[clang] [AST] Avoid repeated hash lookups (NFC) (PR #131064)

[Kazu Hirata via cfe-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/131064

None

>From ce858bc0761b0cd7410ccb0858a4bc692933dbd5 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Wed, 12 Mar 2025 08:52:05 -0700
Subject: [PATCH] [AST] Avoid repeated hash lookups (NFC)

---
 clang/lib/AST/ASTImporter.cpp | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 82180486f3c7c..0d9b5afc4e4a6 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -10527,12 +10527,11 @@ void ASTImporter::CompleteDecl (Decl *D) {
 }
 
 Decl *ASTImporter::MapImported(Decl *From, Decl *To) {
-  llvm::DenseMap<Decl *, Decl *>::iterator Pos = ImportedDecls.find(From);
-  assert((Pos == ImportedDecls.end() || Pos->second == To) &&
-      "Try to import an already imported Decl");
-  if (Pos != ImportedDecls.end())
+  auto [Pos, Inserted] = ImportedDecls.try_emplace(From, To);
+  assert((Inserted || Pos->second == To) &&
+         "Try to import an already imported Decl");
+  if (!Inserted)
     return Pos->second;
-  ImportedDecls[From] = To;
   // This mapping should be maintained only in this function. Therefore do not
   // check for additional consistency.
   ImportedFromDecls[To] = From;