Shape *MakeLoop(BlockSet &Blocks, BlockSet& Entries, BlockSet &NextEntries) {
// Find the inner blocks in this loop. Proceed backwards from the entries until
// you reach a seen block, collecting as you go.
BlockSet InnerBlocks;
BlockSet Queue = Entries;
while (Queue.size() > 0) {
Block *Curr = *(Queue.begin());
Queue.erase(Queue.begin());
if (InnerBlocks.find(Curr) == InnerBlocks.end()) {
// This element is new, mark it as inner and remove from outer
InnerBlocks.insert(Curr);
Blocks.erase(Curr);
// Add the elements prior to it
for (BlockBranchMap::iterator iter = Curr->BranchesIn.begin(); iter != Curr->BranchesIn.end(); iter++) {
Queue.insert(iter->first);
}
}
}
assert(InnerBlocks.size() > 0);
for (BlockSet::iterator iter = InnerBlocks.begin(); iter != InnerBlocks.end(); iter++) {
Block *Curr = *iter;
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *Possible = iter->first;
if (InnerBlocks.find(Possible) == InnerBlocks.end() &&
NextEntries.find(Possible) == NextEntries.find(Possible)) {
NextEntries.insert(Possible);
}
}
}
PrintDebug("creating loop block:\n");
DebugDump(InnerBlocks, " inner blocks:");
DebugDump(Entries, " inner entries:");
DebugDump(Blocks, " outer blocks:");
DebugDump(NextEntries, " outer entries:");
// TODO: Optionally hoist additional blocks into the loop
LoopShape *Loop = new LoopShape();
Notice(Loop);
// Solipsize the loop, replacing with break/continue and marking branches as Processed (will not affect later calculations)
// A. Branches to the loop entries become a continue to this shape
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
Solipsize(*iter, Branch::Continue, Loop, InnerBlocks);
}
// B. Branches to outside the loop (a next entry) become breaks on this shape
for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) {
Solipsize(*iter, Branch::Break, Loop, InnerBlocks);
}
// Finish up
Shape *Inner = Process(InnerBlocks, Entries, NULL);
Loop->Inner = Inner;
return Loop;
}
// If a block has multiple entries but no exits, and it is small enough, it is useful to split it.
// A common example is a C++ function where everything ends up at a final exit block and does some
// RAII cleanup. Without splitting, we will be forced to introduce labelled loops to allow
// reaching the final block
void SplitDeadEnds() {
unsigned TotalCodeSize = 0;
for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
Block *Curr = *iter;
TotalCodeSize += strlen(Curr->Code);
}
BlockSet Splits;
BlockSet Removed;
//DebugDump(Live, "before");
for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
Block *Original = *iter;
if (Original->BranchesIn.size() <= 1 || Original->BranchesOut.size() > 0) continue; // only dead ends, for now
if (contains(Original->BranchesOut, Original)) continue; // cannot split a looping node
if (strlen(Original->Code)*(Original->BranchesIn.size()-1) > TotalCodeSize/5) continue; // if splitting increases raw code size by a significant amount, abort
// Split the node (for simplicity, we replace all the blocks, even though we could have reused the original)
PrintDebug("Splitting block %d\n", Original->Id);
for (BlockSet::iterator iter = Original->BranchesIn.begin(); iter != Original->BranchesIn.end(); iter++) {
Block *Prior = *iter;
Block *Split = new Block(Original->Code, Original->BranchVar);
Parent->AddBlock(Split);
PrintDebug(" to %d\n", Split->Id);
Split->BranchesIn.insert(Prior);
Branch *Details = Prior->BranchesOut[Original];
Prior->BranchesOut[Split] = new Branch(Details->Condition, Details->Code);
Prior->BranchesOut.erase(Original);
for (BlockBranchMap::iterator iter = Original->BranchesOut.begin(); iter != Original->BranchesOut.end(); iter++) {
Block *Post = iter->first;
Branch *Details = iter->second;
Split->BranchesOut[Post] = new Branch(Details->Condition, Details->Code);
Post->BranchesIn.insert(Split);
}
Splits.insert(Split);
Removed.insert(Original);
}
for (BlockBranchMap::iterator iter = Original->BranchesOut.begin(); iter != Original->BranchesOut.end(); iter++) {
Block *Post = iter->first;
Post->BranchesIn.erase(Original);
}
//DebugDump(Live, "mid");
}
for (BlockSet::iterator iter = Splits.begin(); iter != Splits.end(); iter++) {
Live.insert(*iter);
}
for (BlockSet::iterator iter = Removed.begin(); iter != Removed.end(); iter++) {
Live.erase(*iter);
}
//DebugDump(Live, "after");
}
static BlockSet getBlocksWithBranchesThatDependOn(
const BlockSet& blocksWithBackwardsBranches,
const InstructionSet& instructionsThatCanObserveSideEffects,
DependenceAnalysis* dependenceAnalysis,
ControlDependenceAnalysis* controlDependenceAnalysis)
{
BlockSet blocksWithDependentBranches;
report(" Getting blocks with branches that can observe side-effects");
for(auto blockWithBranch : blocksWithBackwardsBranches)
{
auto branch = getBranch(blockWithBranch);
if(branch == nullptr) continue;
auto controlDependentInstructions = getControlDependentInstructions(
branch, instructionsThatCanObserveSideEffects,
controlDependenceAnalysis);
for(auto instruction : controlDependentInstructions)
{
if(dependenceAnalysis->dependsOn(instruction, branch))
{
report(" " << blockWithBranch->label());
blocksWithDependentBranches.insert(blockWithBranch);
break;
}
}
}
return blocksWithDependentBranches;
}
static void chaseDownPredecessors(iterator node, Register value,
DataflowGraph* dfg,
dataflow_iterator block, NodeList& nodes,
InstructionToNodeMap& instructionToNodes, BlockSet& visited)
{
if(!visited.insert(block).second) return;
assert(block->aliveIn().count(value) != 0);
for(auto predecessor : block->predecessors())
{
if(predecessor->aliveOut().count(value) == 0) continue;
bool foundAnyDefinitions = false;
// check the body for a definition
for(auto instruction = predecessor->instructions().rbegin();
instruction != predecessor->instructions().rend(); ++instruction)
{
for(auto destination : instruction->d)
{
if(*destination.pointer == value)
{
auto producer = nodes.end();
auto ptx = static_cast<PTXInstruction*>(instruction->i);
auto existingNode = instructionToNodes.find(ptx);
if(existingNode == instructionToNodes.end())
{
producer = nodes.insert(nodes.end(), Node(ptx));
instructionToNodes.insert(
std::make_pair(ptx, producer));
}
else
{
producer = existingNode->second;
}
report(" " << producer->instruction->toString() << " -> "
<< node->instruction->toString());
node->predecessors.push_back(producer);
producer->successors.push_back(node);
foundAnyDefinitions = true;
break;
}
}
}
if(foundAnyDefinitions) continue;
// if no definitions were found, recurse through predecessors
chaseDownPredecessors(node, value, dfg, predecessor, nodes,
instructionToNodes, visited);
}
}
void DeadCodeEliminationPass::runOnKernel(ir::IRKernel& k)
{
report("Running dead code elimination on kernel " << k.name);
reportE(REPORT_PTX, k);
Analysis* dfgAnalysis = getAnalysis(Analysis::DataflowGraphAnalysis);
assert(dfgAnalysis != 0);
analysis::DataflowGraph& dfg =
*static_cast<analysis::DataflowGraph*>(dfgAnalysis);
assert(dfg.ssa() != analysis::DataflowGraph::SsaType::None);
BlockSet blocks;
report(" Starting by scanning all basic blocks");
for(iterator block = dfg.begin(); block != dfg.end(); ++block)
{
report(" Queueing up BB_" << block->id());
blocks.insert(block);
}
while(!blocks.empty())
{
iterator block = *blocks.begin();
blocks.erase(blocks.begin());
eliminateDeadInstructions(dfg, blocks, block);
}
report("Finished running dead code elimination on kernel " << k.name);
reportE(REPORT_PTX, k);
}
static BlockSet getBlocksWithCallsToFuctionsThatObserveSideEffects(
ir::IRKernel& k)
{
BlockSet blocks;
report(" Getting functions that can observe side-effects");
for(auto block = k.cfg()->begin(); block != k.cfg()->end(); ++block)
{
for(auto instruction : block->instructions)
{
auto ptxInstruction = static_cast<ir::PTXInstruction*>(instruction);
// TODO: Check that the target can observe side effects
if(ptxInstruction->isCall())
