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android / platform / external / v8 / 8de35f54d981bf34ab09571dc32a18f363440a3a / . / src / compiler / scheduler.cc
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// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <deque>
#include <queue>
#include "src/compiler/scheduler.h"
#include "src/bit-vector.h"
#include "src/compiler/control-equivalence.h"
#include "src/compiler/graph.h"
#include "src/compiler/graph-inl.h"
#include "src/compiler/node.h"
#include "src/compiler/node-properties.h"
#include "src/compiler/node-properties-inl.h"
namespace v8 {
namespace internal {
namespace compiler {
static inline void Trace(const char* msg, ...) {
if (FLAG_trace_turbo_scheduler) {
va_list arguments;
va_start(arguments, msg);
base::OS::VPrint(msg, arguments);
va_end(arguments);
}
}
Scheduler::Scheduler(Zone* zone, Graph* graph, Schedule* schedule)
: zone_(zone),
graph_(graph),
schedule_(schedule),
scheduled_nodes_(zone),
schedule_root_nodes_(zone),
schedule_queue_(zone),
node_data_(graph_->NodeCount(), DefaultSchedulerData(), zone) {}
Schedule* Scheduler::ComputeSchedule(Zone* zone, Graph* graph) {
Schedule* schedule = new (graph->zone())
Schedule(graph->zone(), static_cast<size_t>(graph->NodeCount()));
Scheduler scheduler(zone, graph, schedule);
scheduler.BuildCFG();
scheduler.ComputeSpecialRPONumbering();
scheduler.GenerateImmediateDominatorTree();
scheduler.PrepareUses();
scheduler.ScheduleEarly();
scheduler.ScheduleLate();
scheduler.SealFinalSchedule();
return schedule;
}
Scheduler::SchedulerData Scheduler::DefaultSchedulerData() {
SchedulerData def = {schedule_->start(), 0, kUnknown};
return def;
}
Scheduler::SchedulerData* Scheduler::GetData(Node* node) {
DCHECK(node->id() < static_cast<int>(node_data_.size()));
return &node_data_[node->id()];
}
Scheduler::Placement Scheduler::GetPlacement(Node* node) {
SchedulerData* data = GetData(node);
if (data->placement_ == kUnknown) { // Compute placement, once, on demand.
switch (node->opcode()) {
case IrOpcode::kParameter:
// Parameters are always fixed to the start node.
data->placement_ = kFixed;
break;
case IrOpcode::kPhi:
case IrOpcode::kEffectPhi: {
// Phis and effect phis are fixed if their control inputs are, whereas
// otherwise they are coupled to a floating control node.
Placement p = GetPlacement(NodeProperties::GetControlInput(node));
data->placement_ = (p == kFixed ? kFixed : kCoupled);
break;
}
#define DEFINE_CONTROL_CASE(V) case IrOpcode::k##V:
CONTROL_OP_LIST(DEFINE_CONTROL_CASE)
#undef DEFINE_CONTROL_CASE
{
// Control nodes that were not control-reachable from end may float.
data->placement_ = kSchedulable;
break;
}
default:
data->placement_ = kSchedulable;
break;
}
}
return data->placement_;
}
void Scheduler::UpdatePlacement(Node* node, Placement placement) {
SchedulerData* data = GetData(node);
if (data->placement_ != kUnknown) { // Trap on mutation, not initialization.
switch (node->opcode()) {
case IrOpcode::kParameter:
// Parameters are fixed once and for all.
UNREACHABLE();
break;
case IrOpcode::kPhi:
case IrOpcode::kEffectPhi: {
// Phis and effect phis are coupled to their respective blocks.
DCHECK_EQ(Scheduler::kCoupled, data->placement_);
DCHECK_EQ(Scheduler::kFixed, placement);
Node* control = NodeProperties::GetControlInput(node);
BasicBlock* block = schedule_->block(control);
schedule_->AddNode(block, node);
break;
}
#define DEFINE_CONTROL_CASE(V) case IrOpcode::k##V:
CONTROL_OP_LIST(DEFINE_CONTROL_CASE)
#undef DEFINE_CONTROL_CASE
{
// Control nodes force coupled uses to be placed.
Node::Uses uses = node->uses();
for (Node::Uses::iterator i = uses.begin(); i != uses.end(); ++i) {
if (GetPlacement(*i) == Scheduler::kCoupled) {
DCHECK_EQ(node, NodeProperties::GetControlInput(*i));
UpdatePlacement(*i, placement);
}
}
break;
}
default:
DCHECK_EQ(Scheduler::kSchedulable, data->placement_);
DCHECK_EQ(Scheduler::kScheduled, placement);
break;
}
// Reduce the use count of the node's inputs to potentially make them
// schedulable. If all the uses of a node have been scheduled, then the node
// itself can be scheduled.
for (Edge const edge : node->input_edges()) {
DecrementUnscheduledUseCount(edge.to(), edge.index(), edge.from());
}
}
data->placement_ = placement;
}
bool Scheduler::IsCoupledControlEdge(Node* node, int index) {
return GetPlacement(node) == kCoupled &&
NodeProperties::FirstControlIndex(node) == index;
}
void Scheduler::IncrementUnscheduledUseCount(Node* node, int index,
Node* from) {
// Make sure that control edges from coupled nodes are not counted.
if (IsCoupledControlEdge(from, index)) return;
// Tracking use counts for fixed nodes is useless.
if (GetPlacement(node) == kFixed) return;
// Use count for coupled nodes is summed up on their control.
if (GetPlacement(node) == kCoupled) {
Node* control = NodeProperties::GetControlInput(node);
return IncrementUnscheduledUseCount(control, index, from);
}
++(GetData(node)->unscheduled_count_);
if (FLAG_trace_turbo_scheduler) {
Trace(" Use count of #%d:%s (used by #%d:%s)++ = %d\n", node->id(),
node->op()->mnemonic(), from->id(), from->op()->mnemonic(),
GetData(node)->unscheduled_count_);
}
}
void Scheduler::DecrementUnscheduledUseCount(Node* node, int index,
Node* from) {
// Make sure that control edges from coupled nodes are not counted.
if (IsCoupledControlEdge(from, index)) return;
// Tracking use counts for fixed nodes is useless.
if (GetPlacement(node) == kFixed) return;
// Use count for coupled nodes is summed up on their control.
if (GetPlacement(node) == kCoupled) {
Node* control = NodeProperties::GetControlInput(node);
return DecrementUnscheduledUseCount(control, index, from);
}
DCHECK(GetData(node)->unscheduled_count_ > 0);
--(GetData(node)->unscheduled_count_);
if (FLAG_trace_turbo_scheduler) {
Trace(" Use count of #%d:%s (used by #%d:%s)-- = %d\n", node->id(),
node->op()->mnemonic(), from->id(), from->op()->mnemonic(),
GetData(node)->unscheduled_count_);
}
if (GetData(node)->unscheduled_count_ == 0) {
Trace(" newly eligible #%d:%s\n", node->id(), node->op()->mnemonic());
schedule_queue_.push(node);
}
}
BasicBlock* Scheduler::GetCommonDominator(BasicBlock* b1, BasicBlock* b2) {
while (b1 != b2) {
int32_t b1_depth = b1->dominator_depth();
int32_t b2_depth = b2->dominator_depth();
if (b1_depth < b2_depth) {
b2 = b2->dominator();
} else {
b1 = b1->dominator();
}
}
return b1;
}
// -----------------------------------------------------------------------------
// Phase 1: Build control-flow graph.
