5 files changed, 95 insertions, 7 deletions
diff --git a/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp b/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
index 8d8f53d13d8..20adbe11e7a 100644
--- a/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/COFFObjcopy.cpp
@@ -17,6 +17,8 @@
 #include "llvm/Object/Binary.h"
 #include "llvm/Object/COFF.h"
 #include "llvm/Support/Errc.h"
+#include "llvm/Support/JamCRC.h"
+#include "llvm/Support/Path.h"
 #include <cassert>
 
 namespace llvm {
@@ -30,6 +32,61 @@ static bool isDebugSection(const Section &Sec) {
   return Sec.Name.startswith(".debug");
 }
 
+static uint64_t getNextRVA(const Object &Obj) {
+  if (Obj.getSections().empty())
+    return 0;
+  const Section &Last = Obj.getSections().back();
+  return alignTo(Last.Header.VirtualAddress + Last.Header.VirtualSize,
+                 Obj.PeHeader.SectionAlignment);
+}
+
+static uint32_t getCRC32(StringRef Data) {
+  JamCRC CRC;
+  CRC.update(ArrayRef<char>(Data.data(), Data.size()));
+  // The CRC32 value needs to be complemented because the JamCRC dosn't
+  // finalize the CRC32 value. It also dosn't negate the initial CRC32 value
+  // but it starts by default at 0xFFFFFFFF which is the complement of zero.
+  return ~CRC.getCRC();
+}
+
+static std::vector<uint8_t> createGnuDebugLinkSectionContents(StringRef File) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> LinkTargetOrErr =
+      MemoryBuffer::getFile(File);
+  if (!LinkTargetOrErr)
+    error("'" + File + "': " + LinkTargetOrErr.getError().message());
+  auto LinkTarget = std::move(*LinkTargetOrErr);
+  uint32_t CRC32 = getCRC32(LinkTarget->getBuffer());
+
+  StringRef FileName = sys::path::filename(File);
+  size_t CRCPos = alignTo(FileName.size() + 1, 4);
+  std::vector<uint8_t> Data(CRCPos + 4);
+  memcpy(Data.data(), FileName.data(), FileName.size());
+  support::endian::write32le(Data.data() + CRCPos, CRC32);
+  return Data;
+}
+
+static void addGnuDebugLink(Object &Obj, StringRef DebugLinkFile) {
+  uint32_t StartRVA = getNextRVA(Obj);
+
+  std::vector<Section> Sections;
+  Section Sec;
+  Sec.setOwnedContents(createGnuDebugLinkSectionContents(DebugLinkFile));
+  Sec.Name = ".gnu_debuglink";
+  Sec.Header.VirtualSize = Sec.getContents().size();
+  Sec.Header.VirtualAddress = StartRVA;
+  Sec.Header.SizeOfRawData =
+      alignTo(Sec.Header.VirtualSize, Obj.PeHeader.FileAlignment);
+  // Sec.Header.PointerToRawData is filled in by the writer.
+  Sec.Header.PointerToRelocations = 0;
+  Sec.Header.PointerToLinenumbers = 0;
+  // Sec.Header.NumberOfRelocations is filled in by the writer.
+  Sec.Header.NumberOfLinenumbers = 0;
+  Sec.Header.Characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA |
+                               IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_DISCARDABLE;
+  Sections.push_back(Sec);
+  Obj.addSections(Sections);
+}
+
 static Error handleArgs(const CopyConfig &Config, Object &Obj) {
   // Perform the actual section removals.
   Obj.removeSections([&Config](const Section &Sec) {
@@ -109,6 +166,10 @@ static Error handleArgs(const CopyConfig &Config, Object &Obj) {
 
     return false;
   });
+
+  if (!Config.AddGnuDebugLink.empty())
+    addGnuDebugLink(Obj, Config.AddGnuDebugLink);
+
   return Error::success();
 }
 
