[turbofan] support small immediates

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 101 matching lines @@
   }
 
   InstructionOperand UseFixed(Node* node, DoubleRegister reg) {
     return Use(node,
                UnallocatedOperand(UnallocatedOperand::FIXED_DOUBLE_REGISTER,
                                   DoubleRegister::ToAllocationIndex(reg),
                                   GetVReg(node)));
   }
 
   InstructionOperand UseImmediate(Node* node) {
-    int index = sequence()->AddImmediate(ToConstant(node));
-    return ImmediateOperand(index);
+    return sequence()->AddImmediate(ToConstant(node));
   }
 
   InstructionOperand UseLocation(Node* node, LinkageLocation location,
                                  MachineType type) {
     return Use(node, ToUnallocatedOperand(location, type, GetVReg(node)));
   }
 
   InstructionOperand TempRegister() {
     return UnallocatedOperand(UnallocatedOperand::MUST_HAVE_REGISTER,
                               UnallocatedOperand::USED_AT_START,
                               sequence()->NextVirtualRegister());
   }
 
   InstructionOperand TempDoubleRegister() {
     UnallocatedOperand op = UnallocatedOperand(
         UnallocatedOperand::MUST_HAVE_REGISTER,
         UnallocatedOperand::USED_AT_START, sequence()->NextVirtualRegister());
     sequence()->MarkAsDouble(op.virtual_register());
     return op;
   }
 
   InstructionOperand TempRegister(Register reg) {
     return UnallocatedOperand(UnallocatedOperand::FIXED_REGISTER,
                               Register::ToAllocationIndex(reg),
                               InstructionOperand::kInvalidVirtualRegister);
   }
 
   InstructionOperand TempImmediate(int32_t imm) {
-    int index = sequence()->AddImmediate(Constant(imm));
-    return ImmediateOperand(index);
+    return sequence()->AddImmediate(Constant(imm));
   }
 
   InstructionOperand TempLocation(LinkageLocation location, MachineType type) {
     return ToUnallocatedOperand(location, type,
                                 sequence()->NextVirtualRegister());
   }
 
   InstructionOperand Label(BasicBlock* block) {
-    int index = sequence()->AddImmediate(
+    return sequence()->AddImmediate(
         Constant(RpoNumber::FromInt(block->rpo_number())));
-    return ImmediateOperand(index);
   }
 
  protected:
   InstructionSelector* selector() const { return selector_; }
   InstructionSequence* sequence() const { return selector()->sequence(); }
   Zone* zone() const { return selector()->instruction_zone(); }
 
  private:
   int GetVReg(Node* node) const { return selector_->GetVirtualRegister(node); }
 
@@ skipping 205 matching lines @@
                : (frame_state_descriptor->GetTotalSize() +
                   1);  // Include deopt id.
   }
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_