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From: "iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug lto/48094] ld: warning: section has unexpectedly large size errors in objc/obj-c++ lto Date: Mon, 05 Dec 2011 21:03:00 -0000 [thread overview] Message-ID: <bug-48094-4-cT7MTb0vP9@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-48094-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48094 --- Comment #12 from Iain Sandoe <iains at gcc dot gnu.org> 2011-12-05 21:01:09 UTC --- (In reply to comment #11) > I think that later versions of the vendor's tools make some of the ObjC > sections merge-able - so that's a possibility Unfortunately, not the _image_info sections. === So .. this is the problem.... We have n object files input to lto. Each object contains ObjC meta-data... including a single var in the _image_info section. Although these image_info vars will eventually be overlaid, they are not common-like - because they can be non-zero. (Darwin's) ld can merge them, because ld knows that the property of the _image_info section is that it holds a single instance of the L_OBJC_ImageInfo variable. So ld can check that these are compatible between objects, and merge/error as appropriate. but LTO will concatenate them - leading to two problems: (a) the section appears to be too big - complaint from later versions of ld and (b) they are no longer being error-checked and combined - which might have much more subtle implications. > - otherwise - Honza any suggestions? e.g. Is there any annotation or hook that we can use to emulate this behavior? (I don't think DECL_ONE_ONLY is quite right because it might be [legitimately] possible for the vars to have differing values - I need to check that carefully) I guess, ideally, the ObjC meta-data should be re-created after LTO has done its magic -- but that's def. not a stage 3 type job ... .. maybe move it to be a late (Post Optimization) pass? [ISTM, at a first consideration, there should be no need to optimize ObjC metadata under those circumstances, since it should only be created as required in response to the remaining (optimized) content]
next prev parent reply other threads:[~2011-12-05 21:03 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-03-12 17:31 [Bug lto/48094] New: " howarth at nitro dot med.uc.edu 2011-03-12 17:32 ` [Bug lto/48094] " howarth at nitro dot med.uc.edu 2011-03-12 17:49 ` iains at gcc dot gnu.org 2011-03-12 18:38 ` iains at gcc dot gnu.org 2011-03-13 12:13 ` iains at gcc dot gnu.org 2011-03-14 9:40 ` iains at gcc dot gnu.org 2011-11-14 0:05 ` iains at gcc dot gnu.org 2011-12-03 15:50 ` howarth at nitro dot med.uc.edu 2011-12-03 18:32 ` iains at gcc dot gnu.org 2011-12-05 15:25 ` howarth at nitro dot med.uc.edu 2011-12-05 15:31 ` howarth at nitro dot med.uc.edu 2011-12-05 17:24 ` iains at gcc dot gnu.org 2011-12-05 21:03 ` iains at gcc dot gnu.org [this message] 2011-12-06 0:50 ` steven at gcc dot gnu.org 2011-12-06 9:13 ` iains at gcc dot gnu.org 2012-02-12 14:44 ` iains at gcc dot gnu.org 2013-07-16 12:05 ` iains at gcc dot gnu.org 2013-07-16 19:12 ` iains at gcc dot gnu.org 2013-09-14 15:34 ` [Bug target/48094] " iains at gcc dot gnu.org 2013-09-14 15:36 ` iains at gcc dot gnu.org 2013-09-14 15:40 ` iains at gcc dot gnu.org 2013-09-15 18:32 ` mrs at gcc dot gnu.org 2014-04-07 6:41 ` dominiq at gcc dot gnu.org 2014-04-07 8:01 ` dominiq at gcc dot gnu.org
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