On Thu, November 10, 2011 04:04, Eli Friedman wrote: > On Wed, Nov 9, 2011 at 7:34 PM, Richard Smith <[email protected]> wrote: >> On Thu, November 10, 2011 01:11, Eli Friedman wrote: >>> On Mon, Nov 7, 2011 at 1:22 AM, Richard Smith >>> <[email protected]> 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? :)
Absolutely :) There are still potential manifestations of this problem possible, but I believe they can only be triggered in code which contains the 'constexpr' specifier. >> 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. OK, I was a little worried there might be some pathological machine-specific difference, but that's at least in the same ballpark as what we were seeing. Thanks for bringing this to my attention! Richard _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
