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suyu/src/video_core/shader/ast.cpp

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// Copyright 2019 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <string>
#include "common/assert.h"
#include "common/common_types.h"
#include "video_core/shader/ast.h"
#include "video_core/shader/expr.h"
namespace VideoCommon::Shader {
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ASTZipper::ASTZipper() = default;
void ASTZipper::Init(const ASTNode new_first, const ASTNode parent) {
ASSERT(new_first->manager == nullptr);
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first = new_first;
last = new_first;
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ASTNode current = first;
while (current) {
current->manager = this;
current->parent = parent;
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last = current;
current = current->next;
}
}
void ASTZipper::PushBack(const ASTNode new_node) {
ASSERT(new_node->manager == nullptr);
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new_node->previous = last;
if (last) {
last->next = new_node;
}
new_node->next.reset();
last = new_node;
if (!first) {
first = new_node;
}
new_node->manager = this;
}
void ASTZipper::PushFront(const ASTNode new_node) {
ASSERT(new_node->manager == nullptr);
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new_node->previous.reset();
new_node->next = first;
if (first) {
first->previous = new_node;
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}
if (last == first) {
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last = new_node;
}
first = new_node;
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new_node->manager = this;
}
void ASTZipper::InsertAfter(const ASTNode new_node, const ASTNode at_node) {
ASSERT(new_node->manager == nullptr);
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if (!at_node) {
PushFront(new_node);
return;
}
const ASTNode next = at_node->next;
if (next) {
next->previous = new_node;
}
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new_node->previous = at_node;
if (at_node == last) {
last = new_node;
}
new_node->next = next;
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at_node->next = new_node;
new_node->manager = this;
}
void ASTZipper::InsertBefore(const ASTNode new_node, const ASTNode at_node) {
ASSERT(new_node->manager == nullptr);
if (!at_node) {
PushBack(new_node);
return;
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}
const ASTNode previous = at_node->previous;
if (previous) {
previous->next = new_node;
}
new_node->next = at_node;
if (at_node == first) {
first = new_node;
}
new_node->previous = previous;
at_node->previous = new_node;
new_node->manager = this;
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}
void ASTZipper::DetachTail(ASTNode node) {
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ASSERT(node->manager == this);
if (node == first) {
first.reset();
last.reset();
return;
}
last = node->previous;
last->next.reset();
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node->previous.reset();
ASTNode current = std::move(node);
while (current) {
current->manager = nullptr;
current->parent.reset();
current = current->next;
}
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}
void ASTZipper::DetachSegment(const ASTNode start, const ASTNode end) {
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ASSERT(start->manager == this && end->manager == this);
if (start == end) {
DetachSingle(start);
return;
}
const ASTNode prev = start->previous;
const ASTNode post = end->next;
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if (!prev) {
first = post;
} else {
prev->next = post;
}
if (!post) {
last = prev;
} else {
post->previous = prev;
}
start->previous.reset();
end->next.reset();
ASTNode current = start;
bool found = false;
while (current) {
current->manager = nullptr;
current->parent.reset();
found |= current == end;
current = current->next;
}
ASSERT(found);
}
void ASTZipper::DetachSingle(const ASTNode node) {
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ASSERT(node->manager == this);
const ASTNode prev = node->previous;
const ASTNode post = node->next;
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node->previous.reset();
node->next.reset();
if (!prev) {
first = post;
} else {
prev->next = post;
}
if (!post) {
last = prev;
} else {
post->previous = prev;
