[llvm] [X86][BF16] Add X86SubVBroadcastld patterns (PR #76479)

[Phoebe Wang via llvm-commits]

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@@ -1447,6 +1447,17 @@ def : Pat<(vselect_mask VK8WM:$mask,
           (VBROADCASTI32X4Z256rmk VR256X:$src0, VK8WM:$mask, addr:$src)>;
 }
 
+let Predicates = [HasBF16] in {
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phoebewang wrote:

Because v[8,16,32]bf16 are legal only when AVX512BF16 or AVXNECONVERT features are ready.

https://github.com/llvm/llvm-project/pull/76479