[llvm] [AMDGPU] Add regbankselect rules for G_ADD/SUB and variants (PR #159860)

[Anshil Gandhi via llvm-commits]

================
@@ -470,7 +470,20 @@ RegBankLegalizeRules::RegBankLegalizeRules(const GCNSubtarget &_ST,
       .Uni(S16, {{Sgpr32Trunc}, {Sgpr32AExt, Sgpr32AExt}})
       .Div(S16, {{Vgpr16}, {Vgpr16, Vgpr16}})
       .Uni(S32, {{Sgpr32}, {Sgpr32, Sgpr32}})
-      .Div(S32, {{Vgpr32}, {Vgpr32, Vgpr32}});
+      .Div(S32, {{Vgpr32}, {Vgpr32, Vgpr32}})
+      .Uni(V2S16, {{SgprV2S16}, {SgprV2S16, SgprV2S16}})
----------------
gandhi56 wrote:

Added `ScalarizeV2S16` mapping rule.

https://github.com/llvm/llvm-project/pull/159860