revert: re PR middle-end/63155 (memory hog)

revert: re PR middle-end/63155 (memory hog)

2015-03-19  Richard Biener  <rguenther@suse.de>

	Revert
	2015-03-10  Richard Biener  <rguenther@suse.de>

	PR middle-end/63155
	* tree-ssa-coalesce.h (verify_ssa_coalescing): Declare.
	* tree-ssa-coalesce.c: Include timevar.h.
	(attempt_coalesce): Handle graph being NULL.
	(coalesce_partitions): Call verify_ssa_coalescing if ENABLE_CHECKING.
	Split out abnormal coalescing to ...
	(perform_abnormal_coalescing): ... this function.
	(coalesce_ssa_name): Perform abnormal coalescing without computing
	live/conflict.
	(verify_ssa_coalescing_worker): New function.
	(verify_ssa_coalescing): Likewise.

From-SVN: r221515