{
report(" " << ptxInstruction->toString());
blocks.insert(block);
break;
}
}
}
return blocks;
}
Layer Layer::getSubgraphConnectedToTheseOutputs(
const NeuronSet& outputs) const
{
typedef std::set<size_t> BlockSet;
BlockSet blocks;
// TODO: eliminate the reundant inserts
for(auto& output : outputs)
{
size_t block = (output / getOutputBlockingFactor()) % this->blocks();
blocks.insert(block);
}
Layer layer(blocks.size(), getInputBlockingFactor(),
getOutputBlockingFactor(), blockStep());
for(auto& block : blocks)
{
size_t blockIndex = block - *blocks.begin();
layer[blockIndex] = (*this)[block];
layer.at_bias(blockIndex) = at_bias(block);
}
return layer;
}
// Create a list of entries from a block. If LimitTo is provided, only results in that set
// will appear
void GetBlocksOut(Block *Source, BlockSet& Entries, BlockSet *LimitTo=NULL) {
for (BlockBranchMap::iterator iter = Source->BranchesOut.begin(); iter != Source->BranchesOut.end(); iter++) {
if (!LimitTo || LimitTo->find(iter->first) != LimitTo->end()) {
Entries.insert(iter->first);
}
}
}
static bool allPreviousDefinitionsDominateMove(instruction_iterator move,
block_iterator block, BlockSet& visited)
{
if(!visited.insert(block->id()).second) return true;
assert(move->d.size() == 1);
auto destination = *move->d.front().pointer;
// If the value is defined by a phi with multiple sources, then the
// previous definition does not dominate the move
for(auto phi = block->phis().begin(); phi != block->phis().end(); ++phi)
{
if(phi->d == destination)
{
return false;
}
}
// Check all predecessors with the value live out
for(auto predecessor = block->predecessors().begin();
predecessor != block->predecessors().end(); ++predecessor)
{
if((*predecessor)->aliveOut().count(destination) == 0) continue;
if(!allPreviousDefinitionsDominateMove(move, *predecessor, visited))
{
return false;
}
}
return true;
}
ControlFlowGraph::BlockPointerVector
ControlFlowGraph::reverse_topological_sequence() {
typedef std::set<iterator, BlockSetCompare> BlockSet;
typedef std::queue<iterator> Queue;
report("Creating reverse topological order traversal");
BlockSet visited;
BlockPointerVector sequence;
Queue queue;
queue.push(get_exit_block());
while (sequence.size() != size()) {
if(queue.empty()) {
for (pointer_iterator block = sequence.begin();
block != sequence.end(); ++block) {
for (pointer_iterator pred = (*block)->predecessors.begin();
pred != (*block)->predecessors.end(); ++pred) {
if (visited.count(*pred) == 0) {
queue.push(*pred);
break;
}
}
if(!queue.empty()) {
break;
}
}
if(queue.empty()) break; // The remaining blocks are unreachable
}
iterator current = queue.front();
queue.pop();
if(!visited.insert(current).second) continue;
sequence.push_back(current);
report(" Adding block " << current->label());
for (pointer_iterator block = current->predecessors.begin();
block != current->predecessors.end(); ++block) {
bool noDependencies = true;
for (pointer_iterator successor = (*block)->successors.begin();
successor != (*block)->successors.end(); ++successor) {
if (visited.count(*successor) == 0) {
noDependencies = false;
break;
}
}
if(noDependencies) {
queue.push(*block);
}
}
}
return sequence;
}
ControlFlowGraph::BlockPointerVector ControlFlowGraph::pre_order_sequence() {
typedef std::unordered_set<iterator> BlockSet;
typedef std::stack<iterator> Stack;
BlockSet visited;
BlockPointerVector sequence;
Stack stack;
if (!empty()) {
stack.push(get_entry_block());
visited.insert(get_entry_block());
}
while (!stack.empty()) {
iterator current = stack.top();
stack.pop();
sequence.push_back(current);
// favor the fallthrough
iterator fallthrough = end();
if (current->has_fallthrough_edge()) {
edge_iterator fallthroughEdge
= sequence.back()->get_fallthrough_edge();
if (visited.insert(fallthroughEdge->tail).second) {
fallthrough = fallthroughEdge->tail;
}
}
for (pointer_iterator block = current->successors.begin();
block != current->successors.end(); ++block) {
if (visited.insert(*block).second) {
stack.push(*block);
}
}
if (fallthrough != end()) {
stack.push(fallthrough);
}
}
return sequence;
}
ControlFlowGraph::BlockPointerVector ControlFlowGraph::post_order_sequence() {
typedef std::unordered_set<iterator> BlockSet;
typedef std::stack<iterator> Stack;
report("Creating post order traversal");
BlockSet visited;
BlockPointerVector sequence;
Stack stack;
if (!empty()) {
for (pointer_iterator
block = get_entry_block()->successors.begin();
block != get_entry_block()->successors.end(); ++block) {
if (visited.insert(*block).second) {
stack.push(*block);
}
}
}
while (!stack.empty()) {
iterator current = stack.top();
bool one = false;
for (pointer_iterator block = current->successors.begin();
block != current->successors.end(); ++block) {
if (visited.insert(*block).second) {
stack.push(*block);
one = true;
}
}
if(!one) {
stack.pop();
sequence.push_back(current);
report(" Adding block " << current->label());
}
}
report(" Adding block " << get_entry_block()->label());
sequence.push_back(get_entry_block());
return sequence;
}
void FindLive(Block *Root) {
BlockList ToInvestigate;
ToInvestigate.push_back(Root);
while (ToInvestigate.size() > 0) {
Block *Curr = ToInvestigate.front();
ToInvestigate.pop_front();
if (Live.find(Curr) != Live.end()) continue;
Live.insert(Curr);
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
ToInvestigate.push_back(iter->first);
}
}
}
Shape *MakeSimple(BlockSet &Blocks, Block *Inner, BlockSet &NextEntries) {
PrintDebug("creating simple block with block #%d\n", Inner->Id);
SimpleShape *Simple = new SimpleShape;
Notice(Simple);
Simple->Inner = Inner;
Inner->Parent = Simple;
if (Blocks.size() > 1) {
Blocks.erase(Inner);
GetBlocksOut(Inner, NextEntries, &Blocks);
BlockSet JustInner;
JustInner.insert(Inner);
for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) {
Solipsize(*iter, Branch::Direct, Simple, JustInner);
}
}
return Simple;
}
Shape *MakeMultiple(BlockSet &Blocks, BlockSet& Entries, BlockBlockSetMap& IndependentGroups, Shape *Prev, BlockSet &NextEntries) {
PrintDebug("creating multiple block with %d inner groups\n", IndependentGroups.size());
bool Fused = !!(Shape::IsSimple(Prev));
MultipleShape *Multiple = new MultipleShape();
Notice(Multiple);
BlockSet CurrEntries;
for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) {
Block *CurrEntry = iter->first;
BlockSet &CurrBlocks = iter->second;
PrintDebug(" multiple group with entry %d:\n", CurrEntry->Id);
DebugDump(CurrBlocks, " ");
// Create inner block
CurrEntries.clear();
CurrEntries.insert(CurrEntry);
for (BlockSet::iterator iter = CurrBlocks.begin(); iter != CurrBlocks.end(); iter++) {
Block *CurrInner = *iter;
// Remove the block from the remaining blocks
Blocks.erase(CurrInner);
// Find new next entries and fix branches to them
for (BlockBranchMap::iterator iter = CurrInner->BranchesOut.begin(); iter != CurrInner->BranchesOut.end();) {
Block *CurrTarget = iter->first;
BlockBranchMap::iterator Next = iter;
Next++;
if (CurrBlocks.find(CurrTarget) == CurrBlocks.end()) {
NextEntries.insert(CurrTarget);
Solipsize(CurrTarget, Branch::Break, Multiple, CurrBlocks);
}
iter = Next; // increment carefully because Solipsize can remove us
}
}
Multiple->InnerMap[CurrEntry] = Process(CurrBlocks, CurrEntries, NULL);
// If we are not fused, then our entries will actually be checked
if (!Fused) {
CurrEntry->IsCheckedMultipleEntry = true;
}
}
DebugDump(Blocks, " remaining blocks after multiple:");
// Add entries not handled as next entries, they are deferred
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
Block *Entry = *iter;
if (IndependentGroups.find(Entry) == IndependentGroups.end()) {
NextEntries.insert(Entry);
}
}
return Multiple;
}
void StackAllocationPromoter::pruneAllocStackUsage() {
DEBUG(llvm::dbgs() << "*** Pruning : " << *ASI);
BlockSet Blocks;
// Insert all of the blocks that ASI is live in.
