[PATCH] D155761: [lld-macho] Use fixed chunk size for UUID

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: lld-macho, int3, keith.
Herald added projects: lld-macho, All.
MaskRay requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Chunk size decided by the thread count makes the UUID less deterministic.
Follow ELF and just use a fixed chunksize.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D155761

Files:
  lld/MachO/Writer.cpp


Index: lld/MachO/Writer.cpp
===================================================================
--- lld/MachO/Writer.cpp
+++ lld/MachO/Writer.cpp
@@ -1180,10 +1180,7 @@
   TimeTraceScope timeScope("Computing UUID");
 
   ArrayRef<uint8_t> data{buffer->getBufferStart(), buffer->getBufferEnd()};
-  unsigned chunkCount = parallel::strategy.compute_thread_count() * 10;
-  // Round-up integer division
-  size_t chunkSize = (data.size() + chunkCount - 1) / chunkCount;
-  std::vector<ArrayRef<uint8_t>> chunks = split(data, chunkSize);
+  std::vector<ArrayRef<uint8_t>> chunks = split(data, 1024 * 1024);
   // Leave one slot for filename
   std::vector<uint64_t> hashes(chunks.size() + 1);
   SmallVector<std::shared_future<void>> threadFutures;


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