// Internal class to build a control flow graph (i.e the basic blocks and edges
// between them within a Schedule) from the node graph. Visits control edges of
// the graph backwards from an end node in order to find the connected control
// subgraph, needed for scheduling.
class CFGBuilder : public ZoneObject {
public:
CFGBuilder(Zone* zone, Scheduler* scheduler)
: scheduler_(scheduler),
schedule_(scheduler->schedule_),
queued_(scheduler->graph_, 2),
queue_(zone),
control_(zone),
component_entry_(NULL),
component_start_(NULL),
component_end_(NULL) {}
// Run the control flow graph construction algorithm by walking the graph
// backwards from end through control edges, building and connecting the
// basic blocks for control nodes.
void Run() {
ResetDataStructures();
Queue(scheduler_->graph_->end());
while (!queue_.empty()) { // Breadth-first backwards traversal.
Node* node = queue_.front();
queue_.pop();
int max = NodeProperties::PastControlIndex(node);
for (int i = NodeProperties::FirstControlIndex(node); i < max; i++) {
Queue(node->InputAt(i));
}
}
for (NodeVector::iterator i = control_.begin(); i != control_.end(); ++i) {
ConnectBlocks(*i); // Connect block to its predecessor/successors.
}
}
// Run the control flow graph construction for a minimal control-connected
// component ending in {exit} and merge that component into an existing
// control flow graph at the bottom of {block}.
void Run(BasicBlock* block, Node* exit) {
ResetDataStructures();
Queue(exit);
component_entry_ = NULL;
component_start_ = block;
component_end_ = schedule_->block(exit);
scheduler_->equivalence_->Run(exit);
while (!queue_.empty()) { // Breadth-first backwards traversal.
Node* node = queue_.front();
queue_.pop();
// Use control dependence equivalence to find a canonical single-entry
// single-exit region that makes up a minimal component to be scheduled.
if (IsSingleEntrySingleExitRegion(node, exit)) {
Trace("Found SESE at #%d:%s\n", node->id(), node->op()->mnemonic());
DCHECK_EQ(NULL, component_entry_);
component_entry_ = node;
continue;
}
int max = NodeProperties::PastControlIndex(node);
for (int i = NodeProperties::FirstControlIndex(node); i < max; i++) {
Queue(node->InputAt(i));
}
}
DCHECK_NE(NULL, component_entry_);
for (NodeVector::iterator i = control_.begin(); i != control_.end(); ++i) {
ConnectBlocks(*i); // Connect block to its predecessor/successors.
}
}
private:
// TODO(mstarzinger): Only for Scheduler::FuseFloatingControl.
friend class Scheduler;
void FixNode(BasicBlock* block, Node* node) {
schedule_->AddNode(block, node);
scheduler_->UpdatePlacement(node, Scheduler::kFixed);
}
void Queue(Node* node) {
// Mark the connected control nodes as they are queued.
if (!queued_.Get(node)) {
BuildBlocks(node);
queue_.push(node);
queued_.Set(node, true);
control_.push_back(node);
}
}
void BuildBlocks(Node* node) {
switch (node->opcode()) {
case IrOpcode::kEnd:
FixNode(schedule_->end(), node);
break;
case IrOpcode::kStart:
FixNode(schedule_->start(), node);
break;
case IrOpcode::kLoop:
case IrOpcode::kMerge:
BuildBlockForNode(node);
break;
case IrOpcode::kTerminate: {
// Put Terminate in the loop to which it refers.
Node* loop = NodeProperties::GetControlInput(node);
BasicBlock* block = BuildBlockForNode(loop);
FixNode(block, node);
break;
}
case IrOpcode::kBranch:
BuildBlocksForSuccessors(node, IrOpcode::kIfTrue, IrOpcode::kIfFalse);
break;
default:
break;
}
}
void ConnectBlocks(Node* node) {
switch (node->opcode()) {
case IrOpcode::kLoop:
case IrOpcode::kMerge:
ConnectMerge(node);
break;
case IrOpcode::kBranch:
scheduler_->UpdatePlacement(node, Scheduler::kFixed);
ConnectBranch(node);
break;
case IrOpcode::kReturn:
scheduler_->UpdatePlacement(node, Scheduler::kFixed);
ConnectReturn(node);
break;
default:
break;
}
}
BasicBlock* BuildBlockForNode(Node* node) {
BasicBlock* block = schedule_->block(node);
if (block == NULL) {
block = schedule_->NewBasicBlock();
Trace("Create block B%d for #%d:%s\n", block->id().ToInt(), node->id(),
node->op()->mnemonic());
FixNode(block, node);
}
return block;
}
void BuildBlocksForSuccessors(Node* node, IrOpcode::Value a,
IrOpcode::Value b) {
Node* successors[2];
CollectSuccessorProjections(node, successors, a, b);
BuildBlockForNode(successors[0]);
BuildBlockForNode(successors[1]);
}
// Collect the branch-related projections from a node, such as IfTrue,
// IfFalse.