for (auto UI = ASI->use_begin(), E = ASI->use_end(); UI != E; ++UI)
Blocks.insert(UI->getUser()->getParent());
// Clear AllocStack state.
LastStoreInBlock.clear();
for (auto Block : Blocks) {
StoreInst *SI = promoteAllocationInBlock(Block);
LastStoreInBlock[Block] = SI;
}
DEBUG(llvm::dbgs() << "*** Finished pruning : " << *ASI);
}
static void propagateMoveSourceToUsersInBlock(instruction_iterator move,
instruction_iterator position, block_iterator block, BlockSet& visited)
{
// early exit for visited blocks
if(!visited.insert(block->id()).second) return;
assert(move->d.size() == 1);
assert(move->s.size() == 1);
auto destination = *move->d.front().pointer;
auto moveSource = *move->s.front().pointer;
// We can skip PHIs because the use of a PHI would make the removal illegal
// replace uses in the block
for(; position != block->instructions().end(); ++position)
{
for(auto source = position->s.begin();
source != position->s.end(); ++source)
{
if(*source->pointer == destination)
{
*source->pointer = moveSource;
}
}
}
// replace in successors
for(auto successor = block->successors().begin();
successor != block->successors().end(); ++successor)
{
if((*successor)->aliveIn().count(destination) == 0) continue;
propagateMoveSourceToUsersInBlock(move,
(*successor)->instructions().begin(), *successor, visited);
}
}
// If a block has multiple entries but no exits, and it is small enough, it is useful to split it.
// A common example is a C++ function where everything ends up at a final exit block and does some
// RAII cleanup. Without splitting, we will be forced to introduce labelled loops to allow
// reaching the final block
void SplitDeadEnds() {
int TotalCodeSize = 0;
for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
Block *Curr = *iter;
TotalCodeSize += strlen(Curr->Code);
}
for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
Block *Original = *iter;
if (Original->BranchesIn.size() <= 1 || Original->BranchesOut.size() > 0) continue;
if (strlen(Original->Code)*(Original->BranchesIn.size()-1) > TotalCodeSize/5) continue; // if splitting increases raw code size by a significant amount, abort
// Split the node (for simplicity, we replace all the blocks, even though we could have reused the original)
for (BlockBranchMap::iterator iter = Original->BranchesIn.begin(); iter != Original->BranchesIn.end(); iter++) {
Block *Prior = iter->first;
Block *Split = new Block(Original->Code);
Split->BranchesIn[Prior] = new Branch(NULL);
Prior->BranchesOut[Split] = new Branch(Prior->BranchesOut[Original]->Condition, Prior->BranchesOut[Original]->Code);
Prior->BranchesOut.erase(Original);
Parent->AddBlock(Split);
Live.insert(Split);
}
}
}
static BlockSet getBlocksWithBackwardsBranches(CycleAnalysis* cycleAnalysis)
{
auto edges = cycleAnalysis->getAllBackEdges();
report(" Getting blocks with backwards branches");
BlockSet backwardsBranchBlocks;
for(auto& edge : edges)
{
if(edge->type != ir::Edge::Branch) continue;
auto block = edge->head;
if(getBranch(block) == nullptr) continue;
backwardsBranchBlocks.insert(block);
report(" " << block->label());
}
return backwardsBranchBlocks;
}
void ConstantPropagationPass::runOnKernel(ir::IRKernel& k)
{
report("Running constant propagation on kernel " << k.name);
Analysis* dfgAnalysis = getAnalysis("DataflowGraphAnalysis");
assert(dfgAnalysis != 0);
analysis::DataflowGraph& dfg =
*static_cast<analysis::DataflowGraph*>(dfgAnalysis);
dfg.convertToSSAType(analysis::DataflowGraph::Minimal);
assert(dfg.ssa() == analysis::DataflowGraph::Minimal);
BlockSet blocks;
report(" Starting by scanning all basic blocks");
for(iterator block = dfg.begin(); block != dfg.end(); ++block)
{
report(" Queueing up BB_" << block->id());
blocks.insert(block);
}
while(!blocks.empty())
{
iterator block = *blocks.begin();
blocks.erase(blocks.begin());
eliminateRedundantInstructions(dfg, blocks, block);
}
report("Finished running constant propagation on kernel " << k.name);
reportE(REPORT_PTX, k);
}
ControlFlowGraph::ConstBlockPointerVector
ControlFlowGraph::executable_sequence() const {
typedef std::unordered_set<const_iterator> BlockSet;
ConstBlockPointerVector sequence;
BlockSet unscheduled;
for(const_iterator i = begin(); i != end(); ++i) {
unscheduled.insert(i);
}
report("Getting executable sequence.");
sequence.push_back(get_entry_block());
unscheduled.erase(get_entry_block());
report(" added " << get_entry_block()->label());
while (!unscheduled.empty()) {
if (sequence.back()->has_fallthrough_edge()) {
const_edge_iterator fallthroughEdge
= sequence.back()->get_fallthrough_edge();
sequence.push_back(fallthroughEdge->tail);
unscheduled.erase(fallthroughEdge->tail);
}
else {
// find a new block, favor branch targets over random blocks
const_iterator next = *unscheduled.begin();
for(const_edge_pointer_iterator
edge = sequence.back()->out_edges.begin();
edge != sequence.back()->out_edges.end(); ++edge)
{
if(unscheduled.count((*edge)->tail) != 0)
{
next = (*edge)->tail;
}
}
// rewind through fallthrough edges to find the beginning of the
// next chain of fall throughs
report(" restarting at " << next->label());
bool rewinding = true;
while (rewinding) {
rewinding = false;
for (const_edge_pointer_iterator
edge = next->in_edges.begin();
edge != next->in_edges.end(); ++edge) {
if ((*edge)->type == Edge::FallThrough) {
assertM(unscheduled.count((*edge)->head) != 0,
(*edge)->head->label()
<< " has multiple fallthrough branches.");
next = (*edge)->head;
report(" rewinding to " << next->label());
rewinding = true;
break;
}
}
}
sequence.push_back(next);
unscheduled.erase(next);
}
report(" added " << sequence.back()->label());
}
return sequence;
}
Shape *MakeLoop(BlockSet &Blocks, BlockSet& Entries, BlockSet &NextEntries) {
// Find the inner blocks in this loop. Proceed backwards from the entries until
// you reach a seen block, collecting as you go.
