Daniel Berlin wrote: >> > > > It looks like your changeset listed bellow makes performance >> > > > regression ~40% on SPEC2006/leslie3d. I will try to create minimal >> > > > test for this issue this week and update you in any case.
>> > The price of fixing them in 4.2 was a serious performance drop. >> >> There's the option of un-fixing them to get back to the state of 4.1 >> declaring >> them fixed in 4.3 earliest. I would like to understand a few things: 1. What is the overall drop in SPEC scores as a result of this patch? I understand the impact on leslie3d, but what is the overall impact? Hopefully, this is an easy question to answer: run SPEC, revert the patch, run SPEC again. 2. What is the effort required to backport the necessary infrastructure from 4.3? I'm not looking for "a lot" or "is hard", but rather, "two weeks" or "six months". What needs to be backported, and what are the challenges? 3. Is there any conceivable way to fix the alias analysis for 4.2 so that it is robust, but not overly conservative, even if that means a special algorithm just for 4.2? Yes, that would be a bizarre thing to do on a release branch, but humor me: is it possible, and what would it take? Please avoid answering this email with comments about the possible non-existence and/or irrelevance of 4.2. I'm about to post a separate mail about plans for 4.2.0, and such comments would be entirely germane in response to that message. But, for the purposes of this message, please assume a 4.2.0 based on the 4.2 branch in the usual way. Thanks, -- Mark Mitchell CodeSourcery [EMAIL PROTECTED] (650) 331-3385 x713
