public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
* [Bug other/63440] New: -Og does enable -fmerge-constants too
@ 2014-10-02 9:24 rdiezmail-gcc at yahoo dot de
2014-10-06 12:06 ` [Bug other/63440] " rguenth at gcc dot gnu.org
2014-10-06 13:36 ` rdiezmail-gcc at yahoo dot de
0 siblings, 2 replies; 3+ messages in thread
From: rdiezmail-gcc at yahoo dot de @ 2014-10-02 9:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63440
Bug ID: 63440
Summary: -Og does enable -fmerge-constants too
Product: gcc
Version: 4.9.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: rdiezmail-gcc at yahoo dot de
The documentation for -fmerge-constants does not mention that the new
optimization level -Og does enable -fmerge-constants too. Or at least it seems
to do, judging by the generated code size in my tests.
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug other/63440] -Og does enable -fmerge-constants too 2014-10-02 9:24 [Bug other/63440] New: -Og does enable -fmerge-constants too rdiezmail-gcc at yahoo dot de @ 2014-10-06 12:06 ` rguenth at gcc dot gnu.org 2014-10-06 13:36 ` rdiezmail-gcc at yahoo dot de 1 sibling, 0 replies; 3+ messages in thread From: rguenth at gcc dot gnu.org @ 2014-10-06 12:06 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63440 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2014-10-06 Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed. Do you think it is ok to enable -fmerge-constants with -Og? Note that the various "Enabled at levels ..." were not updated for -Og. ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug other/63440] -Og does enable -fmerge-constants too 2014-10-02 9:24 [Bug other/63440] New: -Og does enable -fmerge-constants too rdiezmail-gcc at yahoo dot de 2014-10-06 12:06 ` [Bug other/63440] " rguenth at gcc dot gnu.org @ 2014-10-06 13:36 ` rdiezmail-gcc at yahoo dot de 1 sibling, 0 replies; 3+ messages in thread From: rdiezmail-gcc at yahoo dot de @ 2014-10-06 13:36 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63440 --- Comment #2 from R. Diez <rdiezmail-gcc at yahoo dot de> --- Yes, I would enable -fmerge-constants with -Og. I would do it even for -O0. Merging constants should be safe, and it saves precious program space when generating debug builds for small embedded targets. Besides, in my opinion, it does not make sense that the addresses of some literal strings suddenly change when you enable optimisations, because they get collapsed. Any bugs because of such shared addresses should be apparent in debug builds too. Note that GCC already seems to apply some optimisations when building with -O0. Specifically, I believe that at least some dead code elimination does occur. That would make sense, as you do not want to bloat your debug builds unnecessary. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2014-10-06 13:36 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-10-02 9:24 [Bug other/63440] New: -Og does enable -fmerge-constants too rdiezmail-gcc at yahoo dot de 2014-10-06 12:06 ` [Bug other/63440] " rguenth at gcc dot gnu.org 2014-10-06 13:36 ` rdiezmail-gcc at yahoo dot de
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).