Revert "Fix stepping in for-loops."

src/x64/full-codegen-x64.cc

 // Copyright 2012 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_X64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 1049 matching lines @@
   Comment cmnt(masm_, "[ ForInStatement");
   FeedbackVectorSlot slot = stmt->ForInFeedbackSlot();
   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());
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(equal, &exit);
   Register null_value = rdi;
   __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ cmpp(rax, null_value);
   __ j(equal, &exit);
 
   PrepareForBailoutForId(stmt->PrepareId(), TOS_REG);
 
@@ skipping 127 matching lines @@
   __ Cmp(rax, Smi::FromInt(0));
   __ j(equal, loop_statement.continue_label());
   __ movp(rbx, rax);
 
   // Update the 'each' property or variable from the possibly filtered
   // entry in register rbx.
   __ bind(&update_each);
   __ movp(result_register(), rbx);
   // 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());
   __ SmiAddConstant(Operand(rsp, 0 * kPointerSize), Smi::FromInt(1));
 
   EmitBackEdgeBookkeeping(stmt, &loop);
   __ jmp(&loop);
 
   // Remove the pointers stored on the stack.
   __ bind(loop_statement.break_label());
   __ addp(rsp, Immediate(5 * kPointerSize));
 
   // 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());
+  __ jmp(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 3940 matching lines @@
   DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64