Re-reland: Remove register index/code indirection

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index a0718f3c215a023a1c204b9d6b0ae746ee37c596..fab184adf8090681b2aec00dcc2cfb4964a6a8b4 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -14,8 +14,9 @@
 #include "src/compiler/frame.h"
 #include "src/compiler/instruction-codes.h"
 #include "src/compiler/opcodes.h"
-#include "src/compiler/register-configuration.h"
 #include "src/compiler/source-position.h"
+#include "src/macro-assembler.h"
+#include "src/register-configuration.h"
 #include "src/zone-allocator.h"
 
 namespace v8 {
@@ -373,9 +374,23 @@ class AllocatedOperand : public InstructionOperand {
   }
 
   int index() const {
+    DCHECK(STACK_SLOT == allocated_kind() ||
+           DOUBLE_STACK_SLOT == allocated_kind());
     return static_cast<int64_t>(value_) >> IndexField::kShift;
   }
 
+  Register GetRegister() const {
+    DCHECK(REGISTER == allocated_kind() || DOUBLE_REGISTER == allocated_kind());
+    return Register::from_code(static_cast<int64_t>(value_) >>
+                               IndexField::kShift);
+  }
+
+  DoubleRegister GetDoubleRegister() const {
+    DCHECK(REGISTER == allocated_kind() || DOUBLE_REGISTER == allocated_kind());
+    return DoubleRegister::from_code(static_cast<int64_t>(value_) >>
+                                     IndexField::kShift);
+  }
+
   AllocatedKind allocated_kind() const {
     return AllocatedKindField::decode(value_);
   }