re PR tree-optimization/85529 (wrong code at -O2 and -O3 on x86_64-linux-gnu)

re PR tree-optimization/85529 (wrong code at -O2 and -O3 on x86_64-linux-gnu)

	PR tree-optimization/85529
	* tree-ssa-reassoc.c (optimize_range_tests_var_bound): Add FIRST_BB
	argument.  Don't call get_nonzero_bits if opcode is ERROR_MARK_NODE,
	rhs2 def stmt's bb is dominated by first_bb and it isn't an obvious
	zero extension or masking of the MSB bit.
	(optimize_range_tests): Add FIRST_BB argument, pass it through
	to optimize_range_tests_var_bound.
	(maybe_optimize_range_tests, reassociate_bb): Adjust
	optimize_range_tests callers.

	* gcc.c-torture/execute/pr85529-1.c: New test.
	* gcc.c-torture/execute/pr85529-2.c: New test.
	* gcc.dg/pr85529.c: New test.

From-SVN: r259696