Revert "Continued fix for 351257. Reusing the feedback vector is too complex."

src/a64/full-codegen-a64.cc

Index: src/a64/full-codegen-a64.cc
diff --git a/src/a64/full-codegen-a64.cc b/src/a64/full-codegen-a64.cc
index a5f7311717971745a17d9899d51f3f286dda5fa0..dcab182e6770f3b6999302cdd0d9e250c6a559f6 100644
--- a/src/a64/full-codegen-a64.cc
+++ b/src/a64/full-codegen-a64.cc
@@ -129,6 +129,8 @@ void FullCodeGenerator::Generate() {
   handler_table_ =
       isolate()->factory()->NewFixedArray(function()->handler_count(), TENURED);
 
+  InitializeFeedbackVector();
+
   profiling_counter_ = isolate()->factory()->NewCell(
       Handle<Smi>(Smi::FromInt(FLAG_interrupt_budget), isolate()));
   SetFunctionPosition(function());
@@ -1160,8 +1162,12 @@ void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   // We got a fixed array in register x0. Iterate through that.
   __ Bind(&fixed_array);
 
+  Handle<Object> feedback = Handle<Object>(
+      Smi::FromInt(TypeFeedbackInfo::kForInFastCaseMarker),
+      isolate());
+  StoreFeedbackVectorSlot(slot, feedback);
   __ LoadObject(x1, FeedbackVector());
-  __ Mov(x10, Operand(TypeFeedbackInfo::MegamorphicSentinel(isolate())));
+  __ Mov(x10, Operand(Smi::FromInt(TypeFeedbackInfo::kForInSlowCaseMarker)));
   __ Str(x10, FieldMemOperand(x1, FixedArray::OffsetOfElementAt(slot)));
 
   __ Mov(x1, Operand(Smi::FromInt(1)));  // Smi indicates slow check.
@@ -2408,6 +2414,9 @@ void FullCodeGenerator::EmitCallWithStub(Call* expr) {
   // Record source position for debugger.
   SetSourcePosition(expr->position());
 
+  Handle<Object> uninitialized =
+      TypeFeedbackInfo::UninitializedSentinel(isolate());
+  StoreFeedbackVectorSlot(expr->CallFeedbackSlot(), uninitialized);
   __ LoadObject(x2, FeedbackVector());
   __ Mov(x3, Operand(Smi::FromInt(expr->CallFeedbackSlot())));
 
@@ -2604,6 +2613,9 @@ void FullCodeGenerator::VisitCallNew(CallNew* expr) {
   __ Peek(x1, arg_count * kXRegSize);
 
   // Record call targets in unoptimized code.
+  Handle<Object> uninitialized =
+      TypeFeedbackInfo::UninitializedSentinel(isolate());
+  StoreFeedbackVectorSlot(expr->CallNewFeedbackSlot(), uninitialized);
   __ LoadObject(x2, FeedbackVector());
   __ Mov(x3, Operand(Smi::FromInt(expr->CallNewFeedbackSlot())));