[llvm] Clean up the GSym error aggregation code, and pass the aggregator by reference (PR #89688)

[Kevin Frei via llvm-commits]

https://github.com/kevinfrei updated https://github.com/llvm/llvm-project/pull/89688

>From 0185ab1cf30c7394b1ec86ea11b1fad0161e2218 Mon Sep 17 00:00:00 2001
From: Kevin Frei <freik at meta.com>
Date: Mon, 22 Apr 2024 16:08:41 -0700
Subject: [PATCH] Clean up the aggregation code, and pass the aggregator by
 reference

---
 llvm/include/llvm/DebugInfo/GSYM/OutputAggregator.h | 9 ++++-----
 llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp        | 2 +-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/llvm/include/llvm/DebugInfo/GSYM/OutputAggregator.h b/llvm/include/llvm/DebugInfo/GSYM/OutputAggregator.h
index 8deea3bff1ed76..35ef0a8bc89085 100644
--- a/llvm/include/llvm/DebugInfo/GSYM/OutputAggregator.h
+++ b/llvm/include/llvm/DebugInfo/GSYM/OutputAggregator.h
@@ -57,13 +57,12 @@ class OutputAggregator {
   }
 
   // For multi-threaded usage, we can collect stuff in another aggregator,
-  // then merge it in here
+  // then merge it in here. Note that this is *not* thread safe. It is up to
+  // the caller to ensure that this is only called from one thread at a time.
   void Merge(const OutputAggregator &other) {
     for (auto &&[name, count] : other.Aggregation) {
-      auto it = Aggregation.find(name);
-      if (it == Aggregation.end())
-        Aggregation.emplace(name, count);
-      else
+      auto [it, inserted] = Aggregation.emplace(name, count);
+      if (!inserted)
         it->second += count;
     }
   }
diff --git a/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp b/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp
index ff6b560d11726b..601686fdd3dd51 100644
--- a/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp
+++ b/llvm/lib/DebugInfo/GSYM/DwarfTransformer.cpp
@@ -612,7 +612,7 @@ Error DwarfTransformer::convert(uint32_t NumThreads, OutputAggregator &Out) {
       DWARFDie Die = getDie(*CU);
       if (Die) {
         CUInfo CUI(DICtx, dyn_cast<DWARFCompileUnit>(CU.get()));
-        pool.async([this, CUI, &LogMutex, Out, Die]() mutable {
+        pool.async([this, CUI, &LogMutex, &Out, Die]() mutable {
           std::string storage;
           raw_string_ostream StrStream(storage);
           OutputAggregator ThreadOut(Out.GetOS() ? &StrStream : nullptr);