[builtins] Migrate String.fromCharCode to TurboFan code stub.

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"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 619 matching lines @@
 Node* CodeStubAssembler::AllocateSeqOneByteString(int length) {
   Node* result = Allocate(SeqOneByteString::SizeFor(length));
   StoreMapNoWriteBarrier(result, LoadRoot(Heap::kOneByteStringMapRootIndex));
   StoreObjectFieldNoWriteBarrier(result, SeqOneByteString::kLengthOffset,
                                  SmiConstant(Smi::FromInt(length)));
   StoreObjectFieldNoWriteBarrier(result, SeqOneByteString::kHashFieldSlot,
                                  IntPtrConstant(String::kEmptyHashField));
   return result;
 }
 
+Node* CodeStubAssembler::AllocateSeqOneByteString(Node* context, Node* length) {
+  Variable var_result(this, MachineRepresentation::kTagged);
+
+  // Compute the SeqOneByteString size and check if it fits into new space.
+  Label if_sizeissmall(this), if_notsizeissmall(this, Label::kDeferred),
+      if_join(this);
+  Node* size = WordAnd(
+      IntPtrAdd(
+          IntPtrAdd(length, IntPtrConstant(SeqOneByteString::kHeaderSize)),
+          IntPtrConstant(kObjectAlignmentMask)),
+      IntPtrConstant(~kObjectAlignmentMask));
+  Branch(IntPtrLessThanOrEqual(size,
+                               IntPtrConstant(Page::kMaxRegularHeapObjectSize)),
+         &if_sizeissmall, &if_notsizeissmall);
+
+  Bind(&if_sizeissmall);
+  {
+    // Just allocate the SeqOneByteString in new space.
+    Node* result = Allocate(size);
+    StoreMapNoWriteBarrier(result, LoadRoot(Heap::kOneByteStringMapRootIndex));
+    StoreObjectFieldNoWriteBarrier(result, SeqOneByteString::kLengthOffset,
+                                   SmiFromWord(length));
+    StoreObjectFieldNoWriteBarrier(result, SeqOneByteString::kHashFieldSlot,
+                                   IntPtrConstant(String::kEmptyHashField));
+    var_result.Bind(result);
+    Goto(&if_join);
+  }
+
+  Bind(&if_notsizeissmall);
+  {
+    // We might need to allocate in large object space, go to the runtime.
+    Node* result = CallRuntime(Runtime::kAllocateSeqOneByteString, context,
+                               SmiFromWord(length));
+    var_result.Bind(result);
+    Goto(&if_join);
+  }
+
+  Bind(&if_join);
+  return var_result.value();
+}
+
 Node* CodeStubAssembler::AllocateSeqTwoByteString(int length) {
   Node* result = Allocate(SeqTwoByteString::SizeFor(length));
   StoreMapNoWriteBarrier(result, LoadRoot(Heap::kStringMapRootIndex));
   StoreObjectFieldNoWriteBarrier(result, SeqTwoByteString::kLengthOffset,
                                  SmiConstant(Smi::FromInt(length)));
   StoreObjectFieldNoWriteBarrier(result, SeqTwoByteString::kHashFieldSlot,
                                  IntPtrConstant(String::kEmptyHashField));
   return result;
 }
 
+Node* CodeStubAssembler::AllocateSeqTwoByteString(Node* context, Node* length) {
+  Variable var_result(this, MachineRepresentation::kTagged);
+
+  // Compute the SeqTwoByteString size and check if it fits into new space.
+  Label if_sizeissmall(this), if_notsizeissmall(this, Label::kDeferred),
+      if_join(this);
+  Node* size = WordAnd(
+      IntPtrAdd(IntPtrAdd(WordShl(length, 1),
+                          IntPtrConstant(SeqTwoByteString::kHeaderSize)),
+                IntPtrConstant(kObjectAlignmentMask)),
+      IntPtrConstant(~kObjectAlignmentMask));
+  Branch(IntPtrLessThanOrEqual(size,
+                               IntPtrConstant(Page::kMaxRegularHeapObjectSize)),
+         &if_sizeissmall, &if_notsizeissmall);
+
+  Bind(&if_sizeissmall);
+  {
+    // Just allocate the SeqTwoByteString in new space.
+    Node* result = Allocate(size);
+    StoreMapNoWriteBarrier(result, LoadRoot(Heap::kStringMapRootIndex));
+    StoreObjectFieldNoWriteBarrier(result, SeqTwoByteString::kLengthOffset,
+                                   SmiFromWord(length));
+    StoreObjectFieldNoWriteBarrier(result, SeqTwoByteString::kHashFieldSlot,
+                                   IntPtrConstant(String::kEmptyHashField));
+    var_result.Bind(result);
+    Goto(&if_join);
+  }
+
+  Bind(&if_notsizeissmall);
+  {
+    // We might need to allocate in large object space, go to the runtime.
+    Node* result = CallRuntime(Runtime::kAllocateSeqTwoByteString, context,
+                               SmiFromWord(length));
+    var_result.Bind(result);
+    Goto(&if_join);
+  }
+
+  Bind(&if_join);
+  return var_result.value();
+}
+
 Node* CodeStubAssembler::AllocateJSArray(ElementsKind kind, Node* array_map,
                                          Node* capacity_node, Node* length_node,
                                          compiler::Node* allocation_site,
                                          ParameterMode mode) {
   bool is_double = IsFastDoubleElementsKind(kind);
   int base_size = JSArray::kSize + FixedArray::kHeaderSize;
   int elements_offset = JSArray::kSize;
 
   if (allocation_site != nullptr) {
     base_size += AllocationMemento::kSize;
@@ skipping 956 matching lines @@
   }
   return IntPtrAdd(
       IntPtrConstant(base_size),
       (element_size_shift >= 0)
           ? WordShl(index_node, IntPtrConstant(element_size_shift))
           : WordShr(index_node, IntPtrConstant(-element_size_shift)));
 }
 
 }  // namespace internal
 }  // namespace v8