| raw_pwrite_stream &Out; |
| Preprocessor& PP; |
| IDMap IM; |
| std::vector<llvm::StringMapEntry<OffsetOpt>*> StrEntries; |
| PTHMap PM; |
| CachedStrsTy CachedStrs; |
| uint32_t idcount; |
| Offset CurStrOffset; |
| |
| //// Get the persistent id for the given IdentifierInfo*. |
| uint32_t ResolveID(const IdentifierInfo* II); |
| |
| /// Emit a token to the PTH file. |
| void EmitToken(const Token& T); |
| |
| void Emit8(uint32_t V) { |
| using namespace llvm::support; |
| endian::Writer<little>(Out).write<uint8_t>(V); |
| } |
| |
| void Emit16(uint32_t V) { |
| using namespace llvm::support; |
| endian::Writer<little>(Out).write<uint16_t>(V); |
| } |
| |
| void Emit32(uint32_t V) { |
| using namespace llvm::support; |
| endian::Writer<little>(Out).write<uint32_t>(V); |
| } |
| |
| void EmitBuf(const char *Ptr, unsigned NumBytes) { |
| Out.write(Ptr, NumBytes); |
| } |
| |
| void EmitString(StringRef V) { |
| using namespace llvm::support; |
| endian::Writer<little>(Out).write<uint16_t>(V.size()); |
| EmitBuf(V.data(), V.size()); |
| } |
| |
| /// EmitIdentifierTable - Emits two tables to the PTH file. The first is |
| /// a hashtable mapping from identifier strings to persistent IDs. |
| /// The second is a straight table mapping from persistent IDs to string data |
| /// (the keys of the first table). |
| std::pair<Offset, Offset> EmitIdentifierTable(); |
| |
| /// EmitFileTable - Emit a table mapping from file name strings to PTH |
| /// token data. |
| Offset EmitFileTable() { return PM.Emit(Out); } |
| |
| PTHEntry LexTokens(Lexer& L); |
| Offset EmitCachedSpellings(); |
| |
| public: |
| PTHWriter(raw_pwrite_stream &out, Preprocessor &pp) |
| : Out(out), PP(pp), idcount(0), CurStrOffset(0) {} |
| |
| PTHMap &getPM() { return PM; } |
| void GeneratePTH(StringRef MainFile); |
| }; |
| } // end anonymous namespace |
| |
| uint32_t PTHWriter::ResolveID(const IdentifierInfo* II) { |
| // Null IdentifierInfo's map to the persistent ID 0. |
| if (!II) |
| return 0; |
| |
| IDMap::iterator I = IM.find(II); |
| if (I != IM.end()) |
| return I->second; // We've already added 1. |
| |
| IM[II] = ++idcount; // Pre-increment since '0' is reserved for NULL. |
| return idcount; |
| } |
| |
| void PTHWriter::EmitToken(const Token& T) { |
| // Emit the token kind, flags, and length. |
| Emit32(((uint32_t) T.getKind()) | ((((uint32_t) T.getFlags())) << 8)| |
| (((uint32_t) T.getLength()) << 16)); |
| |
| if (!T.isLiteral()) { |
| Emit32(ResolveID(T.getIdentifierInfo())); |
| } else { |
| // We cache *un-cleaned* spellings. This gives us 100% fidelity with the |
| // source code. |
| StringRef s(T.getLiteralData(), T.getLength()); |
| |
| // Get the string entry. |
| auto &E = *CachedStrs.insert(std::make_pair(s, OffsetOpt())).first; |
| |
| // If this is a new string entry, bump the PTH offset. |
| if (!E.second.hasOffset()) { |
| E.second.setOffset(CurStrOffset); |
| StrEntries.push_back(&E); |
| CurStrOffset += s.size() + 1; |
| } |
| |
| // Emit the relative offset into the PTH file for the spelling string. |
| Emit32(E.second.getOffset()); |
| } |
| |
| // Emit the offset into the original source file of this token so that we |
| // can reconstruct its SourceLocation. |
| Emit32(PP.getSourceManager().getFileOffset(T.getLocation())); |
| } |
| |
| PTHEntry PTHWriter::LexTokens(Lexer& L) { |
