[fullcodegen] Remove for-of iteration support.

This removes support for iterator loops (i.e. for-of loop constructs)
from the {FullCodeGenerator}. Consequently optimized code containing
such constructs must use the {BytecodeGraphBuilder} and can no longer
use the {AstGraphBuilder} for graph building.

R=bmeurer@chromium.org
BUG=v8:5657

Review-Url: https://codereview.chromium.org/2534883004
Cr-Commit-Position: refs/heads/master@{#41357}

src/ast/ast.h

@@ -826,12 +826,6 @@ class ForOfStatement final : public ForEachStatement {
   void set_result_done(Expression* e) { result_done_ = e; }
   void set_assign_each(Expression* e) { assign_each_ = e; }
 
-  BailoutId ContinueId() const { return EntryId(); }
-  BailoutId StackCheckId() const { return BackEdgeId(); }
-
-  static int num_ids() { return parent_num_ids() + 1; }
-  BailoutId BackEdgeId() const { return BailoutId(local_id(0)); }
-
  private:
   friend class AstNodeFactory;
 
@@ -842,8 +836,6 @@ class ForOfStatement final : public ForEachStatement {
         next_result_(NULL),
         result_done_(NULL),
         assign_each_(NULL) {}
-  static int parent_num_ids() { return ForEachStatement::num_ids(); }
-  int local_id(int n) const { return base_id() + parent_num_ids() + n; }
 
   Variable* iterator_;
   Expression* assign_iterator_;

src/compiler/ast-graph-builder.cc

@@ -1265,17 +1265,8 @@ void AstGraphBuilder::VisitForInStatement(ForInStatement* stmt) {
 
 
 void AstGraphBuilder::VisitForOfStatement(ForOfStatement* stmt) {
-  LoopBuilder for_loop(this);
-  VisitForEffect(stmt->assign_iterator());
-  for_loop.BeginLoop(GetVariablesAssignedInLoop(stmt), CheckOsrEntry(stmt));
-  VisitForEffect(stmt->next_result());
-  VisitForTest(stmt->result_done());
-  Node* condition = environment()->Pop();
-  for_loop.BreakWhen(condition);
-  VisitForEffect(stmt->assign_each());
-  VisitIterationBody(stmt, &for_loop, stmt->StackCheckId());
-  for_loop.EndBody();
-  for_loop.EndLoop();
+  // Iterator looping is supported only by going through Ignition first.
+  UNREACHABLE();
 }
 
 

src/full-codegen/full-codegen.cc

@@ -1261,43 +1261,8 @@ void FullCodeGenerator::VisitForStatement(ForStatement* stmt) {
 
 
 void FullCodeGenerator::VisitForOfStatement(ForOfStatement* stmt) {
-  Comment cmnt(masm_, "[ ForOfStatement");
-
-  Iteration loop_statement(this, stmt);
-  increment_loop_depth();
-
-  // var iterator = iterable[Symbol.iterator]();
-  SetExpressionAsStatementPosition(stmt->assign_iterator());
-  VisitForEffect(stmt->assign_iterator());
-
-  // Loop entry.
-  __ bind(loop_statement.continue_label());
-
-  // result = iterator.next()
-  SetExpressionAsStatementPosition(stmt->next_result());
-  VisitForEffect(stmt->next_result());
-
-  // if (result.done) break;
-  Label result_not_done;
-  VisitForControl(stmt->result_done(), loop_statement.break_label(),
-                  &result_not_done, &result_not_done);
-  __ bind(&result_not_done);
-
-  // each = result.value
-  VisitForEffect(stmt->assign_each());
-
-  // Generate code for the body of the loop.
-  Visit(stmt->body());
-
-  // Check stack before looping.
-  PrepareForBailoutForId(stmt->BackEdgeId(), BailoutState::NO_REGISTERS);
-  EmitBackEdgeBookkeeping(stmt, loop_statement.continue_label());
-  __ jmp(loop_statement.continue_label());
-
-  // Exit and decrement the loop depth.
-  PrepareForBailoutForId(stmt->ExitId(), BailoutState::NO_REGISTERS);
-  __ bind(loop_statement.break_label());
-  decrement_loop_depth();
+  // Iterator looping is not supported.
+  UNREACHABLE();
 }
 
 void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {