Using UNSPEC for vector compare to mask register.

Using UNSPEC for vector compare to mask register.

For rtx like (eq:HI (V8SI 90) (V8SI 91)), cse will take it as a
boolean value and try to do some optimization. But it is not true for
vector compare, also other places in rtl passes hold the same
assumption.

2020-07-20  Hongtao Liu  <hongtao.liu@intel.com>

gcc/
	PR target/96243
	* config/i386/i386-expand.c (ix86_expand_sse_cmp): Refine for
	maskcmp.
	(ix86_expand_mask_vec_cmp): Change prototype.
	* config/i386/i386-protos.h (ix86_expand_mask_vec_cmp): Change prototype.
	* config/i386/i386.c (ix86_print_operand): Remove operand
	modifier 'I'.
	* config/i386/sse.md
	(*<avx512>_cmp<mode>3<mask_scalar_merge_name><round_saeonly_name>): Deleted.
	(*<avx512>_cmp<mode>3<mask_scalar_merge_name>): Ditto.
	(*<avx512>_ucmp<mode>3<mask_scalar_merge_name>): Ditto.
	(*<avx512>_ucmp<mode>3<mask_scalar_merge_name>,
	avx512f_maskcmp<mode>3): Ditto.

gcc/testsuite
	* gcc.target/i386/pr92865-1.c: Adjust testcase.