[turbofan] First step towards correctified 64-bit addressing.

src/compiler/instruction.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_COMPILER_INSTRUCTION_H_
 #define V8_COMPILER_INSTRUCTION_H_
 
 #include <deque>
 #include <iosfwd>
 #include <map>
@@ skipping 657 matching lines @@
   explicit Constant(float v) : type_(kFloat32), value_(bit_cast<int32_t>(v)) {}
   explicit Constant(double v) : type_(kFloat64), value_(bit_cast<int64_t>(v)) {}
   explicit Constant(ExternalReference ref)
       : type_(kExternalReference), value_(bit_cast<intptr_t>(ref)) {}
   explicit Constant(Handle<HeapObject> obj)
       : type_(kHeapObject), value_(bit_cast<intptr_t>(obj)) {}
 
   Type type() const { return type_; }
 
   int32_t ToInt32() const {
-    DCHECK_EQ(kInt32, type());
-    return static_cast<int32_t>(value_);
+    DCHECK(type() == kInt32 || type() == kInt64);
+    const int32_t value = static_cast<int32_t>(value_);
+    DCHECK_EQ(value_, static_cast<int64_t>(value));
+    return value;
   }
 
   int64_t ToInt64() const {
     if (type() == kInt32) return ToInt32();
     DCHECK_EQ(kInt64, type());
     return value_;
   }
 
   float ToFloat32() const {
     DCHECK_EQ(kFloat32, type());
@@ skipping 280 matching lines @@
   DeoptimizationVector deoptimization_entries_;
 };
 
 std::ostream& operator<<(std::ostream& os, const InstructionSequence& code);
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_H_