SourceMgr: make valid buffer IDs start from one

Use 0 for the invalid buffer instead of -1/~0 and switch to unsigned
representation to enable more idiomatic usage.

Also introduce a trivial SourceMgr::getMainFileID() instead of hard-coding 0/1
to identify the main file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212398 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/SourceMgr.h

@@ -66,6 +66,8 @@ private:
   DiagHandlerTy DiagHandler;
   void *DiagContext;
 
+  bool isValidBufferID(unsigned i) const { return i && i <= Buffers.size(); }
+
   SourceMgr(const SourceMgr&) LLVM_DELETED_FUNCTION;
   void operator=(const SourceMgr&) LLVM_DELETED_FUNCTION;
 public:
@@ -88,22 +90,27 @@ public:
   void *getDiagContext() const { return DiagContext; }
 
   const SrcBuffer &getBufferInfo(unsigned i) const {
-    assert(i < Buffers.size() && "Invalid Buffer ID!");
-    return Buffers[i];
+    assert(isValidBufferID(i));
+    return Buffers[i - 1];
   }
 
   const MemoryBuffer *getMemoryBuffer(unsigned i) const {
-    assert(i < Buffers.size() && "Invalid Buffer ID!");
-    return Buffers[i].Buffer;
+    assert(isValidBufferID(i));
+    return Buffers[i - 1].Buffer;
   }
 
   size_t getNumBuffers() const {
     return Buffers.size();
   }
 
+  unsigned getMainFileID() const {
+    assert(getNumBuffers());
+    return 1;
+  }
+
   SMLoc getParentIncludeLoc(unsigned i) const {
-    assert(i < Buffers.size() && "Invalid Buffer ID!");
-    return Buffers[i].IncludeLoc;
+    assert(isValidBufferID(i));
+    return Buffers[i - 1].IncludeLoc;
   }
 
   /// Add a new source buffer to this source manager. This takes ownership of
@@ -113,13 +120,13 @@ public:
     NB.Buffer = F;
     NB.IncludeLoc = IncludeLoc;
     Buffers.push_back(NB);
-    return Buffers.size() - 1;
+    return Buffers.size();
   }
 
   /// Search for a file with the specified name in the current directory or in
   /// one of the IncludeDirs.
   ///
-  /// If no file is found, this returns ~0, otherwise it returns the buffer ID
+  /// If no file is found, this returns 0, otherwise it returns the buffer ID
   /// of the stacked file. The full path to the included file can be found in
   /// \p IncludedFile.
   size_t AddIncludeFile(const std::string &Filename, SMLoc IncludeLoc,
@@ -127,19 +134,19 @@ public:
 
   /// Return the ID of the buffer containing the specified location.
   ///
-  /// -1 is returned if the buffer is not found.
-  int FindBufferContainingLoc(SMLoc Loc) const;
+  /// 0 is returned if the buffer is not found.
+  unsigned FindBufferContainingLoc(SMLoc Loc) const;
 
   /// Find the line number for the specified location in the specified file.
   /// This is not a fast method.
-  unsigned FindLineNumber(SMLoc Loc, int BufferID = -1) const {
+  unsigned FindLineNumber(SMLoc Loc, unsigned BufferID = 0) const {
     return getLineAndColumn(Loc, BufferID).first;
   }
 
   /// Find the line and column number for the specified location in the
   /// specified file. This is not a fast method.
-  std::pair<unsigned, unsigned>
-    getLineAndColumn(SMLoc Loc, int BufferID = -1) const;
+  std::pair<unsigned, unsigned> getLineAndColumn(SMLoc Loc,
+                                                 unsigned BufferID = 0) const;
 
   /// Emit a message about the specified location with the specified string.
   ///

lib/MC/MCContext.cpp

@@ -47,8 +47,9 @@ MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
   SecureLog = nullptr;
   SecureLogUsed = false;
 
-  if (SrcMgr && SrcMgr->getNumBuffers() > 0)
-    MainFileName = SrcMgr->getMemoryBuffer(0)->getBufferIdentifier();
+  if (SrcMgr && SrcMgr->getNumBuffers())
+    MainFileName =
+        SrcMgr->getMemoryBuffer(SrcMgr->getMainFileID())->getBufferIdentifier();
 }
 
 MCContext::~MCContext() {

lib/MC/MCDwarf.cpp

@@ -928,7 +928,7 @@ void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
 
   // Finding the line number is the expensive part which is why we just don't
   // pass it in as for some symbols we won't create a dwarf label.
-  int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
+  unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
   unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
 
   // We create a temporary symbol for use for the AT_high_pc and AT_low_pc

lib/MC/MCParser/AsmParser.cpp

@@ -133,7 +133,7 @@ private:
 