| // Pad 0's so that we emit tokens to a 4-byte alignment. |
| // This speed up reading them back in. |
| using namespace llvm::support; |
| endian::Writer<little> LE(Out); |
| uint32_t TokenOff = Out.tell(); |
| for (uint64_t N = llvm::OffsetToAlignment(TokenOff, 4); N; --N, ++TokenOff) |
| LE.write<uint8_t>(0); |
| |
| // Keep track of matching '#if' ... '#endif'. |
| typedef std::vector<std::pair<Offset, unsigned> > PPCondTable; |
| PPCondTable PPCond; |
| std::vector<unsigned> PPStartCond; |
| bool ParsingPreprocessorDirective = false; |
| Token Tok; |
| |
| do { |
| L.LexFromRawLexer(Tok); |
| NextToken: |
| |
| if ((Tok.isAtStartOfLine() || Tok.is(tok::eof)) && |
| ParsingPreprocessorDirective) { |
| // Insert an eod token into the token cache. It has the same |
| // position as the next token that is not on the same line as the |
| // preprocessor directive. Observe that we continue processing |
| // 'Tok' when we exit this branch. |
| Token Tmp = Tok; |
| Tmp.setKind(tok::eod); |
| Tmp.clearFlag(Token::StartOfLine); |
| Tmp.setIdentifierInfo(nullptr); |
| EmitToken(Tmp); |
| ParsingPreprocessorDirective = false; |
| } |
| |
| if (Tok.is(tok::raw_identifier)) { |
| PP.LookUpIdentifierInfo(Tok); |
| EmitToken(Tok); |
| continue; |
| } |
| |
| if (Tok.is(tok::hash) && Tok.isAtStartOfLine()) { |
| // Special processing for #include. Store the '#' token and lex |
| // the next token. |
| assert(!ParsingPreprocessorDirective); |
| Offset HashOff = (Offset) Out.tell(); |
| |
| // Get the next token. |
| Token NextTok; |
| L.LexFromRawLexer(NextTok); |
| |
| // If we see the start of line, then we had a null directive "#". In |
| // this case, discard both tokens. |
| if (NextTok.isAtStartOfLine()) |
| goto NextToken; |
| |
| // The token is the start of a directive. Emit it. |
| EmitToken(Tok); |
| Tok = NextTok; |
| |
| // Did we see 'include'/'import'/'include_next'? |
| if (Tok.isNot(tok::raw_identifier)) { |
| EmitToken(Tok); |
| continue; |
| } |
| |
| IdentifierInfo* II = PP.LookUpIdentifierInfo(Tok); |
| tok::PPKeywordKind K = II->getPPKeywordID(); |
| |
| ParsingPreprocessorDirective = true; |
| |
| switch (K) { |
| case tok::pp_not_keyword: |
| // Invalid directives "#foo" can occur in #if 0 blocks etc, just pass |
| // them through. |
| default: |
| break; |
| |
| case tok::pp_include: |
| case tok::pp_import: |
| case tok::pp_include_next: { |
| // Save the 'include' token. |
| EmitToken(Tok); |
| // Lex the next token as an include string. |
| L.setParsingPreprocessorDirective(true); |
| L.LexIncludeFilename(Tok); |
| L.setParsingPreprocessorDirective(false); |
| assert(!Tok.isAtStartOfLine()); |
| if (Tok.is(tok::raw_identifier)) |
| PP.LookUpIdentifierInfo(Tok); |
| |
| break; |
| } |
| case tok::pp_if: |
| case tok::pp_ifdef: |
| case tok::pp_ifndef: { |
| // Add an entry for '#if' and friends. We initially set the target |
| // index to 0. This will get backpatched when we hit #endif. |
| PPStartCond.push_back(PPCond.size()); |
| PPCond.push_back(std::make_pair(HashOff, 0U)); |
| break; |
| } |
| case tok::pp_endif: { |
| // Add an entry for '#endif'. We set the target table index to itself. |
| // This will later be set to zero when emitting to the PTH file. We |
| // use 0 for uninitialized indices because that is easier to debug. |
| unsigned index = PPCond.size(); |
| // Backpatch the opening '#if' entry. |
| assert(!PPStartCond.empty()); |
| assert(PPCond.size() > PPStartCond.back()); |
| assert(PPCond[PPStartCond.back()].second == 0); |
| PPCond[PPStartCond.back()].second = index; |
| PPStartCond.pop_back(); |
| // Add the new entry to PPCond. |
| PPCond.push_back(std::make_pair(HashOff, index)); |
| EmitToken(Tok); |
| |
| // Some files have gibberish on the same line as '#endif'. |
| // Discard these tokens. |
| do |
| L.LexFromRawLexer(Tok); |
| while (Tok.isNot(tok::eof) && !Tok.isAtStartOfLine()); |
| // We have the next token in hand. |
| // Don't immediately lex the next one. |
| goto NextToken; |
| } |
| case tok::pp_elif: |
| case tok::pp_else: { |
| // Add an entry for #elif or #else. |
| // This serves as both a closing and opening of a conditional block. |
| // This means that its entry will get backpatched later. |
| unsigned index = PPCond.size(); |
| // Backpatch the previous '#if' entry. |
| assert(!PPStartCond.empty()); |
| assert(PPCond.size() > PPStartCond.back()); |
| assert(PPCond[PPStartCond.back()].second == 0); |
| PPCond[PPStartCond.back()].second = index; |
| PPStartCond.pop_back(); |
| // Now add '#elif' as a new block opening. |
| PPCond.push_back(std::make_pair(HashOff, 0U)); |
| PPStartCond.push_back(index); |
| break; |
| } |
| } |
| } |
| |
| EmitToken(Tok); |
| } |
| while (Tok.isNot(tok::eof)); |
| |
| assert(PPStartCond.empty() && "Error: imblanced preprocessor conditionals."); |
| |
| // Next write out PPCond. |
| Offset PPCondOff = (Offset) Out.tell(); |
| |
| // Write out the size of PPCond so that clients can identifer empty tables. |
| Emit32(PPCond.size()); |
| |
| for (unsigned i = 0, e = PPCond.size(); i!=e; ++i) { |
| Emit32(PPCond[i].first - TokenOff); |
| uint32_t x = PPCond[i].second; |
| assert(x != 0 && "PPCond entry not backpatched."); |
| // Emit zero for #endifs. This allows us to do checking when |
| // we read the PTH file back in. |
| Emit32(x == i ? 0 : x); |
| } |
| |
| return PTHEntry(TokenOff, PPCondOff); |
| } |
| |
| Offset PTHWriter::EmitCachedSpellings() { |
| // Write each cached strings to the PTH file. |
| Offset SpellingsOff = Out.tell(); |
| |
| for (std::vector<llvm::StringMapEntry<OffsetOpt>*>::iterator |
| I = StrEntries.begin(), E = StrEntries.end(); I!=E; ++I) |
| EmitBuf((*I)->getKeyData(), (*I)->getKeyLength()+1 /*nul included*/); |
| |
| return SpellingsOff; |
| } |
| |
| static uint32_t swap32le(uint32_t X) { |
| return llvm::support::endian::byte_swap<uint32_t, llvm::support::little>(X); |
| } |
| |
| static void pwrite32le(raw_pwrite_stream &OS, uint32_t Val, uint64_t &Off) { |
| uint32_t LEVal = swap32le(Val); |
| OS.pwrite(reinterpret_cast<const char *>(&LEVal), 4, Off); |
| Off += 4; |
| } |
| |
| void PTHWriter::GeneratePTH(StringRef MainFile) { |
| // Generate the prologue. |
| Out << "cfe-pth" << '\0'; |
| Emit32(PTHManager::Version); |
| |
| // Leave 4 words for the prologue. |
| Offset PrologueOffset = Out.tell(); |
| for (unsigned i = 0; i < 4; ++i) |
| Emit32(0); |
| |
| // Write the name of the MainFile. |
| if (!MainFile.empty()) { |
| EmitString(MainFile); |
| } else { |
| // String with 0 bytes. |
| Emit16(0); |
| } |
| Emit8(0); |
| |
| // Iterate over all the files in SourceManager. Create a lexer |
| // for each file and cache the tokens. |
