[llvm] [LLVM][CodeGen][SVE] Implement nxvf32 fpround to nxvbf16. (PR #107420)

[Kerry McLaughlin via llvm-commits]

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@@ -87,3 +93,122 @@ define <vscale x 8 x double> @fpext_nxv8bf16_to_nxv8f64(<vscale x 8 x bfloat> %a
   %res = fpext <vscale x 8 x bfloat> %a to <vscale x 8 x double>
   ret <vscale x 8 x double> %res
 }
+
+define <vscale x 2 x bfloat> @fptrunc_nxv2f32_to_nxv2bf16(<vscale x 2 x float> %a) {
+; NOBF16-LABEL: fptrunc_nxv2f32_to_nxv2bf16:
+; NOBF16:       // %bb.0:
+; NOBF16-NEXT:    mov z1.s, #32767 // =0x7fff
+; NOBF16-NEXT:    lsr z2.s, z0.s, #16
+; NOBF16-NEXT:    ptrue p0.d
+; NOBF16-NEXT:    fcmuo p0.s, p0/z, z0.s, z0.s
+; NOBF16-NEXT:    and z2.s, z2.s, #0x1
+; NOBF16-NEXT:    add z1.s, z0.s, z1.s
+; NOBF16-NEXT:    orr z0.s, z0.s, #0x400000
+; NOBF16-NEXT:    add z1.s, z2.s, z1.s
+; NOBF16-NEXT:    sel z0.s, p0, z0.s, z1.s
+; NOBF16-NEXT:    lsr z0.s, z0.s, #16
+; NOBF16-NEXT:    ret
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kmclaughlin-arm wrote:

Are these `NOBF16` lines checked? I don't think any of the RUN lines above use this prefix but I might have missed something :)

https://github.com/llvm/llvm-project/pull/107420