BlockSet InnerBlocks;
BlockSet Queue = Entries;
while (Queue.size() > 0) {
Block *Curr = *(Queue.begin());
Queue.erase(Queue.begin());
if (!contains(InnerBlocks, Curr)) {
// This element is new, mark it as inner and remove from outer
InnerBlocks.insert(Curr);
Blocks.erase(Curr);
// Add the elements prior to it
for (BlockSet::iterator iter = Curr->BranchesIn.begin(); iter != Curr->BranchesIn.end(); iter++) {
Queue.insert(*iter);
}
#if 0
// Add elements it leads to, if they are dead ends. There is no reason not to hoist dead ends
// into loops, as it can avoid multiple entries after the loop
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *Target = iter->first;
if (Target->BranchesIn.size() <= 1 && Target->BranchesOut.size() == 0) {
Queue.insert(Target);
}
}
#endif
}
}
assert(InnerBlocks.size() > 0);
for (BlockSet::iterator iter = InnerBlocks.begin(); iter != InnerBlocks.end(); iter++) {
Block *Curr = *iter;
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *Possible = iter->first;
if (!contains(InnerBlocks, Possible)) {
NextEntries.insert(Possible);
}
}
}
#if 0
// We can avoid multiple next entries by hoisting them into the loop.
if (NextEntries.size() > 1) {
BlockBlockSetMap IndependentGroups;
FindIndependentGroups(NextEntries, IndependentGroups, &InnerBlocks);
while (IndependentGroups.size() > 0 && NextEntries.size() > 1) {
Block *Min = NULL;
int MinSize = 0;
for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) {
Block *Entry = iter->first;
BlockSet &Blocks = iter->second;
if (!Min || Blocks.size() < MinSize) { // TODO: code size, not # of blocks
Min = Entry;
MinSize = Blocks.size();
}
}
// check how many new entries this would cause
BlockSet &Hoisted = IndependentGroups[Min];
bool abort = false;
for (BlockSet::iterator iter = Hoisted.begin(); iter != Hoisted.end() && !abort; iter++) {
Block *Curr = *iter;
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *Target = iter->first;
if (Hoisted.find(Target) == Hoisted.end() && NextEntries.find(Target) == NextEntries.end()) {
// abort this hoisting
abort = true;
break;
}
}
}
if (abort) {
IndependentGroups.erase(Min);
continue;
}
// hoist this entry
PrintDebug("hoisting %d into loop\n", Min->Id);
NextEntries.erase(Min);
for (BlockSet::iterator iter = Hoisted.begin(); iter != Hoisted.end(); iter++) {
Block *Curr = *iter;
InnerBlocks.insert(Curr);
Blocks.erase(Curr);
}
IndependentGroups.erase(Min);
}
}
#endif
PrintDebug("creating loop block:\n");
DebugDump(InnerBlocks, " inner blocks:");
DebugDump(Entries, " inner entries:");
DebugDump(Blocks, " outer blocks:");
DebugDump(NextEntries, " outer entries:");
LoopShape *Loop = new LoopShape();
Notice(Loop);
// Solipsize the loop, replacing with break/continue and marking branches as Processed (will not affect later calculations)
// A. Branches to the loop entries become a continue to this shape
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
Solipsize(*iter, Branch::Continue, Loop, InnerBlocks);
}
// B. Branches to outside the loop (a next entry) become breaks on this shape
for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) {
Solipsize(*iter, Branch::Break, Loop, InnerBlocks);
}
// Finish up
Shape *Inner = Process(InnerBlocks, Entries, NULL);
Loop->Inner = Inner;
return Loop;
}
void ReversePostOrderTraversal::analyze(Function& function)
{
typedef util::LargeSet<BasicBlock*> BlockSet;
typedef std::stack<BasicBlock*> BlockStack;
order.clear();
BlockSet visited;
BlockStack stack;
auto cfgAnalysis = getAnalysis("ControlFlowGraph");
auto cfg = static_cast<ControlFlowGraph*>(cfgAnalysis);
report("Creating reverse post order traversal over function '" +
function.name() + "'");
// reverse post order is reversed topological order
stack.push(&*function.entry_block());
while(order.size() != function.size())
{
if(stack.empty())
{
for(auto block : order)
{
auto successors = cfg->getSuccessors(*block);
for(auto successor : successors)
{
if(visited.insert(successor).second)
{
stack.push(successor);
break;
}
}
if(!stack.empty()) break;
}
}
assertM(!stack.empty(), (function.size() - order.size())
<< " blocks are not connected.");
while(!stack.empty())
{
BasicBlock* top = stack.top();
stack.pop();
auto successors = cfg->getSuccessors(*top);
for(auto successor : successors)
{
assert(successor != nullptr);
auto predecessors = cfg->getPredecessors(*successor);
bool allPredecessorsVisited = true;
for(auto predecessor : predecessors)
{
if(visited.count(predecessor) == 0)
{
allPredecessorsVisited = false;
break;
}
}
if(!allPredecessorsVisited) continue;
if(visited.insert(successor).second)
{
stack.push(successor);
}
}
order.push_back(top);
report(" " << top->name());
}
}
// reverse the order
std::reverse(order.begin(), order.end());
}
static void updateUses(iterator block, ir::Instruction::RegisterType registerId,
const ir::PTXOperand& value, BlockSet& visited)
{
typedef analysis::DataflowGraph::RegisterPointerVector
RegisterPointerVector;
if(!visited.insert(block).second) return;
// phi uses
bool replacedPhi = false;
bool anyPhis = false;
ir::Instruction::RegisterType newRegisterId = 0;
for(auto phi = block->phis().begin(); phi != block->phis().end(); ++phi)
{
if(phi->s.size() != 1)
{
for(auto source = phi->s.begin(); source != phi->s.end(); ++source)
{
if(source->id == registerId)
{
anyPhis = true;
report(" could not remove " << phi->toString());
break;
}
}
continue;
}
for(auto source = phi->s.begin(); source != phi->s.end(); ++source)
{
if(source->id == registerId)
{
newRegisterId = phi->d.id;
block->phis().erase(phi);
auto livein = block->aliveIn().find(registerId);
assert(livein != block->aliveIn().end());
block->aliveIn().erase(livein);
report(" removed " << phi->toString());
replacedPhi = true;
break;
}
}
if(replacedPhi)
{
break;
}
}
if(replacedPhi)
{
BlockSet visited;
updateUses(block, newRegisterId, value, visited);
}
// local uses
for(auto instruction = block->instructions().begin();
instruction != block->instructions().end(); ++instruction)
{
auto ptx = static_cast<ir::PTXInstruction*>(instruction->i);
RegisterPointerVector newSources;
for(auto source = instruction->s.begin(); source !=
instruction->s.end(); ++source)
{
if(*source->pointer == registerId)
{
report(" updated use by '" << ptx->toString()
<< "', of r" << registerId);
replaceOperand(*ptx, registerId, value);
}
else
{
newSources.push_back(*source);
}
}
instruction->s = std::move(newSources);
}
if(!anyPhis)
{
auto livein = block->aliveIn().find(registerId);
if(livein != block->aliveIn().end())
{
block->aliveIn().erase(livein);
report(" removed from live-in set of block " <<
block->id());
}
}
auto liveout = block->aliveOut().find(registerId);
if(liveout == block->aliveOut().end()) return;
// uses by successors
bool anyUsesBySuccessors = false;
for(auto successor = block->successors().begin();
successor != block->successors().end(); ++successor)
{
auto livein = (*successor)->aliveIn().find(registerId);
if(livein == (*successor)->aliveIn().end()) continue;
updateUses(*successor, registerId, value, visited);
livein = (*successor)->aliveIn().find(registerId);
if(livein == (*successor)->aliveIn().end()) continue;
anyUsesBySuccessors = true;
}
if(!anyUsesBySuccessors)
{
report(" removed from live-out set of BB_" << block->id());
block->aliveOut().erase(liveout);
}
}
void Relooper::Calculate(Block *Entry) {
// Scan and optimize the input
struct PreOptimizer : public RelooperRecursor {
PreOptimizer(Relooper *Parent) : RelooperRecursor(Parent) {}
BlockSet Live;
void FindLive(Block *Root) {
BlockList ToInvestigate;
ToInvestigate.push_back(Root);
while (ToInvestigate.size() > 0) {
Block *Curr = ToInvestigate.front();
ToInvestigate.pop_front();
if (Live.find(Curr) != Live.end()) continue;
Live.insert(Curr);
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
ToInvestigate.push_back(iter->first);
}
}
}
// If a block has multiple entries but no exits, and it is small enough, it is useful to split it.