// TODO(titzer): consider moving this to node.h
void CollectSuccessorProjections(Node* node, Node** buffer,
IrOpcode::Value true_opcode,
IrOpcode::Value false_opcode) {
buffer[0] = NULL;
buffer[1] = NULL;
for (Node* use : node->uses()) {
if (use->opcode() == true_opcode) {
DCHECK_EQ(NULL, buffer[0]);
buffer[0] = use;
}
if (use->opcode() == false_opcode) {
DCHECK_EQ(NULL, buffer[1]);
buffer[1] = use;
}
}
DCHECK_NE(NULL, buffer[0]);
DCHECK_NE(NULL, buffer[1]);
}
void CollectSuccessorBlocks(Node* node, BasicBlock** buffer,
IrOpcode::Value true_opcode,
IrOpcode::Value false_opcode) {
Node* successors[2];
CollectSuccessorProjections(node, successors, true_opcode, false_opcode);
buffer[0] = schedule_->block(successors[0]);
buffer[1] = schedule_->block(successors[1]);
}
void ConnectBranch(Node* branch) {
BasicBlock* successor_blocks[2];
CollectSuccessorBlocks(branch, successor_blocks, IrOpcode::kIfTrue,
IrOpcode::kIfFalse);
// Consider branch hints.
switch (BranchHintOf(branch->op())) {
case BranchHint::kNone:
break;
case BranchHint::kTrue:
successor_blocks[1]->set_deferred(true);
break;
case BranchHint::kFalse:
successor_blocks[0]->set_deferred(true);
break;
}
if (branch == component_entry_) {
TraceConnect(branch, component_start_, successor_blocks[0]);
TraceConnect(branch, component_start_, successor_blocks[1]);
schedule_->InsertBranch(component_start_, component_end_, branch,
successor_blocks[0], successor_blocks[1]);
} else {
Node* branch_block_node = NodeProperties::GetControlInput(branch);
BasicBlock* branch_block = schedule_->block(branch_block_node);
DCHECK(branch_block != NULL);
TraceConnect(branch, branch_block, successor_blocks[0]);
TraceConnect(branch, branch_block, successor_blocks[1]);
schedule_->AddBranch(branch_block, branch, successor_blocks[0],
successor_blocks[1]);
}
}
void ConnectMerge(Node* merge) {
// Don't connect the special merge at the end to its predecessors.
if (IsFinalMerge(merge)) return;
BasicBlock* block = schedule_->block(merge);
DCHECK(block != NULL);
// For all of the merge's control inputs, add a goto at the end to the
// merge's basic block.
for (Node* const input : merge->inputs()) {
BasicBlock* predecessor_block = schedule_->block(input);
TraceConnect(merge, predecessor_block, block);
schedule_->AddGoto(predecessor_block, block);
}
}
void ConnectReturn(Node* ret) {
Node* return_block_node = NodeProperties::GetControlInput(ret);
BasicBlock* return_block = schedule_->block(return_block_node);
TraceConnect(ret, return_block, NULL);
schedule_->AddReturn(return_block, ret);
}
void TraceConnect(Node* node, BasicBlock* block, BasicBlock* succ) {
DCHECK_NE(NULL, block);
if (succ == NULL) {
Trace("Connect #%d:%s, B%d -> end\n", node->id(), node->op()->mnemonic(),
block->id().ToInt());
} else {
Trace("Connect #%d:%s, B%d -> B%d\n", node->id(), node->op()->mnemonic(),
block->id().ToInt(), succ->id().ToInt());
}
}
bool IsFinalMerge(Node* node) {
return (node->opcode() == IrOpcode::kMerge &&
node == scheduler_->graph_->end()->InputAt(0));
}
bool IsSingleEntrySingleExitRegion(Node* entry, Node* exit) const {
size_t entry_class = scheduler_->equivalence_->ClassOf(entry);
size_t exit_class = scheduler_->equivalence_->ClassOf(exit);
return entry != exit && entry_class == exit_class;
}
void ResetDataStructures() {
control_.clear();
DCHECK(queue_.empty());
DCHECK(control_.empty());
}
Scheduler* scheduler_;
Schedule* schedule_;
NodeMarker<bool> queued_; // Mark indicating whether node is queued.
ZoneQueue<Node*> queue_; // Queue used for breadth-first traversal.
NodeVector control_; // List of encountered control nodes.
Node* component_entry_; // Component single-entry node.
BasicBlock* component_start_; // Component single-entry block.
BasicBlock* component_end_; // Component single-exit block.
};
void Scheduler::BuildCFG() {
Trace("--- CREATING CFG -------------------------------------------\n");
// Instantiate a new control equivalence algorithm for the graph.
equivalence_ = new (zone_) ControlEquivalence(zone_, graph_);
// Build a control-flow graph for the main control-connected component that
// is being spanned by the graph's start and end nodes.
control_flow_builder_ = new (zone_) CFGBuilder(zone_, this);
control_flow_builder_->Run();
// Initialize per-block data.
scheduled_nodes_.resize(schedule_->BasicBlockCount(), NodeVector(zone_));
}
// -----------------------------------------------------------------------------
// Phase 2: Compute special RPO and dominator tree.
// Compute the special reverse-post-order block ordering, which is essentially
// a RPO of the graph where loop bodies are contiguous. Properties:
// 1. If block A is a predecessor of B, then A appears before B in the order,
// unless B is a loop header and A is in the loop headed at B
// (i.e. A -> B is a backedge).
// => If block A dominates block B, then A appears before B in the order.
// => If block A is a loop header, A appears before all blocks in the loop
// headed at A.
// 2. All loops are contiguous in the order (i.e. no intervening blocks that
// do not belong to the loop.)
// Note a simple RPO traversal satisfies (1) but not (2).
class SpecialRPONumberer : public ZoneObject {
public:
SpecialRPONumberer(Zone* zone, Schedule* schedule)
: zone_(zone),
schedule_(schedule),
order_(NULL),
beyond_end_(NULL),
loops_(zone),
backedges_(zone),
stack_(zone),
previous_block_count_(0) {}
// Computes the special reverse-post-order for the main control flow graph,
// that is for the graph spanned between the schedule's start and end blocks.
void ComputeSpecialRPO() {
DCHECK(schedule_->end()->SuccessorCount() == 0);
DCHECK_EQ(NULL, order_); // Main order does not exist yet.
ComputeAndInsertSpecialRPO(schedule_->start(), schedule_->end());
}
// Computes the special reverse-post-order for a partial control flow graph,
// that is for the graph spanned between the given {entry} and {end} blocks,
// then updates the existing ordering with this new information.
void UpdateSpecialRPO(BasicBlock* entry, BasicBlock* end) {
DCHECK_NE(NULL, order_); // Main order to be updated is present.
