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Date: | Sat, 1 Aug 2009 13:10:13 +0300 |
Message-ID: | <647fe9b10908010310of9d1a72k46c228264ead30de@mail.gmail.com> |
Subject: | Re: Some patches to DJGPP v2.04 (GCC-4.4.1 related) |
From: | Ozkan Sezer <sezeroz AT gmail DOT com> |
To: | djgpp-workers AT delorie DOT com |
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On Sat, Aug 1, 2009 at 1:02 PM, Eli Zaretskii<eliz AT gnu DOT org> wrote: >> Date: Sat, 1 Aug 2009 11:47:59 +0300 >> From: Ozkan Sezer <sezeroz AT gmail DOT com> >> >> Although you may want to build using >> -Wstrict-aliasing=2 before finishing your work, because gcc >> seems to hide some of the warnings _and_ may generate >> bad code, and in some worse cases may not warn even >> with that warning flag and still generate bad code which >> happened to me once (that was with gcc-4.5, though..) > > Details, please: how can a warning option cause bad code generation? > Miscommunication, I think: What I suggest is that one shouldn't rely plainly on -Wall to see strict aliasing warnings, but also use -Wstrict-aliasing=2 to see if there are more. If you miss those warnings, you _may_ (or may not) end up having bad binaries. Besides, in some cases, even -Wstrict-aliasing=2 doesn't report the aliasing violations and gcc can silently generate bad code. I hope this was clear enough.
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