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

[Evan Cheng]

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?

Evan

> 
> I didn't test if it would be beneficial to apply the optimization to GEPs with a scale of one but I doubt it'll have a measurable impact.