[llvm] [memprof] Add YAML read/write support to llvm-profdata (PR #118915)

[Teresa Johnson via llvm-commits]

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@@ -3242,18 +3271,54 @@ static int showSampleProfile(ShowFormat SFormat, raw_fd_ostream &OS) {
 static int showMemProfProfile(ShowFormat SFormat, raw_fd_ostream &OS) {
   if (SFormat == ShowFormat::Json)
     exitWithError("JSON output is not supported for MemProf");
-  auto ReaderOr = llvm::memprof::RawMemProfReader::create(
-      Filename, ProfiledBinary, /*KeepNames=*/true);
-  if (Error E = ReaderOr.takeError())
-    // Since the error can be related to the profile or the binary we do not
-    // pass whence. Instead additional context is provided where necessary in
-    // the error message.
-    exitWithError(std::move(E), /*Whence*/ "");
-
-  std::unique_ptr<llvm::memprof::RawMemProfReader> Reader(
-      ReaderOr.get().release());
-
-  Reader->printYAML(OS);
+
+  // Load the file to check the magic bytes.
+  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> BufferOrError =
+      llvm::MemoryBuffer::getFile(Filename);
+  if (auto EC = BufferOrError.getError())
+    exitWithError("Error opening profile file '" + Filename + "'");
+  auto Buffer = std::move(BufferOrError.get());
+
+  // Show the raw profile in YAML.
+  if (memprof::RawMemProfReader::hasFormat(*Buffer)) {
+    auto ReaderOr = llvm::memprof::RawMemProfReader::create(
+        Filename, ProfiledBinary, /*KeepNames=*/true);
+    if (Error E = ReaderOr.takeError())
+      // Since the error can be related to the profile or the binary we do not
+      // pass whence. Instead additional context is provided where necessary in
+      // the error message.
+      exitWithError(std::move(E), /*Whence*/ "");
+
+    std::unique_ptr<llvm::memprof::RawMemProfReader> Reader(
+        ReaderOr.get().release());
+
+    Reader->printYAML(OS);
+    return 0;
+  }
+
+  // Show the indexed MemProf profile in YAML.
+  auto FS = vfs::getRealFileSystem();
+  auto ReaderOrErr = IndexedInstrProfReader::create(Filename, *FS);
+  if (Error E = ReaderOrErr.takeError())
+    exitWithError(std::move(E), Filename);
+
+  auto Reader = std::move(ReaderOrErr.get());
+
+  // Build pairs of GUID and MemProfRecord.
+  memprof::AllMemProfData Data;
+  for (const uint64_t Key : Reader->getMemProfRecordKeys()) {
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teresajohnson wrote:

Can the reader have the functionality in this loop and simply return the AllMemProfData struct directly? The loop seems a bit too low level for what we should have in llvm-profdata IMO.

https://github.com/llvm/llvm-project/pull/118915