[turbofan] Spill rsi and rdi in their existing locations.

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index 7ab2b9077852de9f9b8a01d5e258e6827863dbf0..6b9ad82f341c0f1073389cb0c2ab6018a34a0afe 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -192,6 +192,12 @@ class UnallocatedOperand : public InstructionOperand {
     value_ |= LifetimeField::encode(lifetime);
   }
 
+  UnallocatedOperand(int reg_id, int slot_id, int virtual_register)
+      : UnallocatedOperand(FIXED_REGISTER, reg_id, virtual_register) {
+    value_ |= HasSecondaryStorageField::encode(true);
+    value_ |= SecondaryStorageField::encode(slot_id);
+  }
+
   // Predicates for the operand policy.
   bool HasAnyPolicy() const {
     return basic_policy() == EXTENDED_POLICY && extended_policy() == ANY;
@@ -222,6 +228,15 @@ class UnallocatedOperand : public InstructionOperand {
     return basic_policy() == EXTENDED_POLICY &&
            extended_policy() == FIXED_DOUBLE_REGISTER;
   }
+  bool HasSecondaryStorage() const {
+    return basic_policy() == EXTENDED_POLICY &&
+           extended_policy() == FIXED_REGISTER &&
+           HasSecondaryStorageField::decode(value_);
+  }
+  int GetSecondaryStorage() const {
+    DCHECK(HasSecondaryStorage());
+    return SecondaryStorageField::decode(value_);
+  }
 
   // [basic_policy]: Distinguish between FIXED_SLOT and all other policies.
   BasicPolicy basic_policy() const {
@@ -301,7 +316,9 @@ class UnallocatedOperand : public InstructionOperand {
   // BitFields specific to BasicPolicy::EXTENDED_POLICY.
   class ExtendedPolicyField : public BitField64<ExtendedPolicy, 36, 3> {};
   class LifetimeField : public BitField64<Lifetime, 39, 1> {};
-  class FixedRegisterField : public BitField64<int, 40, 6> {};
+  class HasSecondaryStorageField : public BitField64<bool, 40, 1> {};
+  class FixedRegisterField : public BitField64<int, 41, 6> {};
+  class SecondaryStorageField : public BitField64<int, 47, 3> {};
 
  private:
   explicit UnallocatedOperand(int virtual_register)