[memprof] Make HeapProfileRecords optional

llvm/include/llvm/ProfileData/DataAccessProf.h

@@ -185,6 +185,10 @@ class DataAccessProfData {
   ArrayRef<uint64_t> getKnownColdHashes() const {
     return KnownColdHashes.getArrayRef();
   }
+  [[nodiscard]] bool empty() const {
+    return Records.empty() && KnownColdSymbols.empty() &&
+           KnownColdHashes.empty();
+  }
 
 private:
   /// Serialize the symbol strings into the output stream.

llvm/include/llvm/ProfileData/MemProfYAML.h

@@ -263,7 +263,8 @@ template <> struct MappingTraits<memprof::YamlDataAccessProfData> {
 
 template <> struct MappingTraits<memprof::AllMemProfData> {
   static void mapping(IO &Io, memprof::AllMemProfData &Data) {
-    Io.mapRequired("HeapProfileRecords", Data.HeapProfileRecords);
+    if (!Io.outputting() || !Data.HeapProfileRecords.empty())
+      Io.mapOptional("HeapProfileRecords", Data.HeapProfileRecords);
     // Map data access profiles if reading input, or if writing output &&
     // the struct is populated.
     if (!Io.outputting() || !Data.YamlifiedDataAccessProfiles.isEmpty())

llvm/test/tools/llvm-profdata/memprof-yaml.test

@@ -18,6 +18,11 @@
 ; RUN: llvm-profdata show --memory %t/memprof-out.indexed > %t/memprof-out-no-dap.yaml
 ; RUN: diff -b %t/memprof-in-no-dap.yaml %t/memprof-out-no-dap.yaml
 
+; memprof-in-no-heap.yaml has empty heap access profiles.
+; RUN: llvm-profdata merge --memprof-version=4 %t/memprof-in-no-heap.yaml -o %t/memprof-out-no-heap.indexed
+; RUN: llvm-profdata show --memory %t/memprof-out-no-heap.indexed > %t/memprof-out-no-heap.yaml
+; RUN: diff -b %t/memprof-in-no-heap.yaml %t/memprof-out-no-heap.yaml
+
 ;--- memprof-in.yaml
 ---
 # MemProfSummary:
@@ -151,3 +156,32 @@ HeapProfileRecords:
         - { Function: 0x8888888888888888, LineOffset: 88, Column: 80, IsInlineFrame: false }
         CalleeGuids: [ 0x300 ]
 ...
+;--- memprof-in-no-heap.yaml
+---
+# MemProfSummary:
+#   Total contexts: 0
+#   Total cold contexts: 0
+#   Total hot contexts: 0
+#   Maximum cold context total size: 0
+#   Maximum warm context total size: 0
+#   Maximum hot context total size: 0
+---
+DataAccessProfiles:
+  SampledRecords:
+    - Symbol:          abcde
+      AccessCount:     100
+      Locations:
+      - FileName:      file2.h
+        Line:          123
+      - FileName:      file3.cpp
+        Line:          456
+    - Hash:            101010
+      AccessCount:     200
+      Locations:
+        - FileName:        file.cpp
+          Line:            233
+  KnownColdSymbols:
+    - foo
+    - bar
+  KnownColdStrHashes: [ 999, 1001 ]
+...

llvm/tools/llvm-profdata/llvm-profdata.cpp

@@ -760,7 +760,8 @@ loadInput(const WeightedFile &Input, SymbolRemapper *Remapper,
     auto DataAccessProfData = Reader->takeDataAccessProfData();
 
     // Check for the empty input in case the YAML file is invalid.
-    if (MemProfData.Records.empty()) {
+    if (MemProfData.Records.empty() &&
+        (!DataAccessProfData || DataAccessProfData->empty())) {
       WC->Errors.emplace_back(
           make_error<StringError>("The profile is empty.", std::error_code()),
           Filename);