Interesting. Yes we want to fix the problem, as we're missing out potential optimizations.
For fixing reference counting, couldn't we fix it by doing the final *pdst = src; in each pipe_xxx_reference function in the bottom of p_state.h, and pass only &(*pdst)->reference, &src->reference to the p_refcnt.h's pipe_reference() instead (i.e., just pointers, and no pointer to pointers)? I haven't tested it but it seems that that would eliminate all casts, hence should be correct. Jose ________________________________________ From: Roland Scheidegger [srol...@vmware.com] Sent: Wednesday, December 02, 2009 23:19 To: Jose Fonseca Cc: mesa3d-...@lists.sf.net Subject: Re: [Mesa3d-dev] mesa/gallium strict aliasing bugs On 02.12.2009 18:33, José Fonseca wrote: > I've seen strict aliasing assumption causing bugs in other gallium > components. It seems endemic to our code. Unless we actively decidee to > go and chase the strict aliasing bugs now we should add > -fno-strict-aliasing to all our builds. Do we ever want to fix strict aliasing? If we do, I think the problem with refcounting is pretty fundamental (I traced the crash to aliasing problems there, and hacked up some bogus version which didn't segfault for the testcase I used). At least I can't see a way to make this really work in some nice way. Supposedly gcc supports "__attribute__((__may_alias__))" but I had no luck with it. In gallium (not core mesa) there's only one other offender causing a large amount of warnings, that is util_pack_color, and I think it won't actually cause problems. ------------------------------------------------------------------------------ Join us December 9, 2009 for the Red Hat Virtual Experience, a free event focused on virtualization and cloud computing. Attend in-depth sessions from your desk. Your couch. Anywhere. http://p.sf.net/sfu/redhat-sfdev2dev _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