}
node->manager = nullptr;
node->parent.reset();
}
void ASTZipper::Remove(const ASTNode node) {
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ASSERT(node->manager == this);
const ASTNode next = node->next;
const ASTNode previous = node->previous;
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if (previous) {
previous->next = next;
}
if (next) {
next->previous = previous;
}
node->parent.reset();
node->manager = nullptr;
if (node == last) {
last = previous;
}
if (node == first) {
first = next;
}
}
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class ExprPrinter final {
public:
void operator()(const ExprAnd& expr) {
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inner += "( ";
std::visit(*this, *expr.operand1);
inner += " && ";
std::visit(*this, *expr.operand2);
inner += ')';
}
void operator()(const ExprOr& expr) {
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inner += "( ";
std::visit(*this, *expr.operand1);
inner += " || ";
std::visit(*this, *expr.operand2);
inner += ')';
}
void operator()(const ExprNot& expr) {
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inner += "!";
std::visit(*this, *expr.operand1);
}
void operator()(const ExprPredicate& expr) {
inner += "P" + std::to_string(expr.predicate);
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}
void operator()(const ExprCondCode& expr) {
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u32 cc = static_cast<u32>(expr.cc);
inner += "CC" + std::to_string(cc);
}
void operator()(const ExprVar& expr) {
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inner += "V" + std::to_string(expr.var_index);
}
void operator()(const ExprBoolean& expr) {
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inner += expr.value ? "true" : "false";
}
const std::string& GetResult() const {
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return inner;
}
std::string inner{};
};
class ASTPrinter {
public:
void operator()(const ASTProgram& ast) {
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scope++;
inner += "program {\n";
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ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
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}
inner += "}\n";
scope--;
}
void operator()(const ASTIfThen& ast) {
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ExprPrinter expr_parser{};
std::visit(expr_parser, *ast.condition);
inner += Ident() + "if (" + expr_parser.GetResult() + ") {\n";
scope++;
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ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
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}
scope--;
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inner += Ident() + "}\n";
}
void operator()(const ASTIfElse& ast) {
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inner += Ident() + "else {\n";
scope++;
ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
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}
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scope--;
inner += Ident() + "}\n";
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}
void operator()(const ASTBlockEncoded& ast) {
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inner += Ident() + "Block(" + std::to_string(ast.start) + ", " + std::to_string(ast.end) +
");\n";
}
void operator()(const ASTBlockDecoded& ast) {
inner += Ident() + "Block;\n";
}
void operator()(const ASTVarSet& ast) {
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ExprPrinter expr_parser{};
std::visit(expr_parser, *ast.condition);
inner +=
Ident() + "V" + std::to_string(ast.index) + " := " + expr_parser.GetResult() + ";\n";
}
void operator()(const ASTLabel& ast) {
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inner += "Label_" + std::to_string(ast.index) + ":\n";
}
void operator()(const ASTGoto& ast) {
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ExprPrinter expr_parser{};
std::visit(expr_parser, *ast.condition);
inner += Ident() + "(" + expr_parser.GetResult() + ") -> goto Label_" +
std::to_string(ast.label) + ";\n";
}
void operator()(const ASTDoWhile& ast) {
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ExprPrinter expr_parser{};
std::visit(expr_parser, *ast.condition);
inner += Ident() + "do {\n";
scope++;
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ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
