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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114480] g++: internal compiler error: Segmentation fault
 signal terminated program cc1plus
Date: Tue, 02 Apr 2024 13:28:10 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114480

--- Comment #16 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 57849
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D57849&action=3Dedit
patch for expand

Interestingly this patch for RTL expansion, more specifically
add_scope_conflicts, only slows down things even though it should improve
cache locality.  In particular doing the 2nd stage inbetween makes things
worse.

Maybe this is due to the high in-degree of some blocks in the CFG.

I'll note there's no "change" in the 2nd iteration for SCCs, so optimizing
to only IOR in from (changed) backedges might "work" to reduce work.

Still it's odd the apparent locality improvement doesn't actually help
(as said it might be skewed by a high indegree of an SCC).=