> On Oct 5, 2022, at 1:36 PM, Martin Liška <mli...@suse.cz> wrote: > > On 10/5/22 16:50, Qing Zhao wrote: >> I have two questions on this: > > Hello. > >> >> 1. What’s the motivation to enable -flive-patching with -flto? Is there any >> application that will try -flive-patching with -flto now? > > We're planning supporting GCC LTO Linux kernel support, so that's one > motivation. And the second one is a possible > use in user-space livepatching. Note majority of modern distros default to > -flto (openSUSE, Fedora, Debian, Ubuntu, ...).
Okay, I see. That’s reasonable. > >> >> 2. Why only enable -flive-patching=inline-clone with -flto? > > Because the inline-only-static level (which you added/requested) would have > to properly > block inter-procedural inlining that happens in LTO > (can_inline_edge_by_limits_p) and > I'm not sure it would be properly blocked. So, feel free to extend my patch > if you want? -flive-patching=inline-only-static Only enable static functions inlining, all the inlining of external visible functions are blocked, So, LTO should be compatible with this naturally without any issue, I think. i.e, when "-flive-patching=inline-only-static -flto" present together, all the inter-procedural inlining should be automatically blocked by -flive-patching=inline-only-static already. Do I miss anything here? thanks. Qing > > Martin > >> >> thanks. >
