[stubs] Fine-tune monomorphic IC dispatcher performance

src/code-stub-assembler.cc

 // Copyright 2016 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.
 #include "src/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 #include "src/ic/handler-configuration.h"
 #include "src/ic/stub-cache.h"
 
@@ skipping 4766 matching lines @@
   // the tagging completely.
   Node* previous_feedback =
       LoadFixedArrayElement(type_feedback_vector, slot_id);
   Node* combined_feedback = SmiOr(previous_feedback, SmiFromWord32(feedback));
   StoreFixedArrayElement(type_feedback_vector, slot_id, combined_feedback,
                          SKIP_WRITE_BARRIER);
 }
 
 compiler::Node* CodeStubAssembler::LoadReceiverMap(compiler::Node* receiver) {
   Variable var_receiver_map(this, MachineRepresentation::kTagged);
-  // TODO(ishell): defer blocks when it works.
-  Label load_smi_map(this /*, Label::kDeferred*/), load_receiver_map(this),
+  Label load_smi_map(this, Label::kDeferred), load_receiver_map(this),
       if_result(this);
 
   Branch(TaggedIsSmi(receiver), &load_smi_map, &load_receiver_map);
   Bind(&load_smi_map);
   {
     var_receiver_map.Bind(LoadRoot(Heap::kHeapNumberMapRootIndex));
     Goto(&if_result);
   }
   Bind(&load_receiver_map);
   {
     var_receiver_map.Bind(LoadMap(receiver));
     Goto(&if_result);
   }
   Bind(&if_result);
   return var_receiver_map.value();
 }
 
 compiler::Node* CodeStubAssembler::TryMonomorphicCase(
     compiler::Node* slot, compiler::Node* vector, compiler::Node* receiver_map,
     Label* if_handler, Variable* var_handler, Label* if_miss) {
   DCHECK_EQ(MachineRepresentation::kTagged, var_handler->rep());
 
   // TODO(ishell): add helper class that hides offset computations for a series
   // of loads.
   int32_t header_size = FixedArray::kHeaderSize - kHeapObjectTag;
-  Node* offset = ElementOffsetFromIndex(slot, FAST_HOLEY_ELEMENTS,
-                                        SMI_PARAMETERS, header_size);
-  Node* feedback = Load(MachineType::AnyTagged(), vector, offset);
+  // Adding |header_size| with a separate IntPtrAdd rather than passing it
+  // into ElementOffsetFromIndex() allows it to be folded into a single
+  // [base, index, offset] indirect memory access on x64.
+  Node* offset =
+      ElementOffsetFromIndex(slot, FAST_HOLEY_ELEMENTS, SMI_PARAMETERS);
+  Node* feedback = Load(MachineType::AnyTagged(), vector,
+                        IntPtrAdd(offset, IntPtrConstant(header_size)));
 
   // Try to quickly handle the monomorphic case without knowing for sure
   // if we have a weak cell in feedback. We do know it's safe to look
   // at WeakCell::kValueOffset.
-  GotoUnless(WordEqual(receiver_map, LoadWeakCellValue(feedback)), if_miss);
+  GotoIf(WordNotEqual(receiver_map, LoadWeakCellValue(feedback)), if_miss);
 
-  Node* handler = Load(MachineType::AnyTagged(), vector,
-                       IntPtrAdd(offset, IntPtrConstant(kPointerSize)));
+  Node* handler =
+      Load(MachineType::AnyTagged(), vector,
+           IntPtrAdd(offset, IntPtrConstant(header_size + kPointerSize)));
 
   var_handler->Bind(handler);
   Goto(if_handler);
   return feedback;
 }
 
 void CodeStubAssembler::HandlePolymorphicCase(
     compiler::Node* receiver_map, compiler::Node* feedback, Label* if_handler,
     Variable* var_handler, Label* if_miss, int unroll_count) {
   DCHECK_EQ(MachineRepresentation::kTagged, var_handler->rep());
@@ skipping 3498 matching lines @@
   Node* buffer_bit_field = LoadObjectField(
       buffer, JSArrayBuffer::kBitFieldOffset, MachineType::Uint32());
   Node* was_neutered_mask = Int32Constant(JSArrayBuffer::WasNeutered::kMask);
 
   return Word32NotEqual(Word32And(buffer_bit_field, was_neutered_mask),
                         Int32Constant(0));
 }
 
 }  // namespace internal
 }  // namespace v8