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

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Phoebe Wang (phoebewang)

<details>
<summary>Changes</summary>

Fixes: #<!-- -->83358

---
Full diff: https://github.com/llvm/llvm-project/pull/83720.diff


2 Files Affected:

- (modified) llvm/lib/Target/X86/X86InstrVecCompiler.td (+3) 
- (modified) llvm/test/CodeGen/X86/avx512bf16-vl-intrinsics.ll (+22) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86InstrVecCompiler.td b/llvm/lib/Target/X86/X86InstrVecCompiler.td
index bbd19cf8d5b25e..461b2badc13134 100644
--- a/llvm/lib/Target/X86/X86InstrVecCompiler.td
+++ b/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
diff --git a/llvm/test/CodeGen/X86/avx512bf16-vl-intrinsics.ll b/llvm/test/CodeGen/X86/avx512bf16-vl-intrinsics.ll
index 0826faa1071b01..482713e12d15c7 100644
--- a/llvm/test/CodeGen/X86/avx512bf16-vl-intrinsics.ll
+++ b/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
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/83720