1 files changed, 110 insertions, 0 deletions
diff --git a/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp b/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp
new file mode 100644
index 00000000000..28dc67a9d2a
--- /dev/null
+++ b/llvm/lib/DebugInfo/PDB/Raw/NameMap.cpp
@@ -0,0 +1,110 @@
+//===- NameMap.cpp - PDB Name Map -------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Raw/NameMap.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/DebugInfo/PDB/Raw/StreamReader.h"
+
+using namespace llvm;
+using namespace llvm::pdb;
+
+NameMap::NameMap() {}
+
+std::error_code NameMap::load(StreamReader &Stream) {
+
+  // This is some sort of weird string-set/hash table encoded in the stream.
+  // It starts with the number of bytes in the table.
+  uint32_t NumberOfBytes;
+  Stream.readInteger(NumberOfBytes);
+
+  // Following that field is the starting offset of strings in the name table.
+  uint32_t StringsOffset = Stream.getOffset();
+  Stream.setOffset(StringsOffset + NumberOfBytes);
+
+  // This appears to be equivalent to the total number of strings *actually*
+  // in the name table.
+  uint32_t HashSize;
+  Stream.readInteger(HashSize);
+
+  // This appears to be an upper bound on the number of strings in the name
+  // table.
+  uint32_t MaxNumberOfStrings;
+  Stream.readInteger(MaxNumberOfStrings);
+
+  // This appears to be a hash table which uses bitfields to determine whether
+  // or not a bucket is 'present'.
+  uint32_t NumPresentWords;
+  Stream.readInteger(NumPresentWords);
+
+  // Store all the 'present' bits in a vector for later processing.
+  SmallVector<uint32_t, 1> PresentWords;
+  for (uint32_t I = 0; I != NumPresentWords; ++I) {
+    uint32_t Word;
+    Stream.readInteger(Word);
+    PresentWords.push_back(Word);
+  }
+
+  // This appears to be a hash table which uses bitfields to determine whether
+  // or not a bucket is 'deleted'.
+  uint32_t NumDeletedWords;
+  Stream.readInteger(NumDeletedWords);
+
+  // Store all the 'deleted' bits in a vector for later processing.
+  SmallVector<uint32_t, 1> DeletedWords;
+  for (uint32_t I = 0; I != NumDeletedWords; ++I) {
+    uint32_t Word;
+    Stream.readInteger(Word);
+    DeletedWords.push_back(Word);
+  }
+
+  BitVector Present(MaxNumberOfStrings, false);
+  if (!PresentWords.empty())
+    Present.setBitsInMask(PresentWords.data(), PresentWords.size());
+  BitVector Deleted(MaxNumberOfStrings, false);
+  if (!DeletedWords.empty())
+    Deleted.setBitsInMask(DeletedWords.data(), DeletedWords.size());
+
+  for (uint32_t I = 0; I < MaxNumberOfStrings; ++I) {
+    if (!Present.test(I))
+      continue;
+
+    // For all present entries, dump out their mapping.
+
+    // This appears to be an offset relative to the start of the strings.
+    // It tells us where the null-terminated string begins.
+    uint32_t NameOffset;
+    Stream.readInteger(NameOffset);
+
+    // This appears to be a stream number into the stream directory.
+    uint32_t NameIndex;
+    Stream.readInteger(NameIndex);
+
+    // Compute the offset of the start of the string relative to the stream.
+    uint32_t StringOffset = StringsOffset + NameOffset;
+    uint32_t OldOffset = Stream.getOffset();
+    // Pump out our c-string from the stream.
+    std::string Str;
+    Stream.setOffset(StringOffset);
+    Stream.readZeroString(Str);
+
+    Stream.setOffset(OldOffset);
+    // Add this to a string-map from name to stream number.
+    Mapping.insert({Str, NameIndex});
+  }
+
+  return std::error_code();
+}
+
+bool NameMap::tryGetValue(StringRef Name, uint32_t &Value) const {
+  auto Iter = Mapping.find(Name);
+  if (Iter == Mapping.end())
+    return false;
+  Value = Iter->second;
+  return true;
+}