re PR target/88461 (AVX512: gcc should keep value in kN registers if possible)

re PR target/88461 (AVX512: gcc should keep value in kN registers if possible)

	PR target/88461
	* config/i386/sse.md (VI1248_AVX512VLBW, AVX512ZEXTMASK): New
	mode iterators.
	(<avx512>_testm<mode>3<mask_scalar_merge_name>,
	<avx512>_testnm<mode>3<mask_scalar_merge_name>): Merge patterns
	with VI12_AVX512VL and VI48_AVX512VL iterators into ones with
	VI1248_AVX512VLBW iterator.
	(*<avx512>_testm<VI1248_AVX512VLBW:mode>3_zext,
	*<avx512>_testm<VI1248_AVX512VLBW:mode>3_zext_mask,
	*<avx512>_testnm<VI1248_AVX512VLBW:mode>3_zext,
	*<avx512>_testnm<VI1248_AVX512VLBW:mode>3_zext_mask): New
	define_insns.

	* gcc.target/i386/pr88461.c: New test.

From-SVN: r267077