[llvm-commits] [llvm] r126445 - in /llvm/trunk: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/select-gep.ll

[Benjamin Kramer]

On 25.02.2011, at 18:25, Evan Cheng wrote:

> 
> On Feb 25, 2011, at 7:26 AM, Benjamin Kramer wrote:
> 
>> 
>> On 25.02.2011, at 08:14, Evan Cheng wrote:
>> 
>>> Speculation is nice, but I would feel a lot better if there are hard numbers to back this up. Are we sure these changes are improving performance?
>> 
>> My unscientific test case (gcc compiled with clang -O3 parsing itself) showed a 0.25% speedup with the original patch (all-constant GEPs only, median of 5 runs, i386, penryn). I just retested with the change Frits suggested and it slowed down ~0.6% compared to the original run so I reverted it.
> 
> Thanks. What tests are you using to evaluate this?

I routinely use the nice C files from http://people.csail.mit.edu/smcc/projects/single-file-programs/
which are easy to handle and large enough to get meaningful results for both compile time and run
time. They're extracted from programs that are also part of SPEC CINT, so I'm confident the
improvements will also show up there :)