shader_decode: Implement HADD2_IMM and HMUL2_IMM

src/video_core/shader/decode/arithmetic_half_immediate.cpp

@@ -16,7 +16,34 @@ u32 ShaderIR::DecodeArithmeticHalfImmediate(BasicBlock& bb, u32 pc) {
     const Instruction instr = {program_code[pc]};
     const auto opcode = OpCode::Decode(instr);
 
-    UNIMPLEMENTED();
+    if (opcode->get().GetId() == OpCode::Id::HADD2_IMM) {
+        UNIMPLEMENTED_IF(instr.alu_half_imm.ftz != 0);
+    } else {
+        UNIMPLEMENTED_IF(instr.alu_half_imm.precision != Tegra::Shader::HalfPrecision::None);
+    }
+    UNIMPLEMENTED_IF_MSG(instr.alu_half_imm.saturate != 0,
+                         "Half float immediate saturation not implemented");
+
+    Node op_a = GetRegister(instr.gpr8);
+    op_a = GetOperandAbsNegHalf(op_a, instr.alu_half_imm.abs_a, instr.alu_half_imm.negate_a);
+
+    const Node op_b = UnpackHalfImmediate(instr, true);
+
+    Node value = [&]() {
+        MetaHalfArithmetic meta{true, {instr.alu_half_imm.type_a}};
+        switch (opcode->get().GetId()) {
+        case OpCode::Id::HADD2_IMM:
+            return Operation(OperationCode::HAdd, meta, op_a, op_b);
+        case OpCode::Id::HMUL2_IMM:
+            return Operation(OperationCode::HMul, meta, op_a, op_b);
+        default:
+            UNREACHABLE();
+            return Immediate(0);
+        }
+    }();
+    value = HalfMerge(GetRegister(instr.gpr0), value, instr.alu_half_imm.merge);
+
+    SetRegister(bb, instr.gpr0, value);
 
     return pc;
 }