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}
scope--;
inner += Ident() + "} while (" + expr_parser.GetResult() + ");\n";
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}
void operator()(const ASTReturn& ast) {
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ExprPrinter expr_parser{};
std::visit(expr_parser, *ast.condition);
inner += Ident() + "(" + expr_parser.GetResult() + ") -> " +
(ast.kills ? "discard" : "exit") + ";\n";
}
void operator()(const ASTBreak& ast) {
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ExprPrinter expr_parser{};
std::visit(expr_parser, *ast.condition);
inner += Ident() + "(" + expr_parser.GetResult() + ") -> break;\n";
}
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std::string& Ident() {
if (memo_scope == scope) {
return tabs_memo;
}
tabs_memo = tabs.substr(0, scope * 2);
memo_scope = scope;
return tabs_memo;
}
void Visit(ASTNode& node) {
std::visit(*this, *node->GetInnerData());
}
const std::string& GetResult() const {
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return inner;
}
private:
std::string inner{};
u32 scope{};
std::string tabs_memo{};
u32 memo_scope{};
static std::string tabs;
};
std::string ASTPrinter::tabs = " ";
std::string ASTManager::Print() {
ASTPrinter printer{};
printer.Visit(main_node);
return printer.GetResult();
}
ASTManager::ASTManager(bool full_decompile, bool disable_else_derivation)
: full_decompile{full_decompile}, disable_else_derivation{disable_else_derivation} {};
ASTManager::~ASTManager() {
Clear();
}
void ASTManager::Init() {
main_node = ASTBase::Make<ASTProgram>(ASTNode{});
program = std::get_if<ASTProgram>(main_node->GetInnerData());
false_condition = MakeExpr<ExprBoolean>(false);
}
void ASTManager::DeclareLabel(u32 address) {
const auto pair = labels_map.emplace(address, labels_count);
if (pair.second) {
labels_count++;
labels.resize(labels_count);
}
}
void ASTManager::InsertLabel(u32 address) {
const u32 index = labels_map[address];
const ASTNode label = ASTBase::Make<ASTLabel>(main_node, index);
labels[index] = label;
program->nodes.PushBack(label);
}
void ASTManager::InsertGoto(Expr condition, u32 address) {
const u32 index = labels_map[address];
const ASTNode goto_node = ASTBase::Make<ASTGoto>(main_node, std::move(condition), index);
gotos.push_back(goto_node);
program->nodes.PushBack(goto_node);
}
void ASTManager::InsertBlock(u32 start_address, u32 end_address) {
ASTNode block = ASTBase::Make<ASTBlockEncoded>(main_node, start_address, end_address);
program->nodes.PushBack(std::move(block));
}
void ASTManager::InsertReturn(Expr condition, bool kills) {
ASTNode node = ASTBase::Make<ASTReturn>(main_node, std::move(condition), kills);
program->nodes.PushBack(std::move(node));
}
// The decompile algorithm is based on
// "Taming control flow: A structured approach to eliminating goto statements"
// by AM Erosa, LJ Hendren 1994. In general, the idea is to get gotos to be
// on the same structured level as the label which they jump to. This is done,
// through outward/inward movements and lifting. Once they are at the same
// level, you can enclose them in an "if" structure or a "do-while" structure.
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void ASTManager::Decompile() {
auto it = gotos.begin();
while (it != gotos.end()) {
const ASTNode goto_node = *it;
const auto label_index = goto_node->GetGotoLabel();
if (!label_index) {
return;
}
const ASTNode label = labels[*label_index];
if (!full_decompile) {
// We only decompile backward jumps
if (!IsBackwardsJump(goto_node, label)) {
it++;
continue;
}
}
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if (IndirectlyRelated(goto_node, label)) {
while (!DirectlyRelated(goto_node, label)) {
MoveOutward(goto_node);
}
}
if (DirectlyRelated(goto_node, label)) {
u32 goto_level = goto_node->GetLevel();
const u32 label_level = label->GetLevel();
while (label_level < goto_level) {
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MoveOutward(goto_node);
goto_level--;
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}
// TODO(Blinkhawk): Implement Lifting and Inward Movements
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}
if (label->GetParent() == goto_node->GetParent()) {
bool is_loop = false;
ASTNode current = goto_node->GetPrevious();
while (current) {
if (current == label) {
is_loop = true;
break;
}
current = current->GetPrevious();
}
if (is_loop) {
