[turbofan] add non fixed slot constraint to register allocator

src/compiler/instruction-selector-impl.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_INSTRUCTION_SELECTOR_IMPL_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/linkage.h"
@@ skipping 57 matching lines @@
                                         UnallocatedOperand::USED_AT_START,
                                         GetVReg(node)));
   }
 
   InstructionOperand UseRegister(Node* node) {
     return Use(node, UnallocatedOperand(UnallocatedOperand::MUST_HAVE_REGISTER,
                                         UnallocatedOperand::USED_AT_START,
                                         GetVReg(node)));
   }
 
+  InstructionOperand UseUniqueSlot(Node* node) {
+    return Use(node, UnallocatedOperand(UnallocatedOperand::MUST_HAVE_SLOT,
+                                        GetVReg(node)));
+  }
+
   // Use register or operand for the node. If a register is chosen, it won't
   // alias any temporary or output registers.
   InstructionOperand UseUnique(Node* node) {
     return Use(node,
                UnallocatedOperand(UnallocatedOperand::NONE, GetVReg(node)));
   }
 
   // Use a unique register for the node that does not alias any temporary or
   // output registers.
   InstructionOperand UseUniqueRegister(Node* node) {
@@ skipping 276 matching lines @@
                : (frame_state_descriptor->GetTotalSize() +
                   1);  // Include deopt id.
   }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_