i386: Fix up vec_extract_lo* patterns [PR93670]

i386: Fix up vec_extract_lo* patterns [PR93670]

The VEXTRACT* insns have way too many different CPUID feature flags (ATT
syntax)
vextractf128 $imm, %ymm, %xmm/mem		AVX
vextracti128 $imm, %ymm, %xmm/mem		AVX2
vextract{f,i}32x4 $imm, %ymm, %xmm/mem {k}{z}	AVX512VL+AVX512F
vextract{f,i}32x4 $imm, %zmm, %xmm/mem {k}{z}	AVX512F
vextract{f,i}64x2 $imm, %ymm, %xmm/mem {k}{z}	AVX512VL+AVX512DQ
vextract{f,i}64x2 $imm, %zmm, %xmm/mem {k}{z}	AVX512DQ
vextract{f,i}32x8 $imm, %zmm, %ymm/mem {k}{z}	AVX512DQ
vextract{f,i}64x4 $imm, %zmm, %ymm/mem {k}{z}	AVX512F

As the testcase shows and the patch too, we didn't get it right in all
cases.

The first hunk is about avx512vl_vextractf128v8s[if] incorrectly
requiring TARGET_AVX512DQ.  The corresponding insn is the first
vextract{f,i}32x4 above, so it requires VL+F, and the builtins have it
correct (TARGET_AVX512VL implies TARGET_AVX512F):
BDESC (OPTION_MASK_ISA_AVX512VL, 0, CODE_FOR_avx512vl_vextractf128v8sf, "__builtin_ia32_extractf32x4_256_mask", IX86_BUILTIN_EXTRACTF32X4_256, UNKNOWN, (int) V4SF_FTYPE_V8SF_INT_V4SF_UQI)
BDESC (OPTION_MASK_ISA_AVX512VL, 0, CODE_FOR_avx512vl_vextractf128v8si, "__builtin_ia32_extracti32x4_256_mask", IX86_BUILTIN_EXTRACTI32X4_256, UNKNOWN, (int) V4SI_FTYPE_V8SI_INT_V4SI_UQI)
We only need TARGET_AVX512DQ for avx512vl_vextractf128v4d[if].

The second hunk is about vec_extract_lo_v16s[if]{,_mask}.  These are using
the vextract{f,i}32x8 insns (AVX512DQ above), but we weren't requiring that,
but instead incorrectly && 1 for non-masked and && (64 == 64 && TARGET_AVX512VL)
for masked insns.  This is extraction from ZMM, so it doesn't need VL for
anything.  The hunk actually only requires TARGET_AVX512DQ when the insn
is masked, if it is not masked, when TARGET_AVX512DQ isn't available we can
use vextract{f,i}64x4 instead which is available already in TARGET_AVX512F
and does the same thing, extracts the low 256 bits from 512 bits vector
(often we split it into just nothing, but there are some special cases like
when using xmm16+ when we can't without AVX512VL).

The last hunk is about vec_extract_lo_v8s[if]{,_mask}.  The non-_mask
suffixed ones are ok already and just split into nothing (lowpart subreg).
The masked ones were incorrectly requiring TARGET_AVX512VL and
TARGET_AVX512DQ, when we only need TARGET_AVX512VL.

2020-02-12  Jakub Jelinek  <jakub@redhat.com>

	PR target/93670
	* config/i386/sse.md (VI48F_256_DQ): New mode iterator.
	(avx512vl_vextractf128<mode>): Use it instead of VI48F_256.  Remove
	TARGET_AVX512DQ from condition.
	(vec_extract_lo_<mode><mask_name>): Use <mask_avx512dq_condition>
	instead of <mask_mode512bit_condition> in condition.  If
	TARGET_AVX512DQ is false, emit vextract*64x4 instead of
	vextract*32x8.
	(vec_extract_lo_<mode><mask_name>): Drop <mask_avx512dq_condition>
	from condition.

	* gcc.target/i386/avx512vl-pr93670.c: New test.