#include <hydrogen-escape-analysis.h>

Inheritance diagram for v8::internal::HEscapeAnalysisPhase:

Collaboration diagram for v8::internal::HEscapeAnalysisPhase:

Public Member Functions
	HEscapeAnalysisPhase (HGraph *graph)

void	Run ()

Public Member Functions inherited from v8::internal::HPhase
	HPhase (const char name, HGraph graph)

	~HPhase ()

Private Member Functions
void	CollectCapturedValues ()

bool	HasNoEscapingUses (HValue *value, int size)

void	PerformScalarReplacement ()

void	AnalyzeDataFlow (HInstruction *instr)

HCapturedObject *	NewState (HInstruction *prev)

HCapturedObject *	NewStateForAllocation (HInstruction *prev)

HCapturedObject *	NewStateForLoopHeader (HInstruction prev, HCapturedObject )

HCapturedObject *	NewStateCopy (HInstruction prev, HCapturedObject state)

HPhi *	NewPhiAndInsert (HBasicBlock block, HValue incoming_value, int index)

HValue *	NewMapCheckAndInsert (HCapturedObject state, HCheckMaps mapcheck)

HValue *	NewLoadReplacement (HLoadNamedField load, HValue load_value)

HCapturedObject *	StateAt (HBasicBlock *block)

void	SetStateAt (HBasicBlock block, HCapturedObject state)

Private Attributes
ZoneList< HInstruction * >	captured_

int	number_of_objects_

int	number_of_values_

int	cumulative_values_

ZoneList< HCapturedObject * >	block_states_

Additional Inherited Members
Protected Member Functions inherited from v8::internal::HPhase
HGraph *	graph () const

Detailed Description

Definition at line 15 of file hydrogen-escape-analysis.h.

Constructor & Destructor Documentation

◆ HEscapeAnalysisPhase()

v8::internal::HEscapeAnalysisPhase::HEscapeAnalysisPhase ( HGraph * graph )

inlineexplicit

Definition at line 17 of file hydrogen-escape-analysis.h.

       : HPhase("H_Escape analysis", graph),
         captured_(0, zone()),
         number_of_objects_(0),
         number_of_values_(0),
         cumulative_values_(0),
         block_states_(graph->blocks()->length(), zone()) { }

Member Function Documentation

◆ AnalyzeDataFlow()

void v8::internal::HEscapeAnalysisPhase::AnalyzeDataFlow ( HInstruction * instr )

private

Definition at line 162 of file hydrogen-escape-analysis.cc.

                                                                  {
   HBasicBlock* allocate_block = allocate->block();
   block_states_.AddBlock(NULL, graph()->blocks()->length(), zone());
  
   // Iterate all blocks starting with the allocation block, since the
   // allocation cannot dominate blocks that come before.
   int start = allocate_block->block_id();
   for (int i = start; i < graph()->blocks()->length(); i++) {
     HBasicBlock* block = graph()->blocks()->at(i);
     HCapturedObject* state = StateAt(block);
  
     // Skip blocks that are not dominated by the captured allocation.
     if (!allocate_block->Dominates(block) && allocate_block != block) continue;
     if (FLAG_trace_escape_analysis) {
       PrintF("Analyzing data-flow in B%d\n", block->block_id());
     }
  
