src,test: support node.js >= 8

Teach the object property decoder to recognize the layout of objects
in newer versions of V8.

Fixes: #81
PR-URL: #82
Refs: https://codereview.chromium.org/2842843004/
Refs: nodejs/node#12722
Reviewed-By: Howard Hellyer <[email protected]>

Author: bnoordhuis

Diff for: src/llv8-constants.cc

@@ -423,6 +423,36 @@ void DescriptorArray::Load() {
   kPropertyIndexShift = LoadConstant("prop_index_shift");
   kPropertyTypeMask = LoadConstant("prop_type_mask");
 
+  if (kPropertyTypeMask == -1) {  // node.js >= 8
+    kPropertyAttributesMask = LoadConstant("prop_attributes_mask");
+    kPropertyAttributesShift = LoadConstant("prop_attributes_shift");
+    kPropertyAttributesEnum_NONE = LoadConstant("prop_attributes_NONE");
+    kPropertyAttributesEnum_READ_ONLY =
+        LoadConstant("prop_attributes_READ_ONLY");
+    kPropertyAttributesEnum_DONT_ENUM =
+        LoadConstant("prop_attributes_DONT_ENUM");
+    kPropertyAttributesEnum_DONT_DELETE =
+        LoadConstant("prop_attributes_DONT_ENUM");
+
+    kPropertyKindMask = LoadConstant("prop_kind_mask");
+    kPropertyKindShift = LoadConstant("prop_kind_shift", int64_t(0));
+    kPropertyKindEnum_kAccessor = LoadConstant("prop_kind_Accessor");
+    kPropertyKindEnum_kData = LoadConstant("prop_kind_Data");
+
+    kPropertyLocationMask = LoadConstant("prop_location_mask");
+    kPropertyLocationShift = LoadConstant("prop_location_shift");
+    kPropertyLocationEnum_kDescriptor =
+        LoadConstant("prop_location_Descriptor");
+    kPropertyLocationEnum_kField = LoadConstant("prop_location_Field");
+  } else {  // node.js <= 7
+    kFieldType = LoadConstant("prop_type_field");
+    kConstFieldType = LoadConstant("prop_type_const_field");
+    if (kConstFieldType == -1) {
+      // TODO(indutny): check V8 version?
+      kConstFieldType = kFieldType | 0x2;
+    }
+  }
+
   kRepresentationShift = LoadConstant("prop_representation_shift");
   kRepresentationMask = LoadConstant("prop_representation_mask");
 
@@ -432,13 +462,6 @@ void DescriptorArray::Load() {
     kRepresentationMask = ((1 << 4) - 1) << kRepresentationShift;
   }
 
-  kFieldType = LoadConstant("prop_type_field");
-  kConstFieldType = LoadConstant("prop_type_const_field");
-  if (kConstFieldType == -1) {
-    // TODO(indutny): check V8 version?
-    kConstFieldType = kFieldType | 0x2;
-  }
-
   kRepresentationDouble = LoadConstant("prop_representation_double");
   if (kRepresentationDouble == -1) {
     // TODO(indutny): check V8 version?

Diff for: src/llv8-constants.h

@@ -374,17 +374,37 @@ class DescriptorArray : public Module {
 
   int64_t kPropertyIndexMask;
   int64_t kPropertyIndexShift;
-  int64_t kPropertyTypeMask;
   int64_t kRepresentationMask;
   int64_t kRepresentationShift;
 
-  int64_t kFieldType;
-  int64_t kConstFieldType;
   int64_t kRepresentationDouble;
 
   int64_t kFirstIndex;
   int64_t kSize;
 
+  // node.js <= 7
+  int64_t kPropertyTypeMask = -1;
+  int64_t kConstFieldType = -1;
+  int64_t kFieldType = -1;
+
+  // node.js >= 8
+  int64_t kPropertyAttributesMask = -1;
+  int64_t kPropertyAttributesShift = -1;
+  int64_t kPropertyAttributesEnum_NONE = -1;
+  int64_t kPropertyAttributesEnum_READ_ONLY = -1;
+  int64_t kPropertyAttributesEnum_DONT_ENUM = -1;
+  int64_t kPropertyAttributesEnum_DONT_DELETE = -1;
+
+  int64_t kPropertyKindMask = -1;
+  int64_t kPropertyKindShift = -1;
+  int64_t kPropertyKindEnum_kAccessor = -1;
+  int64_t kPropertyKindEnum_kData = -1;
+
+  int64_t kPropertyLocationMask = -1;
+  int64_t kPropertyLocationShift = -1;
+  int64_t kPropertyLocationEnum_kDescriptor = -1;
+  int64_t kPropertyLocationEnum_kField = -1;
+
  protected:
   void Load();
 };

Diff for: src/llv8-inl.h

@@ -352,13 +352,31 @@ inline Value DescriptorArray::GetValue(int index, Error& err) {
 }
 
 inline bool DescriptorArray::IsFieldDetails(Smi details) {
-  return (details.GetValue() & v8()->descriptor_array()->kPropertyTypeMask) ==
-         v8()->descriptor_array()->kFieldType;
+  // node.js <= 7
+  if (v8()->descriptor_array()->kPropertyTypeMask != -1) {
+    return (details.GetValue() & v8()->descriptor_array()->kPropertyTypeMask) ==
+           v8()->descriptor_array()->kFieldType;
+  }
+
+  // node.js >= 8
+  return (details.GetValue() &
+          v8()->descriptor_array()->kPropertyLocationMask) ==
+         (v8()->descriptor_array()->kPropertyLocationEnum_kField
+          << v8()->descriptor_array()->kPropertyLocationShift);
 }
 
 inline bool DescriptorArray::IsConstFieldDetails(Smi details) {
-  return (details.GetValue() & v8()->descriptor_array()->kPropertyTypeMask) ==
-         v8()->descriptor_array()->kConstFieldType;
+  // node.js <= 7
+  if (v8()->descriptor_array()->kPropertyTypeMask != -1) {
+    return (details.GetValue() & v8()->descriptor_array()->kPropertyTypeMask) ==
+           v8()->descriptor_array()->kConstFieldType;
+  }
+
+  // node.js >= 8
+  return (details.GetValue() &
+          v8()->descriptor_array()->kPropertyAttributesMask) ==
+         (v8()->descriptor_array()->kPropertyAttributesEnum_READ_ONLY
+          << v8()->descriptor_array()->kPropertyAttributesShift);
 }
 
 inline bool DescriptorArray::IsDoubleField(Smi details) {

Diff for: test/scan-test.js

@@ -68,7 +68,14 @@ tape('v8 findrefs and friends', (t) => {
   });
 
   sess.linesUntil(/lldb\-/, (lines) => {
-    t.ok(/Deflate\._handle/.test(lines.join('\n')), 'Should find reference');
+    // `class Deflate extends Zlib` makes instances show up as
+    // Transform objects (which Zlib inherits from) in node.js >= 8.
+    // Note that the version check will have to be redone for node.js >= 10
+    // but that is still a year out and by then llnode probably needs more
+    // fixups anyway.
+    const re =
+        (process.version >= 'v8.' ? /Transform\._handle/ : /Deflate\._handle/);
+    t.ok(re.test(lines.join('\n')), 'Should find reference');
     t.ok(/Object\.holder/.test(lines.join('\n')), 'Should find reference #2');
     t.ok(/\(Array\)\[1\]/.test(lines.join('\n')), 'Should find reference #3');