From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 20 Nov 2012 23:23:57 +0000 (+0000)
Subject: Don't walk a linked list twice in the same function. On my machine this takes
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=289994c1e7f965f2556b8b566738396659066669;p=clang

Don't walk a linked list twice in the same function. On my machine this takes
"clang -cc1" on a file with 10k repetitions of
extern int no_such_variable;
from 1.434s to 1.133s.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168394 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 087a585874..020f3b05fc 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -3299,10 +3299,10 @@ void Redeclarable<decl_type>::setPreviousDeclaration(decl_type *PrevDecl) {
     // Point to previous. Make sure that this is actually the most recent
     // redeclaration, or we can build invalid chains. If the most recent
     // redeclaration is invalid, it won't be PrevDecl, but we want it anyway.
-    RedeclLink = PreviousDeclLink(
-                   llvm::cast<decl_type>(PrevDecl->getMostRecentDecl()));
     First = PrevDecl->getFirstDeclaration();
     assert(First->RedeclLink.NextIsLatest() && "Expected first");
+    decl_type *MostRecent = First->RedeclLink.getNext();
+    RedeclLink = PreviousDeclLink(llvm::cast<decl_type>(MostRecent));
   } else {
     // Make this first.
     First = static_cast<decl_type*>(this);