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decode/arithmetic_half: Fix HADD2 and HMUL2 absolute and negation bits

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The encoding for negation and absolute value was wrong.
Extracting is now done manually. Similar instructions having different
encodings is the rule, not the exception. To keep sanity and readability
I preferred to extract the desired bit manually.

This is implemented against nxas:
8dbc389957/table.h (L68)

That is itself tested against nvdisasm (Nvidia's official disassembler).
This commit is contained in:
ReinUsesLisp 2020-04-20 03:24:00 -03:00
parent 4d7d3651f3
commit dbaebd8582
2 changed files with 37 additions and 16 deletions
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2
src/video_core/engines/shader_bytecode.h
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@ -817,11 +817,9 @@ union Instruction {
BitField<32, 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;
BitField<31, 1, u64> negate_b;
BitField<30, 1, u64> abs_b;
BitField<28, 2, HalfType> type_b;

51
src/video_core/shader/decode/arithmetic_half.cpp
View file

@ -19,22 +19,46 @@ u32 ShaderIR::DecodeArithmeticHalf(NodeBlock& bb, u32 pc) {
const Instruction instr = {program_code[pc]};
const auto opcode = OpCode::Decode(instr);
if (opcode->get().GetId() == OpCode::Id::HADD2_C ||
opcode->get().GetId() == OpCode::Id::HADD2_R) {
bool negate_a = false;
bool negate_b = false;
bool absolute_a = false;
bool absolute_b = false;
switch (opcode->get().GetId()) {
case OpCode::Id::HADD2_R:
if (instr.alu_half.ftz == 0) {
LOG_DEBUG(HW_GPU, "{} without FTZ is not implemented", opcode->get().GetName());
}
negate_a = ((instr.value >> 43) & 1) != 0;
negate_b = ((instr.value >> 31) & 1) != 0;
absolute_a = ((instr.value >> 44) & 1) != 0;
absolute_b = ((instr.value >> 30) & 1) != 0;
break;
case OpCode::Id::HADD2_C:
if (instr.alu_half.ftz == 0) {
LOG_DEBUG(HW_GPU, "{} without FTZ is not implemented", opcode->get().GetName());
}
negate_a = ((instr.value >> 43) & 1) != 0;
negate_b = ((instr.value >> 56) & 1) != 0;
absolute_a = ((instr.value >> 44) & 1) != 0;
absolute_b = ((instr.value >> 54) & 1) != 0;
break;
case OpCode::Id::HMUL2_R:
negate_a = ((instr.value >> 43) & 1) != 0;
absolute_a = ((instr.value >> 44) & 1) != 0;
absolute_b = ((instr.value >> 30) & 1) != 0;
break;
case OpCode::Id::HMUL2_C:
negate_b = ((instr.value >> 31) & 1) != 0;
absolute_a = ((instr.value >> 44) & 1) != 0;
absolute_b = ((instr.value >> 54) & 1) != 0;
break;
}
const bool negate_a =
opcode->get().GetId() != OpCode::Id::HMUL2_R && instr.alu_half.negate_a != 0;
const bool negate_b =
opcode->get().GetId() != OpCode::Id::HMUL2_C && instr.alu_half.negate_b != 0;
Node op_a = UnpackHalfFloat(GetRegister(instr.gpr8), instr.alu_half.type_a);
op_a = GetOperandAbsNegHalf(op_a, instr.alu_half.abs_a, negate_a);
op_a = GetOperandAbsNegHalf(op_a, absolute_a, negate_a);
auto [type_b, op_b] = [&]() -> std::tuple<HalfType, Node> {
auto [type_b, op_b] = [this, instr, opcode]() -> std::pair<HalfType, Node> {
switch (opcode->get().GetId()) {
case OpCode::Id::HADD2_C:
case OpCode::Id::HMUL2_C:
@ -48,17 +72,16 @@ u32 ShaderIR::DecodeArithmeticHalf(NodeBlock& bb, u32 pc) {
}
}();
op_b = UnpackHalfFloat(op_b, type_b);
// redeclaration to avoid a bug in clang with reusing local bindings in lambdas
Node op_b_alt = GetOperandAbsNegHalf(op_b, instr.alu_half.abs_b, negate_b);
op_b = GetOperandAbsNegHalf(op_b, absolute_b, negate_b);
Node value = [&]() {
Node value = [this, opcode, op_a, op_b = op_b] {
switch (opcode->get().GetId()) {
case OpCode::Id::HADD2_C:
case OpCode::Id::HADD2_R:
return Operation(OperationCode::HAdd, PRECISE, op_a, op_b_alt);
return Operation(OperationCode::HAdd, PRECISE, op_a, op_b);
case OpCode::Id::HMUL2_C:
case OpCode::Id::HMUL2_R:
return Operation(OperationCode::HMul, PRECISE, op_a, op_b_alt);
return Operation(OperationCode::HMul, PRECISE, op_a, op_b);
default:
UNIMPLEMENTED_MSG("Unhandled half float instruction: {}", opcode->get().GetName());
return Immediate(0);