[llvm-branch-commits] [llvm] 8f299fd - Fixed false ThinLTO cache misses problem (PR 45819).
Tom Stellard via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Mon Jun 22 16:12:04 PDT 2020
Author: romanova-ekaterina
Date: 2020-06-22T16:10:37-07:00
New Revision: 8f299fd2cff7d99c1aacf602ee50e96ded59d706
URL: https://github.com/llvm/llvm-project/commit/8f299fd2cff7d99c1aacf602ee50e96ded59d706
DIFF: https://github.com/llvm/llvm-project/commit/8f299fd2cff7d99c1aacf602ee50e96ded59d706.diff
LOG: Fixed false ThinLTO cache misses problem (PR 45819).
We relied on the fact that the iterators walks through the elements of a
DenseSet in a deterministic order (which is not true). This caused
ThinLTO cache misses. This patch addresses this problem.
See PR 45819 for additional information
https://bugs.llvm.org/show_bug.cgi?id=45819
Differential Revision: https://reviews.llvm.org/D79772
(cherry picked from commit 252892fea7088abbeff9476e0ecbacc091d135a0)
Added:
Modified:
llvm/lib/LTO/LTO.cpp
Removed:
################################################################################
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index 297b11de17a9..fa2f0777897b 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -147,8 +147,17 @@ void llvm::computeLTOCacheKey(
// Include the hash for the current module
auto ModHash = Index.getModuleHash(ModuleID);
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
+
+ std::vector<uint64_t> ExportsGUID;
+ ExportsGUID.reserve(ExportList.size());
for (const auto &VI : ExportList) {
auto GUID = VI.getGUID();
+ ExportsGUID.push_back(GUID);
+ }
+
+ // Sort the export list elements GUIDs.
+ llvm::sort(ExportsGUID);
+ for (uint64_t GUID : ExportsGUID) {
// The export list can impact the internalization, be conservative here
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&GUID, sizeof(GUID)));
}
@@ -156,12 +165,23 @@ void llvm::computeLTOCacheKey(
// Include the hash for every module we import functions from. The set of
// imported symbols for each module may affect code generation and is
// sensitive to link order, so include that as well.
- for (auto &Entry : ImportList) {
- auto ModHash = Index.getModuleHash(Entry.first());
+ using ImportMapIteratorTy = FunctionImporter::ImportMapTy::const_iterator;
+ std::vector<ImportMapIteratorTy> ImportModulesVector;
+ ImportModulesVector.reserve(ImportList.size());
+
+ for (ImportMapIteratorTy It = ImportList.begin(); It != ImportList.end();
+ ++It) {
+ ImportModulesVector.push_back(It);
+ }
+ llvm::sort(ImportModulesVector,
+ [](const ImportMapIteratorTy &Lhs, const ImportMapIteratorTy &Rhs)
+ -> bool { return Lhs->getKey() < Rhs->getKey(); });
+ for (const ImportMapIteratorTy &EntryIt : ImportModulesVector) {
+ auto ModHash = Index.getModuleHash(EntryIt->first());
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
- AddUint64(Entry.second.size());
- for (auto &Fn : Entry.second)
+ AddUint64(EntryIt->second.size());
+ for (auto &Fn : EntryIt->second)
AddUint64(Fn);
}
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