ComputeAndInsertSpecialRPO(entry, end);
}
// Serialize the previously computed order as a special reverse-post-order
// numbering for basic blocks into the final schedule.
void SerializeRPOIntoSchedule() {
int32_t number = 0;
for (BasicBlock* b = order_; b != NULL; b = b->rpo_next()) {
b->set_rpo_number(number++);
schedule_->rpo_order()->push_back(b);
}
BeyondEndSentinel()->set_rpo_number(number);
}
// Print and verify the special reverse-post-order.
void PrintAndVerifySpecialRPO() {
#if DEBUG
if (FLAG_trace_turbo_scheduler) PrintRPO();
VerifySpecialRPO();
#endif
}
private:
typedef std::pair<BasicBlock*, size_t> Backedge;
// Numbering for BasicBlock::rpo_number for this block traversal:
static const int kBlockOnStack = -2;
static const int kBlockVisited1 = -3;
static const int kBlockVisited2 = -4;
static const int kBlockUnvisited1 = -1;
static const int kBlockUnvisited2 = kBlockVisited1;
struct SpecialRPOStackFrame {
BasicBlock* block;
size_t index;
};
struct LoopInfo {
BasicBlock* header;
ZoneList<BasicBlock*>* outgoing;
BitVector* members;
LoopInfo* prev;
BasicBlock* end;
BasicBlock* start;
void AddOutgoing(Zone* zone, BasicBlock* block) {
if (outgoing == NULL) {
outgoing = new (zone) ZoneList<BasicBlock*>(2, zone);
}
outgoing->Add(block, zone);
}
};
int Push(ZoneVector<SpecialRPOStackFrame>& stack, int depth,
BasicBlock* child, int unvisited) {
if (child->rpo_number() == unvisited) {
stack[depth].block = child;
stack[depth].index = 0;
child->set_rpo_number(kBlockOnStack);
return depth + 1;
}
return depth;
}
BasicBlock* PushFront(BasicBlock* head, BasicBlock* block) {
block->set_rpo_next(head);
return block;
}
static int GetLoopNumber(BasicBlock* block) { return block->loop_number(); }
static void SetLoopNumber(BasicBlock* block, int loop_number) {
return block->set_loop_number(loop_number);
}
static bool HasLoopNumber(BasicBlock* block) {
return block->loop_number() >= 0;
}
// TODO(mstarzinger): We only need this special sentinel because some tests
// use the schedule's end block in actual control flow (e.g. with end having
// successors). Once this has been cleaned up we can use the end block here.
BasicBlock* BeyondEndSentinel() {
if (beyond_end_ == NULL) {
BasicBlock::Id id = BasicBlock::Id::FromInt(-1);
beyond_end_ = new (schedule_->zone()) BasicBlock(schedule_->zone(), id);
}
return beyond_end_;
}
// Compute special RPO for the control flow graph between {entry} and {end},
// mutating any existing order so that the result is still valid.
void ComputeAndInsertSpecialRPO(BasicBlock* entry, BasicBlock* end) {
// RPO should not have been serialized for this schedule yet.
CHECK_EQ(kBlockUnvisited1, schedule_->start()->loop_number());
CHECK_EQ(kBlockUnvisited1, schedule_->start()->rpo_number());
CHECK_EQ(0, static_cast<int>(schedule_->rpo_order()->size()));
// Find correct insertion point within existing order.
BasicBlock* insertion_point = entry->rpo_next();
BasicBlock* order = insertion_point;
// Perform an iterative RPO traversal using an explicit stack,
// recording backedges that form cycles. O(|B|).
DCHECK_LT(previous_block_count_, schedule_->BasicBlockCount());
stack_.resize(schedule_->BasicBlockCount() - previous_block_count_);
previous_block_count_ = schedule_->BasicBlockCount();
int stack_depth = Push(stack_, 0, entry, kBlockUnvisited1);
int num_loops = static_cast<int>(loops_.size());
while (stack_depth > 0) {
int current = stack_depth - 1;
SpecialRPOStackFrame* frame = &stack_[current];
if (frame->block != end &&
frame->index < frame->block->SuccessorCount()) {
// Process the next successor.
BasicBlock* succ = frame->block->SuccessorAt(frame->index++);
if (succ->rpo_number() == kBlockVisited1) continue;
if (succ->rpo_number() == kBlockOnStack) {
// The successor is on the stack, so this is a backedge (cycle).
backedges_.push_back(Backedge(frame->block, frame->index - 1));
if (!HasLoopNumber(succ)) {
// Assign a new loop number to the header if it doesn't have one.
SetLoopNumber(succ, num_loops++);
}
} else {
// Push the successor onto the stack.
DCHECK(succ->rpo_number() == kBlockUnvisited1);
stack_depth = Push(stack_, stack_depth, succ, kBlockUnvisited1);
}
} else {
// Finished with all successors; pop the stack and add the block.
order = PushFront(order, frame->block);
frame->block->set_rpo_number(kBlockVisited1);
stack_depth--;
}
}
// If no loops were encountered, then the order we computed was correct.
if (num_loops > static_cast<int>(loops_.size())) {
// Otherwise, compute the loop information from the backedges in order
// to perform a traversal that groups loop bodies together.
ComputeLoopInfo(stack_, num_loops, &backedges_);
// Initialize the "loop stack". Note the entry could be a loop header.
LoopInfo* loop =
HasLoopNumber(entry) ? &loops_[GetLoopNumber(entry)] : NULL;
order = insertion_point;
// Perform an iterative post-order traversal, visiting loop bodies before
// edges that lead out of loops. Visits each block once, but linking loop
// sections together is linear in the loop size, so overall is
// O(|B| + max(loop_depth) * max(|loop|))
stack_depth = Push(stack_, 0, entry, kBlockUnvisited2);
while (stack_depth > 0) {
SpecialRPOStackFrame* frame = &stack_[stack_depth - 1];
BasicBlock* block = frame->block;
BasicBlock* succ = NULL;
if (block != end && frame->index < block->SuccessorCount()) {
// Process the next normal successor.
succ = block->SuccessorAt(frame->index++);
} else if (HasLoopNumber(block)) {
// Process additional outgoing edges from the loop header.
if (block->rpo_number() == kBlockOnStack) {
// Finish the loop body the first time the header is left on the
// stack.
DCHECK(loop != NULL && loop->header == block);
loop->start = PushFront(order, block);
order = loop->end;
block->set_rpo_number(kBlockVisited2);
// Pop the loop stack and continue visiting outgoing edges within
// the context of the outer loop, if any.
loop = loop->prev;
// We leave the loop header on the stack; the rest of this iteration
// and later iterations will go through its outgoing edges list.
}
// Use the next outgoing edge if there are any.
int outgoing_index =
static_cast<int>(frame->index - block->SuccessorCount());
LoopInfo* info = &loops_[GetLoopNumber(block)];
DCHECK(loop != info);
if (block != entry && info->outgoing != NULL &&
outgoing_index < info->outgoing->length()) {
succ = info->outgoing->at(outgoing_index);
frame->index++;
}
}
if (succ != NULL) {
// Process the next successor.
if (succ->rpo_number() == kBlockOnStack) continue;
if (succ->rpo_number() == kBlockVisited2) continue;
DCHECK(succ->rpo_number() == kBlockUnvisited2);
if (loop != NULL && !loop->members->Contains(succ->id().ToInt())) {
// The successor is not in the current loop or any nested loop.
// Add it to the outgoing edges of this loop and visit it later.
loop->AddOutgoing(zone_, succ);
} else {
// Push the successor onto the stack.
stack_depth = Push(stack_, stack_depth, succ, kBlockUnvisited2);
if (HasLoopNumber(succ)) {
// Push the inner loop onto the loop stack.
DCHECK(GetLoopNumber(succ) < num_loops);
LoopInfo* next = &loops_[GetLoopNumber(succ)];
next->end = order;
next->prev = loop;
loop = next;
}
}
} else {
// Finished with all successors of the current block.
if (HasLoopNumber(block)) {
// If we are going to pop a loop header, then add its entire body.
LoopInfo* info = &loops_[GetLoopNumber(block)];
for (BasicBlock* b = info->start; true; b = b->rpo_next()) {
if (b->rpo_next() == info->end) {
b->set_rpo_next(order);
info->end = order;
break;
}
}
order = info->start;
} else {
// Pop a single node off the stack and add it to the order.
order = PushFront(order, block);
block->set_rpo_number(kBlockVisited2);
}
stack_depth--;
}
}
}
// Publish new order the first time.
if (order_ == NULL) order_ = order;
// Compute the correct loop headers and set the correct loop ends.
LoopInfo* current_loop = NULL;
BasicBlock* current_header = entry->loop_header();
int32_t loop_depth = entry->loop_depth();
if (entry->IsLoopHeader()) --loop_depth; // Entry might be a loop header.
for (BasicBlock* b = order; b != insertion_point; b = b->rpo_next()) {
BasicBlock* current = b;
// Reset BasicBlock::rpo_number again.
current->set_rpo_number(kBlockUnvisited1);
// Finish the previous loop(s) if we just exited them.
while (current_header != NULL && current == current_header->loop_end()) {
DCHECK(current_header->IsLoopHeader());
DCHECK(current_loop != NULL);
current_loop = current_loop->prev;
current_header = current_loop == NULL ? NULL : current_loop->header;
--loop_depth;
}
current->set_loop_header(current_header);
// Push a new loop onto the stack if this loop is a loop header.
if (HasLoopNumber(current)) {
++loop_depth;
current_loop = &loops_[GetLoopNumber(current)];
BasicBlock* end = current_loop->end;
current->set_loop_end(end == NULL ? BeyondEndSentinel() : end);
current_header = current_loop->header;
Trace("B%d is a loop header, increment loop depth to %d\n",
current->id().ToInt(), loop_depth);
}
current->set_loop_depth(loop_depth);
if (current->loop_header() == NULL) {
Trace("B%d is not in a loop (depth == %d)\n", current->id().ToInt(),
current->loop_depth());
} else {
Trace("B%d has loop header B%d, (depth == %d)\n", current->id().ToInt(),
current->loop_header()->id().ToInt(), current->loop_depth());
}
}
}
// Computes loop membership from the backedges of the control flow graph.
void ComputeLoopInfo(ZoneVector<SpecialRPOStackFrame>& queue,
size_t num_loops, ZoneVector<Backedge>* backedges) {
// Extend existing loop membership vectors.
for (LoopInfo& loop : loops_) {
BitVector* new_members = new (zone_)
BitVector(static_cast<int>(schedule_->BasicBlockCount()), zone_);
new_members->CopyFrom(*loop.members);
loop.members = new_members;
}
// Extend loop information vector.
loops_.resize(num_loops, LoopInfo());
// Compute loop membership starting from backedges.
// O(max(loop_depth) * max(|loop|)
for (size_t i = 0; i < backedges->size(); i++) {
BasicBlock* member = backedges->at(i).first;
BasicBlock* header = member->SuccessorAt(backedges->at(i).second);
size_t loop_num = GetLoopNumber(header);
if (loops_[loop_num].header == NULL) {
loops_[loop_num].header = header;
loops_[loop_num].members = new (zone_)
BitVector(static_cast<int>(schedule_->BasicBlockCount()), zone_);
}
int queue_length = 0;
if (member != header) {
// As long as the header doesn't have a backedge to itself,
// Push the member onto the queue and process its predecessors.
if (!loops_[loop_num].members->Contains(member->id().ToInt())) {
loops_[loop_num].members->Add(member->id().ToInt());
}
queue[queue_length++].block = member;
}
// Propagate loop membership backwards. All predecessors of M up to the
// loop header H are members of the loop too. O(|blocks between M and H|).
while (queue_length > 0) {
BasicBlock* block = queue[--queue_length].block;
for (size_t i = 0; i < block->PredecessorCount(); i++) {
BasicBlock* pred = block->PredecessorAt(i);
if (pred != header) {
if (!loops_[loop_num].members->Contains(pred->id().ToInt())) {
loops_[loop_num].members->Add(pred->id().ToInt());
queue[queue_length++].block = pred;
}
}
}
}
}
}
#if DEBUG
void PrintRPO() {
OFStream os(stdout);
os << "RPO with " << loops_.size() << " loops";
if (loops_.size() > 0) {
os << " (";
for (size_t i = 0; i < loops_.size(); i++) {
if (i > 0) os << " ";
os << "B" << loops_[i].header->id();
}
os << ")";
}
os << ":\n";
for (BasicBlock* block = order_; block != NULL; block = block->rpo_next()) {
BasicBlock::Id bid = block->id();
// TODO(jarin,svenpanne): Add formatting here once we have support for
// that in streams (we want an equivalent of PrintF("%5d:", x) here).
os << " " << block->rpo_number() << ":";
for (size_t i = 0; i < loops_.size(); i++) {
bool range = loops_[i].header->LoopContains(block);
bool membership = loops_[i].header != block && range;
os << (membership ? " |" : " ");
os << (range ? "x" : " ");
}
os << " B" << bid << ": ";
if (block->loop_end() != NULL) {
os << " range: [" << block->rpo_number() << ", "
<< block->loop_end()->rpo_number() << ")";
}
if (block->loop_header() != NULL) {
os << " header: B" << block->loop_header()->id();
}
if (block->loop_depth() > 0) {
os << " depth: " << block->loop_depth();
}
os << "\n";
}
}
void VerifySpecialRPO() {
BasicBlockVector* order = schedule_->rpo_order();
DCHECK(order->size() > 0);
DCHECK((*order)[0]->id().ToInt() == 0); // entry should be first.
for (size_t i = 0; i < loops_.size(); i++) {
LoopInfo* loop = &loops_[i];
BasicBlock* header = loop->header;
BasicBlock* end = header->loop_end();
DCHECK(header != NULL);
DCHECK(header->rpo_number() >= 0);
DCHECK(header->rpo_number() < static_cast<int>(order->size()));
DCHECK(end != NULL);
DCHECK(end->rpo_number() <= static_cast<int>(order->size()));
DCHECK(end->rpo_number() > header->rpo_number());
DCHECK(header->loop_header() != header);
// Verify the start ... end list relationship.
int links = 0;
BasicBlock* block = loop->start;
DCHECK_EQ(header, block);
bool end_found;
while (true) {
if (block == NULL || block == loop->end) {
end_found = (loop->end == block);
break;
}
// The list should be in same order as the final result.
