[stubs] Generalize loop handling in CodeStubAssembler and improve common loop performance

src/code-stub-assembler.h

 // 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.
 
 #ifndef V8_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 820 matching lines @@
   // Create a new weak cell with a specified value and install it into a
   // feedback vector.
   compiler::Node* CreateWeakCellInFeedbackVector(
       compiler::Node* feedback_vector, compiler::Node* slot,
       compiler::Node* value);
 
   // Create a new AllocationSite and install it into a feedback vector.
   compiler::Node* CreateAllocationSiteInFeedbackVector(
       compiler::Node* feedback_vector, compiler::Node* slot);
 
+  enum class IndexAdvanceMode { kPre, kPost };
+
+  void BuildFastLoop(
+      MachineRepresentation index_rep, compiler::Node* start_index,
+      compiler::Node* end_index,
+      std::function<void(CodeStubAssembler* assembler, compiler::Node* index)>
+          body,
+      int increment, IndexAdvanceMode mode = IndexAdvanceMode::kPre);
+
+  enum class ForEachDirection { kForward, kReverse };
+
+  void BuildFastFixedArrayForEach(
+      compiler::Node* fixed_array, ElementsKind kind,
+      compiler::Node* first_element_inclusive,
+      compiler::Node* last_element_exclusive,
+      std::function<void(CodeStubAssembler* assembler,
+                         compiler::Node* fixed_array, compiler::Node* offset)>
+          body,
+      ParameterMode mode = INTPTR_PARAMETERS,
+      ForEachDirection direction = ForEachDirection::kReverse);
+
   compiler::Node* GetFixedArrayAllocationSize(compiler::Node* element_count,
                                               ElementsKind kind,
                                               ParameterMode mode) {
     return ElementOffsetFromIndex(element_count, kind, mode,
                                   FixedArray::kHeaderSize);
   }
 
  private:
   enum ElementSupport { kOnlyProperties, kSupportElements };
 
@@ skipping 56 matching lines @@
                                            Label* bailout);
 
   static const int kElementLoopUnrollThreshold = 8;
 };
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_