VectorICs: Bugfix in KeyedStore dispatcher.

src/x87/code-stubs-x87.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 4223 matching lines @@
 
 void VectorStoreICStub::GenerateForTrampoline(MacroAssembler* masm) {
   GenerateImpl(masm, true);
 }
 
 
 // value is on the stack already.
 static void HandlePolymorphicStoreCase(MacroAssembler* masm, Register receiver,
                                        Register key, Register vector,
                                        Register slot, Register feedback,
-                                       Label* miss) {
+                                       bool is_polymorphic, Label* miss) {
   // feedback initially contains the feedback array
   Label next, next_loop, prepare_next;
   Label load_smi_map, compare_map;
   Label start_polymorphic;
+  Label pop_and_miss;
   ExternalReference virtual_register =
       ExternalReference::vector_store_virtual_register(masm->isolate());
 
   __ push(receiver);
   __ push(vector);
 
   Register receiver_map = receiver;
   Register cached_map = vector;
 
   // Receiver might not be a heap object.
@@ skipping 13 matching lines @@
   DCHECK(handler.is(VectorStoreICDescriptor::ValueRegister()));
   __ mov(handler, FieldOperand(feedback, FixedArray::OffsetOfElementAt(1)));
   __ pop(vector);
   __ pop(receiver);
   __ lea(handler, FieldOperand(handler, Code::kHeaderSize));
   __ mov(Operand::StaticVariable(virtual_register), handler);
   __ pop(handler);  // Pop "value".
   __ jmp(Operand::StaticVariable(virtual_register));
 
   // Polymorphic, we have to loop from 2 to N
-
-  // TODO(mvstanton): I think there is a bug here, we are assuming the
-  // array has more than one map/handler pair, but we call this function in the
-  // keyed store with a string key case, where it might be just an array of two
-  // elements.
-
   __ bind(&start_polymorphic);
   __ push(key);
   Register counter = key;
   __ mov(counter, Immediate(Smi::FromInt(2)));
+
+  if (!is_polymorphic) {
+    // If is_polymorphic is false, we may only have a two element array.
+    // Check against length now in that case.
+    __ cmp(counter, FieldOperand(feedback, FixedArray::kLengthOffset));
+    __ j(greater_equal, &pop_and_miss);
+  }
+
   __ bind(&next_loop);
   __ mov(cached_map, FieldOperand(feedback, counter, times_half_pointer_size,
                                   FixedArray::kHeaderSize));
   __ cmp(receiver_map, FieldOperand(cached_map, WeakCell::kValueOffset));
   __ j(not_equal, &prepare_next);
   __ mov(handler, FieldOperand(feedback, counter, times_half_pointer_size,
                                FixedArray::kHeaderSize + kPointerSize));
   __ lea(handler, FieldOperand(handler, Code::kHeaderSize));
   __ pop(key);
   __ pop(vector);
   __ pop(receiver);
   __ mov(Operand::StaticVariable(virtual_register), handler);
   __ pop(handler);  // Pop "value".
   __ jmp(Operand::StaticVariable(virtual_register));
 
   __ bind(&prepare_next);
   __ add(counter, Immediate(Smi::FromInt(2)));
   __ cmp(counter, FieldOperand(feedback, FixedArray::kLengthOffset));
   __ j(less, &next_loop);
 
   // We exhausted our array of map handler pairs.
+  __ bind(&pop_and_miss);
   __ pop(key);
   __ pop(vector);
   __ pop(receiver);
   __ jmp(miss);
 
   __ bind(&load_smi_map);
   __ LoadRoot(receiver_map, Heap::kHeapNumberMapRootIndex);
   __ jmp(&compare_map);
 }
 
@@ skipping 60 matching lines @@
   Label try_array;
   Label not_array, smi_key, key_okay;
   __ CompareRoot(FieldOperand(scratch, 0), Heap::kWeakCellMapRootIndex);
   __ j(not_equal, &try_array);
   HandleMonomorphicStoreCase(masm, receiver, key, vector, slot, scratch, &miss);
 
   // Is it a fixed array?
   __ bind(&try_array);
   __ CompareRoot(FieldOperand(scratch, 0), Heap::kFixedArrayMapRootIndex);
   __ j(not_equal, &not_array);
-  HandlePolymorphicStoreCase(masm, receiver, key, vector, slot, scratch, &miss);
+  HandlePolymorphicStoreCase(masm, receiver, key, vector, slot, scratch, true,
+                             &miss);
 
   __ bind(&not_array);
   __ CompareRoot(scratch, Heap::kmegamorphic_symbolRootIndex);
   __ j(not_equal, &miss);
 
   __ pop(value);
   __ push(slot);
   __ push(vector);
   Code::Flags code_flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::STORE_IC));
@@ skipping 154 matching lines @@
   __ jmp(megamorphic_stub, RelocInfo::CODE_TARGET);
 
   __ bind(&try_poly_name);
   // We might have a name in feedback, and a fixed array in the next slot.
   __ cmp(key, scratch);
   __ j(not_equal, &miss);
   // If the name comparison succeeded, we know we have a fixed array with
   // at least one map/handler pair.
   __ mov(scratch, FieldOperand(vector, slot, times_half_pointer_size,
                                FixedArray::kHeaderSize + kPointerSize));
-  HandlePolymorphicStoreCase(masm, receiver, key, vector, slot, scratch, &miss);
+  HandlePolymorphicStoreCase(masm, receiver, key, vector, slot, scratch, false,
+                             &miss);
 
   __ bind(&miss);
   __ pop(value);
   KeyedStoreIC::GenerateMiss(masm);
 }
 
 
 void CallICTrampolineStub::Generate(MacroAssembler* masm) {
   __ EmitLoadTypeFeedbackVector(ebx);
   CallICStub stub(isolate(), state());
@@ skipping 916 matching lines @@
                            Operand(ebp, 7 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87