[compiler] Introduce proper StrictNotEqualStub.

src/code-stubs.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 <sstream>
 
 #include "src/bootstrapper.h"
 #include "src/compiler/code-stub-assembler.h"
@@ skipping 455 matching lines @@
 void StringLengthStub::GenerateAssembly(
     compiler::CodeStubAssembler* assembler) const {
   compiler::Node* value = assembler->Parameter(0);
   compiler::Node* string =
       assembler->LoadObjectField(value, JSValue::kValueOffset);
   compiler::Node* result =
       assembler->LoadObjectField(string, String::kLengthOffset);
   assembler->Return(result);
 }
 
-void StrictEqualStub::GenerateAssembly(
-    compiler::CodeStubAssembler* assembler) const {
-  // Here's pseudo-code for the algorithm below:
+namespace {
+
+enum StrictEqualMode { kStrictEqual, kStrictNotEqual };
+
+void GenerateStrictEqual(compiler::CodeStubAssembler* assembler,
+                         StrictEqualMode mode) {
+  // Here's pseudo-code for the algorithm below in case of kStrictEqual mode;
+  // for kStrictNotEqual mode we properly negate the result.
   //
   // if (lhs == rhs) {
   //   if (lhs->IsHeapNumber()) return HeapNumber::cast(lhs)->value() != NaN;
   //   return true;
   // }
   // if (!lhs->IsSmi()) {
   //   if (lhs->IsHeapNumber()) {
   //     if (rhs->IsSmi()) {
   //       return Smi::cast(rhs)->value() == HeapNumber::cast(lhs)->value();
   //     } else if (rhs->IsHeapNumber()) {
@@ skipping 33 matching lines @@
   //   }
   // }
 
   typedef compiler::CodeStubAssembler::Label Label;
   typedef compiler::Node Node;
 
   Node* lhs = assembler->Parameter(0);
   Node* rhs = assembler->Parameter(1);
   Node* context = assembler->Parameter(2);
 
-  Label if_true(assembler), if_false(assembler);
+  Label if_equal(assembler), if_notequal(assembler);
 
   // Check if {lhs} and {rhs} refer to the same object.
   Label if_same(assembler), if_notsame(assembler);
   assembler->Branch(assembler->WordEqual(lhs, rhs), &if_same, &if_notsame);
 
   assembler->Bind(&if_same);
   {
     // The {lhs} and {rhs} reference the exact same value, yet we need special
     // treatment for HeapNumber, as NaN is not equal to NaN.
     // TODO(bmeurer): This seems to violate the SIMD.js specification, but it
@@ skipping 13 matching lines @@
       Label if_lhsisnumber(assembler), if_lhsisnotnumber(assembler);
       assembler->Branch(assembler->WordEqual(lhs_map, number_map),
                         &if_lhsisnumber, &if_lhsisnotnumber);
 
       assembler->Bind(&if_lhsisnumber);
       {
         // Convert {lhs} (and therefore {rhs}) to floating point value.
         Node* lhs_value = assembler->LoadHeapNumberValue(lhs);
 
         // Check if the HeapNumber value is a NaN.
-        assembler->BranchIfFloat64IsNaN(lhs_value, &if_false, &if_true);
+        assembler->BranchIfFloat64IsNaN(lhs_value, &if_notequal, &if_equal);
       }
 
       assembler->Bind(&if_lhsisnotnumber);
-      assembler->Goto(&if_true);
+      assembler->Goto(&if_equal);
     }
 
     assembler->Bind(&if_lhsissmi);
-    assembler->Goto(&if_true);
+    assembler->Goto(&if_equal);
   }
 
   assembler->Bind(&if_notsame);
   {
     // The {lhs} and {rhs} reference different objects, yet for Smi, HeapNumber,
     // String and Simd128Value they can still be considered equal.
     Node* number_map = assembler->HeapNumberMapConstant();
 
     // Check if {lhs} is a Smi or a HeapObject.
     Label if_lhsissmi(assembler), if_lhsisnotsmi(assembler);
@@ skipping 16 matching lines @@
         assembler->Branch(assembler->WordIsSmi(rhs), &if_rhsissmi,
                           &if_rhsisnotsmi);
 
         assembler->Bind(&if_rhsissmi);
         {
           // Convert {lhs} and {rhs} to floating point values.
           Node* lhs_value = assembler->LoadHeapNumberValue(lhs);
           Node* rhs_value = assembler->SmiToFloat64(rhs);
 
