dart::InlineExitCollector Class Reference

#include <flow_graph_builder.h>

Inheritance diagram for dart::InlineExitCollector:

Public Member Functions
	InlineExitCollector (FlowGraph *caller_graph, Definition *call)
void	AddExit (DartReturnInstr *exit)
void	Union (const InlineExitCollector *other)
void	PrepareGraphs (FlowGraph *callee_graph)
void	ReplaceCall (BlockEntryInstr *callee_entry)
Public Member Functions inherited from dart::ZoneAllocated
	ZoneAllocated ()
void *	operator new (size_t size)
void *	operator new (size_t size, Zone *zone)
void	operator delete (void *pointer)

Detailed Description

Definition at line 24 of file flow_graph_builder.h.

Constructor & Destructor Documentation

InlineExitCollector()

dart::InlineExitCollector::InlineExitCollector ( FlowGraph *  caller_graph, Definition *  call  )

inline

Definition at line 26 of file flow_graph_builder.h.

      : caller_graph_(caller_graph), call_(call), exits_(4) {}

Member Function Documentation

AddExit()

void dart::InlineExitCollector::AddExit

(

DartReturnInstr *

exit

)

Definition at line 94 of file flow_graph_builder.cc.

                                                       {
  Data data = {nullptr, exit};
  exits_.Add(data);
}

PrepareGraphs()

void dart::InlineExitCollector::PrepareGraphs

(

FlowGraph *

callee_graph

)

Definition at line 40 of file flow_graph_builder.cc.

                                                               {
  COMPILER_TIMINGS_TIMER_SCOPE(callee_graph->thread(), PrepareGraphs);
  ASSERT(callee_graph->graph_entry()->SuccessorCount() == 1);
  ASSERT(callee_graph->max_block_id() > caller_graph_->max_block_id());
  ASSERT(callee_graph->current_ssa_temp_index() >
         caller_graph_->current_ssa_temp_index());
 
  // Adjust the caller's maximum block id and current SSA temp index.
  caller_graph_->set_max_block_id(callee_graph->max_block_id());
  caller_graph_->set_current_ssa_temp_index(
      callee_graph->current_ssa_temp_index());
 
  // Attach the outer environment on each instruction in the callee graph.
  ASSERT(call_->env() != nullptr);
  ASSERT(call_->deopt_id() != DeoptId::kNone);
 
  auto zone = callee_graph->zone();
  auto env = call_->env();
 
  const intptr_t outer_deopt_id = call_->deopt_id();
  // Scale the edge weights by the call count for the inlined function.
  double scale_factor = 1.0;
  if (caller_graph_->graph_entry()->entry_count() != 0) {
    scale_factor =
        static_cast<double>(call_->CallCount()) /
        static_cast<double>(caller_graph_->graph_entry()->entry_count());
  }
  for (BlockIterator block_it = callee_graph->postorder_iterator();
       !block_it.Done(); block_it.Advance()) {
    BlockEntryInstr* block = block_it.Current();
    if (block->IsTargetEntry()) {
      block->AsTargetEntry()->adjust_edge_weight(scale_factor);
    }
    Instruction* instr = block;
    if (block->env() != nullptr) {
      env->DeepCopyToOuter(zone, block, outer_deopt_id);
    }
    for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
      instr = it.Current();
      // TODO(zerny): Avoid creating unnecessary environments. Note that some
      // optimizations need deoptimization info for non-deoptable instructions,
      // eg, LICM on GOTOs.
      if (instr->env() != nullptr) {
        env->DeepCopyToOuter(zone, instr, outer_deopt_id);
      }
    }
    if (instr->IsGoto()) {
      instr->AsGoto()->adjust_edge_weight(scale_factor);
    }
  }
 
  RemoveUnreachableExits(callee_graph);
}

ReplaceCall()

void dart::InlineExitCollector::ReplaceCall

(

BlockEntryInstr *

callee_entry

)

Definition at line 242 of file flow_graph_builder.cc.

                                                                   {
  ASSERT(call_->previous() != nullptr);
  ASSERT(call_->next() != nullptr);
  BlockEntryInstr* call_block = call_->GetBlock();
 
  // Insert the callee graph into the caller graph.
  BlockEntryInstr* callee_exit = nullptr;
  Instruction* callee_last_instruction = nullptr;
 
  if (exits_.length() == 0) {
    // Handle the case when there are no normal return exits from the callee
    // (i.e. the callee unconditionally throws) by inserting an artificial
    // branch (true === true).
    // The true successor is the inlined body, the false successor
    // goes to the rest of the caller graph. It is removed as unreachable code
    // by the constant propagation.
    TargetEntryInstr* false_block = new (Z) TargetEntryInstr(
        caller_graph_->allocate_block_id(), call_block->try_index(),
        CompilerState::Current().GetNextDeoptId());
    false_block->InheritDeoptTargetAfter(caller_graph_, call_, nullptr);
    false_block->LinkTo(call_->next());
    call_block->ReplaceAsPredecessorWith(false_block);
 
