[49/77] Simplify nonzero/num_sign_bits hooks

The two implementations of the reg_nonzero_bits and reg_num_sign_bits
hooks ignored the "known_x", "known_mode" and "known_ret" arguments,
so this patch removes them.  It adds a new scalar_int_mode parameter
that specifies the mode of "x".  (This mode might be different from
"mode", which is the mode in which "x" is used.)

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* rtl.h (rtl_hooks::reg_nonzero_bits): Add a scalar_int_mode
	parameter for the mode of "x".  Remove the "known_x", "known_mode"
	and "known_ret" arguments.  Change the type of the mode argument
	to scalar_int_mode.
	(rtl_hooks:reg_num_sign_bit_copies): Likewise.
	* combine.c (reg_nonzero_bits_for_combine): Update accordingly.
	(reg_num_sign_bit_copies_for_combine): Likewise.
	* rtlanal.c (nonzero_bits1): Likewise.
	(num_sign_bit_copies1): Likewise.
	* rtlhooks-def.h (reg_nonzero_bits_general): Likewise.
	(reg_num_sign_bit_copies_general): Likewise.
	* rtlhooks.c (reg_num_sign_bit_copies_general): Likewise.
	(reg_nonzero_bits_general): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r251501