           // Perform a floating point comparison of {lhs} and {rhs}.
-          assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_true,
-                                          &if_false);
+          assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_equal,
+                                          &if_notequal);
         }
 
         assembler->Bind(&if_rhsisnotsmi);
         {
           // Load the map of {rhs}.
           Node* rhs_map =
               assembler->LoadObjectField(rhs, HeapObject::kMapOffset);
 
           // Check if {rhs} is also a HeapNumber.
           Label if_rhsisnumber(assembler), if_rhsisnotnumber(assembler);
           assembler->Branch(assembler->WordEqual(rhs_map, number_map),
                             &if_rhsisnumber, &if_rhsisnotnumber);
 
           assembler->Bind(&if_rhsisnumber);
           {
             // Convert {lhs} and {rhs} to floating point values.
             Node* lhs_value = assembler->LoadHeapNumberValue(lhs);
             Node* rhs_value = assembler->LoadHeapNumberValue(rhs);
 
             // Perform a floating point comparison of {lhs} and {rhs}.
-            assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_true,
-                                            &if_false);
+            assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_equal,
+                                            &if_notequal);
           }
 
           assembler->Bind(&if_rhsisnotnumber);
-          assembler->Goto(&if_false);
+          assembler->Goto(&if_notequal);
         }
       }
 
       assembler->Bind(&if_lhsisnotnumber);
       {
         // Check if {rhs} is a Smi or a HeapObject.
         Label if_rhsissmi(assembler), if_rhsisnotsmi(assembler);
         assembler->Branch(assembler->WordIsSmi(rhs), &if_rhsissmi,
                           &if_rhsisnotsmi);
 
         assembler->Bind(&if_rhsissmi);
-        assembler->Goto(&if_false);
+        assembler->Goto(&if_notequal);
 
         assembler->Bind(&if_rhsisnotsmi);
         {
           // Load the instance type of {lhs}.
           Node* lhs_instance_type = assembler->LoadMapInstanceType(lhs_map);
 
           // Check if {lhs} is a String.
           Label if_lhsisstring(assembler), if_lhsisnotstring(assembler);
           assembler->Branch(assembler->Int32LessThan(
                                 lhs_instance_type,
                                 assembler->Int32Constant(FIRST_NONSTRING_TYPE)),
                             &if_lhsisstring, &if_lhsisnotstring);
 
           assembler->Bind(&if_lhsisstring);
           {
             // Load the instance type of {rhs}.
             Node* rhs_instance_type = assembler->LoadInstanceType(rhs);
 
             // Check if {rhs} is also a String.
             Label if_rhsisstring(assembler), if_rhsisnotstring(assembler);
             assembler->Branch(assembler->Int32LessThan(
                                   rhs_instance_type, assembler->Int32Constant(
                                                          FIRST_NONSTRING_TYPE)),
                               &if_rhsisstring, &if_rhsisnotstring);
 
             assembler->Bind(&if_rhsisstring);
             {
               // TODO(bmeurer): Optimize this further once the StringEqual
               // functionality is available in TurboFan land.
-              assembler->TailCallRuntime(Runtime::kStringEqual, context, lhs,
-                                         rhs);
+              Runtime::FunctionId function_id = (mode == kStrictEqual)
+                                                    ? Runtime::kStringEqual
+                                                    : Runtime::kStringNotEqual;
+              assembler->TailCallRuntime(function_id, context, lhs, rhs);
             }
 
             assembler->Bind(&if_rhsisnotstring);
-            assembler->Goto(&if_false);
+            assembler->Goto(&if_notequal);
           }
 
           assembler->Bind(&if_lhsisnotstring);
           {
             // Check if {lhs} is a Simd128Value.
             Label if_lhsissimd128value(assembler),
                 if_lhsisnotsimd128value(assembler);
             assembler->Branch(assembler->Word32Equal(
                                   lhs_instance_type,
                                   assembler->Int32Constant(SIMD128_VALUE_TYPE)),
                               &if_lhsissimd128value, &if_lhsisnotsimd128value);
 
