[memprof] Add an overload for RawMemProfReader::create.

[snehasish]

Summary

This allows us to pass in a memory buffer directly simplifying usage
downstream.

[tejohnson]

lgtm

llvm/include/llvm/ProfileData/RawMemProfReader.h

public:
   // Return true if the \p DataBuffer starts with magic bytes indicating it is
   // a raw binary memprof profile.
   static bool hasFormat(const MemoryBuffer &DataBuffer);
   // Return true if the file at \p Path starts with magic bytes indicating it is
   // a raw binary memprof profile.
   static bool hasFormat(const StringRef Path);
 
   // Create a RawMemProfReader after sanity checking the contents of the file at
-  // \p Path. The binary from which the profile has been collected is specified
-  // via a path in \p ProfiledBinary.
+  // \p Path or the \p Buffer. The binary from which the profile has been
+  // collected is specified via a path in \p ProfiledBinary.
   static Expected<std::unique_ptr<RawMemProfReader>>
-  create(const Twine &Path, const StringRef ProfiledBinary,
+  create(const Twine &Path, StringRef ProfiledBinary, bool KeepName = false);
+  static Expected<std::unique_ptr<RawMemProfReader>>
+  create(std::unique_ptr<MemoryBuffer> Buffer, StringRef ProfiledBinary,
          bool KeepName = false);
 
   // Returns a list of build ids recorded in the segment information.
   static std::vector<std::string> peekBuildIds(MemoryBuffer *DataBuffer);
 
   using GuidMemProfRecordPair = std::pair<GlobalValue::GUID, MemProfRecord>;
   using Iterator = InstrProfIterator<GuidMemProfRecordPair, RawMemProfReader>;
   Iterator end() { return Iterator(); }

llvm/lib/ProfileData/RawMemProfReader.cpp

 Expected<std::unique_ptr<RawMemProfReader>>
 RawMemProfReader::create(const Twine &Path, const StringRef ProfiledBinary,
                          bool KeepName) {
   auto BufferOr = MemoryBuffer::getFileOrSTDIN(Path);
   if (std::error_code EC = BufferOr.getError())
     return report(errorCodeToError(EC), Path.getSingleStringRef());
 
   std::unique_ptr<MemoryBuffer> Buffer(BufferOr.get().release());
+  return create(std::move(Buffer), ProfiledBinary, KeepName);
+}
+
+Expected<std::unique_ptr<RawMemProfReader>>
+RawMemProfReader::create(std::unique_ptr<MemoryBuffer> Buffer,
+                         const StringRef ProfiledBinary, bool KeepName) {
   if (Error E = checkBuffer(*Buffer))
-    return report(std::move(E), Path.getSingleStringRef());
+    return report(std::move(E), Buffer->getBufferIdentifier());
 
   if (ProfiledBinary.empty()) {
     // Peek the build ids to print a helpful error message.
     const std::vector<std::string> BuildIds = peekBuildIds(Buffer.get());
     std::string ErrorMessage(
         R"(Path to profiled binary is empty, expected binary with one of the following build ids:
 )");
     for (const auto &Id : BuildIds) {