pdbdump: Print "Publics" stream.

Publics stream seems to contain information as to public symbols.
It actually contains a serialized hash table along with fixed-sized
headers. This patch is not complete. It scans only till the end of
the stream and dump the header information. I'll write code to
de-serialize the hash table later.

Reviewers: zturner

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D20256

llvm-svn: 269484

1 files changed, 132 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/PDB/Raw/PublicsStream.cpp b/llvm/lib/DebugInfo/PDB/Raw/PublicsStream.cpp
new file mode 100644
index 0000000..dbdb1c5
--- /dev/null
+++ b/llvm/lib/DebugInfo/PDB/Raw/PublicsStream.cpp
@@ -0,0 +1,132 @@
+//===- PublicsStream.cpp - PDB Public Symbol Stream -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The data structures defined in this file are based on the reference
+// implementation which is available at
+// https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/dbi/gsi.h
+//
+// When you are reading the reference source code, you'd find the
+// information below useful.
+//
+//  - ppdb1->m_fMinimalDbgInfo seems to be always true.
+//  - SMALLBUCKETS macro is defined.
+//
+// The reference doesn't compile, so I learned just by reading code.
+// It's not guaranteed to be correct.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Raw/PublicsStream.h"
+
+#include "llvm/DebugInfo/CodeView/CodeView.h"
+#include "llvm/DebugInfo/CodeView/TypeRecord.h"
+#include "llvm/DebugInfo/PDB/Raw/MappedBlockStream.h"
+#include "llvm/DebugInfo/PDB/Raw/RawConstants.h"
+#include "llvm/DebugInfo/PDB/Raw/RawError.h"
+#include "llvm/DebugInfo/PDB/Raw/StreamReader.h"
+
+#include "llvm/ADT/BitVector.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/MathExtras.h"
+
+using namespace llvm;
+using namespace llvm::support;
+using namespace llvm::pdb;
+
+
+static const unsigned IPHR_HASH = 4096;
+
+// This is PSGSIHDR struct defined in
+// https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/dbi/gsi.h
+struct PublicsStream::HeaderInfo {
+  ulittle32_t SymHash;
+  ulittle32_t AddrMap;
+  ulittle32_t NumThunks;
+  ulittle32_t SizeOfThunk;
+  ulittle16_t ISectThunkTable;
+  char Padding[2];
+  ulittle32_t OffThunkTable;
+  ulittle32_t NumSects;
+};
+
+
+// This is GSIHashHdr struct defined in
+struct PublicsStream::GSIHashHeader {
+  enum {
+    HdrSignature = -1,
+    HdrVersion = 0xeffe0000 + 19990810,
+  };
+  ulittle32_t VerSignature;
+  ulittle32_t VerHdr;
+  ulittle32_t HrSize;
+  ulittle32_t NumBuckets;
+};
+
+struct PublicsStream::HRFile {
+  ulittle32_t Off;
+  ulittle32_t CRef;
+};
+
+PublicsStream::PublicsStream(PDBFile &File, uint32_t StreamNum)
+    : StreamNum(StreamNum), Stream(StreamNum, File) {}
+
+PublicsStream::~PublicsStream() {}
+
+uint32_t PublicsStream::getSymHash() const { return Header->SymHash; }
+uint32_t PublicsStream::getAddrMap() const { return Header->AddrMap; }
+
+// Publics stream contains fixed-size headers and a serialized hash table.
+// This implementation is not complete yet. It reads till the end of the
+// stream so that we verify the stream is at least not corrupted. However,
+// we skip over the hash table which we believe contains information about
+// public symbols.
+Error PublicsStream::reload() {
+  StreamReader Reader(Stream);
+
+  // Check stream size.
+  if (Reader.bytesRemaining() < sizeof(HeaderInfo) + sizeof(GSIHashHeader))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Publics Stream does not contain a header.");
+
+  // Read PSGSIHDR and GSIHashHdr structs.
+  Header.reset(new HeaderInfo());
+  if (Reader.readObject(Header.get()))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Publics Stream does not contain a header.");
+  HashHdr.reset(new GSIHashHeader());
+  if (Reader.readObject(HashHdr.get()))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Publics Stream does not contain a header.");
+
+  // An array of HRFile follows. Read them.
+  if (HashHdr->HrSize % sizeof(HRFile))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Invalid HR array size.");
+  std::vector<HRFile> HRs(HashHdr->HrSize / sizeof(HRFile));
+  if (auto EC = Reader.readArray<HRFile>(HRs))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Could not read an HR array");
+
+  // A bitmap of a fixed length follows.
+  size_t BitmapSizeInBits = alignTo(IPHR_HASH + 1, 32);
+  std::vector<uint8_t> Bitmap(BitmapSizeInBits / 8);
+  if (auto EC = Reader.readArray<uint8_t>(Bitmap))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Could not read a bitmap.");
+  for (uint8_t B : Bitmap)
+    NumBuckets += countPopulation(B);
+
+  // Buckets follow.
+  if (Reader.bytesRemaining() < NumBuckets * sizeof(uint32_t))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Hash buckets corrupted.");
+
+  return Error::success();
+}