[turbofan] add non fixed slot constraint to register allocator

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index e585eed6d16598ab6668ee64ddec7c2bae534289..2505d8719a5393b1c4fbf36446f748abeab294cb 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -137,6 +137,7 @@ class UnallocatedOperand : public InstructionOperand {
     FIXED_REGISTER,
     FIXED_DOUBLE_REGISTER,
     MUST_HAVE_REGISTER,
+    MUST_HAVE_SLOT,
     SAME_AS_FIRST_INPUT
   };
 
@@ -254,6 +255,10 @@ class UnallocatedOperand : public InstructionOperand {
     return basic_policy() == EXTENDED_POLICY &&
            extended_policy() == MUST_HAVE_REGISTER;
   }
+  bool HasSlotPolicy() const {
+    return basic_policy() == EXTENDED_POLICY &&
+           extended_policy() == MUST_HAVE_SLOT;
+  }
   bool HasSameAsInputPolicy() const {
     return basic_policy() == EXTENDED_POLICY &&
            extended_policy() == SAME_AS_FIRST_INPUT;