1 files changed, 181 insertions, 0 deletions
diff --git a/llvm/lib/DebugInfo/PDB/Native/GlobalsStream.cpp b/llvm/lib/DebugInfo/PDB/Native/GlobalsStream.cpp
new file mode 100644
index 000000000000..f27d60f46815
--- /dev/null
+++ b/llvm/lib/DebugInfo/PDB/Native/GlobalsStream.cpp
@@ -0,0 +1,181 @@
+//===- GlobalsStream.cpp - PDB Index of Symbols by Name ---------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// The on-disk structores used 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.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Native/GlobalsStream.h"
+
+#include "llvm/DebugInfo/CodeView/RecordName.h"
+#include "llvm/DebugInfo/PDB/Native/Hash.h"
+#include "llvm/DebugInfo/PDB/Native/RawError.h"
+#include "llvm/DebugInfo/PDB/Native/SymbolStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/Error.h"
+#include <algorithm>
+
+using namespace llvm;
+using namespace llvm::msf;
+using namespace llvm::pdb;
+
+GlobalsStream::GlobalsStream(std::unique_ptr<MappedBlockStream> Stream)
+    : Stream(std::move(Stream)) {}
+
+GlobalsStream::~GlobalsStream() = default;
+
+Error GlobalsStream::reload() {
+  BinaryStreamReader Reader(*Stream);
+  if (auto E = GlobalsTable.read(Reader))
+    return E;
+  return Error::success();
+}
+
+std::vector<std::pair<uint32_t, codeview::CVSymbol>>
+GlobalsStream::findRecordsByName(StringRef Name,
+                                 const SymbolStream &Symbols) const {
+  std::vector<std::pair<uint32_t, codeview::CVSymbol>> Result;
+
+  // Hash the name to figure out which bucket this goes into.
+  size_t ExpandedBucketIndex = hashStringV1(Name) % IPHR_HASH;
+  int32_t CompressedBucketIndex = GlobalsTable.BucketMap[ExpandedBucketIndex];
+  if (CompressedBucketIndex == -1)
+    return Result;
+
+  uint32_t LastBucketIndex = GlobalsTable.HashBuckets.size() - 1;
+  uint32_t StartRecordIndex =
+      GlobalsTable.HashBuckets[CompressedBucketIndex] / 12;
+  uint32_t EndRecordIndex = 0;
+  if (LLVM_LIKELY(uint32_t(CompressedBucketIndex) < LastBucketIndex)) {
+    EndRecordIndex = GlobalsTable.HashBuckets[CompressedBucketIndex + 1];
+  } else {
+    // If this is the last bucket, it consists of all hash records until the end
+    // of the HashRecords array.
+    EndRecordIndex = GlobalsTable.HashRecords.size() * 12;
+  }
+
+  EndRecordIndex /= 12;
+
+  assert(EndRecordIndex <= GlobalsTable.HashRecords.size());
+  while (StartRecordIndex < EndRecordIndex) {
+    PSHashRecord PSH = GlobalsTable.HashRecords[StartRecordIndex];
+    uint32_t Off = PSH.Off - 1;
+    codeview::CVSymbol Record = Symbols.readRecord(Off);
+    if (codeview::getSymbolName(Record) == Name)
+      Result.push_back(std::make_pair(Off, std::move(Record)));
+    ++StartRecordIndex;
+  }
+  return Result;
+}
+
+static Error checkHashHdrVersion(const GSIHashHeader *HashHdr) {
+  if (HashHdr->VerHdr != GSIHashHeader::HdrVersion)
+    return make_error<RawError>(
+        raw_error_code::feature_unsupported,
+        "Encountered unsupported globals stream version.");
+
+  return Error::success();
+}
+
+static Error readGSIHashHeader(const GSIHashHeader *&HashHdr,
+                               BinaryStreamReader &Reader) {
+  if (Reader.readObject(HashHdr))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Stream does not contain a GSIHashHeader.");
+
+  if (HashHdr->VerSignature != GSIHashHeader::HdrSignature)
+    return make_error<RawError>(
+        raw_error_code::feature_unsupported,
+        "GSIHashHeader signature (0xffffffff) not found.");
+
+  return Error::success();
+}
+
+static Error readGSIHashRecords(FixedStreamArray<PSHashRecord> &HashRecords,
+                                const GSIHashHeader *HashHdr,
+                                BinaryStreamReader &Reader) {
+  if (auto EC = checkHashHdrVersion(HashHdr))
+    return EC;
+
+  // HashHdr->HrSize specifies the number of bytes of PSHashRecords we have.
+  // Verify that we can read them all.
+  if (HashHdr->HrSize % sizeof(PSHashRecord))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Invalid HR array size.");
+  uint32_t NumHashRecords = HashHdr->HrSize / sizeof(PSHashRecord);
+  if (auto EC = Reader.readArray(HashRecords, NumHashRecords))
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Error reading hash records."));
+
+  return Error::success();
+}
+
+static Error
+readGSIHashBuckets(FixedStreamArray<support::ulittle32_t> &HashBuckets,
+                   FixedStreamArray<support::ulittle32_t> &HashBitmap,
+                   const GSIHashHeader *HashHdr,
+                   MutableArrayRef<int32_t> BucketMap,
+                   BinaryStreamReader &Reader) {
+  if (auto EC = checkHashHdrVersion(HashHdr))
+    return EC;
+
+  // Before the actual hash buckets, there is a bitmap of length determined by
+  // IPHR_HASH.
+  size_t BitmapSizeInBits = alignTo(IPHR_HASH + 1, 32);
+  uint32_t NumBitmapEntries = BitmapSizeInBits / 32;
+  if (auto EC = Reader.readArray(HashBitmap, NumBitmapEntries))
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Could not read a bitmap."));
+  uint32_t NumBuckets1 = 0;
+  uint32_t CompressedBucketIdx = 0;
+  for (uint32_t I = 0; I <= IPHR_HASH; ++I) {
+    uint8_t WordIdx = I / 32;
+    uint8_t BitIdx = I % 32;
+    bool IsSet = HashBitmap[WordIdx] & (1U << BitIdx);
+    if (IsSet) {
+      ++NumBuckets1;
+      BucketMap[I] = CompressedBucketIdx++;
+    } else {
+      BucketMap[I] = -1;
+    }
+  }
+
+  uint32_t NumBuckets = 0;
+  for (uint32_t B : HashBitmap)
+    NumBuckets += countPopulation(B);
+
+  // Hash buckets follow.
+  if (auto EC = Reader.readArray(HashBuckets, NumBuckets))
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Hash buckets corrupted."));
+
+  return Error::success();
+}
+
+Error GSIHashTable::read(BinaryStreamReader &Reader) {
+  if (auto EC = readGSIHashHeader(HashHdr, Reader))
+    return EC;
+  if (auto EC = readGSIHashRecords(HashRecords, HashHdr, Reader))
+    return EC;
+  if (HashHdr->HrSize > 0)
+    if (auto EC = readGSIHashBuckets(HashBuckets, HashBitmap, HashHdr,
+                                     BucketMap, Reader))
+      return EC;
+  return Error::success();
+}