   /// This is the current buffer index we're lexing from as managed by the
   /// SourceMgr object.
-  int CurBuffer;
+  unsigned CurBuffer;
 
   AsmCond TheCondState;
   std::vector<AsmCond> TheCondStack;
@@ -162,13 +162,13 @@ private:
   StringRef CppHashFilename;
   int64_t CppHashLineNumber;
   SMLoc CppHashLoc;
-  int CppHashBuf;
+  unsigned CppHashBuf;
   /// When generating dwarf for assembly source files we need to calculate the
   /// logical line number based on the last parsed cpp hash file line comment
   /// and current line. Since this is slow and messes up the SourceMgr's
   /// cache we save the last info we queried with SrcMgr.FindLineNumber().
   SMLoc LastQueryIDLoc;
-  int LastQueryBuffer;
+  unsigned LastQueryBuffer;
   unsigned LastQueryLine;
 
   /// AssemblerDialect. ~OU means unset value and use value provided by MAI.
@@ -310,9 +310,9 @@ private:
   /// current token is not set; clients should ensure Lex() is called
   /// subsequently.
   ///
-  /// \param InBuffer If not -1, should be the known buffer id that contains the
+  /// \param InBuffer If not 0, should be the known buffer id that contains the
   /// location.
-  void jumpToLoc(SMLoc Loc, int InBuffer=-1);
+  void jumpToLoc(SMLoc Loc, unsigned InBuffer = 0);
 
   /// \brief Parse up to the end of statement and a return the contents from the
   /// current token until the end of the statement; the current token on exit
@@ -491,9 +491,9 @@ enum { DEFAULT_ADDRSPACE = 0 };
 AsmParser::AsmParser(SourceMgr &_SM, MCContext &_Ctx, MCStreamer &_Out,
                      const MCAsmInfo &_MAI)
     : Lexer(_MAI), Ctx(_Ctx), Out(_Out), MAI(_MAI), SrcMgr(_SM),
-      PlatformParser(nullptr), CurBuffer(0), MacrosEnabledFlag(true),
-      HadError(false), CppHashLineNumber(0), AssemblerDialect(~0U),
-      IsDarwin(false), ParsingInlineAsm(false) {
+      PlatformParser(nullptr), CurBuffer(_SM.getMainFileID()),
+      MacrosEnabledFlag(true), HadError(false), CppHashLineNumber(0),
+      AssemblerDialect(~0U), IsDarwin(false), ParsingInlineAsm(false) {
   // Save the old handler.
   SavedDiagHandler = SrcMgr.getDiagHandler();
   SavedDiagContext = SrcMgr.getDiagContext();
@@ -566,14 +566,13 @@ bool AsmParser::Error(SMLoc L, const Twine &Msg, ArrayRef<SMRange> Ranges) {
 
 bool AsmParser::enterIncludeFile(const std::string &Filename) {
   std::string IncludedFile;
-  int NewBuf = SrcMgr.AddIncludeFile(Filename, Lexer.getLoc(), IncludedFile);
-  if (NewBuf == -1)
+  unsigned NewBuf =
+      SrcMgr.AddIncludeFile(Filename, Lexer.getLoc(), IncludedFile);
+  if (!NewBuf)
     return true;
 
   CurBuffer = NewBuf;
-
   Lexer.setBuffer(SrcMgr.getMemoryBuffer(CurBuffer));
-
   return false;
 }
 
@@ -582,8 +581,9 @@ bool AsmParser::enterIncludeFile(const std::string &Filename) {
 /// returns true on failure.
 bool AsmParser::processIncbinFile(const std::string &Filename) {
   std::string IncludedFile;
-  int NewBuf = SrcMgr.AddIncludeFile(Filename, Lexer.getLoc(), IncludedFile);
-  if (NewBuf == -1)
+  unsigned NewBuf =
+      SrcMgr.AddIncludeFile(Filename, Lexer.getLoc(), IncludedFile);
+  if (!NewBuf)
     return true;
 
   // Pick up the bytes from the file and emit them.
@@ -591,12 +591,8 @@ bool AsmParser::processIncbinFile(const std::string &Filename) {
   return false;
 }
 
-void AsmParser::jumpToLoc(SMLoc Loc, int InBuffer) {
-  if (InBuffer != -1) {
-    CurBuffer = InBuffer;
-  } else {
-    CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
-  }
+void AsmParser::jumpToLoc(SMLoc Loc, unsigned InBuffer) {
+  CurBuffer = InBuffer ? InBuffer : SrcMgr.FindBufferContainingLoc(Loc);
   Lexer.setBuffer(SrcMgr.getMemoryBuffer(CurBuffer), Loc.getPointer());
 }
 
