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

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 16 matching lines @@
 
   Immediate InputImmediate(int index) {
     return ToImmediate(instr_->InputAt(index));
   }
 
   Operand InputOperand(int index) { return ToOperand(instr_->InputAt(index)); }
 
   Operand OutputOperand() { return ToOperand(instr_->Output()); }
 
   Immediate ToImmediate(InstructionOperand* operand) {
-    Constant constant = ToConstant(operand);
-    if (constant.type() == Constant::kInt32) {
-      return Immediate(constant.ToInt32());
-    }
-    UNREACHABLE();
-    return Immediate(-1);
+    return Immediate(ToConstant(operand).ToInt32());
   }
 
   Operand ToOperand(InstructionOperand* op, int extra = 0) {
     DCHECK(op->IsStackSlot() || op->IsDoubleStackSlot());
     // The linkage computes where all spill slots are located.
     FrameOffset offset = linkage()->GetFrameOffset(op->index(), frame(), extra);
     return Operand(offset.from_stack_pointer() ? rsp : rbp, offset.offset());
   }
 
   static int NextOffset(int* offset) {
@@ skipping 949 matching lines @@
     }
   }
   MarkLazyDeoptSite();
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8