DCHECK(block->rpo_number() == links + header->rpo_number());
links++;
block = block->rpo_next();
DCHECK(links < static_cast<int>(2 * order->size())); // cycle?
}
DCHECK(links > 0);
DCHECK(links == end->rpo_number() - header->rpo_number());
DCHECK(end_found);
// Check loop depth of the header.
int loop_depth = 0;
for (LoopInfo* outer = loop; outer != NULL; outer = outer->prev) {
loop_depth++;
}
DCHECK_EQ(loop_depth, header->loop_depth());
// Check the contiguousness of loops.
int count = 0;
for (int j = 0; j < static_cast<int>(order->size()); j++) {
BasicBlock* block = order->at(j);
DCHECK(block->rpo_number() == j);
if (j < header->rpo_number() || j >= end->rpo_number()) {
DCHECK(!header->LoopContains(block));
} else {
DCHECK(header->LoopContains(block));
DCHECK_GE(block->loop_depth(), loop_depth);
count++;
}
}
DCHECK(links == count);
}
}
#endif // DEBUG
Zone* zone_;
Schedule* schedule_;
BasicBlock* order_;
BasicBlock* beyond_end_;
ZoneVector<LoopInfo> loops_;
ZoneVector<Backedge> backedges_;
ZoneVector<SpecialRPOStackFrame> stack_;
size_t previous_block_count_;
};
BasicBlockVector* Scheduler::ComputeSpecialRPO(Zone* zone, Schedule* schedule) {
SpecialRPONumberer numberer(zone, schedule);
numberer.ComputeSpecialRPO();
numberer.SerializeRPOIntoSchedule();
numberer.PrintAndVerifySpecialRPO();
return schedule->rpo_order();
}
void Scheduler::ComputeSpecialRPONumbering() {
Trace("--- COMPUTING SPECIAL RPO ----------------------------------\n");
// Compute the special reverse-post-order for basic blocks.
special_rpo_ = new (zone_) SpecialRPONumberer(zone_, schedule_);
special_rpo_->ComputeSpecialRPO();
}
void Scheduler::PropagateImmediateDominators(BasicBlock* block) {
for (/*nop*/; block != NULL; block = block->rpo_next()) {
BasicBlock::Predecessors::iterator pred = block->predecessors_begin();
BasicBlock::Predecessors::iterator end = block->predecessors_end();
DCHECK(pred != end); // All blocks except start have predecessors.
BasicBlock* dominator = *pred;
// For multiple predecessors, walk up the dominator tree until a common
// dominator is found. Visitation order guarantees that all predecessors
// except for backwards edges have been visited.
for (++pred; pred != end; ++pred) {
// Don't examine backwards edges.
if ((*pred)->dominator_depth() < 0) continue;
dominator = GetCommonDominator(dominator, *pred);
}
block->set_dominator(dominator);
block->set_dominator_depth(dominator->dominator_depth() + 1);
// Propagate "deferredness" of the dominator.
if (dominator->deferred()) block->set_deferred(true);
Trace("Block B%d's idom is B%d, depth = %d\n", block->id().ToInt(),
dominator->id().ToInt(), block->dominator_depth());
}
}
void Scheduler::GenerateImmediateDominatorTree() {
Trace("--- IMMEDIATE BLOCK DOMINATORS -----------------------------\n");
// Seed start block to be the first dominator.
schedule_->start()->set_dominator_depth(0);
// Build the block dominator tree resulting from the above seed.
PropagateImmediateDominators(schedule_->start()->rpo_next());
}
// -----------------------------------------------------------------------------
// Phase 3: Prepare use counts for nodes.
class PrepareUsesVisitor : public NullNodeVisitor {
public:
explicit PrepareUsesVisitor(Scheduler* scheduler)
: scheduler_(scheduler), schedule_(scheduler->schedule_) {}
void Pre(Node* node) {
if (scheduler_->GetPlacement(node) == Scheduler::kFixed) {
// Fixed nodes are always roots for schedule late.
scheduler_->schedule_root_nodes_.push_back(node);
if (!schedule_->IsScheduled(node)) {
// Make sure root nodes are scheduled in their respective blocks.
Trace("Scheduling fixed position node #%d:%s\n", node->id(),
node->op()->mnemonic());
IrOpcode::Value opcode = node->opcode();
BasicBlock* block =
opcode == IrOpcode::kParameter
? schedule_->start()
: schedule_->block(NodeProperties::GetControlInput(node));
DCHECK(block != NULL);
schedule_->AddNode(block, node);
}
}
}
void PostEdge(Node* from, int index, Node* to) {
// If the edge is from an unscheduled node, then tally it in the use count
// for all of its inputs. The same criterion will be used in ScheduleLate
// for decrementing use counts.
if (!schedule_->IsScheduled(from)) {
DCHECK_NE(Scheduler::kFixed, scheduler_->GetPlacement(from));
scheduler_->IncrementUnscheduledUseCount(to, index, from);
}
}
private:
Scheduler* scheduler_;
Schedule* schedule_;
};
void Scheduler::PrepareUses() {
Trace("--- PREPARE USES -------------------------------------------\n");
// Count the uses of every node, it will be used to ensure that all of a
// node's uses are scheduled before the node itself.
