[PATCH] D54202: [clangd] Drop namespace references in the index.

[Haojian Wu via Phabricator via cfe-commits]

hokein created this revision.
hokein added a reviewer: sammccall.
Herald added subscribers: kadircet, arphaman, jkorous, MaskRay, ioeric, ilya-biryukov.

Namespace references is less useful compared with other symbols, and
they contribute large part of the index. This patch drops them.
The number of refs is reduced from 5.4 million to 4.7 million.

|           | Before | After |
| file size | 78 MB  | 71MB  |
| memory    | 330MB  | 300MB |


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D54202

Files:
  clangd/index/SymbolCollector.cpp
  clangd/index/SymbolCollector.h
  unittests/clangd/SymbolCollectorTests.cpp


Index: unittests/clangd/SymbolCollectorTests.cpp
===================================================================
--- unittests/clangd/SymbolCollectorTests.cpp
+++ unittests/clangd/SymbolCollectorTests.cpp
@@ -443,6 +443,8 @@
   };
   class $bar[[Bar]];
   void $func[[func]]();
+
+  namespace $ns[[NS]] {} // namespace ref is ignored
   )");
   Annotations Main(R"(
   class $bar[[Bar]] {};
@@ -474,6 +476,7 @@
                                   HaveRanges(Main.ranges("bar")))));
   EXPECT_THAT(Refs, Contains(Pair(findSymbol(Symbols, "func").ID,
                                   HaveRanges(Main.ranges("func")))));
+  EXPECT_THAT(Refs, Not(Contains(Pair(findSymbol(Symbols, "NS").ID, _))));
   // Symbols *only* in the main file (a, b, c) had no refs collected.
   auto MainSymbols =
       TestTU::withHeaderCode(SymbolsOnlyInMainCode.code()).headerSymbols();
Index: clangd/index/SymbolCollector.h
===================================================================
--- clangd/index/SymbolCollector.h
+++ clangd/index/SymbolCollector.h
@@ -56,6 +56,9 @@
     bool CountReferences = false;
     /// The symbol ref kinds that will be collected.
     /// If not set, SymbolCollector will not collect refs.
+    /// Note that references of namespace decls are not collected, as they
+    /// contribute large part of the index, anbd they are less useful compared
+    /// with other delcarations.
     RefKind RefFilter = RefKind::Unknown;
     /// If set to true, SymbolCollector will collect all refs (from main file
     /// and included headers); otherwise, only refs from main file will be
Index: clangd/index/SymbolCollector.cpp
===================================================================
--- clangd/index/SymbolCollector.cpp
+++ clangd/index/SymbolCollector.cpp
@@ -356,7 +356,7 @@
     return true;
   if (!shouldCollectSymbol(*ND, *ASTCtx, Opts))
     return true;
-  if (CollectRef &&
+  if (CollectRef && !isa<NamespaceDecl>(ND) &&
       (Opts.RefsInHeaders || SM.getFileID(SpellingLoc) == SM.getMainFileID()))
     DeclRefs[ND].emplace_back(SpellingLoc, Roles);
   // Don't continue indexing if this is a mere reference.


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