From 7fb39dfa7c4d9997d967d6daaae2d65cfa7af2ef Mon Sep 17 00:00:00 2001 From: Teresa Johnson Date: Tue, 25 Sep 2018 20:14:40 +0000 Subject: [ThinLTO] Efficiency fix for writing type id records in per-module indexes Summary: In D49565/r337503, the type id record writing was fixed so that only referenced type ids were emitted into each per-module index for ThinLTO distributed builds. However, this still left an efficiency issue: each per-module index checked all type ids for membership in the referenced set, yielding O(M*N) performance (M indexes and N type ids). Change the TypeIdMap in the summary to be indexed by GUID, to facilitate correlating with type identifier GUIDs referenced in the function summary TypeIdInfo structures. This allowed simplifying other places where a map from type id GUID to type id map entry was previously being used to aid this correlation. Also fix AsmWriter code to handle the rare case of type id GUID collision. For a large internal application, this reduced the thin link time by almost 15%. Reviewers: pcc, vitalybuka Subscribers: mehdi_amini, inglorion, steven_wu, dexonsmith, llvm-commits Differential Revision: https://reviews.llvm.org/D51330 llvm-svn: 343021 --- llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'llvm/lib/Bitcode/Writer/BitcodeWriter.cpp') diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp index b8444bc..0d23bca 100644 --- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp +++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp @@ -3903,12 +3903,13 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() { NameVals.clear(); } - if (!Index.typeIds().empty()) { - for (auto &S : Index.typeIds()) { - // Skip if not referenced in any GV summary within this index file. - if (!ReferencedTypeIds.count(GlobalValue::getGUID(S.first))) - continue; - writeTypeIdSummaryRecord(NameVals, StrtabBuilder, S.first, S.second); + // Walk the GUIDs that were referenced, and write the + // corresponding type id records. + for (auto &T : ReferencedTypeIds) { + auto TidIter = Index.typeIds().equal_range(T); + for (auto It = TidIter.first; It != TidIter.second; ++It) { + writeTypeIdSummaryRecord(NameVals, StrtabBuilder, It->second.first, + It->second.second); Stream.EmitRecord(bitc::FS_TYPE_ID, NameVals); NameVals.clear(); } -- cgit v1.1