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// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <map>
#include <set>
#include <string>
#include "common/assert.h"
#include "common/common_types.h"
#include "video_core/engines/shader_bytecode.h"
#include "video_core/renderer_opengl/gl_shader_decompiler.h"
namespace Tegra {
namespace Shader {
namespace Decompiler {
constexpr u32 PROGRAM_END = MAX_PROGRAM_CODE_LENGTH;
class DecompileFail : public std::runtime_error {
public:
using std::runtime_error::runtime_error;
};
/// Describes the behaviour of code path of a given entry point and a return point.
enum class ExitMethod {
Undetermined, ///< Internal value. Only occur when analyzing JMP loop.
AlwaysReturn, ///< All code paths reach the return point.
Conditional, ///< Code path reaches the return point or an END instruction conditionally.
AlwaysEnd, ///< All code paths reach a END instruction.
};
/// A subroutine is a range of code refereced by a CALL, IF or LOOP instruction.
struct Subroutine {
/// Generates a name suitable for GLSL source code.
std::string GetName() const {
return "sub_" + std::to_string(begin) + "_" + std::to_string(end);
}
u32 begin; ///< Entry point of the subroutine.
u32 end; ///< Return point of the subroutine.
ExitMethod exit_method; ///< Exit method of the subroutine.
std::set<u32> labels; ///< Addresses refereced by JMP instructions.
bool operator<(const Subroutine& rhs) const {
return std::tie(begin, end) < std::tie(rhs.begin, rhs.end);
}
};
/// Analyzes shader code and produces a set of subroutines.
class ControlFlowAnalyzer {
public:
ControlFlowAnalyzer(const ProgramCode& program_code, u32 main_offset)
: program_code(program_code) {
// Recursively finds all subroutines.
const Subroutine& program_main = AddSubroutine(main_offset, PROGRAM_END);
if (program_main.exit_method != ExitMethod::AlwaysEnd)
throw DecompileFail("Program does not always end");
}
std::set<Subroutine> GetSubroutines() {
return std::move(subroutines);
}
private:
const ProgramCode& program_code;
std::set<Subroutine> subroutines;
std::map<std::pair<u32, u32>, ExitMethod> exit_method_map;
/// Adds and analyzes a new subroutine if it is not added yet.
const Subroutine& AddSubroutine(u32 begin, u32 end) {
auto iter = subroutines.find(Subroutine{begin, end});
if (iter != subroutines.end())
return *iter;
Subroutine subroutine{begin, end};
subroutine.exit_method = Scan(begin, end, subroutine.labels);
if (subroutine.exit_method == ExitMethod::Undetermined)
throw DecompileFail("Recursive function detected");
return *subroutines.insert(std::move(subroutine)).first;
}
/// Scans a range of code for labels and determines the exit method.
ExitMethod Scan(u32 begin, u32 end, std::set<u32>& labels) {
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 != PROGRAM_END; ++offset) {
const Instruction instr = {program_code[offset]};
switch (instr.opcode.Value().EffectiveOpCode()) {
case OpCode::Id::EXIT: {
return exit_method = ExitMethod::AlwaysEnd;
}
}
}
return exit_method = ExitMethod::AlwaysReturn;
}
};
class ShaderWriter {
public:
void AddLine(const std::string& text) {
DEBUG_ASSERT(scope >= 0);
if (!text.empty()) {
shader_source += std::string(static_cast<size_t>(scope) * 4, ' ');
}
shader_source += text + '\n';
}
std::string GetResult() {
return std::move(shader_source);
}
int scope = 0;
private:
std::string shader_source;
};
class GLSLGenerator {
public:
GLSLGenerator(const std::set<Subroutine>& subroutines, const ProgramCode& program_code,
u32 main_offset)
: subroutines(subroutines), program_code(program_code), main_offset(main_offset) {
Generate();
}
std::string GetShaderCode() {
return shader.GetResult();
}
private:
const std::set<Subroutine>& subroutines;
const ProgramCode& program_code;
const u32 main_offset;
ShaderWriter shader;
void Generate() {}
};
boost::optional<std::string> DecompileProgram(const ProgramCode& program_code, u32 main_offset) {
try {
auto subroutines = ControlFlowAnalyzer(program_code, main_offset).GetSubroutines();
GLSLGenerator generator(subroutines, program_code, main_offset);
return generator.GetShaderCode();
} catch (const DecompileFail& exception) {
LOG_ERROR(HW_GPU, "Shader decompilation failed: %s", exception.what());
}
return boost::none;
}
} // namespace Decompiler
} // namespace Shader
} // namespace Tegra
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