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483 lines
17 KiB
C++
483 lines
17 KiB
C++
// Copyright 2019 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <list>
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#include <map>
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#include <stack>
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#include <unordered_map>
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#include <unordered_set>
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#include <vector>
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#include "common/assert.h"
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#include "common/common_types.h"
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#include "video_core/shader/control_flow.h"
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#include "video_core/shader/shader_ir.h"
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namespace VideoCommon::Shader {
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namespace {
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using Tegra::Shader::Instruction;
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using Tegra::Shader::OpCode;
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constexpr s32 unassigned_branch = -2;
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struct Query {
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u32 address{};
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std::stack<u32> ssy_stack{};
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std::stack<u32> pbk_stack{};
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};
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struct BlockStack {
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BlockStack() = default;
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BlockStack(const BlockStack& b) = default;
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BlockStack(const Query& q) : ssy_stack{q.ssy_stack}, pbk_stack{q.pbk_stack} {}
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std::stack<u32> ssy_stack{};
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std::stack<u32> pbk_stack{};
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};
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struct BlockBranchInfo {
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Condition condition{};
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s32 address{exit_branch};
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bool kill{};
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bool is_sync{};
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bool is_brk{};
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bool ignore{};
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};
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struct BlockInfo {
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u32 start{};
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u32 end{};
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bool visited{};
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BlockBranchInfo branch{};
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bool IsInside(const u32 address) const {
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return start <= address && address <= end;
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}
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};
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struct CFGRebuildState {
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explicit CFGRebuildState(const ProgramCode& program_code, const std::size_t program_size,
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const u32 start)
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: start{start}, program_code{program_code}, program_size{program_size} {}
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u32 start{};
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std::vector<BlockInfo> block_info{};
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std::list<u32> inspect_queries{};
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std::list<Query> queries{};
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std::unordered_map<u32, u32> registered{};
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std::unordered_set<u32> labels{};
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std::map<u32, u32> ssy_labels{};
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std::map<u32, u32> pbk_labels{};
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std::unordered_map<u32, BlockStack> stacks{};
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const ProgramCode& program_code;
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const std::size_t program_size;
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};
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enum class BlockCollision : u32 { None, Found, Inside };
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std::pair<BlockCollision, u32> TryGetBlock(CFGRebuildState& state, u32 address) {
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const auto& blocks = state.block_info;
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for (u32 index = 0; index < blocks.size(); index++) {
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if (blocks[index].start == address) {
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return {BlockCollision::Found, index};
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}
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if (blocks[index].IsInside(address)) {
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return {BlockCollision::Inside, index};
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}
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}
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return {BlockCollision::None, -1};
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}
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struct ParseInfo {
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BlockBranchInfo branch_info{};
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u32 end_address{};
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};
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BlockInfo& CreateBlockInfo(CFGRebuildState& state, u32 start, u32 end) {
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auto& it = state.block_info.emplace_back();
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it.start = start;
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it.end = end;
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const u32 index = static_cast<u32>(state.block_info.size() - 1);
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state.registered.insert({start, index});
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return it;
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}
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Pred GetPredicate(u32 index, bool negated) {
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return static_cast<Pred>(index + (negated ? 8 : 0));
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}
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/**
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* Returns whether the instruction at the specified offset is a 'sched' instruction.
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* Sched instructions always appear before a sequence of 3 instructions.
