[AVX512] Bring back vector-shuffle lowering support through broadcasts

Ffter commit at rev219046 512-bit broadcasts lowering become non-optimal. Most of tests on broadcasting and embedded broadcasting were changed and they doesn’t produce efficient code.

Example below is from commit changes (it’s the first test from test/CodeGen/X86/avx512-vbroadcast.ll):

 define   <16 x i32> @_inreg16xi32(i32 %a) {
 ; CHECK-LABEL: _inreg16xi32:
 ; CHECK:       ## BB#0:
-; CHECK-NEXT:    vpbroadcastd %edi, %zmm0
+; CHECK-NEXT:    vmovd %edi, %xmm0
+; CHECK-NEXT:    vpbroadcastd %xmm0, %ymm0
+; CHECK-NEXT:    vinserti64x4 $1, %ymm0, %zmm0, %zmm0
 ; CHECK-NEXT:    retq
 %b = insertelement <16 x i32> undef, i32 %a, i32 0
 %c = shufflevector <16 x i32> %b, <16 x i32> undef, <16 x i32> zeroinitializer
 ret <16 x i32> %c
}

Here, 256-bit broadcast was generated instead of 512-bit one.

In this patch
1) I added vector-shuffle lowering through broadcasts
2) Removed asserts and branches likes because this is incorrect
-  assert(Subtarget->hasDQI() && "We can only lower v8i64 with AVX-512-DQI");
3) Fixed lowering tests

llvm-svn: 220774
diff --git a/llvm/lib/Target/X86/X86InstrAVX512.td b/llvm/lib/Target/X86/X86InstrAVX512.td
index 1d1abcf..3dbc3d2 100644
--- a/llvm/lib/Target/X86/X86InstrAVX512.td
+++ b/llvm/lib/Target/X86/X86InstrAVX512.td
@@ -711,6 +711,16 @@
 def : Pat<(v8f64 (X86VBroadcast (v2f64 VR128X:$src))),
           (VBROADCASTSDZrr VR128X:$src)>;
 
+def : Pat<(v16f32 (X86VBroadcast (v16f32 VR512:$src))),
+          (VBROADCASTSSZrr (EXTRACT_SUBREG (v16f32 VR512:$src), sub_xmm))>;
+def : Pat<(v8f64 (X86VBroadcast (v8f64 VR512:$src))),
+          (VBROADCASTSDZrr (EXTRACT_SUBREG (v8f64 VR512:$src), sub_xmm))>;
+
+def : Pat<(v16i32 (X86VBroadcast (v16i32 VR512:$src))),
+          (VPBROADCASTDZrr (EXTRACT_SUBREG (v16i32 VR512:$src), sub_xmm))>;
+def : Pat<(v8i64 (X86VBroadcast (v8i64 VR512:$src))),
+          (VPBROADCASTQZrr (EXTRACT_SUBREG (v8i64 VR512:$src), sub_xmm))>;
+
 def : Pat<(v16f32 (int_x86_avx512_vbroadcast_ss_ps_512 (v4f32 VR128X:$src))),
           (VBROADCASTSSZrr VR128X:$src)>;
 def : Pat<(v8f64 (int_x86_avx512_vbroadcast_sd_pd_512 (v2f64 VR128X:$src))),