3 files changed, 142 insertions, 0 deletions

diff --git a/llvm/lib/Remarks/CMakeLists.txt b/llvm/lib/Remarks/CMakeLists.txt
index 9fbb1f06971..db84d631c2c 100644
--- a/llvm/lib/Remarks/CMakeLists.txt
+++ b/llvm/lib/Remarks/CMakeLists.txt
@@ -3,6 +3,7 @@ add_llvm_library(LLVMRemarks
   BitstreamRemarkSerializer.cpp
   Remark.cpp
   RemarkFormat.cpp
+  RemarkLinker.cpp
   RemarkParser.cpp
   RemarkSerializer.cpp
   RemarkStringTable.cpp
diff --git a/llvm/lib/Remarks/RemarkFormat.cpp b/llvm/lib/Remarks/RemarkFormat.cpp
index f2d0331ec6a..c7fce151eff 100644
--- a/llvm/lib/Remarks/RemarkFormat.cpp
+++ b/llvm/lib/Remarks/RemarkFormat.cpp
@@ -12,6 +12,7 @@
 
 #include "llvm/Remarks/RemarkFormat.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Remarks/BitstreamRemarkContainer.h"
 
 using namespace llvm;
 using namespace llvm::remarks;
@@ -30,3 +31,17 @@ Expected<Format> llvm::remarks::parseFormat(StringRef FormatStr) {
 
   return Result;
 }
+
+Expected<Format> llvm::remarks::magicToFormat(StringRef Magic) {
+  auto Result =
+      StringSwitch<Format>(Magic)
+          .StartsWith("--- ", Format::YAML) // This is only an assumption.
+          .StartsWith(remarks::Magic, Format::YAMLStrTab)
+          .StartsWith(remarks::ContainerMagic, Format::Bitstream)
+          .Default(Format::Unknown);
+
+  if (Result == Format::Unknown)
+    return createStringError(std::make_error_code(std::errc::invalid_argument),
+                             "Unknown remark magic: '%s'", Magic.data());
+  return Result;
+}
diff --git a/llvm/lib/Remarks/RemarkLinker.cpp b/llvm/lib/Remarks/RemarkLinker.cpp
new file mode 100644
index 00000000000..617ce770af6
--- /dev/null
+++ b/llvm/lib/Remarks/RemarkLinker.cpp
@@ -0,0 +1,126 @@
+//===- RemarkLinker.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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides an implementation of the remark linker.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Remarks/RemarkLinker.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Remarks/BitstreamRemarkContainer.h"
+#include "llvm/Remarks/RemarkParser.h"
+#include "llvm/Remarks/RemarkSerializer.h"
+#include "llvm/Support/Error.h"
+
+using namespace llvm;
+using namespace llvm::remarks;
+
+static Expected<StringRef>
+getRemarksSectionName(const object::ObjectFile &Obj) {
+  if (Obj.isMachO())
+    return StringRef("__remarks");
+  // ELF -> .remarks, but there is no ELF support at this point.
+  return createStringError(std::errc::illegal_byte_sequence,
+                           "Unsupported file format.");
+}
+
+Expected<Optional<StringRef>>
+llvm::remarks::getRemarksSectionContents(const object::ObjectFile &Obj) {
+  Expected<StringRef> SectionName = getRemarksSectionName(Obj);
+  if (!SectionName)
+    return SectionName.takeError();
+
+  for (const object::SectionRef &Section : Obj.sections()) {
+    Expected<StringRef> MaybeName = Section.getName();
+    if (!MaybeName)
+      return MaybeName.takeError();
+    if (*MaybeName != *SectionName)
+      continue;
+
+    if (Expected<StringRef> Contents = Section.getContents())
+      return *Contents;
+    else
+      return Contents.takeError();
+  }
+  return Optional<StringRef>{};
+}
+
+Remark &RemarkLinker::keep(std::unique_ptr<Remark> Remark) {
+  StrTab.internalize(*Remark);
+  auto Inserted = Remarks.insert(std::move(Remark));
+  return **Inserted.first;
+}
+
+void RemarkLinker::setExternalFilePrependPath(StringRef PrependPathIn) {
+  PrependPath = PrependPathIn;
+}
+
+// Discard remarks with no source location.
+static bool shouldKeepRemark(const Remark &R) { return R.Loc.hasValue(); }
+
+Error RemarkLinker::link(StringRef Buffer, Optional<Format> RemarkFormat) {
+  if (!RemarkFormat) {
+    Expected<Format> ParserFormat = magicToFormat(Buffer);
+    if (!ParserFormat)
+      return ParserFormat.takeError();
+    RemarkFormat = *ParserFormat;
+  }
+
+  Expected<std::unique_ptr<RemarkParser>> MaybeParser =
+      createRemarkParserFromMeta(
+          *RemarkFormat, Buffer, /*StrTab=*/None,
+          PrependPath ? Optional<StringRef>(StringRef(*PrependPath))
+                      : Optional<StringRef>(None));
+  if (!MaybeParser)
+    return MaybeParser.takeError();
+
+  RemarkParser &Parser = **MaybeParser;
+
+  while (true) {
+    Expected<std::unique_ptr<Remark>> Next = Parser.next();
+    if (Error E = Next.takeError()) {
+      if (E.isA<EndOfFileError>()) {
+        consumeError(std::move(E));
+        break;
+      }
+      return E;
+    }
+
+    assert(*Next != nullptr);
+
+    if (shouldKeepRemark(**Next))
+      keep(std::move(*Next));
+  }
+  return Error::success();
+}
+
+Error RemarkLinker::link(const object::ObjectFile &Obj,
+                         Optional<Format> RemarkFormat) {
+  Expected<Optional<StringRef>> SectionOrErr = getRemarksSectionContents(Obj);
+  if (!SectionOrErr)
+    return SectionOrErr.takeError();
+
+  if (Optional<StringRef> Section = *SectionOrErr)
+    return link(*Section, RemarkFormat);
+  return Error::success();
+}
+
+Error RemarkLinker::serialize(raw_ostream &OS, Format RemarksFormat) const {
+  Expected<std::unique_ptr<RemarkSerializer>> MaybeSerializer =
+      createRemarkSerializer(RemarksFormat, SerializerMode::Standalone, OS,
+                             std::move(const_cast<StringTable &>(StrTab)));
+  if (!MaybeSerializer)
+    return MaybeSerializer.takeError();
+
+  std::unique_ptr<remarks::RemarkSerializer> Serializer =
+      std::move(*MaybeSerializer);
+
+  for (const Remark &R : remarks())
+    Serializer->emit(R);
+  return Error::success();
+}