[llvm] [AMDGPU] lower fptrunc.round(rtz) to cvt_pkrtz_f16_f32 (PR #177069)

[Brox Chen via llvm-commits]

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@@ -206,6 +207,13 @@ Status SIModeRegister::getInstructionMode(MachineInstr &MI,
       MI.setDesc(TII->get(AMDGPU::V_CVT_F32_F64_e32));
       return Status(FP_ROUND_MODE_DP(3), FP_ROUND_MODE_DP(Mode));
     }
+    case AMDGPU::FPTRUNC_ROUND_RTZ_F16_F32_PSEUDO_e32: {
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broxigarchen wrote:

I found out that I have to add a new pseudo for holding the "mode" string from the isel pattern input. If I directly map the `fptrunc.round(rtz)` to the machine inst, the isel errors out that I have a dead input dangling without being used

https://github.com/llvm/llvm-project/pull/177069