shader: implement RDNA2 frexp mantissa

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

@@ -567,6 +567,7 @@ std::string OpcodeToString(Opcode opcode) {
 		case Opcode::VCvtRpiI32F32: return "v_cvt_rpi_i32_f32";
 		case Opcode::VCvtFlrI32F32: return "v_cvt_flr_i32_f32";
 		case Opcode::VFrexpExpI32F32: return "v_frexp_exp_i32_f32";
+		case Opcode::VFrexpMantF32: return "v_frexp_mant_f32";
 		case Opcode::VCvtOffF32I4: return "v_cvt_off_f32_i4";
 		case Opcode::VCvtF32Ubyte0: return "v_cvt_f32_ubyte0";
 		case Opcode::VCvtF32Ubyte1: return "v_cvt_f32_ubyte1";

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

@@ -152,6 +152,7 @@ enum class Opcode {
 	VCvtRpiI32F32,
 	VCvtFlrI32F32,
 	VFrexpExpI32F32,
+	VFrexpMantF32,
 	VCvtOffF32I4,
 	VCvtF32Ubyte0,
 	VCvtF32Ubyte1,

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

@@ -121,6 +121,7 @@ constexpr OpcodeMap VOP1_OPCODE_LIST[] = {
     {0x39u, Opcode::VFfbhU32},
     {0x3au, Opcode::VFfblB32},
     {0x3fu, Opcode::VFrexpExpI32F32},
+    {0x40u, Opcode::VFrexpMantF32},
     {0x42u, Opcode::VMovreldB32},
     {0x43u, Opcode::VMovrelsB32},
     {0x50u, Opcode::VCvtF16U16},
@@ -170,6 +171,7 @@ constexpr OpcodeMap VOP3_ENCODED_VOP1_OPCODE_LIST[] = {
     {0x39u, Opcode::VFfbhU32},
     {0x3au, Opcode::VFfblB32},
     {0x3fu, Opcode::VFrexpExpI32F32},
+    {0x40u, Opcode::VFrexpMantF32},
     {0x42u, Opcode::VMovreldB32},
     {0x43u, Opcode::VMovrelsB32},
     {0x50u, Opcode::VCvtF16U16},
@@ -413,6 +415,7 @@ bool IsVop1FloatSourceOpcode(Opcode opcode) {
 		case Opcode::VCvtRpiI32F32:
 		case Opcode::VCvtFlrI32F32:
 		case Opcode::VFrexpExpI32F32:
+		case Opcode::VFrexpMantF32:
 		case Opcode::VCvtF16F32:
 		case Opcode::VRcpF32:
 		case Opcode::VRcpIflagF32:
@@ -767,6 +770,7 @@ bool IsVop1FloatResultOpcode(Opcode opcode) {
 		case Opcode::VCeilF32:
 		case Opcode::VRndneF32:
 		case Opcode::VFloorF32:
+		case Opcode::VFrexpMantF32:
 		case Opcode::VExpF32:
 		case Opcode::VLogF32:
 		case Opcode::VRsqF32:

src/graphics/shader/recompiler/frontend/translate/Float.cpp

@@ -93,6 +93,26 @@ bool Translator::TranslateFloat16Operation(const IR::Instruction& inst) {
 }
 
 bool Translator::TranslateFloatOperation(const IR::Instruction& inst) {
+	if (inst.op == IR::Opcode::FrexpMantF32) {
+		const auto bits     = ReadU32(inst.src[0]);
+		const auto exponent = IR::U32(
+		    ir.Emit(IR::ValueOpcode::BitFieldUExtract, {bits, IR::Value(23u), IR::Value(8u)}));
+		const auto mantissa = ir.BitwiseAnd(bits, IR::U32(IR::Value(0x007fffffu)));
+		const auto sign     = ir.BitwiseAnd(bits, IR::U32(IR::Value(0x80000000u)));
+		const auto base     = ir.BitwiseOr(sign, IR::U32(IR::Value(0x3f000000u)));
+		const auto normal   = ir.BitwiseOr(base, mantissa);
+		const auto msb      = IR::U32(ir.Emit(IR::ValueOpcode::FindUMsb32, {mantissa}));
+		const auto shift    = ir.ISub(IR::U32(IR::Value(23u)), msb);
+		const auto fraction =
+		    ir.BitwiseAnd(ir.ShiftLeftLogical(mantissa, shift), IR::U32(IR::Value(0x007fffffu)));
+		const auto subnormal = ir.BitwiseOr(base, fraction);
+		const auto zero      = ir.IEqual(mantissa, IR::U32(IR::Value(0u)));
+		const auto finite    = ir.Select(ir.INotEqual(exponent, IR::U32(IR::Value(0u))), normal,
+		                                 ir.Select(zero, bits, subnormal));
+		const auto result = ir.Select(ir.IEqual(exponent, IR::U32(IR::Value(0xffu))), bits, finite);
+		WriteOperand(inst.dst, ir.BitCastF32(result));
+		return true;
+	}
 	IR::ValueOpcode opcode {};
 	switch (inst.op) {
 		case IR::Opcode::RcpF32: opcode = IR::ValueOpcode::FPRecip32; break;

src/graphics/shader/recompiler/ir/opcodes/ShaderIROpcodes.cpp

@@ -104,6 +104,7 @@ constexpr LowerMap LOWER_OPS[] = {
     {Decoder::Opcode::VCvtRpiI32F32, Opcode::ConvertRoundPlusInfF32ToI32},
     {Decoder::Opcode::VCvtFlrI32F32, Opcode::ConvertFloorF32ToI32},
     {Decoder::Opcode::VFrexpExpI32F32, Opcode::FrexpExpI32F32},
+    {Decoder::Opcode::VFrexpMantF32, Opcode::FrexpMantF32},
     {Decoder::Opcode::VCvtOffF32I4, Opcode::ConvertI4ToOffsetF32},
     {Decoder::Opcode::VRcpF32, Opcode::RcpF32},
     {Decoder::Opcode::VRcpIflagF32, Opcode::RcpIflagF32},

src/graphics/shader/recompiler/ir/opcodes/ShaderIROpcodes.inc

@@ -214,6 +214,7 @@ IR_OPCODE(ConvertF16ToI16, General, Conversion)
 IR_OPCODE(ConvertRoundPlusInfF32ToI32, General, Conversion)
 IR_OPCODE(ConvertFloorF32ToI32, General, Conversion)
 IR_OPCODE(FrexpExpI32F32, General, Conversion)
+IR_OPCODE(FrexpMantF32, General, Float)
 IR_OPCODE(ConvertI4ToOffsetF32, General, Conversion)
 IR_OPCODE(LdexpF32, General, Float)
 IR_OPCODE(PackF32ToF16Rtz, General, Conversion)