@@ -1697,13 +1693,15 @@ void AsmParser::DiagHandler(const SMDiagnostic &Diag, void *Context) {
 
   const SourceMgr &DiagSrcMgr = *Diag.getSourceMgr();
   const SMLoc &DiagLoc = Diag.getLoc();
-  int DiagBuf = DiagSrcMgr.FindBufferContainingLoc(DiagLoc);
-  int CppHashBuf = Parser->SrcMgr.FindBufferContainingLoc(Parser->CppHashLoc);
+  unsigned DiagBuf = DiagSrcMgr.FindBufferContainingLoc(DiagLoc);
+  unsigned CppHashBuf =
+      Parser->SrcMgr.FindBufferContainingLoc(Parser->CppHashLoc);
 
   // Like SourceMgr::printMessage() we need to print the include stack if any
   // before printing the message.
-  int DiagCurBuffer = DiagSrcMgr.FindBufferContainingLoc(DiagLoc);
-  if (!Parser->SavedDiagHandler && DiagCurBuffer > 0) {
+  unsigned DiagCurBuffer = DiagSrcMgr.FindBufferContainingLoc(DiagLoc);
+  if (!Parser->SavedDiagHandler && DiagCurBuffer &&
+      DiagCurBuffer != DiagSrcMgr.getMainFileID()) {
     SMLoc ParentIncludeLoc = DiagSrcMgr.getParentIncludeLoc(DiagCurBuffer);
     DiagSrcMgr.PrintIncludeStack(ParentIncludeLoc, OS);
   }
@@ -4582,8 +4580,10 @@ bool AsmParser::parseMSInlineAsm(
   // Build the IR assembly string.
   std::string AsmStringIR;
   raw_string_ostream OS(AsmStringIR);
-  const char *AsmStart = SrcMgr.getMemoryBuffer(0)->getBufferStart();
-  const char *AsmEnd = SrcMgr.getMemoryBuffer(0)->getBufferEnd();
+  StringRef ASMString =
+      SrcMgr.getMemoryBuffer(SrcMgr.getMainFileID())->getBuffer();
+  const char *AsmStart = ASMString.begin();
+  const char *AsmEnd = ASMString.end();
   array_pod_sort(AsmStrRewrites.begin(), AsmStrRewrites.end(), rewritesSort);
   for (const AsmRewrite &AR : AsmStrRewrites) {
     AsmRewriteKind Kind = AR.Kind;

lib/MC/MCParser/DarwinAsmParser.cpp

@@ -650,7 +650,7 @@ bool DarwinAsmParser::parseDirectiveSecureLogUnique(StringRef, SMLoc IDLoc) {
   }
 
   // Write the message.
-  int CurBuf = getSourceManager().FindBufferContainingLoc(IDLoc);
+  unsigned CurBuf = getSourceManager().FindBufferContainingLoc(IDLoc);
   *OS << getSourceManager().getBufferInfo(CurBuf).Buffer->getBufferIdentifier()
       << ":" << getSourceManager().FindLineNumber(IDLoc, CurBuf) << ":"
       << LogMessage + "\n";

lib/Support/SourceMgr.cpp

@@ -27,7 +27,7 @@ static const size_t TabStop = 8;
 
 namespace {
   struct LineNoCacheTy {
-    int LastQueryBufferID;
+    unsigned LastQueryBufferID;
     const char *LastQuery;
     unsigned LineNoOfQuery;
   };
@@ -62,26 +62,27 @@ size_t SourceMgr::AddIncludeFile(const std::string &Filename,
     MemoryBuffer::getFile(IncludedFile.c_str(), NewBuf);
   }
 
-  if (!NewBuf) return ~0U;
+  if (!NewBuf)
+    return 0;
 
   return AddNewSourceBuffer(NewBuf.release(), IncludeLoc);
 }
 
-
-int SourceMgr::FindBufferContainingLoc(SMLoc Loc) const {
+unsigned SourceMgr::FindBufferContainingLoc(SMLoc Loc) const {
   for (unsigned i = 0, e = Buffers.size(); i != e; ++i)
     if (Loc.getPointer() >= Buffers[i].Buffer->getBufferStart() &&
         // Use <= here so that a pointer to the null at the end of the buffer
         // is included as part of the buffer.
         Loc.getPointer() <= Buffers[i].Buffer->getBufferEnd())
-      return i;
-  return -1;
+      return i + 1;
+  return 0;
 }
 
 std::pair<unsigned, unsigned>
-SourceMgr::getLineAndColumn(SMLoc Loc, int BufferID) const {
-  if (BufferID == -1) BufferID = FindBufferContainingLoc(Loc);
-  assert(BufferID != -1 && "Invalid Location!");
+SourceMgr::getLineAndColumn(SMLoc Loc, unsigned BufferID) const {
+  if (!BufferID)
+    BufferID = FindBufferContainingLoc(Loc);
+  assert(BufferID && "Invalid Location!");
 
   const MemoryBuffer *Buff = getMemoryBuffer(BufferID);
 
@@ -125,8 +126,8 @@ SourceMgr::getLineAndColumn(SMLoc Loc, int BufferID) const {
 void SourceMgr::PrintIncludeStack(SMLoc IncludeLoc, raw_ostream &OS) const {
   if (IncludeLoc == SMLoc()) return;  // Top of stack.
 
