Date: Tue, 5 Jun 2007 11:07:54 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: ia64@freebsd.org Cc: Alexander Kabaev <kabaev@gmail.com> Subject: About the GCC 4.2 update Message-ID: <C47F0F9E-C88C-4562-B8E7-DD94144C8E59@mac.com>
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All, GCC 4.2 was just recently imported into the source tree and it's causing some problems. For one: there's *NO* single optimization level known to me at this time that produces correct code in all cases. This is a biggy! The best results are to be had with -O -g. Do not compile at -O2 as that breaks the GNU linker and prevents you from building anything. With -O, GCC still produces bad code and in particular it breaks the kernel, but it only breaks the kernel if you don't compile with INVARIANTS and INVARIANT_SUPPORT. With those options the compiler has a much bigger chance optimizing the code and thus getting it wrong. With the options GCC 4.2 is being restricted and the nice side-effect is that it doesn't have a chance to really get it wrong. So, if you track -CURRENT and want to upgrade to beyond the GCC 4.2 import, make sure you keep backups or you'll be sorry... FYI, -- Marcel Moolenaar xcllnt@mac.com
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