             assembler->Bind(&if_lhsissimd128value);
             {
               // TODO(bmeurer): Inline the Simd128Value equality check.
-              assembler->TailCallRuntime(Runtime::kStrictEqual, context, lhs,
-                                         rhs);
+              Runtime::FunctionId function_id = (mode == kStrictEqual)
+                                                    ? Runtime::kStrictEqual
+                                                    : Runtime::kStrictNotEqual;
+              assembler->TailCallRuntime(function_id, context, lhs, rhs);
             }
 
             assembler->Bind(&if_lhsisnotsimd128value);
-            assembler->Goto(&if_false);
+            assembler->Goto(&if_notequal);
           }
         }
       }
     }
 
     assembler->Bind(&if_lhsissmi);
     {
       // We already know that {lhs} and {rhs} are not reference equal, and {lhs}
       // is a Smi; so {lhs} and {rhs} can only be strictly equal if {rhs} is a
       // HeapNumber with an equal floating point value.
 
       // Check if {rhs} is a Smi or a HeapObject.
       Label if_rhsissmi(assembler), if_rhsisnotsmi(assembler);
       assembler->Branch(assembler->WordIsSmi(rhs), &if_rhsissmi,
                         &if_rhsisnotsmi);
 
       assembler->Bind(&if_rhsissmi);
-      assembler->Goto(&if_false);
+      assembler->Goto(&if_notequal);
 
       assembler->Bind(&if_rhsisnotsmi);
       {
         // Load the map of the {rhs}.
         Node* rhs_map = assembler->LoadObjectField(rhs, HeapObject::kMapOffset);
 
         // The {rhs} could be a HeapNumber with the same value as {lhs}.
         Label if_rhsisnumber(assembler), if_rhsisnotnumber(assembler);
         assembler->Branch(assembler->WordEqual(rhs_map, number_map),
                           &if_rhsisnumber, &if_rhsisnotnumber);
 
         assembler->Bind(&if_rhsisnumber);
         {
           // Convert {lhs} and {rhs} to floating point values.
           Node* lhs_value = assembler->SmiToFloat64(lhs);
           Node* rhs_value = assembler->LoadHeapNumberValue(rhs);
 
           // Perform a floating point comparison of {lhs} and {rhs}.
-          assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_true,
-                                          &if_false);
+          assembler->BranchIfFloat64Equal(lhs_value, rhs_value, &if_equal,
+                                          &if_notequal);
         }
 
         assembler->Bind(&if_rhsisnotnumber);
-        assembler->Goto(&if_false);
+        assembler->Goto(&if_notequal);
       }
     }
   }
 
-  assembler->Bind(&if_true);
-  assembler->Return(assembler->BooleanConstant(true));
+  assembler->Bind(&if_equal);
+  assembler->Return(assembler->BooleanConstant(mode == kStrictEqual));
 
-  assembler->Bind(&if_false);
-  assembler->Return(assembler->BooleanConstant(false));
+  assembler->Bind(&if_notequal);
+  assembler->Return(assembler->BooleanConstant(mode == kStrictNotEqual));
+}
+
+}  // namespace
+
+void StrictEqualStub::GenerateAssembly(
+    compiler::CodeStubAssembler* assembler) const {
+  GenerateStrictEqual(assembler, kStrictEqual);
+}
+
+void StrictNotEqualStub::GenerateAssembly(
+    compiler::CodeStubAssembler* assembler) const {
+  GenerateStrictEqual(assembler, kStrictNotEqual);
 }
 
 void ToBooleanStub::GenerateAssembly(
     compiler::CodeStubAssembler* assembler) const {
   typedef compiler::Node Node;
   typedef compiler::CodeStubAssembler::Label Label;
 
   Node* value = assembler->Parameter(0);
   Label if_valueissmi(assembler), if_valueisnotsmi(assembler);
 
@@ skipping 557 matching lines @@
   if (type->Is(Type::UntaggedPointer())) {
     return Representation::External();
   }
 
   DCHECK(!type->Is(Type::Untagged()));
   return Representation::Tagged();
 }
 
 }  // namespace internal
 }  // namespace v8