[PATCH] D101066: [clangd] Dont index deeply nested symbols

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet updated this revision to Diff 339960.
kadircet added a comment.
Herald added a subscriber: cfe-commits.

- Revert unrelated changes in tests


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D101066/new/

https://reviews.llvm.org/D101066

Files:
  clang-tools-extra/clangd/index/IndexAction.cpp
  clang-tools-extra/clangd/unittests/IndexActionTests.cpp


Index: clang-tools-extra/clangd/unittests/IndexActionTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/IndexActionTests.cpp
+++ clang-tools-extra/clangd/unittests/IndexActionTests.cpp
@@ -281,6 +281,36 @@
       EXPECT_THAT(Ref.Location.FileURI, EndsWith("good.h"));
 }
 
+TEST_F(IndexActionTest, SkipNestedSymbols) {
+  std::string MainFilePath = testPath("main.cpp");
+  addFile(MainFilePath, R"cpp(
+  namespace ns1 {
+  namespace ns2 {
+  namespace ns3 {
+  namespace ns4 {
+  namespace ns5 {
+  namespace ns6 {
+  namespace ns7 {
+  namespace ns8 {
+  namespace ns9 {
+  class Bar {};
+  void foo() {
+    class Baz {};
+  }
+  }
+  }
+  }
+  }
+  }
+  }
+  }
+  }
+  })cpp");
+  IndexFileIn IndexFile = runIndexingAction(MainFilePath, {"-std=c++14"});
+  EXPECT_THAT(*IndexFile.Symbols, testing::Contains(HasName("foo")));
+  EXPECT_THAT(*IndexFile.Symbols, testing::Contains(HasName("Bar")));
+  EXPECT_THAT(*IndexFile.Symbols, Not(testing::Contains(HasName("Baz"))));
+}
 } // namespace
 } // namespace clangd
 } // namespace clang
Index: clang-tools-extra/clangd/index/IndexAction.cpp
===================================================================
--- clang-tools-extra/clangd/index/IndexAction.cpp
+++ clang-tools-extra/clangd/index/IndexAction.cpp
@@ -21,6 +21,7 @@
 #include "clang/Index/IndexingOptions.h"
 #include "clang/Tooling/Tooling.h"
 #include "llvm/ADT/STLExtras.h"
+#include <cstddef>
 #include <functional>
 #include <memory>
 #include <utility>
@@ -138,6 +139,19 @@
         Includes(std::move(Includes)), Opts(Opts),
         PragmaHandler(collectIWYUHeaderMaps(this->Includes.get())) {
     this->Opts.ShouldTraverseDecl = [this](const Decl *D) {
+      // Many operations performed during indexing is linear in terms of depth
+      // of the decl (USR generation, name lookups, figuring out role of a
+      // reference are some examples). Since we index all the decls nested
+      // inside, it becomes quadratic.
+      // So we give up on symbols nested more than a certain level to keep
+      // indexing time reasonable.
+      static constexpr size_t MaxContextDepth = 10;
+      size_t ContextDepth = 0;
+      for (auto *Ctx = D->getDeclContext(); Ctx && !Ctx->isTranslationUnit();
+           Ctx = Ctx->getParent()) {
+        if (++ContextDepth == MaxContextDepth)
+          return false;
+      }
       auto &SM = D->getASTContext().getSourceManager();
       auto FID = SM.getFileID(SM.getExpansionLoc(D->getLocation()));
       if (!FID.isValid())


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