[llvm] [memprof] Clean up writer traits (NFC) (PR #88549)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/88549

RecordWriter does not live past the end of writeMemProfRecords, so it
can be safely on stack.

The constructor of FrameWriter does not take any parameter, so we can
let OnDiskChainedHashTableGenerator::Emit (with a single parameter)
default-construct an instance of the writer trait inside Emit.


>From c16e3e273d9fe141733f4d66a52230132bd4ee6d Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Fri, 12 Apr 2024 10:25:26 -0700
Subject: [PATCH] [memprof] Clean up writer traits (NFC)

RecordWriter does not live past the end of writeMemProfRecords, so it
can be safely on stack.

The constructor of FrameWriter does not take any parameter, so we can
let OnDiskChainedHashTableGenerator::Emit (with a single parameter)
default-construct an instance of the writer trait inside Emit.
---
 llvm/lib/ProfileData/InstrProfWriter.cpp | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/ProfileData/InstrProfWriter.cpp b/llvm/lib/ProfileData/InstrProfWriter.cpp
index 7c56cde3e6cedd..ede042dd6b9c3c 100644
--- a/llvm/lib/ProfileData/InstrProfWriter.cpp
+++ b/llvm/lib/ProfileData/InstrProfWriter.cpp
@@ -428,14 +428,13 @@ static uint64_t writeMemProfRecords(
     llvm::MapVector<GlobalValue::GUID, memprof::IndexedMemProfRecord>
         &MemProfRecordData,
     memprof::MemProfSchema *Schema) {
-  auto RecordWriter =
-      std::make_unique<memprof::RecordWriterTrait>(memprof::Version1);
-  RecordWriter->Schema = Schema;
+  memprof::RecordWriterTrait RecordWriter(memprof::Version1);
+  RecordWriter.Schema = Schema;
   OnDiskChainedHashTableGenerator<memprof::RecordWriterTrait>
       RecordTableGenerator;
   for (auto &[GUID, Record] : MemProfRecordData) {
     // Insert the key (func hash) and value (memprof record).
-    RecordTableGenerator.insert(GUID, Record, *RecordWriter.get());
+    RecordTableGenerator.insert(GUID, Record, RecordWriter);
   }
   // Release the memory of this MapVector as it is no longer needed.
   MemProfRecordData.clear();
@@ -443,14 +442,13 @@ static uint64_t writeMemProfRecords(
   // The call to Emit invokes RecordWriterTrait::EmitData which destructs
   // the memprof record copies owned by the RecordTableGenerator. This works
   // because the RecordTableGenerator is not used after this point.
-  return RecordTableGenerator.Emit(OS.OS, *RecordWriter);
+  return RecordTableGenerator.Emit(OS.OS, RecordWriter);
 }
 
 // Serialize MemProfFrameData.  Return FrameTableOffset.
 static uint64_t writeMemProfFrames(
     ProfOStream &OS,
     llvm::MapVector<memprof::FrameId, memprof::Frame> &MemProfFrameData) {
-  auto FrameWriter = std::make_unique<memprof::FrameWriterTrait>();
   OnDiskChainedHashTableGenerator<memprof::FrameWriterTrait>
       FrameTableGenerator;
   for (auto &[FrameId, Frame] : MemProfFrameData) {
@@ -460,7 +458,7 @@ static uint64_t writeMemProfFrames(
   // Release the memory of this MapVector as it is no longer needed.
   MemProfFrameData.clear();
 
-  return FrameTableGenerator.Emit(OS.OS, *FrameWriter);
+  return FrameTableGenerator.Emit(OS.OS);
 }
 
 static Error writeMemProfV0(