cxx-mem-model merge [0 of 9]

[Andrew MacLeod <amacleod at redhat dot com>]

This is the patchset (9 diffs) for the cxx-mem-model branch which 
implements the C++11 (and future C1x) memory model.

These patches have all been extracted from the branch.  They were 
individually applied to a mainline checkout where a bootstrap was 
performed and a testsuite regression was run.  The only changes were new 
passes resulting from new tests.

Each patch I checked into this branch was reviewed by rth or bkoz before 
it was committed, so it ought to be in fairly good shape having had an 
extra set of eyes on it all along.

rth and I still have a few minor adjustments to perform, but we'll do 
that on mainline once this is merged in.

I would expect to see very little impact on most targets. The new atomic 
operations fall back to the old __sync builtins if there are no new 
patterns.  Its been developed on x86_64-unknown-linux-gnu, and I had 
aldyh bootstrap and run regression test on a PPC and ia64 box a week or 
two ago.

What use to work, should still work. Ha! famous last words :-)

I plan to spend the next couple of months writing testsuite cases to 
fully flush out any bugs, as well as work on providing a buildable 
atomic library as detailed in the wiki (  
http://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary )  That link also has a few 
details on GCC implementation of builtins.

Once approved, I dont think I need a slush, or at least not a very long 
one.  I plan to check in the code from the patchset rather than merge 
from the branch.  what you see here is what you get!  (I'm rebuilding 
from mainline again as I write this...)


Whats the deal on Changelogs?  Do we just put the entire branch 
changelog at the top of the current changelog with a comment  'merged 
from cxx-mem-model' or something to that effect?  It just buggers up the 
date linearality of changelogs.  Or do I add the ChangeLog.mm files and 
make a comment in Changelog to look at ChangeLog.mm?   This doesnt seem 
intrusive enough to require its own.

Maybe the best bet is to just concatenate *all* the comments in the 
various ChangeLog.mm, and make them a single ChangeLog entry in each 
applicable ChangeLog file with the date of the merge.   It could be a 
long entry, but that seems like it might be best...

Anyway, have a look and what do you think?

Andrew

PS  Next release we'll should get some atomic optimizations, all ports 
'ported' to the new patterns (hopefully), C1x support, and just further 
improvements as it starts to get used.