[turbofan] add RegisterConfiguration to decouple arch specific register layouts from compiler

src/compiler/register-configuration.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_REGISTER_CONFIGURATION_H_
+#define V8_COMPILER_REGISTER_CONFIGURATION_H_
+
+#include "src/v8.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+// An architecture independent representation of the sets of registers available
+// for instruction creation.
+class RegisterConfiguration {
+ public:
+  // Architecture independent maxes.
+  static const int kMaxGeneralRegisters = 32;
+  static const int kMaxDoubleRegisters = 32;
+
+  static const RegisterConfiguration* ArchDefault();
+
+  RegisterConfiguration(int num_general_registers, int num_double_registers,
+                        int num_aliased_double_registers,
+                        const char* const* general_register_name,
+                        const char* const* double_register_name);
+
+  int num_general_registers() const { return num_general_registers_; }
+  int num_double_registers() const { return num_double_registers_; }
+  int num_aliased_double_registers() const {
+    return num_aliased_double_registers_;
+  }
+
+  const char* general_register_name(int offset) const {
+    DCHECK(offset >= 0 && offset < kMaxGeneralRegisters);
+    return general_register_names_[offset];
+  }
+  const char* double_register_name(int offset) const {
+    DCHECK(offset >= 0 && offset < kMaxDoubleRegisters);
+    return double_register_names_[offset];
+  }
+
+ private:
+  const int num_general_registers_;
+  const int num_double_registers_;
+  const int num_aliased_double_registers_;
+  const char* const* general_register_names_;
+  const char* const* double_register_names_;
+};
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_COMPILER_REGISTER_CONFIGURATION_H_