[llvm] [AMDGPU][True16][MC] true16 for v_alignbit_b32 (PR #119409)

[Matt Arsenault via llvm-commits]

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@@ -3003,6 +3060,40 @@ def : GCNPat <
   sub1)
 >;
 
+let True16Predicate = UseFakeTrue16Insts in
+def : GCNPat <
+  (i64 (bswap i64:$a)),
+  (REG_SEQUENCE VReg_64,
+  (V_BFI_B32_e64 (S_MOV_B32 (i32 0x00ff00ff)),
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arsenm wrote:

You should be able to use `()` for an empty DAG, I think we have some instances of that in the getVOP* cases 

https://github.com/llvm/llvm-project/pull/119409