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* [Bug lto/105877] New: GNU strip breaks -flto -g .o files
@ 2022-06-07 18:42 slyfox at gcc dot gnu.org
2022-06-07 19:08 ` [Bug lto/105877] " hjl.tools at gmail dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: slyfox at gcc dot gnu.org @ 2022-06-07 18:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105877
Bug ID: 105877
Summary: GNU strip breaks -flto -g .o files
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: lto
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
CC: hjl.tools at gmail dot com, hubicka at gcc dot gnu.org,
marxin at gcc dot gnu.org
Target Milestone: ---
Host: x86_64-unknown-linux-gnu
Initially reported by drnfc on
https://github.com/trofi/nix-guix-gentoo/issues/19 where gcc failed to link
nix-2.9.0 against stripped liblowdown.a. Both are built with -flto.
I'm not sure if it's a strip bug, gcc bug or both. I think (did not check) it
used to work long ago. I'm leaning towards gcc bug and filing it here first.
Here is a minimal reproducer:
// $ cat document.c
void lowdown_doc_new(void) {}
// $ cat markdown.cc
extern "C" { void lowdown_doc_new(void); }
int main(){ lowdown_doc_new(); }
$ gcc -flto -g -c -o document.o document.c
$ cp document.o document-stripped.o
$ strip -g document-stripped.o
$ g++ markdown.cc -o a document.o -flto-partition=max -flto -g
$ g++ markdown.cc -o a document-stripped.o -flto-partition=max -flto -g
ld: /tmp/ccajK6YG.ltrans0.ltrans.o:(.debug_info+0x2f): undefined reference
to `document.c.20ce96f1'
$ gcc -v |& unnix
Using built-in specs.
COLLECT_GCC=/<<NIX>>/gcc-13.0.0/bin/gcc
COLLECT_LTO_WRAPPER=/<<NIX>>/gcc-13.0.0/libexec/gcc/x86_64-unknown-linux-gnu/13.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with:
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20220605 (experimental) (GCC)
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/105877] GNU strip breaks -flto -g .o files
2022-06-07 18:42 [Bug lto/105877] New: GNU strip breaks -flto -g .o files slyfox at gcc dot gnu.org
@ 2022-06-07 19:08 ` hjl.tools at gmail dot com
2022-06-09 10:14 ` hubicka at kam dot mff.cuni.cz
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: hjl.tools at gmail dot com @ 2022-06-07 19:08 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105877
--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
"strip -g" removed .gnu.debuglto_.debug_info sections. Should LTO remove the
references of stripped debug info? Or should "strip -g" keep LTO debug info?
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/105877] GNU strip breaks -flto -g .o files
2022-06-07 18:42 [Bug lto/105877] New: GNU strip breaks -flto -g .o files slyfox at gcc dot gnu.org
2022-06-07 19:08 ` [Bug lto/105877] " hjl.tools at gmail dot com
@ 2022-06-09 10:14 ` hubicka at kam dot mff.cuni.cz
2022-06-13 13:07 ` rguenth at gcc dot gnu.org
2022-06-16 13:27 ` marxin at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: hubicka at kam dot mff.cuni.cz @ 2022-06-09 10:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105877
--- Comment #2 from hubicka at kam dot mff.cuni.cz ---
> "strip -g" removed .gnu.debuglto_.debug_info sections. Should LTO remove the
> references of stripped debug info? Or should "strip -g" keep LTO debug info?
I suppose we should try to immitate what happens without -flto, so
probably check for the presence of debuglto sections and avoid producing
debug info when they have been stripped?
I am not sure how hard would be to implement this especially in
situations where part of object files were stripped and others not?
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/105877] GNU strip breaks -flto -g .o files
2022-06-07 18:42 [Bug lto/105877] New: GNU strip breaks -flto -g .o files slyfox at gcc dot gnu.org
2022-06-07 19:08 ` [Bug lto/105877] " hjl.tools at gmail dot com
2022-06-09 10:14 ` hubicka at kam dot mff.cuni.cz
@ 2022-06-13 13:07 ` rguenth at gcc dot gnu.org
2022-06-16 13:27 ` marxin at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-06-13 13:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105877
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to hubicka from comment #2)
> > "strip -g" removed .gnu.debuglto_.debug_info sections. Should LTO remove the
> > references of stripped debug info? Or should "strip -g" keep LTO debug info?
>
> I suppose we should try to immitate what happens without -flto, so
> probably check for the presence of debuglto sections and avoid producing
> debug info when they have been stripped?
> I am not sure how hard would be to implement this especially in
> situations where part of object files were stripped and others not?
I think it might be possible to detect whether the compiled objects are
stripped and then avoid streaming references to its debug sections by
magically turning it to -g0. But not sure how awkward this will be.
Not sure why strip now strips .gnu.debuglto_.debug_info, it didn't do that
before.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug lto/105877] GNU strip breaks -flto -g .o files
2022-06-07 18:42 [Bug lto/105877] New: GNU strip breaks -flto -g .o files slyfox at gcc dot gnu.org
` (2 preceding siblings ...)
2022-06-13 13:07 ` rguenth at gcc dot gnu.org
@ 2022-06-16 13:27 ` marxin at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: marxin at gcc dot gnu.org @ 2022-06-16 13:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105877
Martin Liška <marxin at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2022-06-16
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-06-16 13:27 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2022-06-07 18:42 [Bug lto/105877] New: GNU strip breaks -flto -g .o files slyfox at gcc dot gnu.org
2022-06-07 19:08 ` [Bug lto/105877] " hjl.tools at gmail dot com
2022-06-09 10:14 ` hubicka at kam dot mff.cuni.cz
2022-06-13 13:07 ` rguenth at gcc dot gnu.org
2022-06-16 13:27 ` marxin at gcc dot gnu.org
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