Revert "Fix stepping in for-loops."

src/arm64/full-codegen-arm64.cc

 // 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 "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 1091 matching lines @@
   FeedbackVectorSlot slot = stmt->ForInFeedbackSlot();
   // TODO(all): This visitor probably needs better comments and a revisit.
   SetStatementPosition(stmt);
 
   Label loop, exit;
   ForIn loop_statement(this, stmt);
   increment_loop_depth();
 
   // Get the object to enumerate over. If the object is null or undefined, skip
   // over the loop.  See ECMA-262 version 5, section 12.6.4.
-  SetExpressionPosition(stmt->enumerable());
   VisitForAccumulatorValue(stmt->enumerable());
   __ JumpIfRoot(x0, Heap::kUndefinedValueRootIndex, &exit);
   Register null_value = x15;
   __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ Cmp(x0, null_value);
   __ B(eq, &exit);
 
   PrepareForBailoutForId(stmt->PrepareId(), TOS_REG);
 
   // Convert the object to a JS object.
@@ skipping 114 matching lines @@
   __ InvokeBuiltin(Builtins::FILTER_KEY, CALL_FUNCTION);
   __ Mov(x3, x0);
   __ Cbz(x0, loop_statement.continue_label());
 
   // Update the 'each' property or variable from the possibly filtered
   // entry in register x3.
   __ Bind(&update_each);
   __ Mov(result_register(), x3);
   // Perform the assignment as if via '='.
   { EffectContext context(this);
-    SetExpressionPosition(stmt->each());
     EmitAssignment(stmt->each());
   }
 
   // Generate code for the body of the loop.
   Visit(stmt->body());
 
   // Generate code for going to the next element by incrementing
   // the index (smi) stored on top of the stack.
   __ Bind(loop_statement.continue_label());
   // TODO(all): We could use a callee saved register to avoid popping.
   __ Pop(x0);
   __ Add(x0, x0, Smi::FromInt(1));
   __ Push(x0);
 
   EmitBackEdgeBookkeeping(stmt, &loop);
   __ B(&loop);
 
   // Remove the pointers stored on the stack.
   __ Bind(loop_statement.break_label());
   __ Drop(5);
 
   // Exit and decrement the loop depth.
   PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
   __ Bind(&exit);
   decrement_loop_depth();
 }
 
 
+void FullCodeGenerator::VisitForOfStatement(ForOfStatement* stmt) {
+  Comment cmnt(masm_, "[ ForOfStatement");
+  SetStatementPosition(stmt);
+
+  Iteration loop_statement(this, stmt);
+  increment_loop_depth();
+
+  // var iterator = iterable[Symbol.iterator]();
+  VisitForEffect(stmt->assign_iterator());
+
+  // Loop entry.
+  __ Bind(loop_statement.continue_label());
+
+  // result = iterator.next()
+  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(), NO_REGISTERS);
+  EmitBackEdgeBookkeeping(stmt, loop_statement.continue_label());
+  __ B(loop_statement.continue_label());
+
+  // Exit and decrement the loop depth.
+  PrepareForBailoutForId(stmt->ExitId(), NO_REGISTERS);
+  __ Bind(loop_statement.break_label());
+  decrement_loop_depth();
+}
+
+
 void FullCodeGenerator::EmitNewClosure(Handle<SharedFunctionInfo> info,
                                        bool pretenure) {
   // Use the fast case closure allocation code that allocates in new space for
   // nested functions that don't need literals cloning. If we're running with
   // the --always-opt or the --prepare-always-opt flag, we need to use the
   // runtime function so that the new function we are creating here gets a
   // chance to have its code optimized and doesn't just get a copy of the
   // existing unoptimized code.
   if (!FLAG_always_opt &&
       !FLAG_prepare_always_opt &&
@@ skipping 3997 matching lines @@
   return previous_;
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64