// A common example is a C++ function where everything ends up at a final exit block and does some
// RAII cleanup. Without splitting, we will be forced to introduce labelled loops to allow
// reaching the final block
void SplitDeadEnds() {
int TotalCodeSize = 0;
for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
Block *Curr = *iter;
TotalCodeSize += strlen(Curr->Code);
}
for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
Block *Original = *iter;
if (Original->BranchesIn.size() <= 1 || Original->BranchesOut.size() > 0) continue;
if (strlen(Original->Code)*(Original->BranchesIn.size()-1) > TotalCodeSize/5) continue; // if splitting increases raw code size by a significant amount, abort
// Split the node (for simplicity, we replace all the blocks, even though we could have reused the original)
for (BlockBranchMap::iterator iter = Original->BranchesIn.begin(); iter != Original->BranchesIn.end(); iter++) {
Block *Prior = iter->first;
Block *Split = new Block(Original->Code);
Split->BranchesIn[Prior] = new Branch(NULL);
Prior->BranchesOut[Split] = new Branch(Prior->BranchesOut[Original]->Condition, Prior->BranchesOut[Original]->Code);
Prior->BranchesOut.erase(Original);
Parent->AddBlock(Split);
Live.insert(Split);
}
}
}
};
PreOptimizer Pre(this);
Pre.FindLive(Entry);
// Add incoming branches from live blocks, ignoring dead code
for (int i = 0; i < Blocks.size(); i++) {
Block *Curr = Blocks[i];
if (Pre.Live.find(Curr) == Pre.Live.end()) continue;
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
iter->first->BranchesIn[Curr] = new Branch(NULL);
}
}
Pre.SplitDeadEnds();
// Recursively process the graph
struct Analyzer : public RelooperRecursor {
Analyzer(Relooper *Parent) : RelooperRecursor(Parent) {}
// Add a shape to the list of shapes in this Relooper calculation
void Notice(Shape *New) {
Parent->Shapes.push_back(New);
}
// Create a list of entries from a block. If LimitTo is provided, only results in that set
// will appear
void GetBlocksOut(Block *Source, BlockSet& Entries, BlockSet *LimitTo=NULL) {
for (BlockBranchMap::iterator iter = Source->BranchesOut.begin(); iter != Source->BranchesOut.end(); iter++) {
if (!LimitTo || LimitTo->find(iter->first) != LimitTo->end()) {
Entries.insert(iter->first);
}
}
}
// Converts/processes all branchings to a specific target
void Solipsize(Block *Target, Branch::FlowType Type, Shape *Ancestor, BlockSet &From) {
PrintDebug("Solipsizing branches into %d\n", Target->Id);
DebugDump(From, " relevant to solipsize: ");
for (BlockBranchMap::iterator iter = Target->BranchesIn.begin(); iter != Target->BranchesIn.end();) {
Block *Prior = iter->first;
if (From.find(Prior) == From.end()) {
iter++;
continue;
}
Branch *TargetIn = iter->second;
Branch *PriorOut = Prior->BranchesOut[Target];
PriorOut->Ancestor = Ancestor; // Do we need this info
PriorOut->Type = Type; // on TargetIn too?
if (MultipleShape *Multiple = Shape::IsMultiple(Ancestor)) {
Multiple->NeedLoop++; // We are breaking out of this Multiple, so need a loop
}
iter++; // carefully increment iter before erasing
Target->BranchesIn.erase(Prior);
Target->ProcessedBranchesIn[Prior] = TargetIn;
Prior->BranchesOut.erase(Target);
Prior->ProcessedBranchesOut[Target] = PriorOut;
PrintDebug(" eliminated branch from %d\n", Prior->Id);
}
}
Shape *MakeSimple(BlockSet &Blocks, Block *Inner, BlockSet &NextEntries) {
PrintDebug("creating simple block with block #%d\n", Inner->Id);
SimpleShape *Simple = new SimpleShape;
Notice(Simple);
Simple->Inner = Inner;
Inner->Parent = Simple;
if (Blocks.size() > 1) {
Blocks.erase(Inner);
GetBlocksOut(Inner, NextEntries, &Blocks);
BlockSet JustInner;
JustInner.insert(Inner);
for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) {
Solipsize(*iter, Branch::Direct, Simple, JustInner);
}
}
return Simple;
}
Shape *MakeLoop(BlockSet &Blocks, BlockSet& Entries, BlockSet &NextEntries) {
// Find the inner blocks in this loop. Proceed backwards from the entries until
// you reach a seen block, collecting as you go.
