[TypeFeedbackVector] Root feedback vectors at function literal site.

src/builtins/x64/builtins-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 977 matching lines @@
   //  -- rdi : target function (preserved for callee)
   // -----------------------------------
   // First lookup code, maybe we don't need to compile!
   Label gotta_call_runtime;
   Label try_shared;
   Label loop_top, loop_bottom;
 
   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
   // rdx : new target
   // rdi : closure
   Register native_context = r14;
   __ movp(native_context, NativeContextOperand());
 
   __ bind(&loop_top);
   // Native context match?
   Register temp = r11;
   __ movp(temp, FieldOperand(map, index, times_pointer_size,
                              SharedFunctionInfo::kOffsetToPreviousContext));
   __ 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;
   __ movp(entry, FieldOperand(map, index, times_pointer_size,
                               SharedFunctionInfo::kOffsetToPreviousCachedCode));
   __ 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);
 
   // Link the closure into the optimized function list.
   // rcx : code entry (entry)
   // r14 : native context
   // rdx : new target
   // rdi : closure
   __ movp(rbx,
@@ skipping 10 matching lines @@
   __ RecordWriteContextSlot(native_context, function_list_offset, closure, r15,
                             kDontSaveFPRegs);
   __ movp(closure, rbx);
   __ jmp(entry);
 
   __ bind(&loop_bottom);
   __ subl(index, Immediate(SharedFunctionInfo::kEntryLength));
   __ 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?
   __ testb(FieldOperand(entry, SharedFunctionInfo::kMarkedForTierUpByteOffset),
            Immediate(1 << SharedFunctionInfo::kMarkedForTierUpBitWithinByte));
   __ j(not_zero, &gotta_call_runtime);
 
   // If SFI points to anything other than CompileLazy, install that.
   __ movp(entry, FieldOperand(entry, SharedFunctionInfo::kCodeOffset));
   __ Move(rbx, masm->CodeObject());
@@ skipping 2180 matching lines @@
 void Builtins::Generate_InterpreterOnStackReplacement(MacroAssembler* masm) {
   Generate_OnStackReplacementHelper(masm, true);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64