Adapt long branches to use bc & balc on r6.

src/mips/assembler-mips.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 398 matching lines @@
   // but it may be bound only once.
   void bind(Label* L);  // Binds an unbound label L to current code position.
 
   enum OffsetSize : int { kOffset26 = 26, kOffset21 = 21, kOffset16 = 16 };
 
   // Determines if Label is bound and near enough so that branch instruction
   // can be used to reach it, instead of jump instruction.
   bool is_near(Label* L);
   bool is_near(Label* L, OffsetSize bits);
   bool is_near_branch(Label* L);
+  inline bool is_near_pre_r6(Label* L) {
+    DCHECK(!IsMipsArchVariant(kMips32r6));
+    return pc_offset() - L->pos() < kMaxBranchOffset - 4 * kInstrSize;
+  }
+  inline bool is_near_r6(Label* L) {
+    DCHECK(IsMipsArchVariant(kMips32r6));
+    return pc_offset() - L->pos() < kMaxCompactBranchOffset - 4 * kInstrSize;
+  }
+
+  int BranchOffset(Instr instr);
 
   // Returns the branch offset to the given label from the current code
   // position. Links the label to the current position if it is still unbound.
   // Manages the jump elimination optimization if the second parameter is true.
   int32_t branch_offset_helper(Label* L, OffsetSize bits);
   inline int32_t branch_offset(Label* L) {
     return branch_offset_helper(L, OffsetSize::kOffset16);
   }
   inline int32_t branch_offset21(Label* L) {
     return branch_offset_helper(L, OffsetSize::kOffset21);
@@ skipping 991 matching lines @@
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ARM_ASSEMBLER_MIPS_H_