    ConstantInstr* true_const = caller_graph_->GetConstant(Bool::True());
    BranchInstr* branch = new (Z) BranchInstr(
        new (Z) StrictCompareInstr(InstructionSource(), Token::kEQ_STRICT,
                                   new (Z) Value(true_const),
                                   new (Z) Value(true_const), false,
                                   CompilerState::Current().GetNextDeoptId()),
        CompilerState::Current().GetNextDeoptId());  // No number check.
    branch->InheritDeoptTarget(zone(), call_);
 
    auto true_target = BranchSimplifier::ToTargetEntry(zone(), callee_entry);
    callee_entry->ReplaceAsPredecessorWith(true_target);
 
    *branch->true_successor_address() = true_target;
    *branch->false_successor_address() = false_block;
 
    call_->previous()->AppendInstruction(branch);
    call_block->set_last_instruction(branch);
 
    // Replace uses of the return value with sentinel constant to maintain
    // valid SSA form - even though the rest of the caller is unreachable.
    call_->ReplaceUsesWith(caller_graph_->GetConstant(Object::sentinel()));
 
    // Update dominator tree.
    for (intptr_t i = 0, n = callee_entry->dominated_blocks().length(); i < n;
         i++) {
      BlockEntryInstr* block = callee_entry->dominated_blocks()[i];
      true_target->AddDominatedBlock(block);
    }
    for (intptr_t i = 0, n = call_block->dominated_blocks().length(); i < n;
         i++) {
      BlockEntryInstr* block = call_block->dominated_blocks()[i];
      false_block->AddDominatedBlock(block);
    }
    call_block->ClearDominatedBlocks();
    call_block->AddDominatedBlock(true_target);
    call_block->AddDominatedBlock(false_block);
 
  } else {
    Definition* callee_result = JoinReturns(
        &callee_exit, &callee_last_instruction, call_block->try_index());
    if (callee_result != nullptr) {
      call_->ReplaceUsesWith(callee_result);
    }
    if (callee_last_instruction == callee_entry) {
      // There are no instructions in the inlined function (e.g., it might be
      // a return of a parameter or a return of a constant defined in the
      // initial definitions).
      call_->previous()->LinkTo(call_->next());
    } else {
      call_->previous()->LinkTo(callee_entry->next());
      callee_last_instruction->LinkTo(call_->next());
    }
    if (callee_exit != callee_entry) {
      // In case of control flow, locally update the predecessors, phis and
      // dominator tree.
      //
      // Pictorially, the graph structure is:
      //
      //   Bc : call_block      Bi : callee_entry
      //     before_call          inlined_head
      //     call               ... other blocks ...
      //     after_call         Be : callee_exit
      //                          inlined_foot
      // And becomes:
      //
      //   Bc : call_block
      //     before_call
      //     inlined_head
      //   ... other blocks ...
      //   Be : callee_exit
      //    inlined_foot
      //    after_call
      //
      // For successors of 'after_call', the call block (Bc) is replaced as a
      // predecessor by the callee exit (Be).
      call_block->ReplaceAsPredecessorWith(callee_exit);
      // For successors of 'inlined_head', the callee entry (Bi) is replaced
      // as a predecessor by the call block (Bc).
      callee_entry->ReplaceAsPredecessorWith(call_block);
 
      // The callee exit is now the immediate dominator of blocks whose
      // immediate dominator was the call block.
      ASSERT(callee_exit->dominated_blocks().is_empty());
      for (intptr_t i = 0; i < call_block->dominated_blocks().length(); ++i) {
        BlockEntryInstr* block = call_block->dominated_blocks()[i];
        callee_exit->AddDominatedBlock(block);
      }
      // The call block is now the immediate dominator of blocks whose
      // immediate dominator was the callee entry.
      call_block->ClearDominatedBlocks();
      for (intptr_t i = 0; i < callee_entry->dominated_blocks().length(); ++i) {
        BlockEntryInstr* block = callee_entry->dominated_blocks()[i];
        call_block->AddDominatedBlock(block);
      }
    }
 
    // Callee entry in not in the graph anymore. Remove it from use lists.
    callee_entry->UnuseAllInputs();
  }
  // Neither call nor the graph entry (if present) are in the
  // graph at this point. Remove them from use lists.
  if (callee_entry->PredecessorCount() > 0) {
    callee_entry->PredecessorAt(0)->AsGraphEntry()->UnuseAllInputs();
  }
  call_->UnuseAllInputs();
}

Union()

void dart::InlineExitCollector::Union

(

const InlineExitCollector *

other

)

Definition at line 99 of file flow_graph_builder.cc.

                                                                {
  // It doesn't make sense to combine different calls or calls from
  // different graphs.
  ASSERT(caller_graph_ == other->caller_graph_);
  ASSERT(call_ == other->call_);
  exits_.AddArray(other->exits_);
}

---

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

• third_party/dart-lang/sdk/runtime/vm/compiler/frontend/flow_graph_builder.h
• third_party/dart-lang/sdk/runtime/vm/compiler/frontend/flow_graph_builder.cc