Megamorphic KeyedLoadIC needs special handling for vector ics.

src/ic/mips/ic-mips.cc

Index: src/ic/mips/ic-mips.cc
diff --git a/src/ic/mips/ic-mips.cc b/src/ic/mips/ic-mips.cc
index ea32f4e80144394b5ef9ed527578513a3468c0f8..42c7ad12413bfa29474834ff91c6c5db404c1ca0 100644
--- a/src/ic/mips/ic-mips.cc
+++ b/src/ic/mips/ic-mips.cc
@@ -536,10 +536,24 @@ void KeyedLoadIC::GenerateMegamorphic(MacroAssembler* masm) {
   __ LoadRoot(at, Heap::kHashTableMapRootIndex);
   __ Branch(&probe_dictionary, eq, t0, Operand(at));
 
+  if (FLAG_vector_ics) {
+    // When vector ics are in use, 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 = VectorLoadICDescriptor::VectorRegister();
+    Register slot = VectorLoadICDescriptor::SlotRegister();
+    DCHECK(!AreAliased(vector, slot, t0, t1, t2, t5));
+    Handle<TypeFeedbackVector> dummy_vector = Handle<TypeFeedbackVector>::cast(
+        masm->isolate()->factory()->keyed_load_dummy_vector());
+    int int_slot = dummy_vector->GetIndex(FeedbackVectorICSlot(0));
+    __ LoadRoot(vector, Heap::kKeyedLoadDummyVectorRootIndex);
+    __ li(slot, Operand(Smi::FromInt(int_slot)));
+  }
+
   Code::Flags flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::LOAD_IC));
   masm->isolate()->stub_cache()->GenerateProbe(
-      masm, Code::LOAD_IC, flags, false, receiver, key, a3, t0, t1, t2);
+      masm, Code::LOAD_IC, flags, false, receiver, key, t0, t1, t2, t5);
   // Cache miss.
   GenerateMiss(masm);