--debug-code: sanity-checking instrumentation for Lithium object accesses

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 9e6f0f0c1cd380dd41eb6c592e8140577a09c10b..3f6d43c77cd748033592d352876c4604091126da 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -5910,6 +5910,53 @@ class HStoreContextSlot V8_FINAL : public HTemplateInstruction<2> {
 // array elements pointer, etc, but not accesses to array elements themselves.
 class HObjectAccess V8_FINAL {
  public:
+  enum Purpose {
+    UNKNOWN_PURPOSE,
+    FOR_ALLOCATION_MEMENTO_SITE,
+    FOR_ALLOCATION_SITE_LIST,
+    FOR_ALLOCATION_SITE_OFFSET,
+    FOR_ARRAY_LENGTH,
+    FOR_BACKING_STORE_OFFSET,
+    FOR_CELL_PAYLOAD,
+    FOR_CELL_VALUE,
+    FOR_CODE_ENTRY_POINTER,
+    FOR_CODE_OFFSET,
+    FOR_CONS_STRING_FIRST,
+    FOR_CONS_STRING_SECOND,
+    FOR_CONTEXT_SLOT,
+    FOR_COUNTER,
+    FOR_ELEMENTS_POINTER,
+    FOR_EXTERNAL_ARRAY_EXTERNAL_POINTER,
+    FOR_FIELD,
+    FOR_FIXED_ARRAY_HEADER,
+    FOR_FIXED_ARRAY_LENGTH,
+    FOR_FUNCTION_CONTEXT_POINTER,
+    FOR_GLOBAL_OBJECT_NATIVE_CONTEXT,
+    FOR_HEAP_NUMBER_VALUE_HIGHEST_BITS,
+    FOR_HEAP_NUMBER_VALUE_LOWEST_BITS,
+    FOR_HEAP_NUMBER_VALUE,
+    FOR_JSARRAY_OFFSET,
+    FOR_JSARRAYBUFFER_BACKING_STORE,
+    FOR_JSARRAYBUFFER_BYTE_LENGTH,
+    FOR_JSARRAYBUFFER_WEAK_FIRST_VIEW,
+    FOR_JSARRAYBUFFERVIEW_BUFFER,
+    FOR_JSARRAYBUFFERVIEW_BYTE_LENGTH,
+    FOR_JSARRAYBUFFERVIEW_BYTE_OFFSET,
+    FOR_JSARRAYBUFFERVIEW_WEAK_NEXT,
+    FOR_JSTYPEDARRAY_LENGTH,
+    FOR_LITERALS_POINTER,
+    FOR_MAP_INSTANCE_SIZE,
+    FOR_MAP_INSTANCE_TYPE,
+    FOR_MAP,
+    FOR_NEXT_FUNCTION_LINK_POINTER,
+    FOR_OPTIMIZED_CODE_MAP,
+    FOR_PROPERTIES_POINTER,
+    FOR_PROPERTY_CELL_VALUE,
+    FOR_PROTOTYPE_OR_INITIAL_MAP,
+    FOR_SHARED_FUNCTION_INFO_POINTER,
+    FOR_STRING_HASH_FIELD,
+    FOR_STRING_LENGTH
+  };
   inline bool IsInobject() const {
     return portion() != kBackingStore && portion() != kExternalMemory;
   }
@@ -5949,43 +5996,56 @@ class HObjectAccess V8_FINAL {
   }
 
   inline HObjectAccess WithRepresentation(Representation representation) {
-    return HObjectAccess(portion(), offset(), representation, name(),
+    Purpose p =
+#ifdef DEBUG
+        purpose();
+#else
+        UNKNOWN_PURPOSE;
+#endif
+    return HObjectAccess(portion(), offset(), p, representation, name(),
                          immutable(), existing_inobject_property());
   }
 
   static HObjectAccess ForHeapNumberValue() {
     return HObjectAccess(
-        kDouble, HeapNumber::kValueOffset, Representation::Double());
+        kDouble, HeapNumber::kValueOffset, FOR_HEAP_NUMBER_VALUE,
+        Representation::Double());
   }
 
   static HObjectAccess ForHeapNumberValueLowestBits() {
     return HObjectAccess(kDouble,
                          HeapNumber::kValueOffset,
+                         FOR_HEAP_NUMBER_VALUE_LOWEST_BITS,
                          Representation::Integer32());
   }
 
   static HObjectAccess ForHeapNumberValueHighestBits() {
     return HObjectAccess(kDouble,
                          HeapNumber::kValueOffset + kIntSize,
+                         FOR_HEAP_NUMBER_VALUE_HIGHEST_BITS,
                          Representation::Integer32());
   }
 
