Baseline for-of implementation

src/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1029 matching lines @@
 
 
 void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   Comment cmnt(masm_, "[ ForInStatement");
   SetStatementPosition(stmt);
 
   Label loop, exit;
   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);
   Register null_value = rdi;
   __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ cmpq(rax, null_value);
   __ j(equal, &exit);
 
   PrepareForBailoutForId(stmt->PrepareId(), TOS_REG);
 
@@ skipping 155 matching lines @@
   __ bind(loop_statement.break_label());
   __ addq(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[@@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
   // 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 3577 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64