From 6eda66b0a9f793c65852aa94430ae9bd891bcf63 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard@metafoo.co.uk>
Date: Wed, 1 Sep 2021 17:57:48 -0700
Subject: [PATCH] PR50294: Fix a performance regression from 2c9dbcd.
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Per the contract of ReadLateParsedTemplates, we should not be returning
the same results multiple times. No functionality change intended, other
than to runtime.

Thanks to Luboš Luňák for identifying the cause of the regression!
---
 clang/lib/Serialization/ASTReader.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 128350ce9ff8f0..dfa7d55af735da 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -8412,6 +8412,8 @@ void ASTReader::ReadLateParsedTemplates(
       LPTMap.insert(std::make_pair(FD, std::move(LT)));
     }
   }
+
+  LateParsedTemplates.clear();
 }
 
 void ASTReader::LoadSelector(Selector Sel) {