[LLD][ELF] Put back rounding which was lost in 8404aeb

Author: aganea

lld/ELF/SyntheticSections.cpp

@@ -2750,7 +2750,8 @@ createSymbols(ArrayRef<std::vector<GdbIndexSection::NameAttrEntry>> nameAttrs,
   size_t concurrency = 1;
   if (threadsEnabled)
     concurrency = std::min<size_t>(
-        hardware_concurrency().compute_thread_count(), numShards);
+        PowerOf2Floor(hardware_concurrency().compute_thread_count()),
+        numShards);
 
   // A sharded map to uniquify symbols by name.
   std::vector<DenseMap<CachedHashStringRef, size_t>> map(numShards);
@@ -3196,7 +3197,8 @@ void MergeNoTailSection::finalizeContents() {
   size_t concurrency = 1;
   if (threadsEnabled)
     concurrency = std::min<size_t>(
-        hardware_concurrency().compute_thread_count(), numShards);
+        PowerOf2Floor(hardware_concurrency().compute_thread_count()),
+        numShards);
 
   // Add section pieces to the builders.
   parallelForEachN(0, concurrency, [&](size_t threadId) {