   static HObjectAccess ForElementsPointer() {
-    return HObjectAccess(kElementsPointer, JSObject::kElementsOffset);
+    return HObjectAccess(kElementsPointer, JSObject::kElementsOffset,
+                         FOR_ELEMENTS_POINTER);
   }
 
   static HObjectAccess ForLiteralsPointer() {
-    return HObjectAccess(kInobject, JSFunction::kLiteralsOffset);
+    return HObjectAccess(kInobject, JSFunction::kLiteralsOffset,
+                         FOR_LITERALS_POINTER);
   }
 
   static HObjectAccess ForNextFunctionLinkPointer() {
-    return HObjectAccess(kInobject, JSFunction::kNextFunctionLinkOffset);
+    return HObjectAccess(kInobject, JSFunction::kNextFunctionLinkOffset,
+                         FOR_NEXT_FUNCTION_LINK_POINTER);
   }
 
   static HObjectAccess ForArrayLength(ElementsKind elements_kind) {
     return HObjectAccess(
         kArrayLengths,
         JSArray::kLengthOffset,
+        FOR_ARRAY_LENGTH,
         IsFastElementsKind(elements_kind)
             ? Representation::Smi() : Representation::Tagged());
   }
@@ -5993,98 +6053,108 @@ class HObjectAccess V8_FINAL {
   static HObjectAccess ForAllocationSiteOffset(int offset);
 
   static HObjectAccess ForAllocationSiteList() {
-    return HObjectAccess(kExternalMemory, 0, Representation::Tagged(),
+    return HObjectAccess(kExternalMemory, 0, FOR_ALLOCATION_SITE_LIST,
+                         Representation::Tagged(),
                          Handle<String>::null(), false, false);
   }
 
   static HObjectAccess ForFixedArrayLength() {
-    return HObjectAccess(
-        kArrayLengths,
-        FixedArray::kLengthOffset,
-        Representation::Smi());
+    return HObjectAccess(kArrayLengths, FixedArray::kLengthOffset,
+                         FOR_FIXED_ARRAY_LENGTH, Representation::Smi());
   }
 
   static HObjectAccess ForStringHashField() {
-    return HObjectAccess(kInobject,
-                         String::kHashFieldOffset,
-                         Representation::Integer32());
+    return HObjectAccess(kInobject, String::kHashFieldOffset,
+                         FOR_STRING_HASH_FIELD, Representation::Integer32());
   }
 
   static HObjectAccess ForStringLength() {
     STATIC_ASSERT(String::kMaxLength <= Smi::kMaxValue);
-    return HObjectAccess(
-        kStringLengths,
-        String::kLengthOffset,
-        Representation::Smi());
+    return HObjectAccess(kStringLengths, String::kLengthOffset,
+                         FOR_STRING_LENGTH, Representation::Smi());
   }
 
   static HObjectAccess ForConsStringFirst() {
-    return HObjectAccess(kInobject, ConsString::kFirstOffset);
+    return HObjectAccess(kInobject, ConsString::kFirstOffset,
+                         FOR_CONS_STRING_FIRST);
   }
 
   static HObjectAccess ForConsStringSecond() {
-    return HObjectAccess(kInobject, ConsString::kSecondOffset);
+    return HObjectAccess(kInobject, ConsString::kSecondOffset,
+                         FOR_CONS_STRING_SECOND);
   }
 
   static HObjectAccess ForPropertiesPointer() {
-    return HObjectAccess(kInobject, JSObject::kPropertiesOffset);
+    return HObjectAccess(kInobject, JSObject::kPropertiesOffset,
+                         FOR_PROPERTIES_POINTER);
   }
 
   static HObjectAccess ForPrototypeOrInitialMap() {
-    return HObjectAccess(kInobject, JSFunction::kPrototypeOrInitialMapOffset);
+    return HObjectAccess(kInobject, JSFunction::kPrototypeOrInitialMapOffset,
+                         FOR_PROTOTYPE_OR_INITIAL_MAP);
   }
 
   static HObjectAccess ForSharedFunctionInfoPointer() {
-    return HObjectAccess(kInobject, JSFunction::kSharedFunctionInfoOffset);
+    return HObjectAccess(kInobject, JSFunction::kSharedFunctionInfoOffset,
+                         FOR_SHARED_FUNCTION_INFO_POINTER);
   }
 
   static HObjectAccess ForCodeEntryPointer() {
-    return HObjectAccess(kInobject, JSFunction::kCodeEntryOffset);
+    return HObjectAccess(kInobject, JSFunction::kCodeEntryOffset,
+                         FOR_CODE_ENTRY_POINTER);
   }
 
