[llvm-commits] [llvm] r52223 - in /llvm/trunk: lib/Transforms/Scalar/TailDuplication.cpp test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll

Evan Cheng evan.cheng at apple.com
Thu Jun 12 13:54:49 PDT 2008


Yeah, this introduces one extra run of dominator tree construction  
(roughly ~1.5% compile time on 403.gcc). I'll back it out for now.

Florian, could you redo your patch? Thanks.

Evan

On Jun 11, 2008, at 11:18 PM, Chris Lattner wrote:

> On Jun 11, 2008, at 12:07 PM, Evan Cheng wrote:
>> URL: http://llvm.org/viewvc/llvm-project?rev=52223&view=rev
>> Log:
>> Avoid duplicating loop header which leads to unnatural loops (and
>> just seem like general badness to me, likely to cause code  
>> explosion).
>> Patch by Florian Brandner.
>
> What is the compile time impact of this?  How about identifying loop
> headers with a simple DFS walk?
>
> -Chris
>
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