CSE2410 Fall 2014 Bounce

// Copyright 2013 the V8 project authors. All rights reserved.

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#include "hydrogen.h"

#include "hydrogen-osr.h"

namespace v8 {

namespace internal {

// True iff. we are compiling for OSR and the statement is the entry.

bool HOsrBuilder::HasOsrEntryAt(IterationStatement* statement) {

  return statement->OsrEntryId() == builder_->current_info()->osr_ast_id();

}

HBasicBlock* HOsrBuilder::BuildOsrLoopEntry(IterationStatement* statement) {

  ASSERT(HasOsrEntryAt(statement));

  Zone* zone = builder_->zone();

  HGraph* graph = builder_->graph();

  // only one OSR point per compile is allowed.

  ASSERT(graph->osr() == NULL);

  // remember this builder as the one OSR builder in the graph.

  graph->set_osr(this);

  HBasicBlock* non_osr_entry = graph->CreateBasicBlock();

  osr_entry_ = graph->CreateBasicBlock();

  HValue* true_value = graph->GetConstantTrue();

  HBranch* test = builder_->New<HBranch>(true_value, ToBooleanStub::Types(),

                                         non_osr_entry, osr_entry_);

  builder_->FinishCurrentBlock(test);

  HBasicBlock* loop_predecessor = graph->CreateBasicBlock();

  builder_->Goto(non_osr_entry, loop_predecessor);

  builder_->set_current_block(osr_entry_);

  osr_entry_->set_osr_entry();

  BailoutId osr_entry_id = statement->OsrEntryId();

  HEnvironment *environment = builder_->environment();

  int first_expression_index = environment->first_expression_index();

  int length = environment->length();

  osr_values_ = new(zone) ZoneList<HUnknownOSRValue*>(length, zone);

  for (int i = 0; i < first_expression_index; ++i) {

    HUnknownOSRValue* osr_value

        = builder_->Add<HUnknownOSRValue>(environment, i);

    environment->Bind(i, osr_value);

    osr_values_->Add(osr_value, zone);

  }

  if (first_expression_index != length) {

    environment->Drop(length - first_expression_index);

    for (int i = first_expression_index; i < length; ++i) {

      HUnknownOSRValue* osr_value

          = builder_->Add<HUnknownOSRValue>(environment, i);

      environment->Push(osr_value);

      osr_values_->Add(osr_value, zone);

    }

  }

  unoptimized_frame_slots_ =

      environment->local_count() + environment->push_count();

  // Keep a copy of the old environment, since the OSR values need it

  // to figure out where exactly they are located in the unoptimized frame.

  environment = environment->Copy();

  builder_->current_block()->UpdateEnvironment(environment);

  builder_->Add<HSimulate>(osr_entry_id);

  builder_->Add<HOsrEntry>(osr_entry_id);

  HContext* context = builder_->Add<HContext>();

  environment->BindContext(context);

  builder_->Goto(loop_predecessor);

  loop_predecessor->SetJoinId(statement->EntryId());

  builder_->set_current_block(loop_predecessor);

  // Create the final loop entry

  osr_loop_entry_ = builder_->BuildLoopEntry();

  return osr_loop_entry_;

}

void HOsrBuilder::FinishGraph() {

  // do nothing for now.

}

void HOsrBuilder::FinishOsrValues() {

  const ZoneList<HPhi*>* phis = osr_loop_entry_->phis();

  for (int j = 0; j < phis->length(); j++) {

    HPhi* phi = phis->at(j);

    if (phi->HasMergedIndex()) {

      osr_values_->at(phi->merged_index())->set_incoming_value(phi);

    }

  }

}

} }  // namespace v8::internal