Make codeview::StringTable.

Previously we had knowledge of how to serialize and deserialize
a string table inside of DebugInfo/PDB, but the string table
that it serializes contains a piece that is actually considered
CodeView and can appear outside of a PDB.  We already have logic
in llvm-readobj and MCCodeView to read and write this format,
so it doesn't make sense to duplicate the logic in DebugInfoPDB
as well.

This patch makes codeview::StringTable (for writing) and
codeview::StringTableRef (for reading), updates DebugInfoPDB
to use these classes for its own writing, and updates llvm-readobj
to additionally use StringTableRef for reading.

It's a bit more difficult to get MCCodeView to use this for
writing, but it's a logical next step.

llvm-svn: 301986

1 files changed, 65 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/StringTable.cpp b/llvm/lib/DebugInfo/CodeView/StringTable.cpp
new file mode 100644
index 00000000000..49e2fe32ab4
--- /dev/null
+++ b/llvm/lib/DebugInfo/CodeView/StringTable.cpp
@@ -0,0 +1,65 @@
+//===- StringTable.cpp - CodeView String Table Reader/Writer ----*- 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/CodeView/StringTable.h"
+
+#include "llvm/Support/BinaryStream.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+
+using namespace llvm;
+using namespace llvm::codeview;
+
+StringTableRef::StringTableRef() {}
+
+Error StringTableRef::initialize(BinaryStreamReader &Reader) {
+  return Reader.readStreamRef(Stream, Reader.bytesRemaining());
+}
+
+StringRef StringTableRef::getString(uint32_t Offset) const {
+  BinaryStreamReader Reader(Stream);
+  Reader.setOffset(Offset);
+  StringRef Result;
+  Error EC = Reader.readCString(Result);
+  assert(!EC);
+  consumeError(std::move(EC));
+  return Result;
+}
+
+uint32_t StringTable::insert(StringRef S) {
+  auto P = Strings.insert({S, StringSize});
+
+  // If a given string didn't exist in the string table, we want to increment
+  // the string table size.
+  if (P.second)
+    StringSize += S.size() + 1; // +1 for '\0'
+  return P.first->second;
+}
+
+uint32_t StringTable::calculateSerializedSize() const { return StringSize; }
+
+Error StringTable::commit(BinaryStreamWriter &Writer) const {
+  assert(Writer.bytesRemaining() == StringSize);
+  uint32_t MaxOffset = 1;
+
+  for (auto &Pair : Strings) {
+    StringRef S = Pair.getKey();
+    uint32_t Offset = Pair.getValue();
+    Writer.setOffset(Offset);
+    if (auto EC = Writer.writeCString(S))
+      return EC;
+    MaxOffset = std::max(MaxOffset, Offset + S.size() + 1);
+  }
+
+  Writer.setOffset(MaxOffset);
+  assert(Writer.bytesRemaining() == 0);
+  return Error::success();
+}
+
+uint32_t StringTable::size() const { return Strings.size(); }