[turbofan] Create ExplicitOperands to specify operands without virtual registers

test/unittests/compiler/instruction-sequence-unittest.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_UNITTESTS_COMPILER_INSTRUCTION_SEQUENCE_UNITTEST_H_
 #define V8_UNITTESTS_COMPILER_INSTRUCTION_SEQUENCE_UNITTEST_H_
 
 #include "src/compiler/instruction.h"
 #include "test/unittests/test-utils.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ skipping 18 matching lines @@
 
   typedef std::pair<VReg, VReg> VRegPair;
 
   enum TestOperandType {
     kInvalid,
     kSameAsFirst,
     kRegister,
     kFixedRegister,
     kSlot,
     kFixedSlot,
+    kExplicit,
     kImmediate,
     kNone,
     kConstant,
     kUnique,
     kUniqueRegister
   };
 
   struct TestOperand {
     TestOperand() : type_(kInvalid), vreg_(), value_(kNoValue) {}
     TestOperand(TestOperandType type, int imm)
         : type_(type), vreg_(), value_(imm) {}
     TestOperand(TestOperandType type, VReg vreg, int value = kNoValue)
         : type_(type), vreg_(vreg), value_(value) {}
 
     TestOperandType type_;
     VReg vreg_;
     int value_;
   };
 
   static TestOperand Same() { return TestOperand(kSameAsFirst, VReg()); }
 
+  static TestOperand ExplicitReg(int index) {
+    TestOperandType type = kExplicit;
+    return TestOperand(type, VReg(), index);
+  }
+
   static TestOperand Reg(VReg vreg, int index = kNoValue) {
     TestOperandType type = kRegister;
     if (index != kNoValue) type = kFixedRegister;
     return TestOperand(type, vreg, index);
   }
 
   static TestOperand Reg(int index = kNoValue) { return Reg(VReg(), index); }
 
   static TestOperand Slot(VReg vreg, int index = kNoValue) {
     TestOperandType type = kSlot;
@@ skipping 165 matching lines @@
   LoopBlocks loop_blocks_;
   InstructionBlock* current_block_;
   bool block_returns_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_UNITTESTS_COMPILER_INSTRUCTION_SEQUENCE_UNITTEST_H_