[X86] Add missing subvector_subreg_lowering for BF16 (#83720)

Author: phoebewang

llvm/lib/Target/X86/X86InstrVecCompiler.td

@@ -83,6 +83,7 @@ defm : subvector_subreg_lowering<VR128, v2f64, VR256, v4f64,  sub_xmm>;
 defm : subvector_subreg_lowering<VR128, v8i16, VR256, v16i16, sub_xmm>;
 defm : subvector_subreg_lowering<VR128, v16i8, VR256, v32i8,  sub_xmm>;
 defm : subvector_subreg_lowering<VR128, v8f16, VR256, v16f16, sub_xmm>;
+defm : subvector_subreg_lowering<VR128, v8bf16, VR256, v16bf16, sub_xmm>;
 
 // A 128-bit subvector extract from the first 512-bit vector position is a
 // subregister copy that needs no instruction. Likewise, a 128-bit subvector
@@ -95,6 +96,7 @@ defm : subvector_subreg_lowering<VR128, v2f64, VR512, v8f64,  sub_xmm>;
 defm : subvector_subreg_lowering<VR128, v8i16, VR512, v32i16, sub_xmm>;
 defm : subvector_subreg_lowering<VR128, v16i8, VR512, v64i8,  sub_xmm>;
 defm : subvector_subreg_lowering<VR128, v8f16, VR512, v32f16, sub_xmm>;
+defm : subvector_subreg_lowering<VR128, v8bf16, VR512, v32bf16, sub_xmm>;
 
 // A 128-bit subvector extract from the first 512-bit vector position is a
 // subregister copy that needs no instruction. Likewise, a 128-bit subvector
@@ -107,6 +109,7 @@ defm : subvector_subreg_lowering<VR256, v4f64,  VR512, v8f64,  sub_ymm>;
 defm : subvector_subreg_lowering<VR256, v16i16, VR512, v32i16, sub_ymm>;
 defm : subvector_subreg_lowering<VR256, v32i8,  VR512, v64i8,  sub_ymm>;
 defm : subvector_subreg_lowering<VR256, v16f16, VR512, v32f16, sub_ymm>;
+defm : subvector_subreg_lowering<VR256, v16bf16, VR512, v32bf16, sub_ymm>;
 
 
 // If we're inserting into an all zeros vector, just use a plain move which

llvm/test/CodeGen/X86/avx512bf16-vl-intrinsics.ll

@@ -381,3 +381,25 @@ entry:
   %1 = shufflevector <8 x bfloat> %0, <8 x bfloat> undef, <16 x i32> zeroinitializer
   ret <16 x bfloat> %1
 }
+
+define <16 x i32> @pr83358() {
+; X86-LABEL: pr83358:
+; X86:       # %bb.0:
+; X86-NEXT:    vcvtneps2bf16y {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0 # encoding: [0x62,0xf2,0x7e,0x28,0x72,0x05,A,A,A,A]
+; X86-NEXT:    # fixup A - offset: 6, value: {{\.?LCPI[0-9]+_[0-9]+}}, kind: FK_Data_4
+; X86-NEXT:    vshufi64x2 $0, %zmm0, %zmm0, %zmm0 # encoding: [0x62,0xf3,0xfd,0x48,0x43,0xc0,0x00]
+; X86-NEXT:    # zmm0 = zmm0[0,1,0,1,0,1,0,1]
+; X86-NEXT:    retl # encoding: [0xc3]
+;
+; X64-LABEL: pr83358:
+; X64:       # %bb.0:
+; X64-NEXT:    vcvtneps2bf16y {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0 # encoding: [0x62,0xf2,0x7e,0x28,0x72,0x05,A,A,A,A]
+; X64-NEXT:    # fixup A - offset: 6, value: {{\.?LCPI[0-9]+_[0-9]+}}-4, kind: reloc_riprel_4byte
+; X64-NEXT:    vshufi64x2 $0, %zmm0, %zmm0, %zmm0 # encoding: [0x62,0xf3,0xfd,0x48,0x43,0xc0,0x00]
+; X64-NEXT:    # zmm0 = zmm0[0,1,0,1,0,1,0,1]
+; X64-NEXT:    retq # encoding: [0xc3]
+  %1 = call <8 x bfloat> @llvm.x86.avx512bf16.cvtneps2bf16.256(<8 x float> <float 1.000000e+00, float 2.000000e+00, float 3.000000e+00, float 4.000000e+00, float 5.000000e+00, float 6.000000e+00, float 7.000000e+00, float 8.000000e+00>)
+  %2 = bitcast <8 x bfloat> %1 to <4 x i32>
+  %3 = shufflevector <4 x i32> %2, <4 x i32> undef, <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3>
+  ret <16 x i32> %3
+}

llvm/test/CodeGen/X86/bfloat.ll

@@ -2423,7 +2423,6 @@ define <16 x bfloat> @fptrunc_v16f32(<16 x float> %a) nounwind {
 ; AVXNC-LABEL: fptrunc_v16f32:
 ; AVXNC:       # %bb.0:
 ; AVXNC-NEXT:    {vex} vcvtneps2bf16 %ymm0, %xmm0
-; AVXNC-NEXT:    vinsertf128 $0, %xmm0, %ymm0, %ymm0
 ; AVXNC-NEXT:    {vex} vcvtneps2bf16 %ymm1, %xmm1
 ; AVXNC-NEXT:    vinsertf128 $1, %xmm1, %ymm0, %ymm0
 ; AVXNC-NEXT:    retq