On Tue, Mar 12, 2024 at 05:21:58PM +0100, Jakub Jelinek wrote:
> On Tue, Mar 12, 2024 at 10:46:42AM +0100, Jan Hubicka wrote:
> > I am sorry for delaying this. I made the variant that simply compares
> > value range of functions and prevents merging if they diverge and wanted
> > to make some bigger statistics. This made me notice some performance
> > problems on clang performance and libstdc++ RB-trees which disrailed me
> > from the original PR. I will finish the statistics today.
>
> With the posted patch, perhaps if we don't want to union jump_tables etc.,
> all we could punt on is differences in the jump_table VRs rather than just
> any SSA_NAME_RANGE_INFO differences.
To expand on this, I think we need to either union or punt on jump_func
differences in any case, because for LTO we can't really punt on
SSA_NAME_RANGE_INFO differences given that we don't stream that out and in.
So the ipa_jump_func are I think the only thing that actually can differ
on the ICF merging candidates from value range POV.
Jakub
