[Interpreter] Use FastCloneShallowObjectStub in CreateObjectLiteral bytecode.

src/interpreter/bytecode-generator.cc

Index: src/interpreter/bytecode-generator.cc
diff --git a/src/interpreter/bytecode-generator.cc b/src/interpreter/bytecode-generator.cc
index a81e1726179a27c1ccd10b70fdee885961cb2c21..a35d181a903eb58d706d3cb6946c732ae1b39c16 100644
--- a/src/interpreter/bytecode-generator.cc
+++ b/src/interpreter/bytecode-generator.cc
@@ -5,6 +5,7 @@
 #include "src/interpreter/bytecode-generator.h"
 
 #include "src/ast/scopes.h"
+#include "src/code-stubs.h"
 #include "src/compiler.h"
 #include "src/interpreter/bytecode-register-allocator.h"
 #include "src/interpreter/control-flow-builders.h"
@@ -1543,10 +1544,21 @@ void BytecodeGenerator::VisitRegExpLiteral(RegExpLiteral* expr) {
 
 
 void BytecodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
-  // Deep-copy the literal boilerplate.
+  // Copy the literal boilerplate.
+  int fast_clone_properties_count = 0;
+  if (FastCloneShallowObjectStub::IsSupported(expr)) {
+    STATIC_ASSERT(

[oth, 2016/04/28 14:17:15]

This assertion might be better placed in the encoding routine.

[rmcilroy, 2016/04/29 13:53:21]

I can't put it in the encode routine since that is generic for all BitField
generic classes. There is a DCHECK in BitField the Encode class that the value
fits in the bitfield, but that might miss something if our test cases aren't
wide enough so I thought it best to add this static assert too.

+        FastCloneShallowObjectStub::kMaximumClonedProperties <=
+        1 << CreateObjectLiteralFlags::FastClonePropertiesCountBits::kShift);
+    fast_clone_properties_count =
+        FastCloneShallowObjectStub::PropertiesCount(expr->properties_count());
+  }
+  uint8_t flags =
+      CreateObjectLiteralFlags::FlagsBits::encode(expr->ComputeFlags()) |

[oth, 2016/04/28 14:17:15]

The code could DCHECK here that the components of flags are orthogonal.

[rmcilroy, 2016/04/29 13:53:21]

Good point. Switched to using kNext in the definition of the flags, which should
ensure they are orthogonal, and added a STATIC_ASSERT in
CreateObjectLiteralFlags instead of a DCHECK here.

+      CreateObjectLiteralFlags::FastClonePropertiesCountBits::encode(
+          fast_clone_properties_count);
   builder()->CreateObjectLiteral(expr->constant_properties(),
-                                 expr->literal_index(),
-                                 expr->ComputeFlags(true));
+                                 expr->literal_index(), flags);
 
   // Allocate in the outer scope since this register is used to return the
   // expression's results to the caller.