EncloseDoWhile(goto_node, label);
} else {
EncloseIfThen(goto_node, label);
}
it = gotos.erase(it);
continue;
}
it++;
}
if (full_decompile) {
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for (const ASTNode& label : labels) {
auto& manager = label->GetManager();
manager.Remove(label);
}
labels.clear();
} else {
auto it = labels.begin();
while (it != labels.end()) {
bool can_remove = true;
ASTNode label = *it;
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for (const ASTNode& goto_node : gotos) {
const auto label_index = goto_node->GetGotoLabel();
if (!label_index) {
return;
}
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ASTNode& glabel = labels[*label_index];
if (glabel == label) {
can_remove = false;
break;
}
}
if (can_remove) {
label->MarkLabelUnused();
}
}
}
}
bool ASTManager::IsBackwardsJump(ASTNode goto_node, ASTNode label_node) const {
u32 goto_level = goto_node->GetLevel();
u32 label_level = label_node->GetLevel();
while (goto_level > label_level) {
goto_level--;
goto_node = goto_node->GetParent();
}
while (label_level > goto_level) {
label_level--;
label_node = label_node->GetParent();
}
while (goto_node->GetParent() != label_node->GetParent()) {
goto_node = goto_node->GetParent();
label_node = label_node->GetParent();
}
ASTNode current = goto_node->GetPrevious();
while (current) {
if (current == label_node) {
return true;
}
current = current->GetPrevious();
}
return false;
}
bool ASTManager::IndirectlyRelated(const ASTNode& first, const ASTNode& second) const {
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return !(first->GetParent() == second->GetParent() || DirectlyRelated(first, second));
}
bool ASTManager::DirectlyRelated(const ASTNode& first, const ASTNode& second) const {
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if (first->GetParent() == second->GetParent()) {
return false;
}
const u32 first_level = first->GetLevel();
const u32 second_level = second->GetLevel();
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u32 min_level;
u32 max_level;
ASTNode max;
ASTNode min;
if (first_level > second_level) {
min_level = second_level;
min = second;
max_level = first_level;
max = first;
} else {
min_level = first_level;
min = first;
max_level = second_level;
max = second;
}
while (max_level > min_level) {
max_level--;
max = max->GetParent();
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}
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return min->GetParent() == max->GetParent();
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}
void ASTManager::ShowCurrentState(std::string state) {
LOG_CRITICAL(HW_GPU, "\nState {}:\n\n{}\n", state, Print());
SanityCheck();
}
void ASTManager::SanityCheck() {
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for (auto& label : labels) {
if (!label->GetParent()) {
LOG_CRITICAL(HW_GPU, "Sanity Check Failed");
}
}
}
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void ASTManager::EncloseDoWhile(ASTNode goto_node, ASTNode label) {
ASTZipper& zipper = goto_node->GetManager();
const ASTNode loop_start = label->GetNext();
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if (loop_start == goto_node) {
zipper.Remove(goto_node);
return;
}
const ASTNode parent = label->GetParent();
const Expr condition = goto_node->GetGotoCondition();
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zipper.DetachSegment(loop_start, goto_node);
const ASTNode do_while_node = ASTBase::Make<ASTDoWhile>(parent, condition);
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ASTZipper* sub_zipper = do_while_node->GetSubNodes();
sub_zipper->Init(loop_start, do_while_node);
zipper.InsertAfter(do_while_node, label);
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sub_zipper->Remove(goto_node);
}
void ASTManager::EncloseIfThen(ASTNode goto_node, ASTNode label) {
ASTZipper& zipper = goto_node->GetManager();
const ASTNode if_end = label->GetPrevious();
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if (if_end == goto_node) {
zipper.Remove(goto_node);
return;
}
const ASTNode prev = goto_node->GetPrevious();
const Expr condition = goto_node->GetGotoCondition();
bool do_else = false;
if (!disable_else_derivation && prev->IsIfThen()) {
const Expr if_condition = prev->GetIfCondition();
do_else = ExprAreEqual(if_condition, condition);
}
const ASTNode parent = label->GetParent();