   static HObjectAccess ForCodeOffset() {
-    return HObjectAccess(kInobject, SharedFunctionInfo::kCodeOffset);
+    return HObjectAccess(kInobject, SharedFunctionInfo::kCodeOffset,
+                         FOR_CODE_OFFSET);
   }
 
   static HObjectAccess ForOptimizedCodeMap() {
     return HObjectAccess(kInobject,
-                         SharedFunctionInfo::kOptimizedCodeMapOffset);
+                         SharedFunctionInfo::kOptimizedCodeMapOffset,
+                         FOR_OPTIMIZED_CODE_MAP);
   }
 
   static HObjectAccess ForFunctionContextPointer() {
-    return HObjectAccess(kInobject, JSFunction::kContextOffset);
+    return HObjectAccess(kInobject, JSFunction::kContextOffset,
+                         FOR_FUNCTION_CONTEXT_POINTER);
   }
 
   static HObjectAccess ForMap() {
-    return HObjectAccess(kMaps, JSObject::kMapOffset);
+    return HObjectAccess(kMaps, JSObject::kMapOffset, FOR_MAP);
   }
 
   static HObjectAccess ForMapInstanceSize() {
     return HObjectAccess(kInobject,
                          Map::kInstanceSizeOffset,
+                         FOR_MAP_INSTANCE_SIZE,
                          Representation::UInteger8());
   }
 
   static HObjectAccess ForMapInstanceType() {
     return HObjectAccess(kInobject,
                          Map::kInstanceTypeOffset,
+                         FOR_MAP_INSTANCE_TYPE,
                          Representation::UInteger8());
   }
 
   static HObjectAccess ForPropertyCellValue() {
-    return HObjectAccess(kInobject, PropertyCell::kValueOffset);
+    return HObjectAccess(kInobject, PropertyCell::kValueOffset,
+                         FOR_PROPERTY_CELL_VALUE);
   }
 
   static HObjectAccess ForCellValue() {
-    return HObjectAccess(kInobject, Cell::kValueOffset);
+    return HObjectAccess(kInobject, Cell::kValueOffset, FOR_CELL_VALUE);
   }
 
   static HObjectAccess ForAllocationMementoSite() {
-    return HObjectAccess(kInobject, AllocationMemento::kAllocationSiteOffset);
+    return HObjectAccess(kInobject, AllocationMemento::kAllocationSiteOffset,
+                         FOR_ALLOCATION_MEMENTO_SITE);
   }
 
   static HObjectAccess ForCounter() {
-    return HObjectAccess(kExternalMemory, 0, Representation::Integer32(),
+    return HObjectAccess(kExternalMemory, 0, FOR_COUNTER,
+                         Representation::Integer32(),
                          Handle<String>::null(), false, false);
   }
 
@@ -6097,14 +6167,17 @@ class HObjectAccess V8_FINAL {
   // properties can have different semantics depending on whether corresponding
   // property was added to the map or not.
   static HObjectAccess ForMapAndOffset(Handle<Map> map, int offset,
+      Purpose purpose,
       Representation representation = Representation::Tagged());
 
   // Create an access to an in-object property in a JSObject.
   // This kind of access can be used for accessing object header fields or
   // in-object properties if the map of the object is not known.
   static HObjectAccess ForObservableJSObjectOffset(int offset,
+      Purpose purpose = FOR_FIELD,
       Representation representation = Representation::Tagged()) {
-    return ForMapAndOffset(Handle<Map>::null(), offset, representation);
+    return ForMapAndOffset(Handle<Map>::null(), offset, purpose,
+                           representation);
   }
 
   // Create an access to an in-object property in a JSArray.
@@ -6124,52 +6197,61 @@ class HObjectAccess V8_FINAL {
   static HObjectAccess ForCellPayload(Isolate* isolate);
 
   static HObjectAccess ForJSTypedArrayLength() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSTypedArray::kLengthOffset);
+    return HObjectAccess(
+        kInobject, JSTypedArray::kLengthOffset, FOR_JSTYPEDARRAY_LENGTH);
   }
 
   static HObjectAccess ForJSArrayBufferBackingStore() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBuffer::kBackingStoreOffset, Representation::External());
+    return HObjectAccess(
+        kInobject, JSArrayBuffer::kBackingStoreOffset,
+        FOR_JSARRAYBUFFER_BACKING_STORE, Representation::External());
   }
 
   static HObjectAccess ForJSArrayBufferByteLength() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBuffer::kByteLengthOffset, Representation::Tagged());
+    return HObjectAccess(
+        kInobject, JSArrayBuffer::kByteLengthOffset,
+        FOR_JSARRAYBUFFER_BYTE_LENGTH);
   }
 
