[llvm] [AMDGPU] selecting v_sat_pk instruction, version 2 (PR #123297)

[via llvm-commits]

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@@ -816,6 +816,14 @@ SITargetLowering::SITargetLowering(const TargetMachine &TM,
                          {MVT::v4f32, MVT::v8f32, MVT::v16f32, MVT::v32f32},
                          Custom);
     }
+
+    // true 16 currently unsupported
+    if (!Subtarget->hasTrue16BitInsts() || (!Subtarget->useRealTrue16Insts() ||
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Shoreshen wrote:

Hi @arsenm , the true 16 is not supported since it has 4 operands. If a sub target uses true 16 and we convert the truncssat_u, the selection will fail since no pattern will fit it.

https://github.com/llvm/llvm-project/pull/123297