[TypeFeedbackVector] Root feedback vectors at function literal site.

src/builtins/x64/builtins-x64.cc

Index: src/builtins/x64/builtins-x64.cc
diff --git a/src/builtins/x64/builtins-x64.cc b/src/builtins/x64/builtins-x64.cc
index 107391504e40eb124dce76dac931a484667d60c6..0f89790806db37673cc01fc85c9aa39058e631ec 100644
--- a/src/builtins/x64/builtins-x64.cc
+++ b/src/builtins/x64/builtins-x64.cc
@@ -995,13 +995,18 @@ void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
   Register closure = rdi;
   Register map = r8;
   Register index = r9;
+
+  // Do we have a valid feedback vector?
+  __ movp(rbx, FieldOperand(closure, JSFunction::kFeedbackVectorOffset));
+  __ movp(rbx, FieldOperand(rbx, Cell::kValueOffset));
+  __ JumpIfRoot(rbx, Heap::kUndefinedValueRootIndex, &gotta_call_runtime);
+
   __ movp(map, FieldOperand(closure, JSFunction::kSharedFunctionInfoOffset));
   __ movp(map, FieldOperand(map, SharedFunctionInfo::kOptimizedCodeMapOffset));
   __ SmiToInteger32(index, FieldOperand(map, FixedArray::kLengthOffset));
   __ cmpl(index, Immediate(2));
-  __ j(less, &gotta_call_runtime);
+  __ j(less, &try_shared);
 
-  // Find literals.
   // r14 : native context
   // r9  : length / index
   // r8  : optimized code map
@@ -1018,17 +1023,6 @@ void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
   __ movp(temp, FieldOperand(temp, WeakCell::kValueOffset));
   __ cmpp(temp, native_context);
   __ j(not_equal, &loop_bottom);
-  // Feedback vector available?
-  __ movp(temp, FieldOperand(map, index, times_pointer_size,
-                             SharedFunctionInfo::kOffsetToPreviousLiterals));
-  __ movp(temp, FieldOperand(temp, WeakCell::kValueOffset));
-  __ JumpIfSmi(temp, &gotta_call_runtime);
-
-  // Save the feedback vector in the closure.
-  __ movp(FieldOperand(closure, JSFunction::kFeedbackVectorOffset), temp);
-  __ movp(r15, index);
-  __ RecordWriteField(closure, JSFunction::kFeedbackVectorOffset, temp, r15,
-                      kDontSaveFPRegs, EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
 
   // Code available?
   Register entry = rcx;
@@ -1037,7 +1031,7 @@ void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
   __ movp(entry, FieldOperand(entry, WeakCell::kValueOffset));
   __ JumpIfSmi(entry, &try_shared);
 
-  // Found literals and code. Get them into the closure and return.
+  // Found code. Get it into the closure and return.
   __ leap(entry, FieldOperand(entry, Code::kHeaderSize));
   __ movp(FieldOperand(closure, JSFunction::kCodeEntryOffset), entry);
   __ RecordWriteCodeEntryField(closure, entry, r15);
@@ -1068,9 +1062,7 @@ void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
   __ cmpl(index, Immediate(1));
   __ j(greater, &loop_top);
 
-  // We found neither literals nor code.
-  __ jmp(&gotta_call_runtime);
-
+  // We found no code.
   __ bind(&try_shared);
   __ movp(entry, FieldOperand(closure, JSFunction::kSharedFunctionInfoOffset));
   // Is the shared function marked for tier up?