| SourceManager &SM = PP.getSourceManager(); |
| const LangOptions &LOpts = PP.getLangOpts(); |
| |
| for (SourceManager::fileinfo_iterator I = SM.fileinfo_begin(), |
| E = SM.fileinfo_end(); I != E; ++I) { |
| const SrcMgr::ContentCache &C = *I->second; |
| const FileEntry *FE = C.OrigEntry; |
| |
| // FIXME: Handle files with non-absolute paths. |
| if (llvm::sys::path::is_relative(FE->getName())) |
| continue; |
| |
| const llvm::MemoryBuffer *B = C.getBuffer(PP.getDiagnostics(), SM); |
| if (!B) continue; |
| |
| FileID FID = SM.createFileID(FE, SourceLocation(), SrcMgr::C_User); |
| const llvm::MemoryBuffer *FromFile = SM.getBuffer(FID); |
| Lexer L(FID, FromFile, SM, LOpts); |
| PM.insert(FE, LexTokens(L)); |
| } |
| |
| // Write out the identifier table. |
| const std::pair<Offset,Offset> &IdTableOff = EmitIdentifierTable(); |
| |
| // Write out the cached strings table. |
| Offset SpellingOff = EmitCachedSpellings(); |
| |
| // Write out the file table. |
| Offset FileTableOff = EmitFileTable(); |
| |
| // Finally, write the prologue. |
| uint64_t Off = PrologueOffset; |
| pwrite32le(Out, IdTableOff.first, Off); |
| pwrite32le(Out, IdTableOff.second, Off); |
| pwrite32le(Out, FileTableOff, Off); |
| pwrite32le(Out, SpellingOff, Off); |
| } |
| |
| namespace { |
| /// StatListener - A simple "interpose" object used to monitor stat calls |
| /// invoked by FileManager while processing the original sources used |
| /// as input to PTH generation. StatListener populates the PTHWriter's |
| /// file map with stat information for directories as well as negative stats. |
| /// Stat information for files are populated elsewhere. |
| class StatListener : public FileSystemStatCache { |
| PTHMap &PM; |
| public: |
| StatListener(PTHMap &pm) : PM(pm) {} |
| ~StatListener() override {} |
| |
| LookupResult getStat(StringRef Path, FileData &Data, bool isFile, |
| std::unique_ptr<vfs::File> *F, |
| vfs::FileSystem &FS) override { |
| LookupResult Result = statChained(Path, Data, isFile, F, FS); |
| |
| if (Result == CacheMissing) // Failed 'stat'. |
| PM.insert(PTHEntryKeyVariant(Path), PTHEntry()); |
| else if (Data.IsDirectory) { |
| // Only cache directories with absolute paths. |
| if (llvm::sys::path::is_relative(Path)) |
| return Result; |
| |
| PM.insert(PTHEntryKeyVariant(&Data, Path), PTHEntry()); |
| } |
| |
| return Result; |
| } |
| }; |
| } // end anonymous namespace |
| |
| void clang::CacheTokens(Preprocessor &PP, raw_pwrite_stream *OS) { |
| // Get the name of the main file. |
| const SourceManager &SrcMgr = PP.getSourceManager(); |
| const FileEntry *MainFile = SrcMgr.getFileEntryForID(SrcMgr.getMainFileID()); |
| SmallString<128> MainFilePath(MainFile->getName()); |
| |
| llvm::sys::fs::make_absolute(MainFilePath); |
| |
| // Create the PTHWriter. |
| PTHWriter PW(*OS, PP); |
| |
| // Install the 'stat' system call listener in the FileManager. |
| auto StatCacheOwner = llvm::make_unique<StatListener>(PW.getPM()); |
| StatListener *StatCache = StatCacheOwner.get(); |
| PP.getFileManager().addStatCache(std::move(StatCacheOwner), |
| /*AtBeginning=*/true); |
| |
| // Lex through the entire file. This will populate SourceManager with |
| // all of the header information. |
| Token Tok; |
| PP.EnterMainSourceFile(); |
| do { PP.Lex(Tok); } while (Tok.isNot(tok::eof)); |
| |
