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shader_ir: Decompile Flow Stack

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This commit is contained in:
Fernando Sahmkow 2019-06-25 11:10:45 -04:00 committed by FernandoS27
parent 459fce3a8f
commit 926b80102f
4 changed files with 206 additions and 11 deletions
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161
src/video_core/shader/control_flow.cpp
View file

@ -1,6 +1,6 @@
#include <list>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <vector>
@ -16,12 +16,80 @@ using Tegra::Shader::OpCode;
constexpr s32 unassigned_branch = -2;
struct ControlStack {
std::array<u32, 20> stack;
u32 index{};
ControlStack() {}
ControlStack(const ControlStack& cp) {
index = cp.index;
std::memcpy(stack.data(), cp.stack.data(), index * sizeof(u32));
}
bool Compare(const ControlStack& cs) const {
if (index != cs.index) {
return false;
}
return std::memcmp(stack.data(), cs.stack.data(), index * sizeof(u32)) == 0;
}
bool SoftCompare(const ControlStack& cs) const {
if (index == 0 || cs.index == 0) {
return index == cs.index;
}
return Top() == cs.Top();
}
u32 Size() const {
return index;
}
u32 Top() const {
return stack[index - 1];
}
bool Push(u32 address) {
if (index >= 20) {
return false;
}
stack[index] = address;
index++;
return true;
}
bool Pop() {
if (index == 0) {
return false;
}
index--;
return true;
}
};
struct Query {
Query() {}
Query(const Query& q) : address{q.address}, ssy_stack{q.ssy_stack}, pbk_stack{q.pbk_stack} {}
u32 address;
ControlStack ssy_stack{};
ControlStack pbk_stack{};
};
struct BlockStack {
BlockStack() = default;
BlockStack(const BlockStack& b) : ssy_stack{b.ssy_stack}, pbk_stack{b.pbk_stack} {}
BlockStack(const Query& q) : ssy_stack{q.ssy_stack}, pbk_stack{q.pbk_stack} {}
ControlStack ssy_stack{};
ControlStack pbk_stack{};
};
struct BlockBranchInfo {
Condition condition{};
s32 address{exit_branch};
bool kill{};
bool is_sync{};
bool is_brk{};
bool ignore{};
};
struct BlockInfo {
@ -64,19 +132,21 @@ struct CFGRebuildState {
// queries.clear();
block_info.clear();
labels.clear();
visited_address.clear();
registered.clear();
ssy_labels.clear();
pbk_labels.clear();
inspect_queries.clear();
queries.clear();
}
std::vector<BlockInfo> block_info{};
std::list<u32> inspect_queries{};
// std::list<Query> queries{};
std::unordered_set<u32> visited_address{};
std::list<Query> queries{};
std::unordered_map<u32, u32> registered{};
std::unordered_set<u32> labels{};
std::set<Stamp> ssy_labels;
std::set<Stamp> pbk_labels;
std::unordered_map<u32, BlockStack> stacks{};
const ProgramCode& program_code;
const std::size_t program_size;
};
@ -107,7 +177,8 @@ BlockInfo* CreateBlockInfo(CFGRebuildState& state, u32 start, u32 end) {
auto& it = state.block_info.emplace_back();
it.start = start;
it.end = end;
state.visited_address.insert(start);
u32 index = state.block_info.size() - 1;
state.registered.insert({start, index});
return &it;
}
@ -136,10 +207,12 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
while (true) {
if (offset >= end_address) {
parse_info.branch_info.address = exit_branch;
parse_info.branch_info.ignore = false;
break;
}
if (state.visited_address.count(offset) != 0) {
if (state.registered.count(offset) != 0) {
parse_info.branch_info.address = offset;
parse_info.branch_info.ignore = true;
break;
}
const Instruction instr = {state.program_code[offset]};
@ -168,6 +241,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
parse_info.branch_info.kill = false;
parse_info.branch_info.is_sync = false;
parse_info.branch_info.is_brk = false;
parse_info.branch_info.ignore = false;
parse_info.end_address = offset;
return ParseResult::ControlCaught;
@ -199,6 +273,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
parse_info.branch_info.kill = false;
parse_info.branch_info.is_sync = false;
parse_info.branch_info.is_brk = false;
parse_info.branch_info.ignore = false;
parse_info.end_address = offset;
return ParseResult::ControlCaught;
@ -222,6 +297,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
parse_info.branch_info.kill = false;
parse_info.branch_info.is_sync = true;
parse_info.branch_info.is_brk = false;
parse_info.branch_info.ignore = false;
parse_info.end_address = offset;
return ParseResult::ControlCaught;
@ -245,6 +321,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
parse_info.branch_info.kill = false;
parse_info.branch_info.is_sync = false;
parse_info.branch_info.is_brk = true;
parse_info.branch_info.ignore = false;
parse_info.end_address = offset;
return ParseResult::ControlCaught;
@ -268,6 +345,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
parse_info.branch_info.kill = true;
parse_info.branch_info.is_sync = false;
parse_info.branch_info.is_brk = false;
parse_info.branch_info.ignore = false;
parse_info.end_address = offset;
return ParseResult::ControlCaught;
@ -322,6 +400,7 @@ bool TryInspectAddress(CFGRebuildState& state) {
block_info->branch = it->branch;
BlockBranchInfo forward_branch{};
forward_branch.address = address;
forward_branch.ignore = true;
it->branch = forward_branch;
return true;
break;
@ -348,6 +427,58 @@ bool TryInspectAddress(CFGRebuildState& state) {
return true;
}
bool TryQuery(CFGRebuildState& state) {
auto gather_labels = ([](ControlStack& cc, std::set<Stamp> labels, BlockInfo& block) {
Stamp start{block.start, 0};
Stamp end{block.end, 0};
auto gather_start = labels.lower_bound(start);
auto gather_end = labels.upper_bound(end);
while (gather_start != gather_end) {
cc.Push(gather_start->target);
gather_start++;
}
});
if (state.queries.empty()) {
return false;
}
Query& q = state.queries.front();
u32 block_index = state.registered[q.address];
BlockInfo& block = state.block_info[block_index];
if (block.visited) {
BlockStack& stack = state.stacks[q.address];
bool all_okay = q.ssy_stack.Compare(stack.ssy_stack) && q.pbk_stack.Compare(stack.pbk_stack);
state.queries.pop_front();
return all_okay;
}
block.visited = true;
BlockStack bs{q};
state.stacks[q.address] = bs;
Query q2(q);
state.queries.pop_front();
gather_labels(q2.ssy_stack, state.ssy_labels, block);
gather_labels(q2.pbk_stack, state.pbk_labels, block);
if (!block.branch.condition.IsUnconditional()) {
q2.address = block.end + 1;
state.queries.push_back(q2);
}
Query conditional_query{q2};
if (block.branch.is_sync) {
if (block.branch.address == unassigned_branch) {
block.branch.address = conditional_query.ssy_stack.Top();
}
conditional_query.ssy_stack.Pop();
}
if (block.branch.is_brk) {
if (block.branch.address == unassigned_branch) {
block.branch.address = conditional_query.pbk_stack.Top();
}
conditional_query.pbk_stack.Pop();
}
conditional_query.address = block.branch.address;
state.queries.push_back(conditional_query);
return true;
}
bool ScanFlow(const ProgramCode& program_code, u32 program_size, u32 start_address,
ShaderCharacteristics& result_out) {
CFGRebuildState state{program_code, program_size};
@ -360,20 +491,34 @@ bool ScanFlow(const ProgramCode& program_code, u32 program_size, u32 start_addre
return false;
}
}
// Decompile Stacks
Query start_query{};
start_query.address = start_address;
state.queries.push_back(start_query);
bool decompiled = true;
while (!state.queries.empty()) {
if (!TryQuery(state)) {
decompiled = false;
break;
}
}
// Sort and organize results
std::sort(state.block_info.begin(), state.block_info.end(),
[](const BlockInfo& a, const BlockInfo& b) -> bool { return a.start < b.start; });
// Remove unvisited blocks
result_out.blocks.clear();
result_out.decompilable = false;
result_out.decompilable = decompiled;
result_out.start = start_address;
result_out.end = start_address;
for (auto& block : state.block_info) {
ShaderBlock new_block{};
new_block.start = block.start;
new_block.end = block.end;
new_block.ignore_branch = block.branch.ignore;
if (!new_block.ignore_branch) {
new_block.branch.cond = block.branch.condition;
new_block.branch.kills = block.branch.kill;
new_block.branch.address = block.branch.address;
}
result_out.end = std::max(result_out.end, block.end);
result_out.blocks.push_back(new_block);
}

