Avoid jumping to the runtime for ForInFilter

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index 83bc1ae91d7fcfe99fff316def388f097ec09968..99bda1814d7c0be18420e7a0fa81dccbabb40b96 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -1078,11 +1078,11 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   __ lw(a1, MemOperand(sp, 1 * kPointerSize));
   __ Branch(loop_statement.break_label(), hs, a0, Operand(a1));
 
-  // Get the current entry of the array into register a3.
+  // Get the current entry of the array into result_register.
   __ lw(a2, MemOperand(sp, 2 * kPointerSize));
   __ Addu(a2, a2, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
   __ Lsa(t0, a2, a0, kPointerSizeLog2 - kSmiTagSize);
-  __ lw(a3, MemOperand(t0));  // Current entry.
+  __ lw(result_register(), MemOperand(t0));  // Current entry.
 
   // Get the expected map from the stack or a smi in the
   // permanent slow case into register a2.
@@ -1097,24 +1097,25 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
 
   // We need to filter the key, record slow-path here.
   int const vector_index = SmiFromSlot(slot)->value();
-  __ EmitLoadTypeFeedbackVector(a0);
+  __ EmitLoadTypeFeedbackVector(a3);
   __ li(a2, Operand(TypeFeedbackVector::MegamorphicSentinel(isolate())));
-  __ sw(a2, FieldMemOperand(a0, FixedArray::OffsetOfElementAt(vector_index)));
+  __ sw(a2, FieldMemOperand(a3, FixedArray::OffsetOfElementAt(vector_index)));
 
-  // Convert the entry to a string or (smi) 0 if it isn't a property
-  // any more. If the property has been removed while iterating, we
-  // just skip it.
-  __ Push(a1, a3);  // Enumerable and current entry.
-  __ CallRuntime(Runtime::kForInFilter);
+  // a0 contains the key. The receiver in a1 is the second argument to the
+  // ForInFilterStub. ForInFilter returns undefined if the receiver doesn't
+  // have the key or returns the name-converted key.
+  __ mov(a0, result_register());

[Igor Sheludko, 2016/07/20 14:22:02]

Maybe put the mov instruction before the comment?

+  ForInFilterStub filter_stub(isolate());
+  __ CallStub(&filter_stub);
+  RestoreContext();
   PrepareForBailoutForId(stmt->FilterId(), BailoutState::TOS_REGISTER);
-  __ mov(a3, result_register());
   __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
-  __ Branch(loop_statement.continue_label(), eq, a3, Operand(at));
+  __ Branch(loop_statement.continue_label(), eq, result_register(),
+            Operand(at));
 
   // Update the 'each' property or variable from the possibly filtered
-  // entry in register a3.
+  // entry in the result_register.
   __ bind(&update_each);
-  __ mov(result_register(), a3);
   // Perform the assignment as if via '='.
   { EffectContext context(this);
     EmitAssignment(stmt->each(), stmt->EachFeedbackSlot());