gl_shader_decompiler: Implement HADD2_IMM and HMUL2_IMM

src/video_core/engines/shader_bytecode.h

@@ -589,6 +589,31 @@ union Instruction {
         BitField<35, 2, HalfType> type_c;
     } alu_half;
 
+    union {
+        BitField<39, 2, HalfPrecision> precision;
+        BitField<39, 1, u64> ftz;
+        BitField<52, 1, u64> saturate;
+        BitField<49, 2, HalfMerge> merge;
+
+        BitField<43, 1, u64> negate_a;
+        BitField<44, 1, u64> abs_a;
+        BitField<47, 2, HalfType> type_a;
+    } alu_half_imm;
+
+    union {
+        BitField<29, 1, u64> first_negate;
+        BitField<20, 9, u64> first;
+
+        BitField<56, 1, u64> second_negate;
+        BitField<30, 9, u64> second;
+
+        u32 PackImmediates() const {
+            // Immediates are half floats shifted.
+            constexpr u32 imm_shift = 6;
+            return static_cast<u32>((first << imm_shift) | (second << (16 + imm_shift)));
+        }
+    } half_imm;
+
     union {
         BitField<40, 1, u64> invert;
     } popc;
@@ -1183,8 +1208,10 @@ public:
         LEA_HI,
         HADD2_C,
         HADD2_R,
+        HADD2_IMM,
         HMUL2_C,
         HMUL2_R,
+        HMUL2_IMM,
         POPC_C,
         POPC_R,
         POPC_IMM,
@@ -1259,6 +1286,7 @@ public:
         ArithmeticInteger,
         ArithmeticIntegerImmediate,
         ArithmeticHalf,
+        ArithmeticHalfImmediate,
         Bfe,
         Shift,
         Ffma,
@@ -1432,8 +1460,10 @@ private:
             INST("00011000--------", Id::LEA_HI, Type::ArithmeticInteger, "LEA_HI"),
             INST("0111101-1-------", Id::HADD2_C, Type::ArithmeticHalf, "HADD2_C"),
             INST("0101110100010---", Id::HADD2_R, Type::ArithmeticHalf, "HADD2_R"),
+            INST("0111101-0-------", Id::HADD2_IMM, Type::ArithmeticHalfImmediate, "HADD2_IMM"),
             INST("0111100-1-------", Id::HMUL2_C, Type::ArithmeticHalf, "HMUL2_C"),
             INST("0101110100001---", Id::HMUL2_R, Type::ArithmeticHalf, "HMUL2_R"),
+            INST("0111100-0-------", Id::HMUL2_IMM, Type::ArithmeticHalfImmediate, "HMUL2_IMM"),
             INST("0101000010000---", Id::MUFU, Type::Arithmetic, "MUFU"),
             INST("0100110010010---", Id::RRO_C, Type::Arithmetic, "RRO_C"),
             INST("0101110010010---", Id::RRO_R, Type::Arithmetic, "RRO_R"),

src/video_core/renderer_opengl/gl_shader_decompiler.cpp

@@ -920,6 +920,19 @@ private:
         return fmt::format("uintBitsToFloat({})", instr.alu.GetImm20_32());
     }
 
+    /// Generates code representing a vec2 pair unpacked from a half float immediate
+    static std::string UnpackHalfImmediate(const Instruction& instr, bool negate) {
+        const std::string immediate = GetHalfFloat(std::to_string(instr.half_imm.PackImmediates()));
+        if (!negate) {
+            return immediate;
+        }
+        const std::string negate_first = instr.half_imm.first_negate != 0 ? "-" : "";
+        const std::string negate_second = instr.half_imm.second_negate != 0 ? "-" : "";
+        const std::string negate_vec = "vec2(" + negate_first + "1, " + negate_second + "1)";
+
+        return '(' + immediate + " * " + negate_vec + ')';
+    }
+
     /// Generates code representing a texture sampler.
     std::string GetSampler(const Sampler& sampler, Tegra::Shader::TextureType type, bool is_array,
                            bool is_shadow) {
@@ -1877,6 +1890,36 @@ private:
                                         instr.alu_half.saturate != 0);
             break;
         }
+        case OpCode::Type::ArithmeticHalfImmediate: {
+            if (opcode->GetId() == OpCode::Id::HADD2_IMM) {
+                ASSERT_MSG(instr.alu_half_imm.ftz == 0, "Unimplemented");
+            } else {
+                ASSERT_MSG(instr.alu_half_imm.precision == Tegra::Shader::HalfPrecision::None,
+                           "Unimplemented");
+            }
+
+            const std::string op_a = GetHalfFloat(
+                regs.GetRegisterAsInteger(instr.gpr8, 0, false), instr.alu_half_imm.type_a,
+                instr.alu_half_imm.abs_a != 0, instr.alu_half_imm.negate_a != 0);
+
+            const std::string op_b = UnpackHalfImmediate(instr, true);
+
+            const std::string result = [&]() {
+                switch (opcode->GetId()) {
+                case OpCode::Id::HADD2_IMM:
+                    return op_a + " + " + op_b;
+                case OpCode::Id::HMUL2_IMM:
+                    return op_a + " * " + op_b;
+                default:
+                    UNREACHABLE();
+                    return std::string("0");
+                }
+            }();
+
+            regs.SetRegisterToHalfFloat(instr.gpr0, 0, result, instr.alu_half_imm.merge, 1, 1,
+                                        instr.alu_half_imm.saturate != 0);
+            break;
+        }
         case OpCode::Type::Ffma: {
             const std::string op_a = regs.GetRegisterAsFloat(instr.gpr8);
             std::string op_b = instr.ffma.negate_b ? "-" : "";