[crankshaft] Re-add fast-case for string add left/right.

src/code-stubs-hydrogen.cc

 // Copyright 2012 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-stubs.h"
 
 #include "src/bailout-reason.h"
 #include "src/field-index.h"
 #include "src/hydrogen.h"
 #include "src/ic/ic.h"
@@ skipping 95 matching lines @@
                                  HValue* code_object, HValue* literals);
   void BuildInstallCode(HValue* js_function, HValue* shared_info);
 
   HInstruction* LoadFromOptimizedCodeMap(HValue* optimized_map,
                                          HValue* iterator,
                                          int field_offset);
   void BuildInstallFromOptimizedCodeMap(HValue* js_function,
                                         HValue* shared_info,
                                         HValue* native_context);
 
+  HValue* CheckString(HValue* input, bool convert);
+
  private:
   HValue* BuildArraySingleArgumentConstructor(JSArrayBuilder* builder);
   HValue* BuildArrayNArgumentsConstructor(JSArrayBuilder* builder,
                                           ElementsKind kind);
 
   base::SmartArrayPointer<HParameter*> parameters_;
   HValue* arguments_length_;
   CompilationInfo* info_;
   CodeStubDescriptor descriptor_;
   HContext* context_;
@@ skipping 1323 matching lines @@
                               result_type, state.fixed_right_arg(),
                               allocation_mode, state.strength());
 }
 
 
 Handle<Code> BinaryOpWithAllocationSiteStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 
+HValue* CodeStubGraphBuilderBase::CheckString(HValue* input, bool convert) {
+  if (!convert) return BuildCheckString(input);
+  IfBuilder if_inputissmi(this);
+  HValue* inputissmi = if_inputissmi.If<HIsSmiAndBranch>(input);
+  if_inputissmi.Then();
+  {
+    // Convert the input smi to a string.
+    Push(BuildNumberToString(input, Type::SignedSmall()));
+  }
+  if_inputissmi.Else();
+  {
+    HValue* input_map =
+        Add<HLoadNamedField>(input, inputissmi, HObjectAccess::ForMap());
+    HValue* input_instance_type = Add<HLoadNamedField>(
+        input_map, inputissmi, HObjectAccess::ForMapInstanceType());
+    IfBuilder if_inputisstring(this);
+    if_inputisstring.If<HCompareNumericAndBranch>(
+        input_instance_type, Add<HConstant>(FIRST_NONSTRING_TYPE), Token::LT);
+    if_inputisstring.Then();
+    {
+      // The input is already a string.
+      Push(input);
+    }
+    if_inputisstring.Else();
+    {
+      // Convert to primitive first (if necessary), see
+      // ES6 section 12.7.3 The Addition operator.
+      IfBuilder if_inputisprimitive(this);
+      STATIC_ASSERT(FIRST_PRIMITIVE_TYPE == FIRST_TYPE);
+      if_inputisprimitive.If<HCompareNumericAndBranch>(
+          input_instance_type, Add<HConstant>(LAST_PRIMITIVE_TYPE), Token::LTE);
+      if_inputisprimitive.Then();
+      {
+        // The input is already a primitive.
+        Push(input);
+      }
+      if_inputisprimitive.Else();
+      {
+        // TODO(bmeurer): Add support for fast ToPrimitive conversion using
+        // a dedicated ToPrimitiveStub.
+        Add<HPushArguments>(input);
+        Push(Add<HCallRuntime>(Runtime::FunctionForId(Runtime::kToPrimitive),
+                               1));
+      }
+      if_inputisprimitive.End();
+      // Convert the primitive to a string value.
+      ToStringDescriptor descriptor(isolate());
+      ToStringStub stub(isolate());
+      HValue* values[] = {context(), Pop()};
+      Push(AddUncasted<HCallWithDescriptor>(
+          Add<HConstant>(stub.GetCode()), 0, descriptor,
+          Vector<HValue*>(values, arraysize(values))));
+    }
+    if_inputisstring.End();
+  }
+  if_inputissmi.End();
+  return Pop();
+}
+
+
 template <>
 HValue* CodeStubGraphBuilder<StringAddStub>::BuildCodeInitializedStub() {
   StringAddStub* stub = casted_stub();
   StringAddFlags flags = stub->flags();
   PretenureFlag pretenure_flag = stub->pretenure_flag();
 
   HValue* left = GetParameter(StringAddStub::kLeft);
   HValue* right = GetParameter(StringAddStub::kRight);
 
   // Make sure that both arguments are strings if not known in advance.
   if ((flags & STRING_ADD_CHECK_LEFT) == STRING_ADD_CHECK_LEFT) {
-    left = BuildCheckString(left);
+    left =
+        CheckString(left, (flags & STRING_ADD_CONVERT) == STRING_ADD_CONVERT);
   }
   if ((flags & STRING_ADD_CHECK_RIGHT) == STRING_ADD_CHECK_RIGHT) {
-    right = BuildCheckString(right);
+    right =
+        CheckString(right, (flags & STRING_ADD_CONVERT) == STRING_ADD_CONVERT);
   }
 
   return BuildStringAdd(left, right, HAllocationMode(pretenure_flag));
 }
 
 
 Handle<Code> StringAddStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
@@ skipping 725 matching lines @@
   return Pop();
 }
 
 
 Handle<Code> KeyedLoadGenericStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 }  // namespace internal
 }  // namespace v8