[AST] Store the OwnedTagDecl as a trailing object in ElaboratedType.
The TagDecl *OwnedTagDecl in ElaboratedType is quite commonly
null (at least when parsing all of Boost, it is non-null for only about 600
of the 66k ElaboratedType). Therefore we can save a pointer in the
common case by storing it as a trailing object, and storing a bit in the
bit-fields of Type indicating when the pointer is null.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D50715
llvm-svn: 339862
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 91e9f3e..0a40ee5 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -4136,8 +4136,10 @@
(void)CheckT;
}
- T = new (*this, TypeAlignment)
- ElaboratedType(Keyword, NNS, NamedType, Canon, OwnedTagDecl);
+ void *Mem = Allocate(ElaboratedType::totalSizeToAlloc<TagDecl *>(!!OwnedTagDecl),
+ TypeAlignment);
+ T = new (Mem) ElaboratedType(Keyword, NNS, NamedType, Canon, OwnedTagDecl);
+
Types.push_back(T);
ElaboratedTypes.InsertNode(T, InsertPos);
return QualType(T, 0);