[cfe-commits] r143922 - in /cfe/trunk: include/clang/AST/APValue.h lib/AST/APValue.cpp lib/AST/ExprConstant.cpp lib/CodeGen/CGExprConstant.cpp test/SemaCXX/constant-expression-cxx11.cpp

[Eli Friedman]

On Wed, Nov 9, 2011 at 7:34 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> On Thu, November 10, 2011 01:11, Eli Friedman wrote:
>> On Mon, Nov 7, 2011 at 1:22 AM, Richard Smith
>> <richard-llvm at metafoo.co.uk> wrote:
>>
>>> Author: rsmith
>>> Date: Mon Nov  7 03:22:26 2011
>>> New Revision: 143922
>>>
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=143922&view=rev
>>> Log:
>>> Constant expression evaluation: support for arrays.
>>>
>>>
>>> Modified:
>>>    cfe/trunk/include/clang/AST/APValue.h
>>>    cfe/trunk/lib/AST/APValue.cpp
>>>    cfe/trunk/lib/AST/ExprConstant.cpp
>>>    cfe/trunk/lib/CodeGen/CGExprConstant.cpp
>>>    cfe/trunk/test/SemaCXX/constant-expression-cxx11.cpp
>>>
>>
>> This commit appears to have caused a large compile-time regression on
>> MultiSource/Benchmarks/Trimaran/netbench-crc.  Please investigate.
>
> Hi Eli,
>
> r144260 should remove the issue in the short term. This test contains two
> large arrays whose initializers we can now evaluate, and the in-memory
> representation of such arrays is currently quite wasteful in cases like this.
> My current plan is to get all the functionality in place before reworking the
> representation, though I do have a concrete plan for that rework, and could
> bring that forward if there is a pressing need.

Okay; can you just leave r144260 in until you're finished with that
new representation? :)

> How large a regression are you
> seeing? The performance difference was quite modest on the machines we tested
> with here.

We measured a difference on the order of 10%.  Not huge, but
definitely large enough to be worth worrying about.

-Eli