On Sun, 12 Feb 2023, Deepak R Varma wrote: > On Sat, Feb 11, 2023 at 03:25:03PM -0800, Bart Van Assche wrote: > > On 2/7/23 03:54, Deepak R Varma wrote: > > > When adding two bit-field mask values, an OR operation offers higher > > > performance over an arithmetic operation. So, convert such addition to > > > an OR based expression. > > > > Where is the evidence that supports this claim? On the following page I read > > that there is no performance difference when using a modern CPU: https://cs.stackexchange.com/questions/75811/why-is-addition-as-fast-as-bit-wise-operations-in-modern-processors > > > > Hello Bart, > You are correct. Modern CPU designs have improved addition and the performance > is at par with the bitwise operation. The document I had read earlier mentioned > a performance improvement for old CPUs and microprocessors, which today is not > the case. Thank you for sharing the link. > > > > Issue identified using orplus.cocci semantic patch script. > > > > Where is that script located? Can it be deleted such that submission of > > patches similar to this patch stops? > > I have added Julia to this email to understand how to best use this semantic > patch. I already discussed with her on improving the Semantic patch such that it > doesn't suggest making change when constants are involved. FWIW, the semantic patch was never motivated by efficiency, but rather with the goal of making the code more understandable. julia
