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From: "jirislaby at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug lto/107014] New: flatten+lto
Date: Fri, 23 Sep 2022 07:38:17 +0000 [thread overview]
Message-ID: <bug-107014-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107014
Bug ID: 107014
Summary: flatten+lto
Product: gcc
Version: 12.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
Assignee: unassigned at gcc dot gnu.org
Reporter: jirislaby at gmail dot com
CC: marxin at gcc dot gnu.org
Target Milestone: ---
Maybe this is simply a dup of bug 77472, but I am not sure what the proper
solution is supposed to be.
In the kernel, when LTO is enabled, we disable flatten completely, so that the
build is able to finish -- in ~ 2 minutes, w/ 4G of RAM.
With flatten enabled, the build didn't finish in 10 minutes, eating 40G of RAM
at that point.
There is only a single user of flatten in the kernel: pcpu_build_alloc_info().
Here:
https://github.com/torvalds/linux/blob/bf682942cd26ce9cd5e87f73ae099b383041e782/mm/percpu.c#L2852-L2855
And that on its own makes the link not to finish in a reasonable time, with
reasonable RAM. I suppose much inlining happens in such a long function. But:
shouldn't really there be any limit?
I am going to link this bug in the commit message disabling flatten on LTO, so
that we have a reference of why/how...
next reply other threads:[~2022-09-23 7:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-23 7:38 jirislaby at gmail dot com [this message]
2022-09-23 7:55 ` [Bug lto/107014] flatten+lto fails the kernel build marxin at gcc dot gnu.org
2022-09-23 8:04 ` rguenth at gcc dot gnu.org
2022-09-23 8:21 ` amonakov at gcc dot gnu.org
2022-09-23 8:24 ` jirislaby at gmail dot com
2022-09-23 8:28 ` amonakov at gcc dot gnu.org
2022-09-23 9:52 ` jirislaby at gmail dot com
2022-09-23 10:12 ` amonakov at gcc dot gnu.org
2022-09-23 10:36 ` jakub at gcc dot gnu.org
2022-09-25 19:56 ` andi-gcc at firstfloor dot org
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