1 files changed, 103 insertions, 0 deletions
diff --git a/Common/DWARF.cpp b/Common/DWARF.cpp
new file mode 100644
index 000000000000..077adbcaf858
--- /dev/null
+++ b/Common/DWARF.cpp
@@ -0,0 +1,103 @@
+//===- DWARF.cpp ----------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "lld/Common/DWARF.h"
+#include "lld/Common/ErrorHandler.h"
+
+using namespace llvm;
+
+namespace lld {
+
+DWARFCache::DWARFCache(std::unique_ptr<llvm::DWARFContext> d)
+    : dwarf(std::move(d)) {
+  for (std::unique_ptr<DWARFUnit> &cu : dwarf->compile_units()) {
+    auto report = [](Error err) {
+      handleAllErrors(std::move(err),
+                      [](ErrorInfoBase &info) { warn(info.message()); });
+    };
+    Expected<const DWARFDebugLine::LineTable *> expectedLT =
+        dwarf->getLineTableForUnit(cu.get(), report);
+    const DWARFDebugLine::LineTable *lt = nullptr;
+    if (expectedLT)
+      lt = *expectedLT;
+    else
+      report(expectedLT.takeError());
+    if (!lt)
+      continue;
+    lineTables.push_back(lt);
+
+    // Loop over variable records and insert them to variableLoc.
+    for (const auto &entry : cu->dies()) {
+      DWARFDie die(cu.get(), &entry);
+      // Skip all tags that are not variables.
+      if (die.getTag() != dwarf::DW_TAG_variable)
+        continue;
+
+      // Skip if a local variable because we don't need them for generating
+      // error messages. In general, only non-local symbols can fail to be
+      // linked.
+      if (!dwarf::toUnsigned(die.find(dwarf::DW_AT_external), 0))
+        continue;
+
+      // Get the source filename index for the variable.
+      unsigned file = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_file), 0);
+      if (!lt->hasFileAtIndex(file))
+        continue;
+
+      // Get the line number on which the variable is declared.
+      unsigned line = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_line), 0);
+
+      // Here we want to take the variable name to add it into variableLoc.
+      // Variable can have regular and linkage name associated. At first, we try
+      // to get linkage name as it can be different, for example when we have
+      // two variables in different namespaces of the same object. Use common
+      // name otherwise, but handle the case when it also absent in case if the
+      // input object file lacks some debug info.
+      StringRef name =
+          dwarf::toString(die.find(dwarf::DW_AT_linkage_name),
+                          dwarf::toString(die.find(dwarf::DW_AT_name), ""));
+      if (!name.empty())
+        variableLoc.insert({name, {lt, file, line}});
+    }
+  }
+}
+
+// Returns the pair of file name and line number describing location of data
+// object (variable, array, etc) definition.
+Optional<std::pair<std::string, unsigned>>
+DWARFCache::getVariableLoc(StringRef name) {
+  // Return if we have no debug information about data object.
+  auto it = variableLoc.find(name);
+  if (it == variableLoc.end())
+    return None;
+
+  // Take file name string from line table.
+  std::string fileName;
+  if (!it->second.lt->getFileNameByIndex(
+          it->second.file, {},
+          DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, fileName))
+    return None;
+
+  return std::make_pair(fileName, it->second.line);
+}
+
+// Returns source line information for a given offset
+// using DWARF debug info.
+Optional<DILineInfo> DWARFCache::getDILineInfo(uint64_t offset,
+                                               uint64_t sectionIndex) {
+  DILineInfo info;
+  for (const llvm::DWARFDebugLine::LineTable *lt : lineTables) {
+    if (lt->getFileLineInfoForAddress(
+            {offset, sectionIndex}, nullptr,
+            DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, info))
+      return info;
+  }
+  return None;
+}
+
+} // namespace lld