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

src/compiler/machine-type.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_MACHINE_TYPE_H_
 #define V8_COMPILER_MACHINE_TYPE_H_
 
 #include <iosfwd>
 
 #include "src/base/bits.h"
@@ skipping 63 matching lines @@
   return static_cast<MachineType>(result);
 }
 
 // Gets only the representation of the given type.
 inline MachineType RepresentationOf(MachineType machine_type) {
   int result = machine_type & kRepMask;
   CHECK(base::bits::IsPowerOfTwo32(result));
   return static_cast<MachineType>(result);
 }
 
+// Gets the log2 of the element size in bytes of the machine type.
+inline int ElementSizeLog2Of(MachineType machine_type) {
+  switch (RepresentationOf(machine_type)) {
+    case kRepBit:
+    case kRepWord8:
+      return 0;
+    case kRepWord16:
+      return 1;
+    case kRepWord32:
+    case kRepFloat32:
+      return 2;
+    case kRepWord64:
+    case kRepFloat64:
+      return 3;
+    case kRepTagged:
+      return kPointerSizeLog2;
+    default:
+      break;
+  }
+  UNREACHABLE();
+  return -1;
+}
+
 // Gets the element size in bytes of the machine type.
 inline int ElementSizeOf(MachineType machine_type) {
-  switch (RepresentationOf(machine_type)) {
-    case kRepBit:
-    case kRepWord8:
-      return 1;
-    case kRepWord16:
-      return 2;
-    case kRepWord32:
-    case kRepFloat32:
-      return 4;
-    case kRepWord64:
-    case kRepFloat64:
-      return 8;
-    case kRepTagged:
-      return kPointerSize;
-    default:
-      UNREACHABLE();
-      return kPointerSize;
-  }
+  const int shift = ElementSizeLog2Of(machine_type);
+  DCHECK_NE(-1, shift);
+  return 1 << shift;
 }
 
 // Describes the inputs and outputs of a function or call.
 template <typename T>
 class Signature : public ZoneObject {
  public:
   Signature(size_t return_count, size_t parameter_count, T* reps)
       : return_count_(return_count),
         parameter_count_(parameter_count),
         reps_(reps) {}
@@ skipping 52 matching lines @@
   size_t parameter_count_;
   T* reps_;
 };
 
 typedef Signature<MachineType> MachineSignature;
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_MACHINE_TYPE_H_