* tree-ssa-threadbackward.c: Include tree-inline.h
	(profitable_jump_thread_path): Use estimate_num_insns to estimate
	size of copied block; for cold paths reduce duplication.
	(find_jump_threads_backwards): Remove redundant tests.
	(pass_thread_jumps::gate): Enable for -Os.
	* gcc.dg/tree-ssa/ssa-dom-thread-7.c: Update testcase.

From-SVN: r239219