BlockSet InnerBlocks;
BlockSet Queue = Entries;
while (Queue.size() > 0) {
Block *Curr = *(Queue.begin());
Queue.erase(Queue.begin());
if (InnerBlocks.find(Curr) == InnerBlocks.end()) {
// This element is new, mark it as inner and remove from outer
InnerBlocks.insert(Curr);
Blocks.erase(Curr);
// Add the elements prior to it
for (BlockBranchMap::iterator iter = Curr->BranchesIn.begin(); iter != Curr->BranchesIn.end(); iter++) {
Queue.insert(iter->first);
}
}
}
assert(InnerBlocks.size() > 0);
for (BlockSet::iterator iter = InnerBlocks.begin(); iter != InnerBlocks.end(); iter++) {
Block *Curr = *iter;
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *Possible = iter->first;
if (InnerBlocks.find(Possible) == InnerBlocks.end() &&
NextEntries.find(Possible) == NextEntries.find(Possible)) {
NextEntries.insert(Possible);
}
}
}
PrintDebug("creating loop block:\n");
DebugDump(InnerBlocks, " inner blocks:");
DebugDump(Entries, " inner entries:");
DebugDump(Blocks, " outer blocks:");
DebugDump(NextEntries, " outer entries:");
// TODO: Optionally hoist additional blocks into the loop
LoopShape *Loop = new LoopShape();
Notice(Loop);
// Solipsize the loop, replacing with break/continue and marking branches as Processed (will not affect later calculations)
// A. Branches to the loop entries become a continue to this shape
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
Solipsize(*iter, Branch::Continue, Loop, InnerBlocks);
}
// B. Branches to outside the loop (a next entry) become breaks on this shape
for (BlockSet::iterator iter = NextEntries.begin(); iter != NextEntries.end(); iter++) {
Solipsize(*iter, Branch::Break, Loop, InnerBlocks);
}
// Finish up
Shape *Inner = Process(InnerBlocks, Entries, NULL);
Loop->Inner = Inner;
return Loop;
}
// For each entry, find the independent group reachable by it. The independent group is
// the entry itself, plus all the blocks it can reach that cannot be directly reached by another entry. Note that we
// ignore directly reaching the entry itself by another entry.
void FindIndependentGroups(BlockSet &Blocks, BlockSet &Entries, BlockBlockSetMap& IndependentGroups) {
typedef std::map<Block*, Block*> BlockBlockMap;
struct HelperClass {
BlockBlockSetMap& IndependentGroups;
BlockBlockMap Ownership; // For each block, which entry it belongs to. We have reached it from there.
HelperClass(BlockBlockSetMap& IndependentGroupsInit) : IndependentGroups(IndependentGroupsInit) {}
void InvalidateWithChildren(Block *New) { // TODO: rename New
BlockList ToInvalidate; // Being in the list means you need to be invalidated
ToInvalidate.push_back(New);
while (ToInvalidate.size() > 0) {
Block *Invalidatee = ToInvalidate.front();
ToInvalidate.pop_front();
Block *Owner = Ownership[Invalidatee];
if (IndependentGroups.find(Owner) != IndependentGroups.end()) { // Owner may have been invalidated, do not add to IndependentGroups!
IndependentGroups[Owner].erase(Invalidatee);
}
if (Ownership[Invalidatee]) { // may have been seen before and invalidated already
Ownership[Invalidatee] = NULL;
for (BlockBranchMap::iterator iter = Invalidatee->BranchesOut.begin(); iter != Invalidatee->BranchesOut.end(); iter++) {
Block *Target = iter->first;
BlockBlockMap::iterator Known = Ownership.find(Target);
if (Known != Ownership.end()) {
Block *TargetOwner = Known->second;
if (TargetOwner) {
ToInvalidate.push_back(Target);
}
}
}
}
}
}
};
HelperClass Helper(IndependentGroups);
// We flow out from each of the entries, simultaneously.
// When we reach a new block, we add it as belonging to the one we got to it from.
// If we reach a new block that is already marked as belonging to someone, it is reachable by
// two entries and is not valid for any of them. Remove it and all it can reach that have been
// visited.
BlockList Queue; // Being in the queue means we just added this item, and we need to add its children
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
Block *Entry = *iter;
Helper.Ownership[Entry] = Entry;
IndependentGroups[Entry].insert(Entry);
Queue.push_back(Entry);
}
while (Queue.size() > 0) {
Block *Curr = Queue.front();
Queue.pop_front();
Block *Owner = Helper.Ownership[Curr]; // Curr must be in the ownership map if we are in the queue
if (!Owner) continue; // we have been invalidated meanwhile after being reached from two entries
// Add all children
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *New = iter->first;
BlockBlockMap::iterator Known = Helper.Ownership.find(New);
if (Known == Helper.Ownership.end()) {
// New node. Add it, and put it in the queue
Helper.Ownership[New] = Owner;
IndependentGroups[Owner].insert(New);
Queue.push_back(New);
continue;
}
Block *NewOwner = Known->second;
if (!NewOwner) continue; // We reached an invalidated node
if (NewOwner != Owner) {
// Invalidate this and all reachable that we have seen - we reached this from two locations
Helper.InvalidateWithChildren(New);
}
// otherwise, we have the same owner, so do nothing
}
}
// Having processed all the interesting blocks, we remain with just one potential issue:
// If a->b, and a was invalidated, but then b was later reached by someone else, we must
// invalidate b. To check for this, we go over all elements in the independent groups,
// if an element has a parent which does *not* have the same owner, we must remove it
// and all its children.
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
BlockSet &CurrGroup = IndependentGroups[*iter];
BlockList ToInvalidate;
for (BlockSet::iterator iter = CurrGroup.begin(); iter != CurrGroup.end(); iter++) {
Block *Child = *iter;
for (BlockBranchMap::iterator iter = Child->BranchesIn.begin(); iter != Child->BranchesIn.end(); iter++) {
Block *Parent = iter->first;
if (Helper.Ownership[Parent] != Helper.Ownership[Child]) {
ToInvalidate.push_back(Child);
}
}
}
while (ToInvalidate.size() > 0) {
Block *Invalidatee = ToInvalidate.front();
ToInvalidate.pop_front();
Helper.InvalidateWithChildren(Invalidatee);
}
}
// Remove empty groups
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
if (IndependentGroups[*iter].size() == 0) {
IndependentGroups.erase(*iter);
}
}
#if DEBUG
PrintDebug("Investigated independent groups:\n");
for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) {
DebugDump(iter->second, " group: ");
}
#endif
}
Shape *MakeMultiple(BlockSet &Blocks, BlockSet& Entries, BlockBlockSetMap& IndependentGroups, Shape *Prev, BlockSet &NextEntries) {
PrintDebug("creating multiple block with %d inner groups\n", IndependentGroups.size());
bool Fused = !!(Shape::IsSimple(Prev));
MultipleShape *Multiple = new MultipleShape();
Notice(Multiple);
BlockSet CurrEntries;
for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end(); iter++) {
Block *CurrEntry = iter->first;
BlockSet &CurrBlocks = iter->second;
PrintDebug(" multiple group with entry %d:\n", CurrEntry->Id);
DebugDump(CurrBlocks, " ");
// Create inner block
CurrEntries.clear();
CurrEntries.insert(CurrEntry);
for (BlockSet::iterator iter = CurrBlocks.begin(); iter != CurrBlocks.end(); iter++) {
Block *CurrInner = *iter;
// Remove the block from the remaining blocks
Blocks.erase(CurrInner);
// Find new next entries and fix branches to them
for (BlockBranchMap::iterator iter = CurrInner->BranchesOut.begin(); iter != CurrInner->BranchesOut.end();) {
Block *CurrTarget = iter->first;
BlockBranchMap::iterator Next = iter;
Next++;
if (CurrBlocks.find(CurrTarget) == CurrBlocks.end()) {
NextEntries.insert(CurrTarget);
Solipsize(CurrTarget, Branch::Break, Multiple, CurrBlocks);
}
iter = Next; // increment carefully because Solipsize can remove us
}
}
Multiple->InnerMap[CurrEntry] = Process(CurrBlocks, CurrEntries, NULL);
// If we are not fused, then our entries will actually be checked
if (!Fused) {
CurrEntry->IsCheckedMultipleEntry = true;
}
}
DebugDump(Blocks, " remaining blocks after multiple:");
// Add entries not handled as next entries, they are deferred
for (BlockSet::iterator iter = Entries.begin(); iter != Entries.end(); iter++) {
Block *Entry = *iter;
if (IndependentGroups.find(Entry) == IndependentGroups.end()) {
NextEntries.insert(Entry);
}
}
return Multiple;
}
// Main function.
