PROPOSAL: targetm.expand_tree_builtin hook

[Paolo Bonzini]

Something akin to this I proposed for re-doing Altivec builtins.

  http://gcc.gnu.org/ml/gcc-patches/2004-04/msg00791.html
I'm doing something very similar but based on a fold_builtin hook, only 
because I started my AltiVec work about at the same time as Richard 
prepared that RFC.

fold_builtin seems to be not too late in the game, and anyway it would 
be easy to convert to something like the expand_tree_builtin hook you 
propose.

Aside from that, I think it would be great if you could commit
this functionality!  Can you? :-)
It is not complete, it should be extracted from the patch, and renamed 
as you suggested.

Or, I can send you my patch for a fold_builtin target hook.

Paolo