[turbofan] Add backend support for signed loads.

test/cctest/compiler/call-tester.h

 // 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.
 
 #ifndef V8_CCTEST_COMPILER_CALL_TESTER_H_
 #define V8_CCTEST_COMPILER_CALL_TESTER_H_
 
 #include "src/v8.h"
 
 #include "src/simulator.h"
@@ skipping 68 matching lines @@
   static MachineType Representation() { return kMachUint64; }
 };
 
 template <>
 struct ReturnValueTraits<int16_t> {
   static int16_t Cast(uintptr_t r) { return static_cast<int16_t>(r); }
   static MachineType Representation() { return kMachInt16; }
 };
 
 template <>
+struct ReturnValueTraits<uint16_t> {
+  static uint16_t Cast(uintptr_t r) { return static_cast<uint16_t>(r); }
+  static MachineType Representation() { return kMachUint16; }
+};
+
+template <>
 struct ReturnValueTraits<int8_t> {
   static int8_t Cast(uintptr_t r) { return static_cast<int8_t>(r); }
   static MachineType Representation() { return kMachInt8; }
 };
 
 template <>
+struct ReturnValueTraits<uint8_t> {
+  static uint8_t Cast(uintptr_t r) { return static_cast<uint8_t>(r); }
+  static MachineType Representation() { return kMachUint8; }
+};
+
+template <>
 struct ReturnValueTraits<double> {
   static double Cast(uintptr_t r) {
     UNREACHABLE();
     return 0.0;
   }
   static MachineType Representation() { return kMachFloat64; }
 };
 
 
 template <typename R>
@@ skipping 261 matching lines @@
 
  private:
   CallHelper* helper() { return static_cast<C*>(this); }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CCTEST_COMPILER_CALL_TESTER_H_