PrepareUsesVisitor prepare_uses(this);
graph_->VisitNodeInputsFromEnd(&prepare_uses);
}
// -----------------------------------------------------------------------------
// Phase 4: Schedule nodes early.
class ScheduleEarlyNodeVisitor {
public:
ScheduleEarlyNodeVisitor(Zone* zone, Scheduler* scheduler)
: scheduler_(scheduler), schedule_(scheduler->schedule_), queue_(zone) {}
// Run the schedule early algorithm on a set of fixed root nodes.
void Run(NodeVector* roots) {
for (NodeVectorIter i = roots->begin(); i != roots->end(); ++i) {
queue_.push(*i);
while (!queue_.empty()) {
VisitNode(queue_.front());
queue_.pop();
}
}
}
private:
// Visits one node from the queue and propagates its current schedule early
// position to all uses. This in turn might push more nodes onto the queue.
void VisitNode(Node* node) {
Scheduler::SchedulerData* data = scheduler_->GetData(node);
// Fixed nodes already know their schedule early position.
if (scheduler_->GetPlacement(node) == Scheduler::kFixed) {
data->minimum_block_ = schedule_->block(node);
Trace("Fixing #%d:%s minimum_block = B%d, dominator_depth = %d\n",
node->id(), node->op()->mnemonic(),
data->minimum_block_->id().ToInt(),
data->minimum_block_->dominator_depth());
}
// No need to propagate unconstrained schedule early positions.
if (data->minimum_block_ == schedule_->start()) return;
// Propagate schedule early position.
DCHECK(data->minimum_block_ != NULL);
Node::Uses uses = node->uses();
for (Node::Uses::iterator i = uses.begin(); i != uses.end(); ++i) {
PropagateMinimumPositionToNode(data->minimum_block_, *i);
}
}
// Propagates {block} as another minimum position into the given {node}. This
// has the net effect of computing the minimum dominator block of {node} that
// still post-dominates all inputs to {node} when the queue is processed.
void PropagateMinimumPositionToNode(BasicBlock* block, Node* node) {
Scheduler::SchedulerData* data = scheduler_->GetData(node);
// No need to propagate to fixed node, it's guaranteed to be a root.
if (scheduler_->GetPlacement(node) == Scheduler::kFixed) return;
// Coupled nodes influence schedule early position of their control.
if (scheduler_->GetPlacement(node) == Scheduler::kCoupled) {
Node* control = NodeProperties::GetControlInput(node);
PropagateMinimumPositionToNode(block, control);
}
// Propagate new position if it is deeper down the dominator tree than the
// current. Note that all inputs need to have minimum block position inside
// the dominator chain of {node}'s minimum block position.
DCHECK(InsideSameDominatorChain(block, data->minimum_block_));
if (block->dominator_depth() > data->minimum_block_->dominator_depth()) {
data->minimum_block_ = block;
queue_.push(node);
Trace("Propagating #%d:%s minimum_block = B%d, dominator_depth = %d\n",
node->id(), node->op()->mnemonic(),
data->minimum_block_->id().ToInt(),
data->minimum_block_->dominator_depth());
}
}
#if DEBUG
bool InsideSameDominatorChain(BasicBlock* b1, BasicBlock* b2) {
BasicBlock* dominator = scheduler_->GetCommonDominator(b1, b2);
return dominator == b1 || dominator == b2;
}
#endif
Scheduler* scheduler_;
Schedule* schedule_;
ZoneQueue<Node*> queue_;
};
void Scheduler::ScheduleEarly() {
Trace("--- SCHEDULE EARLY -----------------------------------------\n");
if (FLAG_trace_turbo_scheduler) {
Trace("roots: ");
for (Node* node : schedule_root_nodes_) {
Trace("#%d:%s ", node->id(), node->op()->mnemonic());
}
Trace("\n");
}
// Compute the minimum block for each node thereby determining the earliest
// position each node could be placed within a valid schedule.
ScheduleEarlyNodeVisitor schedule_early_visitor(zone_, this);
schedule_early_visitor.Run(&schedule_root_nodes_);
}
// -----------------------------------------------------------------------------
// Phase 5: Schedule nodes late.
class ScheduleLateNodeVisitor {
public:
ScheduleLateNodeVisitor(Zone* zone, Scheduler* scheduler)
: scheduler_(scheduler), schedule_(scheduler_->schedule_) {}
// Run the schedule late algorithm on a set of fixed root nodes.
void Run(NodeVector* roots) {
for (NodeVectorIter i = roots->begin(); i != roots->end(); ++i) {
ProcessQueue(*i);
}
}
private:
void ProcessQueue(Node* root) {
ZoneQueue<Node*>* queue = &(scheduler_->schedule_queue_);
for (Node* node : root->inputs()) {
// Don't schedule coupled nodes on their own.
if (scheduler_->GetPlacement(node) == Scheduler::kCoupled) {
node = NodeProperties::GetControlInput(node);
}
// Test schedulability condition by looking at unscheduled use count.
if (scheduler_->GetData(node)->unscheduled_count_ != 0) continue;
queue->push(node);
while (!queue->empty()) {
VisitNode(queue->front());
queue->pop();
}
}
}
// Visits one node from the queue of schedulable nodes and determines its
// schedule late position. Also hoists nodes out of loops to find a more
// optimal scheduling position.
void VisitNode(Node* node) {
DCHECK_EQ(0, scheduler_->GetData(node)->unscheduled_count_);
// Don't schedule nodes that are already scheduled.
if (schedule_->IsScheduled(node)) return;
DCHECK_EQ(Scheduler::kSchedulable, scheduler_->GetPlacement(node));
// Determine the dominating block for all of the uses of this node. It is
// the latest block that this node can be scheduled in.
Trace("Scheduling #%d:%s\n", node->id(), node->op()->mnemonic());
BasicBlock* block = GetCommonDominatorOfUses(node);
DCHECK_NOT_NULL(block);
// The schedule early block dominates the schedule late block.
BasicBlock* min_block = scheduler_->GetData(node)->minimum_block_;
DCHECK_EQ(min_block, scheduler_->GetCommonDominator(block, min_block));
Trace("Schedule late of #%d:%s is B%d at loop depth %d, minimum = B%d\n",
node->id(), node->op()->mnemonic(), block->id().ToInt(),
block->loop_depth(), min_block->id().ToInt());
// Hoist nodes out of loops if possible. Nodes can be hoisted iteratively
// into enclosing loop pre-headers until they would preceed their schedule
// early position.
