From 6c4cc0cd062fbbba5349da1108d3c23cb330ca8a Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Tue, 2 Feb 2021 21:07:00 -0300
Subject: shader: SSA and dominance
---
.../frontend/maxwell/control_flow.cpp | 130 ++++++++++++++++++++-
1 file changed, 124 insertions(+), 6 deletions(-)
(limited to 'src/shader_recompiler/frontend/maxwell/control_flow.cpp')
diff --git a/src/shader_recompiler/frontend/maxwell/control_flow.cpp b/src/shader_recompiler/frontend/maxwell/control_flow.cpp
index fc4dba8269..21ee981371 100644
--- a/src/shader_recompiler/frontend/maxwell/control_flow.cpp
+++ b/src/shader_recompiler/frontend/maxwell/control_flow.cpp
@@ -36,6 +36,7 @@ static std::array<Block, 2> Split(Block&& block, Location pc, BlockId new_id) {
.cond{true},
.branch_true{new_id},
.branch_false{UNREACHABLE_BLOCK_ID},
+ .imm_predecessors{},
},
Block{
.begin{pc},
@@ -46,6 +47,7 @@ static std::array<Block, 2> Split(Block&& block, Location pc, BlockId new_id) {
.cond{block.cond},
.branch_true{block.branch_true},
.branch_false{block.branch_false},
+ .imm_predecessors{},
},
};
}
@@ -108,7 +110,7 @@ static bool HasFlowTest(Opcode opcode) {
}
}
-static std::string Name(const Block& block) {
+static std::string NameOf(const Block& block) {
if (block.begin.IsVirtual()) {
return fmt::format("\"Virtual {}\"", block.id);
} else {
@@ -154,13 +156,127 @@ bool Block::Contains(Location pc) const noexcept {
}
Function::Function(Location start_address)
- : entrypoint{start_address}, labels{Label{
+ : entrypoint{start_address}, labels{{
.address{start_address},
.block_id{0},
.stack{},
}} {}
+void Function::BuildBlocksMap() {
+ const size_t num_blocks{NumBlocks()};
+ blocks_map.resize(num_blocks);
+ for (size_t block_index = 0; block_index < num_blocks; ++block_index) {
+ Block& block{blocks_data[block_index]};
+ blocks_map[block.id] = █
+ }
+}
+
+void Function::BuildImmediatePredecessors() {
+ for (const Block& block : blocks_data) {
+ if (block.branch_true != UNREACHABLE_BLOCK_ID) {
+ blocks_map[block.branch_true]->imm_predecessors.push_back(block.id);
+ }
+ if (block.branch_false != UNREACHABLE_BLOCK_ID) {
+ blocks_map[block.branch_false]->imm_predecessors.push_back(block.id);
+ }
+ }
+}
+
+void Function::BuildPostOrder() {
+ boost::container::small_vector<BlockId, 0x110> block_stack;
+ post_order_map.resize(NumBlocks());
+
+ Block& first_block{blocks_data[blocks.front()]};
+ first_block.post_order_visited = true;
+ block_stack.push_back(first_block.id);
+
+ const auto visit_branch = [&](BlockId block_id, BlockId branch_id) {
+ if (branch_id == UNREACHABLE_BLOCK_ID) {
+ return false;
+ }
+ if (blocks_map[branch_id]->post_order_visited) {
+ return false;
+ }
+ blocks_map[branch_id]->post_order_visited = true;
+
+ // Calling push_back twice is faster than insert on msvc
+ block_stack.push_back(block_id);
+ block_stack.push_back(branch_id);
+ return true;
+ };
+ while (!block_stack.empty()) {
+ const Block* const block{blocks_map[block_stack.back()]};
+ block_stack.pop_back();
+
+ if (!visit_branch(block->id, block->branch_true) &&
+ !visit_branch(block->id, block->branch_false)) {
+ post_order_map[block->id] = static_cast<u32>(post_order_blocks.size());
+ post_order_blocks.push_back(block->id);
+ }
+ }
+}
+
+void Function::BuildImmediateDominators() {
+ auto transform_block_id{std::views::transform([this](BlockId id) { return blocks_map[id]; })};
+ auto reverse_order_but_first{std::views::reverse | std::views::drop(1) | transform_block_id};
+ auto has_idom{std::views::filter([](Block* block) { return block->imm_dominator; })};
+ auto intersect{[this](Block* finger1, Block* finger2) {
+ while (finger1 != finger2) {
+ while (post_order_map[finger1->id] < post_order_map[finger2->id]) {
+ finger1 = finger1->imm_dominator;
+ }
+ while (post_order_map[finger2->id] < post_order_map[finger1->id]) {
+ finger2 = finger2->imm_dominator;
+ }
+ }
