[llvm] [AMDGPU][True16][CodeGen] gisel true16 for G_Merge and ICMP (PR #128913)

[Matt Arsenault via llvm-commits]

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@@ -1478,10 +1478,17 @@ bool AMDGPUInstructionSelector::selectG_ICMP_or_FCMP(MachineInstr &I) const {
   if (Opcode == -1)
     return false;
 
-  MachineInstr *ICmp = BuildMI(*BB, &I, DL, TII.get(Opcode),
-            I.getOperand(0).getReg())
-            .add(I.getOperand(2))
-            .add(I.getOperand(3));
+  MachineInstrBuilder ICmp =
+      BuildMI(*BB, &I, DL, TII.get(Opcode), I.getOperand(0).getReg());
+  if (AMDGPU::hasNamedOperand(Opcode, AMDGPU::OpName::src0_modifiers))
+    ICmp.addImm(0);
+  ICmp.add(I.getOperand(2));
+  if (AMDGPU::hasNamedOperand(Opcode, AMDGPU::OpName::src1_modifiers))
+    ICmp.addImm(0);
+  ICmp.add(I.getOperand(3));
+  if (AMDGPU::hasNamedOperand(Opcode, AMDGPU::OpName::op_sel))
+    ICmp.addImm(0); // op_sel
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arsenm wrote:

This is pretty ugly. Can you just two do complete BuildMIs for the has/has not case? 

https://github.com/llvm/llvm-project/pull/128913