commit 5638c1146ea2fb951932a55c9a4aa01d994f0d26
author Richard Smith <richard-llvm@metafoo.co.uk> Wed Feb 25 00:56:02 2015 +0000
committer Richard Smith <richard-llvm@metafoo.co.uk> Wed Feb 25 00:56:02 2015 +0000
tree 9c8dfb64567d32c7b55049b71d9d5a2cbdd8b62f
parent 8bc9ccc60a0ae3b38b37bf0916e27bc95e968be2

[modules] Fix a bug that would result in a build with P paths through a module
graph with M modules to take O(P) time, not just O(M) time, when using explicit
module builds.

llvm-svn: 230412

clang/lib/Frontend/CompilerInstance.cpp

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 832aee2..fc97981 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1288,6 +1288,9 @@
     bool needsImportVisitation() const override { return true; }
 
     void visitImport(StringRef FileName) override {
+      if (!CI.ExplicitlyLoadedModuleFiles.insert(FileName).second)
+        return;
+
       ModuleFileStack.push_back(FileName);
       if (ASTReader::readASTFileControlBlock(FileName, CI.getFileManager(),
                                              *this)) {