shader: implement RDNA2 scalar 16-bit sign extension

src/graphics/shader/recompiler/frontend/decode/ScalarAluOps.cpp

@@ -53,6 +53,7 @@ constexpr OpcodeMap SOP1_OPCODE_LIST[] = {
     {0x14u, Opcode::S_FF1_I32_B64},
     {0x15u, Opcode::S_FLBIT_I32_B32},
     {0x16u, Opcode::S_FLBIT_I32_B64},
+    {0x1au, Opcode::S_SEXT_I32_I16},
     {0x1bu, Opcode::S_BITSET0_B32},
     {0x1cu, Opcode::S_BITSET0_B64},
     {0x1du, Opcode::S_BITSET1_B32},

src/graphics/shader/recompiler/frontend/decode/ShaderDecoder.cpp

@@ -503,6 +503,7 @@ std::string InstructionToString(const Instruction& inst) {
 			                                               OperandToString(inst.dst).c_str(),
 			                                               OperandToString(inst.src0).c_str()));
 		case Opcode::S_ABS_I32:
+		case Opcode::S_SEXT_I32_I16:
 		case Opcode::S_BREV_B32:
 		case Opcode::S_BREV_B64:
 		case Opcode::S_BCNT1_I32_B32:

src/graphics/shader/recompiler/frontend/decode/ShaderDecoder.h

@@ -45,6 +45,7 @@ enum class Opcode {
 	S_CMOV_B64,
 	S_MOVK_I32,
 	S_ABS_I32,
+	S_SEXT_I32_I16,
 	S_ABSDIFF_I32,
 	S_BREV_B32,
 	S_BREV_B64,