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// 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/assert.h"
#include "common/common_types.h"
#include "video_core/engines/shader_bytecode.h"
#include "video_core/engines/shader_header.h"
#include "video_core/shader/control_flow.h"
#include "video_core/shader/node_helper.h"
#include "video_core/shader/shader_ir.h"
namespace VideoCommon::Shader {
using Tegra::Shader::Instruction;
using Tegra::Shader::OpCode;
namespace {
/**
* 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;
}
} // namespace
void ShaderIR::Decode() {
std::memcpy(&header, program_code.data(), sizeof(Tegra::Shader::Header));
disable_flow_stack = false;
const auto info = ScanFlow(program_code, MAX_PROGRAM_LENGTH * sizeof(u64), main_offset);
if (info) {
const auto& shader_info = *info;
coverage_begin = shader_info.start;
coverage_end = shader_info.end;
if (shader_info.decompilable) {
disable_flow_stack = true;
const auto insert_block = ([this](NodeBlock& nodes, u32 label) {
if (label == exit_branch) {
return;
}
basic_blocks.insert({label, nodes});
});
const auto& blocks = shader_info.blocks;
NodeBlock current_block;
u32 current_label = exit_branch;
for (auto& block : blocks) {
if (shader_info.labels.count(block.start) != 0) {
insert_block(current_block, current_label);
current_block.clear();
current_label = block.start;
}
if (!block.ignore_branch) {
DecodeRangeInner(current_block, block.start, block.end);
InsertControlFlow(current_block, block);
} else {
DecodeRangeInner(current_block, block.start, block.end + 1);
}
}
insert_block(current_block, current_label);
return;
}
LOG_WARNING(HW_GPU, "Flow Stack Removing Failed! Falling back to old method");
// we can't decompile it, fallback to standard method
for (const auto& block : shader_info.blocks) {
basic_blocks.insert({block.start, DecodeRange(block.start, block.end + 1)});
}
return;
}
LOG_WARNING(HW_GPU, "Flow Analysis Failed! Falling back to brute force compiling");
// Now we need to deal with an undecompilable shader. We need to brute force
// a shader that captures every position.
coverage_begin = main_offset;
const u32 shader_end = static_cast<u32>(program_size / sizeof(u64));
coverage_end = shader_end;
for (u32 label = main_offset; label < shader_end; label++) {
basic_blocks.insert({label, DecodeRange(label, label + 1)});
}
}
NodeBlock ShaderIR::DecodeRange(u32 begin, u32 end) {
NodeBlock basic_block;
DecodeRangeInner(basic_block, begin, end);
return basic_block;
}
void ShaderIR::DecodeRangeInner(NodeBlock& bb, u32 begin, u32 end) {
for (u32 pc = begin; pc < (begin > end ? MAX_PROGRAM_LENGTH : end);) {
pc = DecodeInstr(bb, pc);
}
}
void ShaderIR::InsertControlFlow(NodeBlock& bb, const ShaderBlock& block) {
const auto apply_conditions = ([&](const Condition& cond, Node n) -> Node {
Node result = n;
if (cond.cc != ConditionCode::T) {
result = Conditional(GetConditionCode(cond.cc), {result});
}
if (cond.predicate != Pred::UnusedIndex) {
u32 pred = static_cast<u32>(cond.predicate);
const bool is_neg = pred > 7;
if (is_neg) {
pred -= 8;
}
result = Conditional(GetPredicate(pred, is_neg), {result});
}
return result;
});
if (block.branch.address < 0) {
if (block.branch.kills) {
Node n = Operation(OperationCode::Discard);
n = apply_conditions(block.branch.cond, n);
bb.push_back(n);
global_code.push_back(n);
return;
}
Node n = Operation(OperationCode::Exit);
n = apply_conditions(block.branch.cond, n);
bb.push_back(n);
global_code.push_back(n);
return;
}
Node n = Operation(OperationCode::Branch, Immediate(block.branch.address));
n = apply_conditions(block.branch.cond, n);
bb.push_back(n);
global_code.push_back(n);
}
u32 ShaderIR::DecodeInstr(NodeBlock& 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::*)(NodeBlock&, u32)> 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::Texture, &ShaderIR::DecodeTexture},
{OpCode::Type::Image, &ShaderIR::DecodeImage},
{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::Video, &ShaderIR::DecodeVideo},
{OpCode::Type::Xmad, &ShaderIR::DecodeXmad},
};
std::vector<Node> tmp_block;
if (const auto decoder = decoders.find(opcode->get().GetType()); decoder != decoders.end()) {
pc = (this->*decoder->second)(tmp_block, pc);
} else {
pc = DecodeOther(tmp_block, 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)) {
const Node conditional =
Conditional(GetPredicate(pred_index, instr.negate_pred != 0), std::move(tmp_block));
global_code.push_back(conditional);
bb.push_back(conditional);
} else {
for (auto& node : tmp_block) {
global_code.push_back(node);
bb.push_back(node);
}
}
return pc + 1;
}
} // namespace VideoCommon::Shader
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