Reapply: [llvm-objcopy] [COFF] Implement --add-gnu-debuglink

This was reverted since it broke a couple buildbots. The reason
for the breakage is not yet known, but this time, the test has
got more diagnostics added, to hopefully allow figuring out
what goes wrong.

Differential Revision: https://reviews.llvm.org/D57007

llvm-svn: 351931

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 db3589bb119..05e46291c39 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) {