Baseline for-of implementation

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
diff --git a/src/x64/full-codegen-x64.cc b/src/x64/full-codegen-x64.cc
index ed4896d8186326d12cdef5cdec78f366141b11a1..62c6073a2fe96c333f07192ac156ed8b88aaa048 100644
--- a/src/x64/full-codegen-x64.cc
+++ b/src/x64/full-codegen-x64.cc
@@ -1046,9 +1046,8 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   ForIn loop_statement(this, stmt);
   increment_loop_depth();
 
-  // Get the object to enumerate over. Both SpiderMonkey and JSC
-  // ignore null and undefined in contrast to the specification; see
-  // ECMA-262 section 12.6.4.
+  // 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.
   VisitForAccumulatorValue(stmt->enumerable());
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(equal, &exit);
@@ -1224,6 +1223,64 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
 }
 
 
+void FullCodeGenerator::VisitForOfStatement(ForOfStatement* stmt) {
+  Comment cmnt(masm_, "[ ForOfStatement");
+  SetStatementPosition(stmt);
+
+  Iteration loop_statement(this, stmt);
+  increment_loop_depth();
+
+  // var iterator = iterable[@@iterator]()
+  VisitForAccumulatorValue(stmt->assign_iterator());
+
+  // As with for-in, skip the loop if the iterator is null or undefined.
+  __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
+  __ j(equal, loop_statement.break_label());
+  __ CompareRoot(rax, Heap::kNullValueRootIndex);
+  __ j(equal, loop_statement.break_label());
+
+  // Convert the iterator to a JS object.
+  Label convert, done_convert;
+  __ JumpIfSmi(rax, &convert);
+  __ CmpObjectType(rax, FIRST_SPEC_OBJECT_TYPE, rcx);
+  __ j(above_equal, &done_convert);
+  __ bind(&convert);
+  __ push(rax);
+  __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
+  __ bind(&done_convert);
+
+  // 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