Avoid creating weak cells for literal arrays that are empty of literals.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index e7a567527d9a3156ca822aa98460a2002d37161a..ac41762cea78e8fa9681a509f922716be61b3078 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -962,13 +962,30 @@ void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
   const int bailout_id = BailoutId::None().ToInt();
   __ cmpl(temp, Immediate(bailout_id));
   __ j(not_equal, &loop_bottom);
+
   // Literals available?
+  Label got_literals, maybe_cleared_weakcell;
   __ movp(temp, FieldOperand(map, index, times_pointer_size,
                              SharedFunctionInfo::kOffsetToPreviousLiterals));
+  // temp contains either a WeakCell pointing to the literals array or the
+  // literals array directly.
+  STATIC_ASSERT(WeakCell::kValueOffset == FixedArray::kLengthOffset);
+  __ movp(r15, FieldOperand(temp, WeakCell::kValueOffset));
+  __ JumpIfSmi(r15, &maybe_cleared_weakcell);
+  // r15 is a pointer, therefore temp is a WeakCell pointing to a literals
+  // array.
   __ movp(temp, FieldOperand(temp, WeakCell::kValueOffset));
-  __ JumpIfSmi(temp, &gotta_call_runtime);
+  __ jmp(&got_literals);
+
+  // r15 is a smi. If it's 0, then we are looking at a cleared WeakCell
+  // around the literals array, and we should visit the runtime. If it's > 0,
+  // then temp already contains the literals array.
+  __ bind(&maybe_cleared_weakcell);
+  __ cmpp(r15, Immediate(0));
+  __ j(equal, &gotta_call_runtime);
 
   // Save the literals in the closure.
+  __ bind(&got_literals);
   __ movp(FieldOperand(closure, JSFunction::kLiteralsOffset), temp);
   __ movp(r15, index);
   __ RecordWriteField(closure, JSFunction::kLiteralsOffset, temp, r15,