So... It's been a long journey, but I think I'm at a point in which, even though VTA is not completely finished, it's already enough of an improvement that it could go in, be useful and get wider testing.
To the best of my knowledge, all of the concerns and objections that were raised have already been addressed: we have low memory and compile-time overhead in general, and we have significantly improved debug information. Besides all the data that Jakub has already posted, Mark Wielaard has done some Systemtap testing, comparing debug information for parameters of inlined functions using a pristine Fedora kernel vs results using a vta4.4 compiler to compile the same kernel sources. Out of 42249 inlined function parameters for which some debug information was emitted, GCC 4.4 emitted location information for only 280, whereas the backport of VTA to GCC 4.4 emitted location information for as many as 7544. The careful reader will note that 34705 parameters still don't get location information. That's a lot. No investigation has been done as to how many of them are indeed unavailable, and therefore couldn't possibly and shouldn't have got debug location/value information, but I'd be surprised if it's this many. As I pointed out before, the code is not perfect, and there is certainly room for further improvements, but waiting for perfection will take too long ;-) Seriously, if VTA could be merged soonish, or at least accepted soon for a merge at a later date, Fedora would adopt it right away in its development tree, and then we'd get much broader testing. So, what does it take to get it merged soonish, even if not enabled by default? Thanks, -- 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 Brazil Compiler Engineer
