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Diffstat (limited to '')
| -rw-r--r-- | src/video_core/shader/decode.cpp | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/src/video_core/shader/decode.cpp b/src/video_core/shader/decode.cpp new file mode 100644 index 000000000..c973328ab --- /dev/null +++ b/src/video_core/shader/decode.cpp @@ -0,0 +1,199 @@ +// Copyright 2018 yuzu Emulator Project +// Licensed under GPLv2 or any later version +// Refer to the license.txt file included. + +#include <cstring> +#include <set> + +#include <fmt/format.h> + +#include "common/common_types.h" +#include "video_core/engines/shader_bytecode.h" +#include "video_core/engines/shader_header.h" +#include "video_core/shader/shader_ir.h" + +namespace VideoCommon::Shader { + +using Tegra::Shader::Instruction; +using Tegra::Shader::OpCode; + +/// Merges exit method of two parallel branches. +constexpr ExitMethod ParallelExit(ExitMethod a, ExitMethod b) { + if (a == ExitMethod::Undetermined) { + return b; + } + if (b == ExitMethod::Undetermined) { + return a; + } + if (a == b) { + return a; + } + return ExitMethod::Conditional; +} + +/** + * Returns whether the instruction at the specified offset is a 'sched' instruction. + * Sched instructions always appear before a sequence of 3 instructions. + */ +constexpr bool IsSchedInstruction(u32 offset, u32 main_offset) { + constexpr u32 SchedPeriod = 4; + u32 absolute_offset = offset - main_offset; + + return (absolute_offset % SchedPeriod) == 0; +} + +void ShaderIR::Decode() { + std::memcpy(&header, program_code.data(), sizeof(Tegra::Shader::Header)); + + std::set<u32> labels; + const ExitMethod exit_method = Scan(main_offset, MAX_PROGRAM_LENGTH, labels); + if (exit_method != ExitMethod::AlwaysEnd) { + UNREACHABLE_MSG("Program does not always end"); + } + + if (labels.empty()) { + basic_blocks.insert({main_offset, DecodeRange(main_offset, MAX_PROGRAM_LENGTH)}); + return; + } + + labels.insert(main_offset); + + for (const u32 label : labels) { + const auto next_it = labels.lower_bound(label + 1); + const u32 next_label = next_it == labels.end() ? MAX_PROGRAM_LENGTH : *next_it; + + basic_blocks.insert({label, DecodeRange(label, next_label)}); + } +} + +ExitMethod ShaderIR::Scan(u32 begin, u32 end, std::set<u32>& labels) { + const auto [iter, inserted] = + exit_method_map.emplace(std::make_pair(begin, end), ExitMethod::Undetermined); + ExitMethod& exit_method = iter->second; + if (!inserted) + return exit_method; + + for (u32 offset = begin; offset != end && offset != MAX_PROGRAM_LENGTH; ++offset) { + coverage_begin = std::min(coverage_begin, offset); + coverage_end = std::max(coverage_end, offset + 1); + + const Instruction instr = {program_code[offset]}; + const auto opcode = OpCode::Decode(instr); + if (!opcode) + continue; + switch (opcode->get().GetId()) { + case OpCode::Id::EXIT: { + // The EXIT instruction can be predicated, which means that the shader can conditionally + // end on this instruction. We have to consider the case where the condition is not met + // and check the exit method of that other basic block. + using Tegra::Shader::Pred; + if (instr.pred.pred_index == static_cast<u64>(Pred::UnusedIndex)) { + return exit_method = ExitMethod::AlwaysEnd; + } else { + const ExitMethod not_met = Scan(offset + 1, end, labels); + return exit_method = ParallelExit(ExitMethod::AlwaysEnd, not_met); + } + } + case OpCode::Id::BRA: { + const u32 target = offset + instr.bra.GetBranchTarget(); + labels.insert(target); + const ExitMethod no_jmp = Scan(offset + 1, end, labels); + const ExitMethod jmp = Scan(target, end, labels); + return exit_method = ParallelExit(no_jmp, jmp); + } + case OpCode::Id::SSY: + case