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*/
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constexpr bool IsSchedInstruction(u32 offset, u32 main_offset) {
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constexpr u32 SchedPeriod = 4;
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u32 absolute_offset = offset - main_offset;
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return (absolute_offset % SchedPeriod) == 0;
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}
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enum class ParseResult : u32 {
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ControlCaught,
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BlockEnd,
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AbnormalFlow,
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};
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std::pair<ParseResult, ParseInfo> ParseCode(CFGRebuildState& state, u32 address) {
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u32 offset = static_cast<u32>(address);
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const u32 end_address = static_cast<u32>(state.program_size / sizeof(Instruction));
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ParseInfo parse_info{};
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const auto insert_label = [](CFGRebuildState& state, u32 address) {
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const auto pair = state.labels.emplace(address);
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if (pair.second) {
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state.inspect_queries.push_back(address);
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}
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};
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while (true) {
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if (offset >= end_address) {
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// ASSERT_OR_EXECUTE can't be used, as it ignores the break
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ASSERT_MSG(false, "Shader passed the current limit!");
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parse_info.branch_info.address = exit_branch;
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parse_info.branch_info.ignore = false;
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break;
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}
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if (state.registered.count(offset) != 0) {
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parse_info.branch_info.address = offset;
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parse_info.branch_info.ignore = true;
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break;
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}
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if (IsSchedInstruction(offset, state.start)) {
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offset++;
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continue;
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}
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const Instruction instr = {state.program_code[offset]};
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const auto opcode = OpCode::Decode(instr);
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if (!opcode || opcode->get().GetType() != OpCode::Type::Flow) {
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offset++;
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continue;
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}
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switch (opcode->get().GetId()) {
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case OpCode::Id::EXIT: {
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const auto pred_index = static_cast<u32>(instr.pred.pred_index);
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parse_info.branch_info.condition.predicate =
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GetPredicate(pred_index, instr.negate_pred != 0);
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if (parse_info.branch_info.condition.predicate == Pred::NeverExecute) {
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offset++;
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continue;
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}
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const ConditionCode cc = instr.flow_condition_code;
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parse_info.branch_info.condition.cc = cc;
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if (cc == ConditionCode::F) {
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offset++;
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continue;
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}
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parse_info.branch_info.address = exit_branch;
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parse_info.branch_info.kill = false;
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parse_info.branch_info.is_sync = false;
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parse_info.branch_info.is_brk = false;
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parse_info.branch_info.ignore = false;
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parse_info.end_address = offset;
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return {ParseResult::ControlCaught, parse_info};
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}
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case OpCode::Id::BRA: {
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if (instr.bra.constant_buffer != 0) {
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return {ParseResult::AbnormalFlow, parse_info};
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}
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const auto pred_index = static_cast<u32>(instr.pred.pred_index);
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parse_info.branch_info.condition.predicate =
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GetPredicate(pred_index, instr.negate_pred != 0);
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if (parse_info.branch_info.condition.predicate == Pred::NeverExecute) {
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offset++;
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continue;
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}
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const ConditionCode cc = instr.flow_condition_code;
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parse_info.branch_info.condition.cc = cc;
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if (cc == ConditionCode::F) {
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offset++;
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continue;
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}
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const u32 branch_offset = offset + instr.bra.GetBranchTarget();
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if (branch_offset == 0) {
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parse_info.branch_info.address = exit_branch;
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} else {
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parse_info.branch_info.address = branch_offset;
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}
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insert_label(state, branch_offset);
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parse_info.branch_info.kill = false;
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parse_info.branch_info.is_sync = false;
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parse_info.branch_info.is_brk = false;
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parse_info.branch_info.ignore = false;
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parse_info.end_address = offset;
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return {ParseResult::ControlCaught, parse_info};
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}
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case OpCode::Id::SYNC: {
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const auto pred_index = static_cast<u32>(instr.pred.pred_index);
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parse_info.branch_info.condition.predicate =
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GetPredicate(pred_index, instr.negate_pred != 0);
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if (parse_info.branch_info.condition.predicate == Pred::NeverExecute) {
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offset++;
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continue;
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}
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const ConditionCode cc = instr.flow_condition_code;
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parse_info.branch_info.condition.cc = cc;
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if (cc == ConditionCode::F) {
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offset++;
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continue;
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}
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parse_info.branch_info.address = unassigned_branch;
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parse_info.branch_info.kill = false;
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parse_info.branch_info.is_sync = true;
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parse_info.branch_info.is_brk = false;