+ return finger1;
+ }};
+ for (Block& block : blocks_data) {
+ block.imm_dominator = nullptr;
+ }
+ Block* const start_block{&blocks_data[blocks.front()]};
+ start_block->imm_dominator = start_block;
+
+ bool changed{true};
+ while (changed) {
+ changed = false;
+ for (Block* const block : post_order_blocks | reverse_order_but_first) {
+ Block* new_idom{};
+ for (Block* predecessor : block->imm_predecessors | transform_block_id | has_idom) {
+ new_idom = new_idom ? intersect(predecessor, new_idom) : predecessor;
+ }
+ changed |= block->imm_dominator != new_idom;
+ block->imm_dominator = new_idom;
+ }
+ }
+}
+
+void Function::BuildDominanceFrontier() {
+ auto transform_block_id{std::views::transform([this](BlockId id) { return blocks_map[id]; })};
+ auto has_enough_predecessors{[](Block& block) { return block.imm_predecessors.size() >= 2; }};
+ for (Block& block : blocks_data | std::views::filter(has_enough_predecessors)) {
+ for (Block* current : block.imm_predecessors | transform_block_id) {
+ while (current != block.imm_dominator) {
+ current->dominance_frontiers.push_back(current->id);
+ current = current->imm_dominator;
+ }
+ }
+ }
+}
+
CFG::CFG(Environment& env_, Location start_address) : env{env_} {
+ VisitFunctions(start_address);
+
+ for (Function& function : functions) {
+ function.BuildBlocksMap();
+ function.BuildImmediatePredecessors();
+ function.BuildPostOrder();
+ function.BuildImmediateDominators();
+ function.BuildDominanceFrontier();
+ }
+}
+
+void CFG::VisitFunctions(Location start_address) {
functions.emplace_back(start_address);
for (FunctionId function_id = 0; function_id < functions.size(); ++function_id) {
while (!functions[function_id].labels.empty()) {
@@ -202,6 +318,7 @@ void CFG::AnalyzeLabel(FunctionId function_id, Label& label) {
.cond{true},
.branch_true{UNREACHABLE_BLOCK_ID},
.branch_false{UNREACHABLE_BLOCK_ID},
+ .imm_predecessors{},
};
// Analyze instructions until it reaches an already visited block or there's a branch
bool is_branch{false};
@@ -310,7 +427,7 @@ CFG::AnalysisState CFG::AnalyzeInst(Block& block, FunctionId function_id, Locati
// Technically CAL pushes into PRET, but that's implicit in the function call for us
// Insert the function into the list if it doesn't exist
if (std::ranges::find(functions, cal_pc, &Function::entrypoint) == functions.end()) {
- functions.push_back(cal_pc);
+ functions.emplace_back(cal_pc);
}
// Handle CAL like a regular instruction
break;
@@ -352,6 +469,7 @@ void CFG::AnalyzeCondInst(Block& block, FunctionId function_id, Location pc,
.cond{cond},
.branch_true{conditional_block_id},
.branch_false{UNREACHABLE_BLOCK_ID},
+ .imm_predecessors{},
})};
// Set the end properties of the conditional instruction and give it a new identity
Block& conditional_block{block};
@@ -465,14 +583,14 @@ std::string CFG::Dot() const {
dot += fmt::format("\t\tnode [style=filled];\n");
for (const u32 block_index : function.blocks) {
const Block& block{function.blocks_data[block_index]};
- const std::string name{Name(block)};
+ const std::string name{NameOf(block)};
const auto add_branch = [&](BlockId branch_id, bool add_label) {
const auto it{std::ranges::find(function.blocks_data, branch_id, &Block::id)};
dot += fmt::format("\t\t{}->", name);
if (it == function.blocks_data.end()) {
dot += fmt::format("\"Unknown label {}\"", branch_id);
} else {
- dot += Name(*it);
+ dot += NameOf(*it);
};
if (add_label && block.cond != true && block.cond != false) {
dot += fmt::format(" [label=\"{}\"]", block.cond);
@@ -520,7 +638,7 @@ std::string CFG::Dot() const {
if (functions.front().blocks.empty()) {
dot += "Start;\n";
} else {
- dot += fmt::format("\tStart -> {};\n", Name(functions.front().blocks_data.front()));
+ dot += fmt::format("\tStart -> {};\n", NameOf(functions.front().blocks_data.front()));
}
dot += fmt::format("\tStart [shape=diamond];\n");
}
--
cgit v1.2.3-70-g09d2