[Patch,tree-optimization]: Add new path Splitting pass on tree ssa

[Patch,tree-optimization]: Add new path Splitting pass on tree ssa
representation

	* Makefile.in (OBJS): Add gimple-ssa-split-paths.o
	* common.opt (-fsplit-paths): New flag controlling path splitting.
	* doc/invoke.texi (fsplit-paths): Document.
	* opts.c (default_options_table): Add -fsplit-paths to -O2.
	* passes.def: Add split_paths pass.
	* timevar.def (TV_SPLIT_PATHS): New timevar.
	* tracer.c: Include "tracer.h"
	(ignore_bb_p): No longer static.
	(transform_duplicate): New function, broken out of tail_duplicate.
	(tail_duplicate): Use transform_duplicate.
	* tracer.h (ignore_bb_p): Declare
	(transform_duplicate): Likewise.
	* tree-pass.h (make_pass_split_paths): Declare.
	* gimple-ssa-split-paths.c: New file.

	* gcc.dg/tree-ssa/split-path-1.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@230364 138bc75d-0d04-0410-961f-82ee72b054a4