| // Generate the PTH file. |
| PP.getFileManager().removeStatCache(StatCache); |
| PW.GeneratePTH(MainFilePath.str()); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| class PTHIdKey { |
| public: |
| const IdentifierInfo* II; |
| uint32_t FileOffset; |
| }; |
| |
| class PTHIdentifierTableTrait { |
| public: |
| typedef PTHIdKey* key_type; |
| typedef key_type key_type_ref; |
| |
| typedef uint32_t data_type; |
| typedef data_type data_type_ref; |
| |
| typedef unsigned hash_value_type; |
| typedef unsigned offset_type; |
| |
| static hash_value_type ComputeHash(PTHIdKey* key) { |
| return llvm::HashString(key->II->getName()); |
| } |
| |
| static std::pair<unsigned,unsigned> |
| EmitKeyDataLength(raw_ostream& Out, const PTHIdKey* key, uint32_t) { |
| using namespace llvm::support; |
| unsigned n = key->II->getLength() + 1; |
| endian::Writer<little>(Out).write<uint16_t>(n); |
| return std::make_pair(n, sizeof(uint32_t)); |
| } |
| |
| static void EmitKey(raw_ostream& Out, PTHIdKey* key, unsigned n) { |
| // Record the location of the key data. This is used when generating |
| // the mapping from persistent IDs to strings. |
| key->FileOffset = Out.tell(); |
| Out.write(key->II->getNameStart(), n); |
| } |
| |
| static void EmitData(raw_ostream& Out, PTHIdKey*, uint32_t pID, |
| unsigned) { |
| using namespace llvm::support; |
| endian::Writer<little>(Out).write<uint32_t>(pID); |
| } |
| }; |
| } // end anonymous namespace |
| |
| /// EmitIdentifierTable - Emits two tables to the PTH file. The first is |
| /// a hashtable mapping from identifier strings to persistent IDs. The second |
| /// is a straight table mapping from persistent IDs to string data (the |
| /// keys of the first table). |
| /// |
| std::pair<Offset,Offset> PTHWriter::EmitIdentifierTable() { |
| // Build two maps: |
| // (1) an inverse map from persistent IDs -> (IdentifierInfo*,Offset) |
| // (2) a map from (IdentifierInfo*, Offset)* -> persistent IDs |
| |
| // Note that we use 'calloc', so all the bytes are 0. |
| PTHIdKey *IIDMap = (PTHIdKey*)calloc(idcount, sizeof(PTHIdKey)); |
| |
| // Create the hashtable. |
| llvm::OnDiskChainedHashTableGenerator<PTHIdentifierTableTrait> IIOffMap; |
| |
| // Generate mapping from persistent IDs -> IdentifierInfo*. |
| for (IDMap::iterator I = IM.begin(), E = IM.end(); I != E; ++I) { |
| // Decrement by 1 because we are using a vector for the lookup and |
| // 0 is reserved for NULL. |
| assert(I->second > 0); |
| assert(I->second-1 < idcount); |
| unsigned idx = I->second-1; |
| |
| // Store the mapping from persistent ID to IdentifierInfo* |
| IIDMap[idx].II = I->first; |
| |
| // Store the reverse mapping in a hashtable. |
| IIOffMap.insert(&IIDMap[idx], I->second); |
| } |
| |
| // Write out the inverse map first. This causes the PCIDKey entries to |
| // record PTH file offsets for the string data. This is used to write |
| // the second table. |
| Offset StringTableOffset = IIOffMap.Emit(Out); |
| |
| // Now emit the table mapping from persistent IDs to PTH file offsets. |
| Offset IDOff = Out.tell(); |
| Emit32(idcount); // Emit the number of identifiers. |
| for (unsigned i = 0 ; i < idcount; ++i) |
| Emit32(IIDMap[i].FileOffset); |
| |
| // Finally, release the inverse map. |
| free(IIDMap); |
| |
| return std::make_pair(IDOff, StringTableOffset); |
| } |