OpCode::Id::PBK: { + // The SSY and PBK use a similar encoding as the BRA instruction. + UNIMPLEMENTED_IF_MSG(instr.bra.constant_buffer != 0, + "Constant buffer branching is not supported"); + const u32 target = offset + instr.bra.GetBranchTarget(); + labels.insert(target); + // Continue scanning for an exit method. + break; + } + } + } + return exit_method = ExitMethod::AlwaysReturn; +} + +BasicBlock ShaderIR::DecodeRange(u32 begin, u32 end) { + BasicBlock basic_block; + for (u32 pc = begin; pc < (begin > end ? MAX_PROGRAM_LENGTH : end);) { + pc = DecodeInstr(basic_block, pc); + } + return std::move(basic_block); +} + +u32 ShaderIR::DecodeInstr(BasicBlock& bb, u32 pc) { + // Ignore sched instructions when generating code. + if (IsSchedInstruction(pc, main_offset)) { + return pc + 1; + } + + const Instruction instr = {program_code[pc]}; + const auto opcode = OpCode::Decode(instr); + + // Decoding failure + if (!opcode) { + UNIMPLEMENTED_MSG("Unhandled instruction: {0:x}", instr.value); + return pc + 1; + } + + bb.push_back( + Comment(fmt::format("{}: {} (0x{:016x})", pc, opcode->get().GetName(), instr.value))); + + using Tegra::Shader::Pred; + UNIMPLEMENTED_IF_MSG(instr.pred.full_pred == Pred::NeverExecute, + "NeverExecute predicate not implemented"); + + static const std::map<OpCode::Type, u32 (ShaderIR::*)(BasicBlock & code, u32 pc)> decoders = { + {OpCode::Type::Arithmetic, &ShaderIR::DecodeArithmetic}, + {OpCode::Type::ArithmeticImmediate, &ShaderIR::DecodeArithmeticImmediate}, + {OpCode::Type::Bfe, &ShaderIR::DecodeBfe}, + {OpCode::Type::Bfi, &ShaderIR::DecodeBfi}, + {OpCode::Type::Shift, &ShaderIR::DecodeShift}, + {OpCode::Type::ArithmeticInteger, &ShaderIR::DecodeArithmeticInteger}, + {OpCode::Type::ArithmeticIntegerImmediate, &ShaderIR::DecodeArithmeticIntegerImmediate}, + {OpCode::Type::ArithmeticHalf, &ShaderIR::DecodeArithmeticHalf}, + {OpCode::Type::ArithmeticHalfImmediate, &ShaderIR::DecodeArithmeticHalfImmediate}, + {OpCode::Type::Ffma, &ShaderIR::DecodeFfma}, + {OpCode::Type::Hfma2, &ShaderIR::DecodeHfma2}, + {OpCode::Type::Conversion, &ShaderIR::DecodeConversion}, + {OpCode::Type::Memory, &ShaderIR::DecodeMemory}, + {OpCode::Type::FloatSetPredicate, &ShaderIR::DecodeFloatSetPredicate}, + {OpCode::Type::IntegerSetPredicate, &ShaderIR::DecodeIntegerSetPredicate}, + {OpCode::Type::HalfSetPredicate, &ShaderIR::DecodeHalfSetPredicate}, + {OpCode::Type::PredicateSetRegister, &ShaderIR::DecodePredicateSetRegister}, + {OpCode::Type::PredicateSetPredicate, &ShaderIR::DecodePredicateSetPredicate}, + {OpCode::Type::RegisterSetPredicate, &ShaderIR::DecodeRegisterSetPredicate}, + {OpCode::Type::FloatSet, &ShaderIR::DecodeFloatSet}, + {OpCode::Type::IntegerSet, &ShaderIR::DecodeIntegerSet}, + {OpCode::Type::HalfSet, &ShaderIR::DecodeHalfSet}, + {OpCode::Type::Xmad, &ShaderIR::DecodeXmad}, + }; + + std::vector<Node> code; + if (const auto decoder = decoders.find(opcode->get().GetType()); decoder != decoders.end()) { + pc = (this->*decoder->second)(code, pc); + } else { + pc = DecodeOther(code, pc); + } + + // Some instructions (like SSY) don't have a predicate field, they are always unconditionally + // executed. + const bool can_be_predicated = OpCode::IsPredicatedInstruction(opcode->get().GetId()); + const auto pred_index = static_cast<u32>(instr.pred.pred_index); + + if (can_be_predicated && pred_index != static_cast<u32>(Pred::UnusedIndex)) { + bb.push_back( + Conditional(GetPredicate(pred_index, instr.negate_pred != 0), std::move(code))); + } else { + for (auto& node : code) { + bb.push_back(std::move(node)); + } + } + + return pc + 1; +} + +} // namespace VideoCommon::Shader
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