diff --git a/llvm/tools/llvm-objcopy/COFF/Object.cpp b/llvm/tools/llvm-objcopy/COFF/Object.cpp
index 83435dffa98..8c382c1faef 100644
--- a/llvm/tools/llvm-objcopy/COFF/Object.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/Object.cpp
@@ -129,7 +129,7 @@ void Object::removeSections(function_ref<bool(const Section &)> ToRemove) {
 void Object::truncateSections(function_ref<bool(const Section &)> ToTruncate) {
   for (Section &Sec : Sections) {
     if (ToTruncate(Sec)) {
-      Sec.Contents = ArrayRef<uint8_t>();
+      Sec.clearContents();
       Sec.Relocs.clear();
       Sec.Header.SizeOfRawData = 0;
     }
diff --git a/llvm/tools/llvm-objcopy/COFF/Object.h b/llvm/tools/llvm-objcopy/COFF/Object.h
index 0630f9c5ff8..afa272286ef 100644
--- a/llvm/tools/llvm-objcopy/COFF/Object.h
+++ b/llvm/tools/llvm-objcopy/COFF/Object.h
@@ -35,11 +35,35 @@ struct Relocation {
 
 struct Section {
   object::coff_section Header;
-  ArrayRef<uint8_t> Contents;
   std::vector<Relocation> Relocs;
   StringRef Name;
   ssize_t UniqueId;
   size_t Index;
+
+  ArrayRef<uint8_t> getContents() const {
+    if (!OwnedContents.empty())
+      return OwnedContents;
+    return ContentsRef;
+  }
+
+  void setContentsRef(ArrayRef<uint8_t> Data) {
+    OwnedContents.clear();
+    ContentsRef = Data;
+  }
+
+  void setOwnedContents(std::vector<uint8_t> &&Data) {
+    ContentsRef = ArrayRef<uint8_t>();
+    OwnedContents = std::move(Data);
+  }
+
+  void clearContents() {
+    ContentsRef = ArrayRef<uint8_t>();
+    OwnedContents.clear();
+  }
+
+private:
+  ArrayRef<uint8_t> ContentsRef;
+  std::vector<uint8_t> OwnedContents;
 };
 
 struct Symbol {
diff --git a/llvm/tools/llvm-objcopy/COFF/Reader.cpp b/llvm/tools/llvm-objcopy/COFF/Reader.cpp
index 2446277cc2b..87dd60a43cf 100644
--- a/llvm/tools/llvm-objcopy/COFF/Reader.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/Reader.cpp
@@ -69,8 +69,10 @@ Error COFFReader::readSections(Object &Obj) const {
     Sections.push_back(Section());
     Section &S = Sections.back();
     S.Header = *Sec;
-    if (auto EC = COFFObj.getSectionContents(Sec, S.Contents))
+    ArrayRef<uint8_t> Contents;
+    if (auto EC = COFFObj.getSectionContents(Sec, Contents))
       return errorCodeToError(EC);
+    S.setContentsRef(Contents);
     ArrayRef<coff_relocation> Relocs = COFFObj.getRelocations(Sec);
     for (const coff_relocation &R : Relocs)
       S.Relocs.push_back(R);
diff --git a/llvm/tools/llvm-objcopy/COFF/Writer.cpp b/llvm/tools/llvm-objcopy/COFF/Writer.cpp
index 4f57131d5ab..5ea3707e971 100644
--- a/llvm/tools/llvm-objcopy/COFF/Writer.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/Writer.cpp
@@ -286,14 +286,15 @@ void COFFWriter::writeHeaders(bool IsBigObj) {
 void COFFWriter::writeSections() {
   for (const auto &S : Obj.getSections()) {
     uint8_t *Ptr = Buf.getBufferStart() + S.Header.PointerToRawData;
-    std::copy(S.Contents.begin(), S.Contents.end(), Ptr);
+    ArrayRef<uint8_t> Contents = S.getContents();
+    std::copy(Contents.begin(), Contents.end(), Ptr);
 
     // For executable sections, pad the remainder of the raw data size with
     // 0xcc, which is int3 on x86.
     if ((S.Header.Characteristics & IMAGE_SCN_CNT_CODE) &&
-        S.Header.SizeOfRawData > S.Contents.size())
-      memset(Ptr + S.Contents.size(), 0xcc,
-             S.Header.SizeOfRawData - S.Contents.size());
+        S.Header.SizeOfRawData > Contents.size())
+      memset(Ptr + Contents.size(), 0xcc,
+             S.Header.SizeOfRawData - Contents.size());
 
     Ptr += S.Header.SizeOfRawData;
     for (const auto &R : S.Relocs) {