[CodeView] Handle Cross Module Imports and Exports.

While it's not entirely clear why a compiler or linker might
put this information into an object or PDB file, one has been
spotted in the wild which was causing llvm-pdbdump to crash.

This patch adds support for reading-writing these sections.
Since I don't know how to get one of the native tools to
generate this kind of debug info, the only test here is one
in which we feed YAML into the tool to produce a PDB and
then spit out YAML from the resulting PDB and make sure that
it matches.

llvm-svn: 304738

1 files changed, 91 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/DebugCrossImpSubsection.cpp b/llvm/lib/DebugInfo/CodeView/DebugCrossImpSubsection.cpp
new file mode 100644
index 00000000000..e0ceefcd5fa
--- /dev/null
+++ b/llvm/lib/DebugInfo/CodeView/DebugCrossImpSubsection.cpp
@@ -0,0 +1,91 @@
+//===- DebugCrossImpSubsection.cpp ------------------------------*- 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/DebugCrossImpSubsection.h"
+
+#include "llvm/DebugInfo/CodeView/CodeViewError.h"
+#include "llvm/DebugInfo/CodeView/DebugStringTableSubsection.h"
+
+using namespace llvm;
+using namespace llvm::codeview;
+
+namespace llvm {
+Error VarStreamArrayExtractor<CrossModuleImportItem>::extract(
+    BinaryStreamRef Stream, uint32_t &Len,
+    codeview::CrossModuleImportItem &Item) {
+  BinaryStreamReader Reader(Stream);
+  if (Reader.bytesRemaining() < sizeof(CrossModuleImport))
+    return make_error<CodeViewError>(
+        cv_error_code::insufficient_buffer,
+        "Not enough bytes for a Cross Module Import Header!");
+  if (auto EC = Reader.readObject(Item.Header))
+    return EC;
+  if (Reader.bytesRemaining() < Item.Header->Count * sizeof(uint32_t))
+    return make_error<CodeViewError>(
+        cv_error_code::insufficient_buffer,
+        "Not enough to read specified number of Cross Module References!");
+  if (auto EC = Reader.readArray(Item.Imports, Item.Header->Count))
+    return EC;
+  return Error::success();
+}
+}
+
+Error DebugCrossModuleImportsSubsectionRef::initialize(
+    BinaryStreamReader Reader) {
+  return Reader.readArray(References, Reader.bytesRemaining());
+}
+
+Error DebugCrossModuleImportsSubsectionRef::initialize(BinaryStreamRef Stream) {
+  BinaryStreamReader Reader(Stream);
+  return initialize(Reader);
+}
+
+void DebugCrossModuleImportsSubsection::addImport(StringRef Module,
+                                                  uint32_t ImportId) {
+  Strings.insert(Module);
+  std::vector<support::ulittle32_t> Targets = {support::ulittle32_t(ImportId)};
+  auto Result = Mappings.insert(std::make_pair(Module, Targets));
+  if (!Result.second)
+    Result.first->getValue().push_back(Targets[0]);
+}
+
+uint32_t DebugCrossModuleImportsSubsection::calculateSerializedSize() const {
+  uint32_t Size = 0;
+  for (const auto &Item : Mappings) {
+    Size += sizeof(CrossModuleImport);
+    Size += sizeof(support::ulittle32_t) * Item.second.size();
+  }
+  return Size;
+}
+
+Error DebugCrossModuleImportsSubsection::commit(
+    BinaryStreamWriter &Writer) const {
+  using T = decltype(&*Mappings.begin());
+  std::vector<T> Ids;
+  Ids.reserve(Mappings.size());
+
+  for (const auto &M : Mappings)
+    Ids.push_back(&M);
+
+  std::sort(Ids.begin(), Ids.end(), [this](const T &L1, const T &L2) {
+    return Strings.getStringId(L1->getKey()) <
+           Strings.getStringId(L2->getKey());
+  });
+
+  for (const auto &Item : Ids) {
+    CrossModuleImport Imp;
+    Imp.ModuleNameOffset = Strings.getStringId(Item->getKey());
+    Imp.Count = Item->getValue().size();
+    if (auto EC = Writer.writeObject(Imp))
+      return EC;
+    if (auto EC = Writer.writeArray(makeArrayRef(Item->getValue())))
+      return EC;
+  }
+  return Error::success();
+}