MIPS64: Improve long branches utilizing code range.

src/mips64/constants-mips64.h

 // Copyright 2012 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_MIPS_CONSTANTS_H_
 #define  V8_MIPS_CONSTANTS_H_
 
 // UNIMPLEMENTED_ macro for MIPS.
 #ifdef DEBUG
 #define UNIMPLEMENTED_MIPS()                                                  \
@@ skipping 941 matching lines @@
   inline int32_t Imm16Value() const {
     DCHECK(InstructionType() == kImmediateType);
     return Bits(kImm16Shift + kImm16Bits - 1, kImm16Shift);
   }
 
   inline int32_t Imm21Value() const {
     DCHECK(InstructionType() == kImmediateType);
     return Bits(kImm21Shift + kImm21Bits - 1, kImm21Shift);
   }
 
-  inline int32_t Imm26Value() const {
+  inline int64_t Imm26Value() const {
     DCHECK(InstructionType() == kJumpType);
     return Bits(kImm26Shift + kImm26Bits - 1, kImm26Shift);
   }
 
   // Say if the instruction should not be used in a branch delay slot.
   bool IsForbiddenInBranchDelay() const;
   // Say if the instruction 'links'. e.g. jal, bal.
   bool IsLinkingInstruction() const;
   // Say if the instruction is a break or a trap.
   bool IsTrap() const;
@@ skipping 21 matching lines @@
 // TODO(plind): below should be based on kPointerSize
 // TODO(plind): find all usages and remove the needless instructions for n64.
 const int kCArgsSlotsSize = kCArgSlotCount * Instruction::kInstrSize * 2;
 
 const int kInvalidStackOffset = -1;
 const int kBranchReturnOffset = 2 * Instruction::kInstrSize;
 
 } }   // namespace v8::internal
 
 #endif    // #ifndef V8_MIPS_CONSTANTS_H_