Avoid compile time hog on vect_peel_nonlinear_iv_init for nonlinear induction vec_step_op_mul when iteration count is too big.

There's loop in vect_peel_nonlinear_iv_init to get init_expr *
pow (step_expr, skip_niters). When skipn_iters is too big, compile time
hogs. To avoid that, optimize init_expr * pow (step_expr, skip_niters) to
init_expr << (exact_log2 (step_expr) * skip_niters) when step_expr is
pow of 2, otherwise give up vectorization when skip_niters >=
TYPE_PRECISION (TREE_TYPE (init_expr)).

Also give up vectorization when niters_skip is negative which will be
used for fully masked loop.

gcc/ChangeLog:

	PR tree-optimization/111820
	PR tree-optimization/111833
	* tree-vect-loop-manip.cc (vect_can_peel_nonlinear_iv_p): Give
	up vectorization for nonlinear iv vect_step_op_mul when
	step_expr is not exact_log2 and niters is greater than
	TYPE_PRECISION (TREE_TYPE (step_expr)). Also don't vectorize
	for nagative niters_skip which will be used by fully masked
	loop.
	(vect_can_advance_ivs_p): Pass whole phi_info to
	vect_can_peel_nonlinear_iv_p.
	* tree-vect-loop.cc (vect_peel_nonlinear_iv_init): Optimize
	init_expr * pow (step_expr, skipn) to init_expr
	<< (log2 (step_expr) * skipn) when step_expr is exact_log2.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr111820-1.c: New test.
	* gcc.target/i386/pr111820-2.c: New test.
	* gcc.target/i386/pr111820-3.c: New test.
	* gcc.target/i386/pr103144-mul-1.c: Adjust testcase.
	* gcc.target/i386/pr103144-mul-2.c: Adjust testcase.

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