Messages in this thread | | | Date | Wed, 18 Oct 2023 17:27:54 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH v2 04/13] linkmode: convert linkmode_{test,set,clear,mod}_bit() to macros |
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On Mon, 16 Oct 2023 18:52:38 +0200 Alexander Lobakin wrote: > Since commit b03fc1173c0c ("bitops: let optimize out non-atomic bitops > on compile-time constants"), the non-atomic bitops are macros which can > be expanded by the compilers into compile-time expressions, which will > result in better optimized object code. Unfortunately, turned out that > passing `volatile` to those macros discards any possibility of > optimization, as the compilers then don't even try to look whether > the passed bitmap is known at compilation time. In addition to that, > the mentioned linkmode helpers are marked with `inline`, not > `__always_inline`, meaning that it's not guaranteed some compiler won't > uninline them for no reason, which will also effectively prevent them > from being optimized (it's a well-known thing the compilers sometimes > uninline `2 + 2`). > Convert linkmode_*_bit() from inlines to macros. Their calling > convention are 1:1 with the corresponding bitops, so that it's not even > needed to enumerate and map the arguments, only the names. No changes in > vmlinux' object code (compiled by LLVM for x86_64) whatsoever, but that > doesn't necessarily means the change is meaningless.
Acked-by: Jakub Kicinski <kuba@kernel.org>
This one can go in with the rest, it's trivial enough.
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