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parse_info.branch_info.ignore = false;
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parse_info.end_address = offset;
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return {ParseResult::ControlCaught, parse_info};
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}
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case OpCode::Id::BRK: {
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const auto pred_index = static_cast<u32>(instr.pred.pred_index);
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parse_info.branch_info.condition.predicate =
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GetPredicate(pred_index, instr.negate_pred != 0);
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if (parse_info.branch_info.condition.predicate == Pred::NeverExecute) {
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offset++;
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continue;
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}
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const ConditionCode cc = instr.flow_condition_code;
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parse_info.branch_info.condition.cc = cc;
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if (cc == ConditionCode::F) {
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offset++;
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continue;
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}
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parse_info.branch_info.address = unassigned_branch;
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parse_info.branch_info.kill = false;
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parse_info.branch_info.is_sync = false;
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parse_info.branch_info.is_brk = true;
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parse_info.branch_info.ignore = false;
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parse_info.end_address = offset;
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return {ParseResult::ControlCaught, parse_info};
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}
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case OpCode::Id::KIL: {
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const auto pred_index = static_cast<u32>(instr.pred.pred_index);
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parse_info.branch_info.condition.predicate =
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GetPredicate(pred_index, instr.negate_pred != 0);
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if (parse_info.branch_info.condition.predicate == Pred::NeverExecute) {
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offset++;
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continue;
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}
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const ConditionCode cc = instr.flow_condition_code;
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parse_info.branch_info.condition.cc = cc;
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if (cc == ConditionCode::F) {
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offset++;
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continue;
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}
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parse_info.branch_info.address = exit_branch;
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parse_info.branch_info.kill = true;
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parse_info.branch_info.is_sync = false;
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parse_info.branch_info.is_brk = false;
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parse_info.branch_info.ignore = false;
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parse_info.end_address = offset;
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return {ParseResult::ControlCaught, parse_info};
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}
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case OpCode::Id::SSY: {
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const u32 target = offset + instr.bra.GetBranchTarget();
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insert_label(state, target);
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state.ssy_labels.emplace(offset, target);
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break;
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}
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case OpCode::Id::PBK: {
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const u32 target = offset + instr.bra.GetBranchTarget();
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insert_label(state, target);
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state.pbk_labels.emplace(offset, target);
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break;
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}
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case OpCode::Id::BRX: {
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return {ParseResult::AbnormalFlow, parse_info};
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}
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default:
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break;
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}
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offset++;
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}
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parse_info.branch_info.kill = false;
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parse_info.branch_info.is_sync = false;
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parse_info.branch_info.is_brk = false;
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parse_info.end_address = offset - 1;
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return {ParseResult::BlockEnd, parse_info};
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}
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bool TryInspectAddress(CFGRebuildState& state) {
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if (state.inspect_queries.empty()) {
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return false;
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}
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const u32 address = state.inspect_queries.front();
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state.inspect_queries.pop_front();
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const auto [result, block_index] = TryGetBlock(state, address);
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switch (result) {
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case BlockCollision::Found: {
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return true;
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}
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case BlockCollision::Inside: {
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// This case is the tricky one:
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// We need to Split the block in 2 sepparate blocks
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const u32 end = state.block_info[block_index].end;
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BlockInfo& new_block = CreateBlockInfo(state, address, end);
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BlockInfo& current_block = state.block_info[block_index];
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current_block.end = address - 1;
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new_block.branch = current_block.branch;
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BlockBranchInfo forward_branch{};
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forward_branch.address = address;
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forward_branch.ignore = true;
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current_block.branch = forward_branch;
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return true;
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}
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default:
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break;
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}
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const auto [parse_result, parse_info] = ParseCode(state, address);
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if (parse_result == ParseResult::AbnormalFlow) {
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// if it's AbnormalFlow, we end it as false, ending the CFG reconstruction
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return false;
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}
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BlockInfo& block_info = CreateBlockInfo(state, address, parse_info.end_address);
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block_info.branch = parse_info.branch_info;
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if (parse_info.branch_info.condition.IsUnconditional()) {
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return true;
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}
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const u32 fallthrough_address = parse_info.end_address + 1;
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state.inspect_queries.push_front(fallthrough_address);
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return true;
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}
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bool TryQuery(CFGRebuildState& state) {