// Process a set of blocks with specified entries, returns a shape
// The Make* functions receive a NextEntries. If they fill it with data, those are the entries for the
// ->Next block on them, and the blocks are what remains in Blocks (which Make* modify). In this way
// we avoid recursing on Next (imagine a long chain of Simples, if we recursed we could blow the stack).
Shape *Process(BlockSet &Blocks, BlockSet& InitialEntries, Shape *Prev) {
PrintDebug("Process() called\n");
BlockSet *Entries = &InitialEntries;
BlockSet TempEntries[2];
int CurrTempIndex = 0;
BlockSet *NextEntries;
Shape *Ret = NULL;
#define Make(call) \
Shape *Temp = call; \
if (Prev) Prev->Next = Temp; \
if (!Ret) Ret = Temp; \
if (!NextEntries->size()) { PrintDebug("Process() returning\n"); return Ret; } \
Prev = Temp; \
Entries = NextEntries; \
continue;
while (1) {
PrintDebug("Process() running\n");
DebugDump(Blocks, " blocks : ");
DebugDump(*Entries, " entries: ");
CurrTempIndex = 1-CurrTempIndex;
NextEntries = &TempEntries[CurrTempIndex];
NextEntries->clear();
if (Entries->size() == 0) return Ret;
if (Entries->size() == 1) {
Block *Curr = *(Entries->begin());
if (Curr->BranchesIn.size() == 0) {
// One entry, no looping ==> Simple
Make(MakeSimple(Blocks, Curr, *NextEntries));
}
// One entry, looping ==> Loop
Make(MakeLoop(Blocks, *Entries, *NextEntries));
}
// More than one entry, try to eliminate through a Multiple groups of
// independent blocks from an entry/ies. It is important to remove through
// multiples as opposed to looping since the former is more performant.
BlockBlockSetMap IndependentGroups;
FindIndependentGroups(Blocks, *Entries, IndependentGroups);
PrintDebug("Independent groups: %d\n", IndependentGroups.size());
if (IndependentGroups.size() > 0) {
// We can handle a group in a multiple if its entry cannot be reached by another group.
// Note that it might be reachable by itself - a loop. But that is fine, we will create
// a loop inside the multiple block (which is the performant order to do it).
for (BlockBlockSetMap::iterator iter = IndependentGroups.begin(); iter != IndependentGroups.end();) {
Block *Entry = iter->first;
BlockSet &Group = iter->second;
BlockBlockSetMap::iterator curr = iter++; // iterate carefully, we may delete
for (BlockBranchMap::iterator iterBranch = Entry->BranchesIn.begin(); iterBranch != Entry->BranchesIn.end(); iterBranch++) {
Block *Origin = iterBranch->first;
if (Group.find(Origin) == Group.end()) {
// Reached from outside the group, so we cannot handle this
PrintDebug("Cannot handle group with entry %d because of incoming branch from %d\n", Entry->Id, Origin->Id);
IndependentGroups.erase(curr);
break;
}
}
}
// As an optimization, if we have 2 independent groups, and one is a small dead end, we can handle only that dead end.
// The other then becomes a Next - without nesting in the code and recursion in the analysis.
// TODO: if the larger is the only dead end, handle that too
// TODO: handle >2 groups
// TODO: handle not just dead ends, but also that do not branch to the NextEntries. However, must be careful
// there since we create a Next, and that Next can prevent eliminating a break (since we no longer
// naturally reach the same place), which may necessitate a one-time loop, which makes the unnesting
// pointless.
if (IndependentGroups.size() == 2) {
// Find the smaller one
BlockBlockSetMap::iterator iter = IndependentGroups.begin();
Block *SmallEntry = iter->first;
int SmallSize = iter->second.size();
iter++;
Block *LargeEntry = iter->first;
int LargeSize = iter->second.size();
if (SmallSize != LargeSize) { // ignore the case where they are identical - keep things symmetrical there
if (SmallSize > LargeSize) {
Block *Temp = SmallEntry;
SmallEntry = LargeEntry;
LargeEntry = Temp; // Note: we did not flip the Sizes too, they are now invalid. TODO: use the smaller size as a limit?
}
// Check if dead end
bool DeadEnd = true;
BlockSet &SmallGroup = IndependentGroups[SmallEntry];
for (BlockSet::iterator iter = SmallGroup.begin(); iter != SmallGroup.end(); iter++) {
Block *Curr = *iter;
for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
Block *Target = iter->first;
if (SmallGroup.find(Target) == SmallGroup.end()) {
DeadEnd = false;
break;
}
}
if (!DeadEnd) break;
}
if (DeadEnd) {
PrintDebug("Removing nesting by not handling large group because small group is dead end\n");
IndependentGroups.erase(LargeEntry);
}
}
}
PrintDebug("Handleable independent groups: %d\n", IndependentGroups.size());
if (IndependentGroups.size() > 0) {
// Some groups removable ==> Multiple
Make(MakeMultiple(Blocks, *Entries, IndependentGroups, Prev, *NextEntries));
}
}
// No independent groups, must be loopable ==> Loop
Make(MakeLoop(Blocks, *Entries, *NextEntries));
}
}
};
// Main
BlockSet AllBlocks;
for (int i = 0; i < Blocks.size(); i++) {
AllBlocks.insert(Blocks[i]);
#if DEBUG
PrintDebug("Adding block %d (%s)\n", Blocks[i]->Id, Blocks[i]->Code);
for (BlockBranchMap::iterator iter = Blocks[i]->BranchesOut.begin(); iter != Blocks[i]->BranchesOut.end(); iter++) {
PrintDebug(" with branch out to %d\n", iter->first->Id);
}
#endif
}
BlockSet Entries;
Entries.insert(Entry);
Root = Analyzer(this).Process(AllBlocks, Entries, NULL);
// Post optimizations
struct PostOptimizer {
Relooper *Parent;
void *Closure;
PostOptimizer(Relooper *ParentInit) : Parent(ParentInit), Closure(NULL) {}
#define RECURSE_MULTIPLE_MANUAL(func, manual) \
for (BlockShapeMap::iterator iter = manual->InnerMap.begin(); iter != manual->InnerMap.end(); iter++) { \
func(iter->second); \
}
#define RECURSE_MULTIPLE(func) RECURSE_MULTIPLE_MANUAL(func, Multiple);
#define RECURSE_LOOP(func) \
func(Loop->Inner);
#define SHAPE_SWITCH(var, simple, multiple, loop) \
if (SimpleShape *Simple = Shape::IsSimple(var)) { \
simple; \
} else if (MultipleShape *Multiple = Shape::IsMultiple(var)) { \
multiple; \
} else if (LoopShape *Loop = Shape::IsLoop(var)) { \
loop; \
}
#define SHAPE_SWITCH_AUTO(var, simple, multiple, loop, func) \
if (SimpleShape *Simple = Shape::IsSimple(var)) { \
simple; \
func(Simple->Next); \
} else if (MultipleShape *Multiple = Shape::IsMultiple(var)) { \
multiple; \
RECURSE_MULTIPLE(func) \
func(Multiple->Next); \
} else if (LoopShape *Loop = Shape::IsLoop(var)) { \
loop; \
RECURSE_LOOP(func); \
func(Loop->Next); \
}
// Remove unneeded breaks and continues.
