r269717 - Switch from SmallVector to TinyPtrVector for the list of attributes on a declaration. This removes a memory allocation for the common case where the declaration has only one attribute.

[David Blaikie via cfe-commits]

On Mon, May 16, 2016 at 3:53 PM, Richard Smith via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: rsmith
> Date: Mon May 16 17:53:19 2016
> New Revision: 269717
>
> URL: http://llvm.org/viewvc/llvm-project?rev=269717&view=rev
> Log:
> Switch from SmallVector to TinyPtrVector for the list of attributes on a
> declaration. This removes a memory allocation for the common case where the
> declaration has only one attribute.
>

Just out of curiosity - if the SmallVector had a small size of 2, why was
an allocation done for a single attribute?


>
> Modified:
>     cfe/trunk/include/clang/AST/AttrIterator.h
>
> Modified: cfe/trunk/include/clang/AST/AttrIterator.h
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/AttrIterator.h?rev=269717&r1=269716&r2=269717&view=diff
>
> ==============================================================================
> --- cfe/trunk/include/clang/AST/AttrIterator.h (original)
> +++ cfe/trunk/include/clang/AST/AttrIterator.h Mon May 16 17:53:19 2016
> @@ -15,6 +15,7 @@
>  #define LLVM_CLANG_AST_ATTRITERATOR_H
>
>  #include "clang/Basic/LLVM.h"
> +#include "llvm/ADT/TinyPtrVector.h"
>  #include <iterator>
>
>  namespace clang {
> @@ -39,8 +40,8 @@ void operator delete[](void *Ptr, const
>  namespace clang {
>
>  /// AttrVec - A vector of Attr, which is how they are stored on the AST.
> -typedef SmallVector<Attr*, 2> AttrVec;
> -typedef SmallVector<const Attr*, 2> ConstAttrVec;
> +typedef llvm::TinyPtrVector<Attr*> AttrVec;
> +typedef llvm::TinyPtrVector<const Attr*> ConstAttrVec;
>
>  /// specific_attr_iterator - Iterates over a subrange of an AttrVec, only
>  /// providing attributes that are of a specific type.
>
>
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