Vector ICs: Like megamorphic keyed koads, use a dummy vector for stores

src/ic/mips64/ic-mips64.cc

Index: src/ic/mips64/ic-mips64.cc
diff --git a/src/ic/mips64/ic-mips64.cc b/src/ic/mips64/ic-mips64.cc
index 770fa77808dd5ef7631d3aeefd2d3e051f914d54..92bb9706680d61014b47af8dda457f694001f36b 100644
--- a/src/ic/mips64/ic-mips64.cc
+++ b/src/ic/mips64/ic-mips64.cc
@@ -424,9 +424,9 @@ void KeyedLoadIC::GenerateMegamorphic(MacroAssembler* masm) {
   DCHECK(!AreAliased(vector, slot, a4, a5, a6, t1));
   Handle<TypeFeedbackVector> dummy_vector = Handle<TypeFeedbackVector>::cast(
       masm->isolate()->factory()->keyed_load_dummy_vector());
-  int int_slot = dummy_vector->GetIndex(FeedbackVectorICSlot(0));
+  int slot_index = dummy_vector->GetIndex(FeedbackVectorICSlot(0));
   __ LoadRoot(vector, Heap::kKeyedLoadDummyVectorRootIndex);
-  __ li(slot, Operand(Smi::FromInt(int_slot)));
+  __ li(slot, Operand(Smi::FromInt(slot_index)));
 
   Code::Flags flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::LOAD_IC));
@@ -664,6 +664,20 @@ void KeyedStoreIC::GenerateMegamorphic(MacroAssembler* masm,
   __ ld(a4, FieldMemOperand(key, HeapObject::kMapOffset));
   __ lb(a4, FieldMemOperand(a4, Map::kInstanceTypeOffset));
   __ JumpIfNotUniqueNameInstanceType(a4, &slow);
+
+  if (FLAG_vector_stores) {
+    // The handlers in the stub cache expect a vector and slot. Since we won't
+    // change the IC from any downstream misses, a dummy vector can be used.
+    Register vector = LoadWithVectorDescriptor::VectorRegister();
+    Register slot = LoadWithVectorDescriptor::SlotRegister();
+    DCHECK(!AreAliased(vector, slot, a3, a4, a5, a6));
+    Handle<TypeFeedbackVector> dummy_vector = Handle<TypeFeedbackVector>::cast(
+        masm->isolate()->factory()->keyed_store_dummy_vector());
+    int slot_index = dummy_vector->GetIndex(FeedbackVectorICSlot(0));
+    __ LoadRoot(vector, Heap::kKeyedStoreDummyVectorRootIndex);
+    __ li(slot, Operand(Smi::FromInt(slot_index)));
+  }
+
   Code::Flags flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::STORE_IC));
   masm->isolate()->stub_cache()->GenerateProbe(