Revert "Add a premonomorphic state to the call target cache."

src/a64/code-stubs-a64.cc

Index: src/a64/code-stubs-a64.cc
diff --git a/src/a64/code-stubs-a64.cc b/src/a64/code-stubs-a64.cc
index 036e59a1833b531429beaaec4a79461acaf02c93..bf6ab321b5939b3a25b2c3e39d8cce6094c0f650 100644
--- a/src/a64/code-stubs-a64.cc
+++ b/src/a64/code-stubs-a64.cc
@@ -3195,8 +3195,6 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
             masm->isolate()->heap()->undefined_value());
   ASSERT_EQ(*TypeFeedbackInfo::UninitializedSentinel(masm->isolate()),
             masm->isolate()->heap()->the_hole_value());
-  ASSERT_EQ(*TypeFeedbackInfo::PremonomorphicSentinel(masm->isolate()),
-            masm->isolate()->heap()->null_value());
 
   // Load the cache state.
   __ Add(x4, x2, Operand::UntagSmiAndScale(x3, kPointerSizeLog2));
@@ -3224,22 +3222,7 @@ static void GenerateRecordCallTarget(MacroAssembler* masm) {
 
   // A monomorphic miss (i.e, here the cache is not uninitialized) goes
   // megamorphic.
-  Label not_uninitialized;
-  __ JumpIfNotRoot(x4, Heap::kTheHoleValueRootIndex, &not_uninitialized);
-
-  // PremonomorphicSentinel is an immortal immovable object (null) so no
-  // write-barrier is needed.
-  __ Add(x4, x2, Operand::UntagSmiAndScale(x3, kPointerSizeLog2));
-  __ LoadRoot(x10, Heap::kNullValueRootIndex);
-  __ Str(x10, FieldMemOperand(x4, FixedArray::kHeaderSize));
-  __ B(&done);
-
-  // If the cache isn't uninitialized, it is either premonomorphic or
-  // monomorphic. If it is premonomorphic, we initialize it thus making
-  // it monomorphic. Otherwise, we go megamorphic.
-  __ Bind(&not_uninitialized);
-  __ JumpIfRoot(x4, Heap::kNullValueRootIndex, &initialize);
-
+  __ JumpIfRoot(x4, Heap::kTheHoleValueRootIndex, &initialize);
   // MegamorphicSentinel is an immortal immovable object (undefined) so no
   // write-barrier is needed.
   __ Bind(&megamorphic);