On Tue, Nov 18, 2025 at 05:20:05PM +0300, Nazir Bilal Yavuz wrote: > Thanks, done.
I took a look at the v3 patches. Here are my high-level thoughts:
+ /* + * Parse data and transfer into line_buf. To get benefit from inlining, + * call CopyReadLineText() with the constant boolean variables. + */ + if (cstate->simd_continue) + result = CopyReadLineText(cstate, is_csv, true); + else + result = CopyReadLineText(cstate, is_csv, false);
I'm curious whether this actually generates different code, and if it does, if it's actually faster. We're already branching on cstate->simd_continue here.
I've compiled both versions with -O2 and confirmed they generate different code. When simd_continue is passed as a constant to CopyReadLineText, the compiler optimizes out the condition checks from the SIMD path. A small benchmark on a 1GB+ file shows the expected benefit which is around 6% performance improvement. I've attached the assembly outputs in case someone wants to check something else.
Regards,
Ayoub Kazar
Correction to my last post:
I also tried files that alternated lines with no special characters and lines with 1/3rd special characters, thinking I could force the algorithm to continually check whether or not it should use simd and therefore force more overhead in the try-simd/don't-try-simd housekeeping code. The text file was still 20% faster (not 50% faster as I originally stated --- that was a typo). The CSV file was still 13% faster.
Also, apologies for posting at the top in my last e-mail.
