Make DWARFDebugLine use StringRef for directory/file tables. NFC

Differential Revision: http://reviews.llvm.org/D32728

llvm-svn: 301940

llvm/include/llvm/DebugInfo/DWARF/DWARFDebugLine.h

@@ -30,7 +30,7 @@ public:
   struct FileNameEntry {
     FileNameEntry() = default;
 
-    const char *Name = nullptr;
+    StringRef Name = StringRef();
     uint64_t DirIdx = 0;
     uint64_t ModTime = 0;
     uint64_t Length = 0;
@@ -63,7 +63,7 @@ public:
     /// The number assigned to the first special opcode.
     uint8_t OpcodeBase;
     std::vector<uint8_t> StandardOpcodeLengths;
-    std::vector<const char *> IncludeDirectories;
+    std::vector<StringRef> IncludeDirectories;
     std::vector<FileNameEntry> FileNames;
 
     bool IsDWARF64;

llvm/include/llvm/Support/DataExtractor.h

@@ -58,6 +58,28 @@ public:
   ///     NULL will be returned.
   const char *getCStr(uint32_t *offset_ptr) const;
 
+  /// Extract a C string from \a *OffsetPtr.
+  ///
+  /// Returns a StringRef for the C String from the data at the offset
+  /// pointed to by \a OffsetPtr. A variable length NULL terminated C
+  /// string will be extracted and the \a OffsetPtr will be
+  /// updated with the offset of the byte that follows the NULL
+  /// terminator byte.
+  ///
+  /// \param[in,out] OffsetPtr
+  ///     A pointer to an offset within the data that will be advanced
+  ///     by the appropriate number of bytes if the value is extracted
+  ///     correctly. If the offset is out of bounds or there are not
+  ///     enough bytes to extract this value, the offset will be left
+  ///     unmodified.
+  ///
+  /// \return
+  ///     A StringRef for the C string value in the data. If the offset
+  ///     pointed to by \a OffsetPtr is out of bounds, or if the
+  ///     offset plus the length of the C string is out of bounds,
+  ///     a default-initialized StringRef will be returned.
+  StringRef getCStrRef(uint32_t *OffsetPtr) const;
+
   /// Extract an unsigned integer of size \a byte_size from \a
   /// *offset_ptr.
   ///

llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

@@ -107,25 +107,22 @@ bool DWARFDebugLine::Prologue::parse(DataExtractor DebugLineData,
   }
 
   while (*OffsetPtr < EndPrologueOffset) {
-    const char *S = DebugLineData.getCStr(OffsetPtr);
-    if (S && S[0])
-      IncludeDirectories.push_back(S);
-    else
+    StringRef S = DebugLineData.getCStrRef(OffsetPtr);
+    if (S.empty())
       break;
+    IncludeDirectories.push_back(S);
   }
 
   while (*OffsetPtr < EndPrologueOffset) {
-    const char *Name = DebugLineData.getCStr(OffsetPtr);
-    if (Name && Name[0]) {
-      FileNameEntry FileEntry;
-      FileEntry.Name = Name;
-      FileEntry.DirIdx = DebugLineData.getULEB128(OffsetPtr);
-      FileEntry.ModTime = DebugLineData.getULEB128(OffsetPtr);
-      FileEntry.Length = DebugLineData.getULEB128(OffsetPtr);
-      FileNames.push_back(FileEntry);
-    } else {
+    StringRef Name = DebugLineData.getCStrRef(OffsetPtr);
+    if (Name.empty())
       break;
-    }
+    FileNameEntry FileEntry;
+    FileEntry.Name = Name;
+    FileEntry.DirIdx = DebugLineData.getULEB128(OffsetPtr);
+    FileEntry.ModTime = DebugLineData.getULEB128(OffsetPtr);
+    FileEntry.Length = DebugLineData.getULEB128(OffsetPtr);
+    FileNames.push_back(FileEntry);
   }
 
   if (*OffsetPtr != EndPrologueOffset) {
@@ -637,7 +634,7 @@ bool DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex,
   if (Kind == FileLineInfoKind::None || !hasFileAtIndex(FileIndex))
     return false;
   const FileNameEntry &Entry = Prologue.FileNames[FileIndex - 1];
-  const char *FileName = Entry.Name;
+  StringRef FileName = Entry.Name;
   if (Kind != FileLineInfoKind::AbsoluteFilePath ||
       sys::path::is_absolute(FileName)) {
     Result = FileName;
@@ -646,7 +643,7 @@ bool DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex,
 
   SmallString<16> FilePath;
   uint64_t IncludeDirIndex = Entry.DirIdx;
-  const char *IncludeDir = "";
+  StringRef IncludeDir;
   // Be defensive about the contents of Entry.
   if (IncludeDirIndex > 0 &&
       IncludeDirIndex <= Prologue.IncludeDirectories.size())

llvm/lib/Support/DataExtractor.cpp

@@ -128,6 +128,16 @@ const char *DataExtractor::getCStr(uint32_t *offset_ptr) const {
   return nullptr;
 }
 
+StringRef DataExtractor::getCStrRef(uint32_t *OffsetPtr) const {
+  uint32_t Start = *OffsetPtr;
+  StringRef::size_type Pos = Data.find('\0', Start);
+  if (Pos != StringRef::npos) {
+    *OffsetPtr = Pos + 1;
+    return StringRef(Data.data() + Start, Pos - Start);
+  }
+  return StringRef();
+}
+
 uint64_t DataExtractor::getULEB128(uint32_t *offset_ptr) const {
   uint64_t result = 0;
   if (Data.empty())