1 files changed, 121 insertions, 0 deletions

diff --git a/contrib/llvm-project/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp b/contrib/llvm-project/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp
new file mode 100644
index 000000000000..f65ec27ff875
--- /dev/null
+++ b/contrib/llvm-project/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp
@@ -0,0 +1,121 @@
+//===--- DebugInfoSupport.cpp -- Utils for debug info support ---*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Utilities to preserve and parse debug info from LinkGraphs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/Debugging/DebugInfoSupport.h"
+
+#include "llvm/Support/SmallVectorMemoryBuffer.h"
+
+#define DEBUG_TYPE "orc"
+
+using namespace llvm;
+using namespace llvm::orc;
+using namespace llvm::jitlink;
+
+namespace {
+static DenseSet<StringRef> DWARFSectionNames = {
+#define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME, OPTION)        \
+  StringRef(ELF_NAME),
+#include "llvm/BinaryFormat/Dwarf.def"
+#undef HANDLE_DWARF_SECTION
+};
+
+// We might be able to drop relocations to symbols that do end up
+// being pruned by the linker, but for now we just preserve all
+static void preserveDWARFSection(LinkGraph &G, Section &Sec) {
+  DenseMap<Block *, Symbol *> Preserved;
+  for (auto Sym : Sec.symbols()) {
+    if (Sym->isLive())
+      Preserved[&Sym->getBlock()] = Sym;
+    else if (!Preserved.count(&Sym->getBlock()))
+      Preserved[&Sym->getBlock()] = Sym;
+  }
+  for (auto Block : Sec.blocks()) {
+    auto &PSym = Preserved[Block];
+    if (!PSym)
+      PSym = &G.addAnonymousSymbol(*Block, 0, 0, false, true);
+    else if (!PSym->isLive())
+      PSym->setLive(true);
+  }
+}
+
+static SmallVector<char, 0> getSectionData(Section &Sec) {
+  SmallVector<char, 0> SecData;
+  SmallVector<Block *, 8> SecBlocks(Sec.blocks().begin(), Sec.blocks().end());
+  std::sort(SecBlocks.begin(), SecBlocks.end(), [](Block *LHS, Block *RHS) {
+    return LHS->getAddress() < RHS->getAddress();
+  });
+  // Convert back to what object file would have, one blob of section content
+  // Assumes all zerofill
+  // TODO handle alignment?
+  // TODO handle alignment offset?
+  for (auto *Block : SecBlocks) {
+    if (Block->isZeroFill())
+      SecData.resize(SecData.size() + Block->getSize(), 0);
+    else
+      SecData.append(Block->getContent().begin(), Block->getContent().end());
+  }
+  return SecData;
+}
+
+static void dumpDWARFContext(DWARFContext &DC) {
+  auto options = llvm::DIDumpOptions();
+  options.DumpType &= ~DIDT_UUID;
+  options.DumpType &= ~(1 << DIDT_ID_DebugFrame);
+  LLVM_DEBUG(DC.dump(dbgs(), options));
+}
+
+} // namespace
+
+Error llvm::orc::preserveDebugSections(LinkGraph &G) {
+  if (!G.getTargetTriple().isOSBinFormatELF()) {
+    return make_error<StringError>(
+        "preserveDebugSections only supports ELF LinkGraphs!",
+        inconvertibleErrorCode());
+  }
+  for (auto &Sec : G.sections()) {
+    if (DWARFSectionNames.count(Sec.getName())) {
+      LLVM_DEBUG(dbgs() << "Preserving DWARF section " << Sec.getName()
+                        << "\n");
+      preserveDWARFSection(G, Sec);
+    }
+  }
+  return Error::success();
+}
+
+Expected<std::pair<std::unique_ptr<DWARFContext>,
+                   StringMap<std::unique_ptr<MemoryBuffer>>>>
+llvm::orc::createDWARFContext(LinkGraph &G) {
+  if (!G.getTargetTriple().isOSBinFormatELF()) {
+    return make_error<StringError>(
+        "createDWARFContext only supports ELF LinkGraphs!",
+        inconvertibleErrorCode());
+  }
+  StringMap<std::unique_ptr<MemoryBuffer>> DWARFSectionData;
+  for (auto &Sec : G.sections()) {
+    if (DWARFSectionNames.count(Sec.getName())) {
+      auto SecData = getSectionData(Sec);
+      auto Name = Sec.getName();
+      // DWARFContext expects the section name to not start with a dot
+      if (Name.starts_with("."))
+        Name = Name.drop_front();
+      LLVM_DEBUG(dbgs() << "Creating DWARFContext section " << Name
+                        << " with size " << SecData.size() << "\n");
+      DWARFSectionData[Name] =
+          std::make_unique<SmallVectorMemoryBuffer>(std::move(SecData));
+    }
+  }
+  auto Ctx =
+      DWARFContext::create(DWARFSectionData, G.getPointerSize(),
+                           G.getEndianness() == llvm::endianness::little);
+  dumpDWARFContext(*Ctx);
+  return std::make_pair(std::move(Ctx), std::move(DWARFSectionData));
+}