BasicBlock* hoist_block = GetPreHeader(block);
while (hoist_block != NULL &&
hoist_block->dominator_depth() >= min_block->dominator_depth()) {
Trace(" hoisting #%d:%s to block B%d\n", node->id(),
node->op()->mnemonic(), hoist_block->id().ToInt());
DCHECK_LT(hoist_block->loop_depth(), block->loop_depth());
block = hoist_block;
hoist_block = GetPreHeader(hoist_block);
}
// Schedule the node or a floating control structure.
if (NodeProperties::IsControl(node)) {
ScheduleFloatingControl(block, node);
} else {
ScheduleNode(block, node);
}
}
BasicBlock* GetPreHeader(BasicBlock* block) {
if (block->IsLoopHeader()) {
return block->dominator();
} else if (block->loop_header() != NULL) {
return block->loop_header()->dominator();
} else {
return NULL;
}
}
BasicBlock* GetCommonDominatorOfUses(Node* node) {
BasicBlock* block = NULL;
for (Edge edge : node->use_edges()) {
BasicBlock* use_block = GetBlockForUse(edge);
block = block == NULL ? use_block : use_block == NULL
? block
: scheduler_->GetCommonDominator(
block, use_block);
}
return block;
}
BasicBlock* GetBlockForUse(Edge edge) {
Node* use = edge.from();
IrOpcode::Value opcode = use->opcode();
if (opcode == IrOpcode::kPhi || opcode == IrOpcode::kEffectPhi) {
// If the use is from a coupled (i.e. floating) phi, compute the common
// dominator of its uses. This will not recurse more than one level.
if (scheduler_->GetPlacement(use) == Scheduler::kCoupled) {
Trace(" inspecting uses of coupled #%d:%s\n", use->id(),
use->op()->mnemonic());
DCHECK_EQ(edge.to(), NodeProperties::GetControlInput(use));
return GetCommonDominatorOfUses(use);
}
// If the use is from a fixed (i.e. non-floating) phi, use the block
// of the corresponding control input to the merge.
if (scheduler_->GetPlacement(use) == Scheduler::kFixed) {
Trace(" input@%d into a fixed phi #%d:%s\n", edge.index(), use->id(),
use->op()->mnemonic());
Node* merge = NodeProperties::GetControlInput(use, 0);
opcode = merge->opcode();
DCHECK(opcode == IrOpcode::kMerge || opcode == IrOpcode::kLoop);
use = NodeProperties::GetControlInput(merge, edge.index());
}
}
BasicBlock* result = schedule_->block(use);
if (result == NULL) return NULL;
Trace(" must dominate use #%d:%s in B%d\n", use->id(),
use->op()->mnemonic(), result->id().ToInt());
return result;
}
void ScheduleFloatingControl(BasicBlock* block, Node* node) {
scheduler_->FuseFloatingControl(block, node);
}
void ScheduleNode(BasicBlock* block, Node* node) {
schedule_->PlanNode(block, node);
scheduler_->scheduled_nodes_[block->id().ToSize()].push_back(node);
scheduler_->UpdatePlacement(node, Scheduler::kScheduled);
}
Scheduler* scheduler_;
Schedule* schedule_;
};
void Scheduler::ScheduleLate() {
Trace("--- SCHEDULE LATE ------------------------------------------\n");
if (FLAG_trace_turbo_scheduler) {
Trace("roots: ");
for (Node* node : schedule_root_nodes_) {
Trace("#%d:%s ", node->id(), node->op()->mnemonic());
}
Trace("\n");
}
// Schedule: Places nodes in dominator block of all their uses.
ScheduleLateNodeVisitor schedule_late_visitor(zone_, this);
schedule_late_visitor.Run(&schedule_root_nodes_);
}
// -----------------------------------------------------------------------------
// Phase 6: Seal the final schedule.
void Scheduler::SealFinalSchedule() {
Trace("--- SEAL FINAL SCHEDULE ------------------------------------\n");
// Serialize the assembly order and reverse-post-order numbering.
special_rpo_->SerializeRPOIntoSchedule();
special_rpo_->PrintAndVerifySpecialRPO();
// Add collected nodes for basic blocks to their blocks in the right order.
int block_num = 0;
for (NodeVector& nodes : scheduled_nodes_) {
BasicBlock::Id id = BasicBlock::Id::FromInt(block_num++);
BasicBlock* block = schedule_->GetBlockById(id);
for (NodeVectorRIter i = nodes.rbegin(); i != nodes.rend(); ++i) {
schedule_->AddNode(block, *i);
}
}
}
// -----------------------------------------------------------------------------
void Scheduler::FuseFloatingControl(BasicBlock* block, Node* node) {
Trace("--- FUSE FLOATING CONTROL ----------------------------------\n");
if (FLAG_trace_turbo_scheduler) {
OFStream os(stdout);
os << "Schedule before control flow fusion:\n" << *schedule_;
}
// Iterate on phase 1: Build control-flow graph.
control_flow_builder_->Run(block, node);
// Iterate on phase 2: Compute special RPO and dominator tree.
special_rpo_->UpdateSpecialRPO(block, schedule_->block(node));
// TODO(mstarzinger): Currently "iterate on" means "re-run". Fix that.
for (BasicBlock* b = block->rpo_next(); b != NULL; b = b->rpo_next()) {
b->set_dominator_depth(-1);
b->set_dominator(NULL);
}
PropagateImmediateDominators(block->rpo_next());
// Iterate on phase 4: Schedule nodes early.
// TODO(mstarzinger): The following loop gathering the propagation roots is a
// temporary solution and should be merged into the rest of the scheduler as
// soon as the approach settled for all floating loops.
NodeVector propagation_roots(control_flow_builder_->control_);
for (Node* node : control_flow_builder_->control_) {
for (Node* use : node->uses()) {
if (use->opcode() == IrOpcode::kPhi ||
use->opcode() == IrOpcode::kEffectPhi) {
propagation_roots.push_back(use);
}
}
}
if (FLAG_trace_turbo_scheduler) {
Trace("propagation roots: ");
for (Node* node : propagation_roots) {
Trace("#%d:%s ", node->id(), node->op()->mnemonic());
}
Trace("\n");
}
ScheduleEarlyNodeVisitor schedule_early_visitor(zone_, this);
schedule_early_visitor.Run(&propagation_roots);
// Move previously planned nodes.
// TODO(mstarzinger): Improve that by supporting bulk moves.
scheduled_nodes_.resize(schedule_->BasicBlockCount(), NodeVector(zone_));
MovePlannedNodes(block, schedule_->block(node));
if (FLAG_trace_turbo_scheduler) {
OFStream os(stdout);
os << "Schedule after control flow fusion:\n" << *schedule_;
}
}
void Scheduler::MovePlannedNodes(BasicBlock* from, BasicBlock* to) {
Trace("Move planned nodes from B%d to B%d\n", from->id().ToInt(),
to->id().ToInt());
NodeVector* nodes = &(scheduled_nodes_[from->id().ToSize()]);
for (NodeVectorIter i = nodes->begin(); i != nodes->end(); ++i) {
schedule_->SetBlockForNode(to, *i);
scheduled_nodes_[to->id().ToSize()].push_back(*i);
}
nodes->clear();
}
} // namespace compiler
} // namespace internal
} // namespace v8