Consider frequency in cost estimation when converting scalar to vector.

Consider frequency in cost estimation when converting scalar to vector.

n some benchmark, I notice stv failed due to cost unprofitable, but the igain
is inside the loop, but sse<->integer conversion is outside the loop, current cost
model doesn't consider the frequency of those gain/cost.
The patch weights those cost with frequency.

gcc/ChangeLog:

	PR target/120215
	* config/i386/i386-features.cc
	(scalar_chain::mark_dual_mode_def): Weight
	cost of integer<->sse move with bb frequency when it's
	optimized_for_speed_p.
	(general_scalar_chain::compute_convert_gain): Ditto, and
	adjust function prototype to return true/false when cost model
	is profitable or not.
	(timode_scalar_chain::compute_convert_gain): Ditto.
	(convert_scalars_to_vector): Adjust after the upper two
	function prototype are changed.
	* config/i386/i386-features.h (class scalar_chain): Change
	n_integer_to_sse/n_sse_to_integer to cost_sse_integer, and add
	weighted_cost_sse_integer.
	(class general_scalar_chain): Adjust prototype to return bool
	intead of int.
	(class timode_scalar_chain): Ditto.