[PATCH v2 0/5] unssa improvements

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

This serie improves the out-of-SSA step by:
* simplify the conversion of the phi-nodes & phi-sources into copies
* eliminate some copies which are trivially not needed.

The elimination step is significant since on a small corpus which
produced 267 copies, after the patch only 165 remain.


Changes since v1:
  * during unSSA, do not use kill_instruction() on OP_PHI
  * fix related to the fact that after unSSA, pseudos *can*
    again be defined by several instructions. If it's effectively the
    case, their ->def is set to NULL (and must, of course, not be used).

Note: this serie depends on the serie 'fix uses of killed instructions'
    and on the changes to the testsuite for checking after some patterns
    in the output.

This serie can also be found on github:
	https://github.com/lucvoo/sparse/tree/sent/unssa-simple

Luc Van Oostenryck (5):
  unssa: do not try to update liveness
  unssa: simplify rewrite of OP_PHISOURCE
  unssa: try to avoid some OP_PHI copies
  unssa: eliminate trivial phisrc copies
  unssa: update comment about the unneeded copies

 unssa.c | 142 ++++++++++++++++++++++++++++++++++------------------------------
 1 file changed, 75 insertions(+), 67 deletions(-)

-- 
2.10.2