1
src/video_core/shader/control_flow.h
View file

@ -29,6 +29,7 @@ struct ShaderBlock {
ShaderBlock(const ShaderBlock& sb) = default;
u32 start{};
u32 end{};
bool ignore_branch{};
struct Branch {
Condition cond{};
bool kills{};

46
src/video_core/shader/decode.cpp
View file

@ -44,6 +44,17 @@ void ShaderIR::Decode() {
coverage_begin = shader_info.start;
coverage_end = shader_info.end;
if (shader_info.decompilable) {
std::list<ShaderBlock>& blocks = shader_info.blocks;
for (auto& block : blocks) {
NodeBlock nodes;
if (!block.ignore_branch) {
nodes = DecodeRange(block.start, block.end);
InsertControlFlow(nodes, block);
} else {
nodes = DecodeRange(block.start, block.end + 1);
}
basic_blocks.insert({block.start, nodes});
}
return;
}
// we can't decompile it, fallback to standard method
@ -73,6 +84,41 @@ NodeBlock ShaderIR::DecodeRange(u32 begin, u32 end) {
return basic_block;
}
void ShaderIR::InsertControlFlow(NodeBlock& bb, const ShaderBlock& block) {
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);
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)) {

3
src/video_core/shader/shader_ir.h
View file

@ -22,6 +22,8 @@
namespace VideoCommon::Shader {
struct ShaderBlock;
using ProgramCode = std::vector<u64>;
constexpr u32 MAX_PROGRAM_LENGTH = 0x1000;
@ -125,6 +127,7 @@ private:
void Decode();
NodeBlock DecodeRange(u32 begin, u32 end);
void InsertControlFlow(NodeBlock& bb, const ShaderBlock& block);
/**
* Decodes a single instruction from Tegra to IR.