     // Go through all instructions of the current block.
     for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
       HInstruction* instr = it.Current();
       switch (instr->opcode()) {
         case HValue::kAllocate: {
           if (instr != allocate) continue;
           state = NewStateForAllocation(allocate);
           break;
         }
         case HValue::kLoadNamedField: {
           HLoadNamedField* load = HLoadNamedField::cast(instr);
           int index = load->access().offset() / kPointerSize;
           if (load->object() != allocate) continue;
           DCHECK(load->access().IsInobject());
           HValue* replacement =
             NewLoadReplacement(load, state->OperandAt(index));
           load->DeleteAndReplaceWith(replacement);
           if (FLAG_trace_escape_analysis) {
             PrintF("Replacing load #%d with #%d (%s)\n", load->id(),
                    replacement->id(), replacement->Mnemonic());
           }
           break;
         }
         case HValue::kStoreNamedField: {
           HStoreNamedField* store = HStoreNamedField::cast(instr);
           int index = store->access().offset() / kPointerSize;
           if (store->object() != allocate) continue;
           DCHECK(store->access().IsInobject());
           state = NewStateCopy(store->previous(), state);
           state->SetOperandAt(index, store->value());
           if (store->has_transition()) {
             state->SetOperandAt(0, store->transition());
           }
           if (store->HasObservableSideEffects()) {
             state->ReuseSideEffectsFromStore(store);
           }
           store->DeleteAndReplaceWith(store->ActualValue());
           if (FLAG_trace_escape_analysis) {
             PrintF("Replacing store #%d%s\n", instr->id(),
                    store->has_transition() ? " (with transition)" : "");
           }
           break;
         }
         case HValue::kArgumentsObject:
         case HValue::kCapturedObject:
         case HValue::kSimulate: {
           for (int i = 0; i < instr->OperandCount(); i++) {
             if (instr->OperandAt(i) != allocate) continue;
             instr->SetOperandAt(i, state);
           }
           break;
         }
         case HValue::kCheckHeapObject: {
           HCheckHeapObject* check = HCheckHeapObject::cast(instr);
           if (check->value() != allocate) continue;
           check->DeleteAndReplaceWith(check->ActualValue());
           break;
         }
         case HValue::kCheckMaps: {
           HCheckMaps* mapcheck = HCheckMaps::cast(instr);
           if (mapcheck->value() != allocate) continue;
           NewMapCheckAndInsert(state, mapcheck);
           mapcheck->DeleteAndReplaceWith(mapcheck->ActualValue());
           break;
         }
         default:
           // Nothing to see here, move along ...
           break;
       }
     }
  
     // Propagate the block state forward to all successor blocks.
     for (int i = 0; i < block->end()->SuccessorCount(); i++) {
       HBasicBlock* succ = block->end()->SuccessorAt(i);
       if (!allocate_block->Dominates(succ)) continue;
       if (succ->predecessors()->length() == 1) {
         // Case 1: This is the only predecessor, just reuse state.
         SetStateAt(succ, state);
       } else if (StateAt(succ) == NULL && succ->IsLoopHeader()) {
         // Case 2: This is a state that enters a loop header, be
         // pessimistic about loop headers, add phis for all values.
         SetStateAt(succ, NewStateForLoopHeader(succ->first(), state));
       } else if (StateAt(succ) == NULL) {
         // Case 3: This is the first state propagated forward to the
         // successor, leave a copy of the current state.
         SetStateAt(succ, NewStateCopy(succ->first(), state));
       } else {
         // Case 4: This is a state that needs merging with previously
         // propagated states, potentially introducing new phis lazily or
         // adding values to existing phis.
         HCapturedObject* succ_state = StateAt(succ);
         for (int index = 0; index < number_of_values_; index++) {
           HValue* operand = state->OperandAt(index);
           HValue* succ_operand = succ_state->OperandAt(index);
           if (succ_operand->IsPhi() && succ_operand->block() == succ) {
             // Phi already exists, add operand.
             HPhi* phi = HPhi::cast(succ_operand);
             phi->SetOperandAt(succ->PredecessorIndexOf(block), operand);
           } else if (succ_operand != operand) {
             // Phi does not exist, introduce one.
             HPhi* phi = NewPhiAndInsert(succ, succ_operand, index);
             phi->SetOperandAt(succ->PredecessorIndexOf(block), operand);
             succ_state->SetOperandAt(index, phi);
           }
         }
       }
     }
   }
  
   // All uses have been handled.
   DCHECK(allocate->HasNoUses());
   allocate->DeleteAndReplaceWith(NULL);
 }

Referenced by PerformScalarReplacement().

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◆ CollectCapturedValues()

void v8::internal::HEscapeAnalysisPhase::CollectCapturedValues ( )

private

Definition at line 41 of file hydrogen-escape-analysis.cc.

                                                  {
   int block_count = graph()->blocks()->length();
   for (int i = 0; i < block_count; ++i) {
     HBasicBlock* block = graph()->blocks()->at(i);
     for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
       HInstruction* instr = it.Current();
       if (!instr->IsAllocate()) continue;
       HAllocate* allocate = HAllocate::cast(instr);
       if (!allocate->size()->IsInteger32Constant()) continue;
       int size_in_bytes = allocate->size()->GetInteger32Constant();
       if (HasNoEscapingUses(instr, size_in_bytes)) {
         if (FLAG_trace_escape_analysis) {
           PrintF("#%d (%s) is being captured\n", instr->id(),
                  instr->Mnemonic());
         }
         captured_.Add(instr, zone());
       }
     }
   }
 }

References captured_, v8::internal::HPhase::graph(), HasNoEscapingUses(), v8::internal::HValue::id(), v8::internal::HValue::Mnemonic(), and v8::internal::PrintF().

Referenced by Run().

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◆ HasNoEscapingUses()

bool v8::internal::HEscapeAnalysisPhase::HasNoEscapingUses	(	HValue *	value,
		int	size
	)

private

Definition at line 11 of file hydrogen-escape-analysis.cc.

                                                                     {
   for (HUseIterator it(value->uses()); !it.Done(); it.Advance()) {
     HValue* use = it.value();
     if (use->HasEscapingOperandAt(it.index())) {
       if (FLAG_trace_escape_analysis) {
         PrintF("#%d (%s) escapes through #%d (%s) @%d\n", value->id(),
                value->Mnemonic(), use->id(), use->Mnemonic(), it.index());
       }
       return false;
     }
     if (use->HasOutOfBoundsAccess(size)) {
       if (FLAG_trace_escape_analysis) {
         PrintF("#%d (%s) out of bounds at #%d (%s) @%d\n", value->id(),
                value->Mnemonic(), use->id(), use->Mnemonic(), it.index());
       }
       return false;
     }
     int redefined_index = use->RedefinedOperandIndex();
     if (redefined_index == it.index() && !HasNoEscapingUses(use, size)) {
       if (FLAG_trace_escape_analysis) {
         PrintF("#%d (%s) escapes redefinition #%d (%s) @%d\n", value->id(),
                value->Mnemonic(), use->id(), use->Mnemonic(), it.index());
       }
       return false;
     }
   }
   return true;
 }

References v8::internal::HValue::id(), v8::internal::HValue::Mnemonic(), v8::internal::PrintF(), size, use(), and v8::internal::HValue::uses().

Referenced by CollectCapturedValues().

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◆ NewLoadReplacement()

HValue * v8::internal::HEscapeAnalysisPhase::NewLoadReplacement	(	HLoadNamedField *	load,
		HValue *	load_value
	)

private

Definition at line 143 of file hydrogen-escape-analysis.cc.

                                                {
   HValue* replacement = load_value;
   Representation representation = load->representation();
   if (representation.IsSmiOrInteger32() || representation.IsDouble()) {
     Zone* zone = graph()->zone();
     HInstruction* new_instr =
         HForceRepresentation::New(zone, NULL, load_value, representation);
     new_instr->InsertAfter(load);
     replacement = new_instr;
   }
   return replacement;
 }

References v8::internal::HPhase::graph(), v8::internal::HInstruction::InsertAfter(), v8::internal::Representation::IsDouble(), v8::internal::Representation::IsSmiOrInteger32(), and NULL.

Referenced by AnalyzeDataFlow().

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◆ NewMapCheckAndInsert()

HValue * v8::internal::HEscapeAnalysisPhase::NewMapCheckAndInsert	(	HCapturedObject *	state,
		HCheckMaps *	mapcheck
	)

private

Definition at line 128 of file hydrogen-escape-analysis.cc.

                                                                          {
   Zone* zone = graph()->zone();
   HValue* value = state->map_value();
   // TODO(mstarzinger): This will narrow a map check against a set of maps
   // down to the first element in the set. Revisit and fix this.
   HCheckValue* check = HCheckValue::New(
       zone, NULL, value, mapcheck->maps()->at(0), false);
   check->InsertBefore(mapcheck);
   return check;
 }

References v8::internal::HPhase::graph(), and NULL.

Referenced by AnalyzeDataFlow().

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◆ NewPhiAndInsert()

HPhi * v8::internal::HEscapeAnalysisPhase::NewPhiAndInsert	(	HBasicBlock *	block,
		HValue *	incoming_value,
		int	index
	)

private

Definition at line 114 of file hydrogen-escape-analysis.cc.

                                                        {
   Zone* zone = graph()->zone();
   HPhi* phi = new(zone) HPhi(HPhi::kInvalidMergedIndex, zone);
   for (int i = 0; i < block->predecessors()->length(); i++) {
     phi->AddInput(incoming_value);
   }
   block->AddPhi(phi);
   return phi;
 }

References v8::internal::HPhase::graph().

Referenced by AnalyzeDataFlow(), and NewStateForLoopHeader().

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◆ NewState()

HCapturedObject * v8::internal::HEscapeAnalysisPhase::NewState ( HInstruction * prev )

private

Definition at line 63 of file hydrogen-escape-analysis.cc.

                                                                       {
   Zone* zone = graph()->zone();
   HCapturedObject* state =
       new(zone) HCapturedObject(number_of_values_, number_of_objects_, zone);
   state->InsertAfter(previous);
   return state;
 }

References v8::internal::HPhase::graph(), number_of_objects_, and number_of_values_.

Referenced by NewStateCopy(), NewStateForAllocation(), and NewStateForLoopHeader().

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◆ NewStateCopy()

HCapturedObject * v8::internal::HEscapeAnalysisPhase::NewStateCopy	(	HInstruction *	prev,
		HCapturedObject *	state
	)

private

Definition at line 100 of file hydrogen-escape-analysis.cc.

                                 {
   HCapturedObject* state = NewState(previous);
   for (int index = 0; index < number_of_values_; index++) {
     HValue* operand = old_state->OperandAt(index);
     state->SetOperandAt(index, operand);
   }
   return state;
 }

References NewState(), number_of_values_, v8::internal::HValue::OperandAt(), and v8::internal::HValue::SetOperandAt().

Referenced by AnalyzeDataFlow().

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◆ NewStateForAllocation()

HCapturedObject * v8::internal::HEscapeAnalysisPhase::NewStateForAllocation ( HInstruction * prev )

private

Definition at line 73 of file hydrogen-escape-analysis.cc.

                             {
   HConstant* undefined = graph()->GetConstantUndefined();
   HCapturedObject* state = NewState(previous);
   for (int index = 0; index < number_of_values_; index++) {
     state->SetOperandAt(index, undefined);
   }
   return state;
 }

References v8::internal::HPhase::graph(), NewState(), and number_of_values_.

Referenced by AnalyzeDataFlow().

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◆ NewStateForLoopHeader()

HCapturedObject * v8::internal::HEscapeAnalysisPhase::NewStateForLoopHeader	(	HInstruction *	prev,
		HCapturedObject *	old_state
	)

private

Definition at line 85 of file hydrogen-escape-analysis.cc.

                                 {
   HBasicBlock* block = previous->block();
   HCapturedObject* state = NewState(previous);
   for (int index = 0; index < number_of_values_; index++) {
     HValue* operand = old_state->OperandAt(index);
     HPhi* phi = NewPhiAndInsert(block, operand, index);
     state->SetOperandAt(index, phi);
   }
   return state;
 }

References v8::internal::HValue::block(), NewPhiAndInsert(), NewState(), number_of_values_, and v8::internal::HValue::OperandAt().

Referenced by AnalyzeDataFlow().

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◆ PerformScalarReplacement()

void v8::internal::HEscapeAnalysisPhase::PerformScalarReplacement ( )

private

Definition at line 294 of file hydrogen-escape-analysis.cc.

                                                     {
   for (int i = 0; i < captured_.length(); i++) {
     HAllocate* allocate = HAllocate::cast(captured_.at(i));
  
     // Compute number of scalar values and start with clean slate.
     int size_in_bytes = allocate->size()->GetInteger32Constant();
     number_of_values_ = size_in_bytes / kPointerSize;
     number_of_objects_++;
     block_states_.Rewind(0);
  
     // Perform actual analysis step.
     AnalyzeDataFlow(allocate);
  
     cumulative_values_ += number_of_values_;
     DCHECK(allocate->HasNoUses());
     DCHECK(!allocate->IsLinked());
   }
 }

References AnalyzeDataFlow(), block_states_, captured_, cumulative_values_, DCHECK, v8::internal::kPointerSize, number_of_objects_, and number_of_values_.

Referenced by Run().

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◆ Run()

void v8::internal::HEscapeAnalysisPhase::Run ( )

Definition at line 314 of file hydrogen-escape-analysis.cc.

                                {
   // TODO(mstarzinger): We disable escape analysis with OSR for now, because
   // spill slots might be uninitialized. Needs investigation.
   if (graph()->has_osr()) return;
   int max_fixpoint_iteration_count = FLAG_escape_analysis_iterations;
   for (int i = 0; i < max_fixpoint_iteration_count; i++) {
     CollectCapturedValues();
     if (captured_.is_empty()) break;
     PerformScalarReplacement();
     captured_.Rewind(0);
   }
 }

References captured_, CollectCapturedValues(), v8::internal::HPhase::graph(), and PerformScalarReplacement().

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◆ SetStateAt()

void v8::internal::HEscapeAnalysisPhase::SetStateAt	(	HBasicBlock *	block,
		HCapturedObject *	state
	)

inlineprivate

Definition at line 48 of file hydrogen-escape-analysis.h.

                                                               {
     block_states_.Set(block->block_id(), state);
   }

References block_states_, and v8::internal::List< T, AllocationPolicy >::Set().

Referenced by AnalyzeDataFlow().

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◆ StateAt()

HCapturedObject* v8::internal::HEscapeAnalysisPhase::StateAt ( HBasicBlock * block )

inlineprivate

Definition at line 44 of file hydrogen-escape-analysis.h.

                                                {
     return block_states_.at(block->block_id());
   }

References v8::internal::List< T, AllocationPolicy >::at(), and block_states_.

Referenced by AnalyzeDataFlow().

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Member Data Documentation

◆ block_states_

ZoneList<HCapturedObject*> v8::internal::HEscapeAnalysisPhase::block_states_

private

Definition at line 64 of file hydrogen-escape-analysis.h.

Referenced by AnalyzeDataFlow(), PerformScalarReplacement(), SetStateAt(), and StateAt().

◆ captured_

ZoneList<HInstruction*> v8::internal::HEscapeAnalysisPhase::captured_

private

Definition at line 53 of file hydrogen-escape-analysis.h.

Referenced by CollectCapturedValues(), PerformScalarReplacement(), and Run().

◆ cumulative_values_

int v8::internal::HEscapeAnalysisPhase::cumulative_values_

private

Definition at line 60 of file hydrogen-escape-analysis.h.

Referenced by PerformScalarReplacement().

◆ number_of_objects_

int v8::internal::HEscapeAnalysisPhase::number_of_objects_

private

Definition at line 56 of file hydrogen-escape-analysis.h.

Referenced by NewState(), and PerformScalarReplacement().

◆ number_of_values_

int v8::internal::HEscapeAnalysisPhase::number_of_values_

private

Definition at line 59 of file hydrogen-escape-analysis.h.

Referenced by AnalyzeDataFlow(), NewState(), NewStateCopy(), NewStateForAllocation(), NewStateForLoopHeader(), and PerformScalarReplacement().

The documentation for this class was generated from the following files:

/mnt/V8SourceCode/src/hydrogen-escape-analysis.h
/mnt/V8SourceCode/src/hydrogen-escape-analysis.cc

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ HEscapeAnalysisPhase()

Member Function Documentation

◆ AnalyzeDataFlow()

◆ CollectCapturedValues()

◆ HasNoEscapingUses()

◆ NewLoadReplacement()

◆ NewMapCheckAndInsert()

◆ NewPhiAndInsert()

◆ NewState()

◆ NewStateCopy()

◆ NewStateForAllocation()

◆ NewStateForLoopHeader()

◆ PerformScalarReplacement()

◆ Run()

◆ SetStateAt()

◆ StateAt()

Member Data Documentation

◆ block_states_

◆ captured_

◆ cumulative_values_

◆ number_of_objects_

◆ number_of_values_