// A flow operation is trivially unneeded if the shape we naturally get to by normal code
// execution is the same as the flow forces us to.
void RemoveUnneededFlows(Shape *Root, Shape *Natural=NULL) {
Shape *Next = Root;
while (Next) {
Root = Next;
Next = NULL;
SHAPE_SWITCH(Root, {
// If there is a next block, we already know at Simple creation time to make direct branches,
// and we can do nothing more. If there is no next however, then Natural is where we will
// go to by doing nothing, so we can potentially optimize some branches to direct.
if (Simple->Next) {
Next = Simple->Next;
} else {
for (BlockBranchMap::iterator iter = Simple->Inner->ProcessedBranchesOut.begin(); iter != Simple->Inner->ProcessedBranchesOut.end(); iter++) {
Block *Target = iter->first;
Branch *Details = iter->second;
if (Details->Type != Branch::Direct && Target->Parent == Natural) {
Details->Type = Branch::Direct;
if (MultipleShape *Multiple = Shape::IsMultiple(Details->Ancestor)) {
Multiple->NeedLoop--;
}
}
}
}
}, {
for (BlockShapeMap::iterator iter = Multiple->InnerMap.begin(); iter != Multiple->InnerMap.end(); iter++) {
RemoveUnneededFlows(iter->second, Multiple->Next);
}
Next = Multiple->Next;
}, {
void StackAllocationPromoter::promoteAllocationToPhi() {
DEBUG(llvm::dbgs() << "*** Placing Phis for : " << *ASI);
// A list of blocks that will require new Phi values.
BlockSet PhiBlocks;
// The "piggy-bank" data-structure that we use for processing the dom-tree
// bottom-up.
NodePriorityQueue PQ;
// Collect all of the stores into the AllocStack. We know that at this point
// we have at most one store per block.
for (auto UI = ASI->use_begin(), E = ASI->use_end(); UI != E; ++UI) {
SILInstruction *II = UI->getUser();
// We need to place Phis for this block.
if (isa<StoreInst>(II)) {
// If the block is in the dom tree (dominated by the entry block).
if (DomTreeNode *Node = DT->getNode(II->getParent()))
PQ.push(std::make_pair(Node, DomTreeLevels[Node]));
}
}
DEBUG(llvm::dbgs() << "*** Found: " << PQ.size() << " Defs\n");
// A list of nodes for which we already calculated the dominator frontier.
llvm::SmallPtrSet<DomTreeNode *, 32> Visited;
SmallVector<DomTreeNode *, 32> Worklist;
// Scan all of the definitions in the function bottom-up using the priority
// queue.
while (!PQ.empty()) {
DomTreeNodePair RootPair = PQ.top();
PQ.pop();
DomTreeNode *Root = RootPair.first;
unsigned RootLevel = RootPair.second;
// Walk all dom tree children of Root, inspecting their successors. Only
// J-edges, whose target level is at most Root's level are added to the
// dominance frontier.
Worklist.clear();
Worklist.push_back(Root);
while (!Worklist.empty()) {
DomTreeNode *Node = Worklist.pop_back_val();
SILBasicBlock *BB = Node->getBlock();
// For all successors of the node:
for (auto &Succ : BB->getSuccessors()) {
DomTreeNode *SuccNode = DT->getNode(Succ);
// Skip D-edges (edges that are dom-tree edges).
if (SuccNode->getIDom() == Node)
continue;
// Ignore J-edges that point to nodes that are not smaller or equal
// to the root level.
unsigned SuccLevel = DomTreeLevels[SuccNode];
if (SuccLevel > RootLevel)
continue;
// Ignore visited nodes.
if (!Visited.insert(SuccNode).second)
continue;
// If the new PHInode is not dominated by the allocation then it's dead.
if (!DT->dominates(ASI->getParent(), SuccNode->getBlock()))
continue;
// If the new PHInode is properly dominated by the deallocation then it
// is obviously a dead PHInode, so we don't need to insert it.
if (DSI && DT->properlyDominates(DSI->getParent(),
SuccNode->getBlock()))
continue;
// The successor node is a new PHINode. If this is a new PHI node
// then it may require additional definitions, so add it to the PQ.
if (PhiBlocks.insert(Succ).second)
PQ.push(std::make_pair(SuccNode, SuccLevel));
}
// Add the children in the dom-tree to the worklist.
for (auto CI = Node->begin(), CE = Node->end(); CI != CE; ++CI)
if (!Visited.count(*CI))
Worklist.push_back(*CI);
}
}
DEBUG(llvm::dbgs() << "*** Found: " << PhiBlocks.size() << " new PHIs\n");
NumPhiPlaced += PhiBlocks.size();
// At this point we calculated the locations of all of the new Phi values.
// Next, add the Phi values and promote all of the loads and stores into the
// new locations.
// Replace the dummy values with new block arguments.
addBlockArguments(PhiBlocks);
// Hook up the Phi nodes, loads, and debug_value_addr with incoming values.
fixBranchesAndUses(PhiBlocks);
DEBUG(llvm::dbgs() << "*** Finished placing Phis ***\n");
}
static void eliminateDeadInstructions(analysis::DataflowGraph& dfg,
BlockSet& blocks, iterator block)
{
typedef analysis::DataflowGraph::Block Block;
typedef analysis::DataflowGraph::RegisterSet RegisterSet;
typedef std::vector<unsigned int> KillList;
typedef std::vector<PhiInstructionVector::iterator> PhiKillList;
typedef std::vector<RegisterSet::iterator> AliveKillList;
report(" Eliminating dead instructions from BB_" << block->id());
report(" Removing dead alive out values");
AliveKillList aliveOutKillList;
for(RegisterSet::iterator aliveOut = block->aliveOut().begin();
aliveOut != block->aliveOut().end(); ++aliveOut)
{
if(canRemoveAliveOut(dfg, block, *aliveOut))
{
report(" removed " << aliveOut->id);
aliveOutKillList.push_back(aliveOut);
}
}
for(AliveKillList::iterator killed = aliveOutKillList.begin();
killed != aliveOutKillList.end(); ++killed)
{
block->aliveOut().erase(*killed);
}
KillList killList;
report(" Removing dead instructions");
unsigned int index = 0;
for(InstructionVector::iterator instruction = block->instructions().begin();
instruction != block->instructions().end(); ++instruction)
{
if(canRemoveInstruction(block, instruction))
{
report(" removed '" << instruction->i->toString() << "'");
killList.push_back(index);
// schedule the block for more work
report(" scheduled this block again");
blocks.insert(block);
}
else
{
++index;
}
}
for(KillList::iterator killed = killList.begin();
killed != killList.end(); ++killed)
{
dfg.erase(block, *killed);
}
PhiKillList phiKillList;
report(" Removing dead phi instructions");
for(PhiInstructionVector::iterator phi = block->phis().begin();
phi != block->phis().end(); ++phi)
{
if(canRemovePhi(block, *phi))
{
report(" removed " << phi->d.id);
phiKillList.push_back(phi);
}
}
report(" Removing dead alive in values");
AliveKillList aliveInKillList;
for(RegisterSet::iterator aliveIn = block->aliveIn().begin();
aliveIn != block->aliveIn().end(); ++aliveIn)
{
if(canRemoveAliveIn(block, *aliveIn))
{
report(" removed " << aliveIn->id);
aliveInKillList.push_back(aliveIn);
// schedule the predecessors for more work
for(BlockPointerSet::iterator predecessor =
block->predecessors().begin();
predecessor != block->predecessors().end(); ++predecessor)
{
report(" scheduled predecessor BB_" << (*predecessor)->id());
blocks.insert(*predecessor);
}
}
}
for(AliveKillList::iterator killed = aliveInKillList.begin();
killed != aliveInKillList.end(); ++killed)
{
block->aliveIn().erase(*killed);
}
}
