westonpace commented on PR #37610: URL: https://github.com/apache/arrow/pull/37610#issuecomment-1710473070
> Am I missing another concern here? Consider the file `level_comparison_avx2.cc`. It doesn't contain any explicit bmi2 instructions. Currently, we compile it with `-mavx2 -march=haswell` and so it also won't contain any implicit bmi2 instructions (inserted by the compiler). However, if I understand this PR, it is changing this to compile with `-mbmi2 -mavx2 -march=haswell`. So, even though there are not any explicit bmi2 instructions, isn't the compiler free to insert bmi2 instructions in an optimization pass? That being said, I just tested this file, and several others with avx2 in the name, and adding the `-mbmi2` flag did not change the compiled object file at all. So maybe gcc doesn't do any bmi2-specific optimization or maybe these files just can't take advantage of it. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
