On Oct 14, 2015, Richard Biener <richard.guent...@gmail.com> wrote: > On Wed, Oct 14, 2015 at 5:25 AM, Alexandre Oliva <aol...@redhat.com> wrote: >> On Oct 12, 2015, Richard Biener <richard.guent...@gmail.com> wrote: >> >>> On Sat, Oct 10, 2015 at 3:16 PM, Alexandre Oliva <aol...@redhat.com> wrote: >>>> On Oct 9, 2015, Richard Biener <richard.guent...@gmail.com> wrote: >>>> >>>>> Ok. Note that I think emit_block_move shouldn't mess with the >>>>> addressable flag. >>>> >>>> I have successfully tested a patch that stops it from doing so, >>>> reverting https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49429#c11 but >>>> according to bugs 49429 and 49454, it looks like removing it would mess >>>> with escape analysis introduced in r175063 for bug 44194. The thread >>>> that introduces the mark_addressable calls suggests some discomfort with >>>> this solution, and even a suggestion that the markings should be >>>> deferred past the end of expand, but in the end there was agreement to >>>> go with it. https://gcc.gnu.org/ml/gcc-patches/2011-06/msg01746.html >> >>> Aww, indeed. Of course the issue is that we don't track pointers to the >>> stack introduced during RTL properly. >> >>> Thanks for checking. Might want to add a comment before that >>> addressable setting now that you've done the archeology. >> >> I decided to give the following approach a try instead. The following >> patch was regstrapped on x86_64-linux-gnu and i686-linux-gnu. >> Ok to install?
> It looks ok to me but lacks a comment in mark_addressable_1 why we > do this queueing when currently expanding to RTL. >> +/* Mark X as addressable or queue it up if called during expand. */ >> + >> +static void >> +mark_addressable_1 (tree x) How about this: /* Mark X as addressable or queue it up if called during expand. We don't want to apply it immediately during expand because decls are made addressable at that point due to RTL-only concerns, such as uses of memcpy for block moves, and TREE_ADDRESSABLE changes is_gimple_reg, which might make it seem like a variable that used to be a gimple_reg shouldn't have been an SSA name. So we queue up this flag setting and only apply it when we're done with GIMPLE and only RTL issues matter. */ -- Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ You must be the change you wish to see in the world. -- Gandhi Be Free! -- http://FSFLA.org/ FSF Latin America board member Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer
