On Mon 30 Jul 2012 04:07:01 NZST +1200, Weddington, Eric wrote: > There are known issues with LTO and AVR, though unknown reasons why.
Would you have a link to that known issues list? > For now I would suggest that you avoid that feature. That's a shame :-( > However, please file a bug report at the GCC Bugzilla database. That > way we can keep track of the various LTO issues and eventually try to > get them fixed. When I started on that report I find that I don't have enough information. My findings are * binutils 2.22 really increases program size, and the combination with avr-gcc 4.6.2 and LTO fails. What actually is the reason for this? And is this a gcc problem? * Program size from avr-gcc 4.3 to 4.6 decreases steadily, generally speaking. LTO with 4.6 has a positive effect with binutils 2.19.1 and is non-functional with 2.22. * 4.7 is, from previous posts on this list, the best optimised and least buggy gcc version. However its program size gives no advantage over 4.3 in any of the ways I have tried, which is unfortunate. More precisely, without LTO it produces larger code than 4.3 - no incentive to upgrade. *With* LTO (and the old binutils) it matches 4.3. Would you like me to report this as an LTO *problem*? How do you suggest I do that without looking like an idiot...? ;-) The 2 problems I see here are: * binutils 2.22 make programs *bigger*. I wouldn't have expected binutils to do something like that, what could be the reason? * gcc 4.7, with all the work Johann has put into it, produces code that is at least as big as the one from 4.3. Is this expected, or did I build the tool(s) wrong? I'll put a report in if it helps, if you can help me be a bit more specific. Thanks, Volker -- Volker Kuhlmann http://volker.dnsalias.net/ Please do not CC list postings to me. _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org https://lists.nongnu.org/mailman/listinfo/avr-gcc-list
