[llvm] d34be64 - [ThinLTO]Sort imported GUIDs before cache key update (#92622)

[via llvm-commits]

Author: Mingming Liu
Date: 2024-05-18T19:39:57-07:00
New Revision: d34be649af1aa849c21a5a0570617c3a89d5f0b8

URL: https://github.com/llvm/llvm-project/commit/d34be649af1aa849c21a5a0570617c3a89d5f0b8
DIFF: https://github.com/llvm/llvm-project/commit/d34be649af1aa849c21a5a0570617c3a89d5f0b8.diff

LOG: [ThinLTO]Sort imported GUIDs before cache key update (#92622)

Add 'sort' here since it's helpful when container type
changes (for example, https://github.com/llvm/llvm-project/pull/88024
wants to change container type from `unordered_set` to `DenseMap)

@MaskRay points out `std::` doesn't randomize the iteration order of
`unordered_{set,map}`, and the iteration order for single build is
deterministic.

Added: 
    

Modified: 
    llvm/lib/LTO/LTO.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index 21cad1de0ced5..5c603ac6ab472 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -199,13 +199,19 @@ void llvm::computeLTOCacheKey(
              [](const ImportModule &Lhs, const ImportModule &Rhs) -> bool {
                return Lhs.getHash() < Rhs.getHash();
              });
+  std::vector<uint64_t> ImportedGUIDs;
   for (const ImportModule &Entry : ImportModulesVector) {
     auto ModHash = Entry.getHash();
     Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
 
     AddUint64(Entry.getFunctions().size());
+
+    ImportedGUIDs.clear();
     for (auto &Fn : Entry.getFunctions())
-      AddUint64(Fn);
+      ImportedGUIDs.push_back(Fn);
+    llvm::sort(ImportedGUIDs);
+    for (auto &GUID : ImportedGUIDs)
+      AddUint64(GUID);
   }
 
   // Include the hash for the resolved ODR.