re PR lto/66752 (spec2000 255.vortex performance compiled with GCC is ~20% lower...

re PR lto/66752 (spec2000 255.vortex performance compiled with GCC is ~20% lower than with CLANG)

	PR lto/66752
	* tree-ssa-threadedge.c (simplify_conrol_stmt_condition): If we are
	unable to find X NE 0 in the tables, return X as the simplified
	condition.
	(fsm_find_control_statement_thread_paths): If nodes in NEXT_PATH are
	in VISISTED_BBS, then return failure.  Else add nodes from NEXT_PATH
	to VISISTED_BBS.  */
	* tree-ssa-threadupdate.c (duplicate_thread_path): Fix up edge flags
	after removing the control flow statement and unnecessary edges.

testsuite/
	PR lto/66752
	* gcc.dg/tree-ssa/pr66752-2.c: New test.
	* gcc.dg/torture/pr66752-1.c: New test
	* g++.dg/torture/pr66752-2.C: New test.

From-SVN: r226125