[cfe-commits] r125756 - in /cfe/trunk: include/clang/AST/DeclBase.h lib/AST/DeclBase.cpp

[Francois Pichet]

On Fri, Feb 18, 2011 at 10:36 AM, Douglas Gregor <dgregor at apple.com> wrote:
>
> On Feb 17, 2011, at 1:51 PM, Argyrios Kyrtzidis wrote:
>
>> On Feb 17, 2011, at 10:14 AM, Douglas Gregor wrote:
>>
>>> Author: dgregor
>>> Date: Thu Feb 17 12:14:32 2011
>>> New Revision: 125756
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=125756&view=rev
>>> Log:
>>> Remove the last virtual member function from the Decl hierarchy,
>>> reducing the size of all declarations by one pointer. For a 64-bit
>>> Clang parsing Cocoa.h, this saves ~630k of memory (about 3.5% of
>>> ASTContext's memory usage for this header).
>>
>> Is there any speed difference ?
>
>
> I finally got around to measuring this, and unfortunately, there appears to be a performance loss of about 2% on Cocoa.h. Interesting that we got a win from devirtualizing the Stmt/Expr hierarchy, while we ended up with a loss here... probably because we hit the virtuals in the Decl hierarchy far more often in Sema.
>
> Anyway, thanks for the prod. 2% speed loss for 3.5% memory improvement isn't worthwhile, IMO, so I'll see about backing out these changes.

great, it is very painful to debug clang with no vtable in Decl.