   static HObjectAccess ForExternalArrayExternalPointer() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        ExternalArray::kExternalPointerOffset, Representation::External());
+    return HObjectAccess(
+        kInobject, ExternalArray::kExternalPointerOffset,
+        FOR_EXTERNAL_ARRAY_EXTERNAL_POINTER, Representation::External());
   }
 
   static HObjectAccess ForJSArrayBufferViewWeakNext() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBufferView::kWeakNextOffset);
+    return HObjectAccess(
+        kInobject, JSArrayBufferView::kWeakNextOffset,
+        FOR_JSARRAYBUFFERVIEW_WEAK_NEXT);
   }
 
   static HObjectAccess ForJSArrayBufferWeakFirstView() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBuffer::kWeakFirstViewOffset);
+    return HObjectAccess(
+        kInobject, JSArrayBuffer::kWeakFirstViewOffset,
+        FOR_JSARRAYBUFFER_WEAK_FIRST_VIEW);
   }
 
   static HObjectAccess ForJSArrayBufferViewBuffer() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBufferView::kBufferOffset);
+    return HObjectAccess(
+        kInobject, JSArrayBufferView::kBufferOffset,
+        FOR_JSARRAYBUFFERVIEW_BUFFER);
   }
 
   static HObjectAccess ForJSArrayBufferViewByteOffset() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBufferView::kByteOffsetOffset);
+    return HObjectAccess(
+        kInobject, JSArrayBufferView::kByteOffsetOffset,
+        FOR_JSARRAYBUFFERVIEW_BYTE_OFFSET);
   }
 
   static HObjectAccess ForJSArrayBufferViewByteLength() {
-    return HObjectAccess::ForObservableJSObjectOffset(
-        JSArrayBufferView::kByteLengthOffset);
+    return HObjectAccess(
+        kInobject, JSArrayBufferView::kByteLengthOffset,
+        FOR_JSARRAYBUFFERVIEW_BYTE_LENGTH);
   }
 
   static HObjectAccess ForGlobalObjectNativeContext() {
-    return HObjectAccess(kInobject, GlobalObject::kNativeContextOffset);
+    return HObjectAccess(kInobject, GlobalObject::kNativeContextOffset,
+                         FOR_GLOBAL_OBJECT_NATIVE_CONTEXT);
   }
 
   void PrintTo(StringStream* stream) const;
@@ -6178,6 +6260,10 @@ class HObjectAccess V8_FINAL {
     return value_ == that.value_;  // portion and offset must match
   }
 
+#ifdef DEBUG
+  Purpose purpose() const { return purpose_; }
+#endif
+
  protected:
   void SetGVNFlags(HValue *instr, PropertyAccessType access_type);
 
@@ -6196,24 +6282,27 @@ class HObjectAccess V8_FINAL {
 
   HObjectAccess() : value_(0) {}
 
-  HObjectAccess(Portion portion, int offset,
+  HObjectAccess(Portion portion, int offset, Purpose purpose,
                 Representation representation = Representation::Tagged(),
                 Handle<String> name = Handle<String>::null(),
                 bool immutable = false,
                 bool existing_inobject_property = true)
-    : value_(PortionField::encode(portion) |
-             RepresentationField::encode(representation.kind()) |
-             ImmutableField::encode(immutable ? 1 : 0) |
-             ExistingInobjectPropertyField::encode(
-                 existing_inobject_property ? 1 : 0) |
-             OffsetField::encode(offset)),
-      name_(name) {
+      : value_(PortionField::encode(portion) |
+               RepresentationField::encode(representation.kind()) |
+               ImmutableField::encode(immutable ? 1 : 0) |
+               ExistingInobjectPropertyField::encode(
+                   existing_inobject_property ? 1 : 0) |
+                   OffsetField::encode(offset)),
+#ifdef DEBUG
+        purpose_(purpose),
+#endif
+        name_(name) {
     // assert that the fields decode correctly
     ASSERT(this->offset() == offset);
     ASSERT(this->portion() == portion);
     ASSERT(this->immutable() == immutable);
     ASSERT(this->existing_inobject_property() == existing_inobject_property);
-    ASSERT(RepresentationField::decode(value_) == representation.kind());
+    ASSERT(this->representation().Equals(representation));
     ASSERT(!this->existing_inobject_property() || IsInobject());
   }
 
@@ -6224,6 +6313,9 @@ class HObjectAccess V8_FINAL {
   class OffsetField : public BitField<int, 9, 23> {};
 
   uint32_t value_;  // encodes portion, representation, immutable, and offset
+#ifdef DEBUG
+  Purpose purpose_;
+#endif
   Handle<String> name_;
 
   friend class HLoadNamedField;