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const auto gather_labels = [](std::stack<u32>& cc, std::map<u32, u32>& labels,
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BlockInfo& block) {
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auto gather_start = labels.lower_bound(block.start);
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const auto gather_end = labels.upper_bound(block.end);
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while (gather_start != gather_end) {
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cc.push(gather_start->second);
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++gather_start;
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}
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};
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if (state.queries.empty()) {
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return false;
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}
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Query& q = state.queries.front();
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const u32 block_index = state.registered[q.address];
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BlockInfo& block = state.block_info[block_index];
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// If the block is visited, check if the stacks match, else gather the ssy/pbk
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// labels into the current stack and look if the branch at the end of the block
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// consumes a label. Schedule new queries accordingly
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if (block.visited) {
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BlockStack& stack = state.stacks[q.address];
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const bool all_okay = (stack.ssy_stack.empty() || q.ssy_stack == stack.ssy_stack) &&
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(stack.pbk_stack.empty() || q.pbk_stack == stack.pbk_stack);
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state.queries.pop_front();
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return all_okay;
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}
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block.visited = true;
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state.stacks.insert_or_assign(q.address, BlockStack{q});
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Query q2(q);
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state.queries.pop_front();
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gather_labels(q2.ssy_stack, state.ssy_labels, block);
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gather_labels(q2.pbk_stack, state.pbk_labels, block);
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if (!block.branch.condition.IsUnconditional()) {
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q2.address = block.end + 1;
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state.queries.push_back(q2);
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}
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Query conditional_query{q2};
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if (block.branch.is_sync) {
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if (block.branch.address == unassigned_branch) {
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block.branch.address = conditional_query.ssy_stack.top();
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}
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conditional_query.ssy_stack.pop();
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}
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if (block.branch.is_brk) {
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if (block.branch.address == unassigned_branch) {
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block.branch.address = conditional_query.pbk_stack.top();
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}
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conditional_query.pbk_stack.pop();
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}
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conditional_query.address = block.branch.address;
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state.queries.push_back(std::move(conditional_query));
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return true;
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}
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} // Anonymous namespace
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std::optional<ShaderCharacteristics> ScanFlow(const ProgramCode& program_code,
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std::size_t program_size, u32 start_address) {
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CFGRebuildState state{program_code, program_size, start_address};
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// Inspect Code and generate blocks
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state.labels.clear();
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state.labels.emplace(start_address);
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state.inspect_queries.push_back(state.start);
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while (!state.inspect_queries.empty()) {
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if (!TryInspectAddress(state)) {
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return {};
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}
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}
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// Decompile Stacks
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state.queries.push_back(Query{state.start, {}, {}});
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bool decompiled = true;
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while (!state.queries.empty()) {
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if (!TryQuery(state)) {
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decompiled = false;
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break;
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}
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}
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// Sort and organize results
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std::sort(state.block_info.begin(), state.block_info.end(),
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[](const BlockInfo& a, const BlockInfo& b) { return a.start < b.start; });
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ShaderCharacteristics result_out{};
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result_out.decompilable = decompiled;
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result_out.start = start_address;
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result_out.end = start_address;
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for (const auto& block : state.block_info) {
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ShaderBlock new_block{};
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new_block.start = block.start;
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new_block.end = block.end;
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new_block.ignore_branch = block.branch.ignore;
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if (!new_block.ignore_branch) {
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new_block.branch.cond = block.branch.condition;
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new_block.branch.kills = block.branch.kill;
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new_block.branch.address = block.branch.address;
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}
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result_out.end = std::max(result_out.end, block.end);
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result_out.blocks.push_back(new_block);
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}
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if (result_out.decompilable) {
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result_out.labels = std::move(state.labels);
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return {std::move(result_out)};
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}
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// If it's not decompilable, merge the unlabelled blocks together
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auto back = result_out.blocks.begin();
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auto next = std::next(back);
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while (next != result_out.blocks.end()) {
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if (state.labels.count(next->start) == 0 && next->start == back->end + 1) {
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back->end = next->end;
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next = result_out.blocks.erase(next);
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continue;
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}
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back = next;
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++next;
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}
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return {std::move(result_out)};
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}
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} // namespace VideoCommon::Shader
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