provides a mechanism for optimizing compilers to select the different Register configuration.

src/register-configuration.h

Index: src/register-configuration.h
diff --git a/src/register-configuration.h b/src/register-configuration.h
index f12bc7c07c6dfb4beb79477f5a88ce16502b4c71..8c6b21852e1726f645835bffd2aea587cbafe3cc 100644
--- a/src/register-configuration.h
+++ b/src/register-configuration.h
@@ -10,6 +10,9 @@
 namespace v8 {
 namespace internal {
 
+// Define the optimized compiler type.
+enum JITCompiler { CRANKSHAFT, TURBOFAN };

[danno, 2015/10/19 10:48:59]

Please put this inside the RegisterConfiguration class and call it
CompilerSelector.

+
 // An architecture independent representation of the sets of registers available
 // for instruction creation.
 class RegisterConfiguration {
@@ -18,7 +21,8 @@ class RegisterConfiguration {
   static const int kMaxGeneralRegisters = 32;
   static const int kMaxDoubleRegisters = 32;
 
-  static const RegisterConfiguration* ArchDefault();
+  static const RegisterConfiguration* ArchDefault(
+      JITCompiler compiler = CRANKSHAFT);

[danno, 2015/10/19 10:48:59]

Please don't specify a parameter default here, it should always be explicit.

 
   RegisterConfiguration(int num_general_registers, int num_double_registers,
                         int num_allocatable_general_registers,