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zipper.DetachSegment(goto_node, if_end);
ASTNode if_node;
if (do_else) {
if_node = ASTBase::Make<ASTIfElse>(parent);
} else {
Expr neg_condition = MakeExprNot(condition);
if_node = ASTBase::Make<ASTIfThen>(parent, neg_condition);
}
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ASTZipper* sub_zipper = if_node->GetSubNodes();
sub_zipper->Init(goto_node, if_node);
zipper.InsertAfter(if_node, prev);
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sub_zipper->Remove(goto_node);
}
void ASTManager::MoveOutward(ASTNode goto_node) {
ASTZipper& zipper = goto_node->GetManager();
const ASTNode parent = goto_node->GetParent();
ASTZipper& zipper2 = parent->GetManager();
const ASTNode grandpa = parent->GetParent();
const bool is_loop = parent->IsLoop();
const bool is_else = parent->IsIfElse();
const bool is_if = parent->IsIfThen();
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const ASTNode prev = goto_node->GetPrevious();
const ASTNode post = goto_node->GetNext();
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const Expr condition = goto_node->GetGotoCondition();
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zipper.DetachSingle(goto_node);
if (is_loop) {
const u32 var_index = NewVariable();
const Expr var_condition = MakeExpr<ExprVar>(var_index);
const ASTNode var_node = ASTBase::Make<ASTVarSet>(parent, var_index, condition);
const ASTNode var_node_init = ASTBase::Make<ASTVarSet>(parent, var_index, false_condition);
zipper2.InsertBefore(var_node_init, parent);
zipper.InsertAfter(var_node, prev);
goto_node->SetGotoCondition(var_condition);
const ASTNode break_node = ASTBase::Make<ASTBreak>(parent, var_condition);
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zipper.InsertAfter(break_node, var_node);
} else if (is_if || is_else) {
const u32 var_index = NewVariable();
const Expr var_condition = MakeExpr<ExprVar>(var_index);
const ASTNode var_node = ASTBase::Make<ASTVarSet>(parent, var_index, condition);
const ASTNode var_node_init = ASTBase::Make<ASTVarSet>(parent, var_index, false_condition);
if (is_if) {
zipper2.InsertBefore(var_node_init, parent);
} else {
zipper2.InsertBefore(var_node_init, parent->GetPrevious());
}
zipper.InsertAfter(var_node, prev);
goto_node->SetGotoCondition(var_condition);
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if (post) {
zipper.DetachTail(post);
const ASTNode if_node = ASTBase::Make<ASTIfThen>(parent, MakeExprNot(var_condition));
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ASTZipper* sub_zipper = if_node->GetSubNodes();
sub_zipper->Init(post, if_node);
zipper.InsertAfter(if_node, var_node);
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}
} else {
UNREACHABLE();
}
const ASTNode next = parent->GetNext();
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if (is_if && next && next->IsIfElse()) {
zipper2.InsertAfter(goto_node, next);
goto_node->SetParent(grandpa);
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return;
}
zipper2.InsertAfter(goto_node, parent);
goto_node->SetParent(grandpa);
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}
class ASTClearer {
public:
ASTClearer() = default;
void operator()(const ASTProgram& ast) {
ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
}
}
void operator()(const ASTIfThen& ast) {
ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
}
}
void operator()(const ASTIfElse& ast) {
ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
}
}
void operator()([[maybe_unused]] const ASTBlockEncoded& ast) {}
void operator()(ASTBlockDecoded& ast) {
ast.nodes.clear();
}
void operator()([[maybe_unused]] const ASTVarSet& ast) {}
void operator()([[maybe_unused]] const ASTLabel& ast) {}
void operator()([[maybe_unused]] const ASTGoto& ast) {}
void operator()(const ASTDoWhile& ast) {
ASTNode current = ast.nodes.GetFirst();
while (current) {
Visit(current);
current = current->GetNext();
}
}
void operator()([[maybe_unused]] const ASTReturn& ast) {}
void operator()([[maybe_unused]] const ASTBreak& ast) {}
void Visit(const ASTNode& node) {
std::visit(*this, *node->GetInnerData());
node->Clear();
}
};
void ASTManager::Clear() {
if (!main_node) {
return;
}
ASTClearer clearer{};
clearer.Visit(main_node);
main_node.reset();
program = nullptr;
labels_map.clear();
labels.clear();
gotos.clear();
}
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} // namespace VideoCommon::Shader