[turbofan] Introduce dedicated StringIndexOf operator.

src/compiler/verifier.cc

 // Copyright 2014 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/compiler/verifier.h"
 
 #include <algorithm>
 #include <deque>
 #include <queue>
 #include <sstream>
@@ skipping 908 matching lines @@
     case IrOpcode::kStringFromCharCode:
       // Number -> String
       CheckValueInputIs(node, 0, Type::Number());
       CheckTypeIs(node, Type::String());
       break;
     case IrOpcode::kStringFromCodePoint:
       // (Unsigned32) -> String
       CheckValueInputIs(node, 0, Type::Number());
       CheckTypeIs(node, Type::String());
       break;
-    case IrOpcode::kReferenceEqual: {
+    case IrOpcode::kStringIndexOf:
+      // (String, String, SignedSmall) -> SignedSmall
+      CheckValueInputIs(node, 0, Type::String());
+      CheckValueInputIs(node, 1, Type::String());
+      CheckValueInputIs(node, 2, Type::SignedSmall());
+      CheckTypeIs(node, Type::SignedSmall());
+      break;
+
+    case IrOpcode::kReferenceEqual:
       // (Unique, Any) -> Boolean  and
       // (Any, Unique) -> Boolean
       CheckTypeIs(node, Type::Boolean());
       break;
-    }
+
     case IrOpcode::kObjectIsCallable:
     case IrOpcode::kObjectIsNonCallable:
     case IrOpcode::kObjectIsNumber:
     case IrOpcode::kObjectIsReceiver:
     case IrOpcode::kObjectIsSmi:
     case IrOpcode::kObjectIsString:
     case IrOpcode::kObjectIsUndetectable:
     case IrOpcode::kArrayBufferWasNeutered:
       CheckValueInputIs(node, 0, Type::Any());
       CheckTypeIs(node, Type::Boolean());
@@ skipping 745 matching lines @@
          replacement->op()->EffectOutputCount() > 0);
   DCHECK(!NodeProperties::IsFrameStateEdge(edge) ||
          replacement->opcode() == IrOpcode::kFrameState);
 }
 
 #endif  // DEBUG
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8