-  int CurBuf = FindBufferContainingLoc(IncludeLoc);
-  assert(CurBuf != -1 && "Invalid or unspecified location!");
+  unsigned CurBuf = FindBufferContainingLoc(IncludeLoc);
+  assert(CurBuf && "Invalid or unspecified location!");
 
   PrintIncludeStack(getBufferInfo(CurBuf).IncludeLoc, OS);
 
@@ -149,8 +150,8 @@ SMDiagnostic SourceMgr::GetMessage(SMLoc Loc, SourceMgr::DiagKind Kind,
   std::string LineStr;
   
   if (Loc.isValid()) {
-    int CurBuf = FindBufferContainingLoc(Loc);
-    assert(CurBuf != -1 && "Invalid or unspecified location!");
+    unsigned CurBuf = FindBufferContainingLoc(Loc);
+    assert(CurBuf && "Invalid or unspecified location!");
 
     const MemoryBuffer *CurMB = getMemoryBuffer(CurBuf);
     BufferID = CurMB->getBufferIdentifier();
@@ -208,8 +209,8 @@ void SourceMgr::PrintMessage(raw_ostream &OS, const SMDiagnostic &Diagnostic,
   }
 
   if (Diagnostic.getLoc().isValid()) {
-    int CurBuf = FindBufferContainingLoc(Diagnostic.getLoc());
-    assert(CurBuf != -1 && "Invalid or unspecified location!");
+    unsigned CurBuf = FindBufferContainingLoc(Diagnostic.getLoc());
+    assert(CurBuf && "Invalid or unspecified location!");
     PrintIncludeStack(getBufferInfo(CurBuf).IncludeLoc, OS);
   }
 

lib/TableGen/TGLexer.cpp

@@ -27,7 +27,7 @@
 using namespace llvm;
 
 TGLexer::TGLexer(SourceMgr &SM) : SrcMgr(SM) {
-  CurBuffer = 0;
+  CurBuffer = SrcMgr.getMainFileID();
   CurBuf = SrcMgr.getMemoryBuffer(CurBuffer);
   CurPtr = CurBuf->getBufferStart();
   TokStart = nullptr;
@@ -304,7 +304,7 @@ bool TGLexer::LexInclude() {
   
   CurBuffer = SrcMgr.AddIncludeFile(Filename, SMLoc::getFromPointer(CurPtr),
                                     IncludedFile);
-  if (CurBuffer == -1) {
+  if (!CurBuffer) {
     PrintError(getLoc(), "Could not find include file '" + Filename + "'");
     return true;
   }

lib/TableGen/TGLexer.h

@@ -73,7 +73,7 @@ class TGLexer {
 
   /// CurBuffer - This is the current buffer index we're lexing from as managed
   /// by the SourceMgr object.
-  int CurBuffer;
+  unsigned CurBuffer;
 
 public:
   typedef std::map<std::string, SMLoc> DependenciesMapTy;

tools/llvm-mc/llvm-mc.cpp

@@ -242,7 +242,7 @@ static int AsLexInput(SourceMgr &SrcMgr, MCAsmInfo &MAI,
                       tool_output_file *Out) {
 
   AsmLexer Lexer(MAI);
-  Lexer.setBuffer(SrcMgr.getMemoryBuffer(0));
+  Lexer.setBuffer(SrcMgr.getMemoryBuffer(SrcMgr.getMainFileID()));
 
   bool Error = false;
   while (Lexer.Lex().isNot(AsmToken::Eof)) {

utils/TableGen/CTagsEmitter.cpp

@@ -37,8 +37,8 @@ public:
       : Id(&Name), Loc(Location) {}
   int operator<(const Tag &B) const { return *Id < *B.Id; }
   void emit(raw_ostream &OS) const {
-    int BufferID = SrcMgr.FindBufferContainingLoc(Loc);
-    const MemoryBuffer *CurMB = SrcMgr.getMemoryBuffer(BufferID);
+    const MemoryBuffer *CurMB =
+        SrcMgr.getMemoryBuffer(SrcMgr.FindBufferContainingLoc(Loc));
     const char *BufferName = CurMB->getBufferIdentifier();
     std::pair<unsigned, unsigned> LineAndColumn = SrcMgr.getLineAndColumn(Loc);
     OS << *Id << "\t" << BufferName << "\t" << LineAndColumn.first << "\n";